[ { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9xae2-2b037", "eprint_status": "archive", "datestamp": "2023-12-12 17:43:50", "lastmod": "2023-12-12 17:43:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Meier-Madeline-C", "name": { "family": "Meier", "given": "Madeline C." }, "orcid": "0000-0003-1608-0810" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" } ] }, "title": "Inclination of polarized illumination increases symmetry of structures grown via inorganic phototropism", "ispublished": "pub", "full_text_status": "public", "keywords": "Electrical and Electronic Engineering; Process Chemistry and Technology; Mechanics of Materials; General Materials Science", "note": "
\u00a9 The Royal Society of Chemistry 2023.
\n\nThis work was supported by the National Science Foundation, Directorate for Mathematical & Physical Sciences, Division of Materials Research under Award Number DMR 1905963. Research was in part carried out at the Molecular Materials Resource Center in the Beckman Institute of the California Institute of Technology. The authors gratefully acknowledge J. Thompson for insightful discussions, W.-H. Cheng and S. Yalamanchili for assistance with substrate preparation, and R. Gerhart, N. Hart, and B. Markowicz for assistance with photoelectrochemical cell fabrication. MCM acknowledges a Graduate Research Fellowship from the National Science Foundation and the Resnick Institute at Caltech for fellowship support.
\n\nThe authors declare no conflict of interest.
\n\nThis article is part of the themed collection: Celebrating 10 Years of Materials Horizons: 10th Anniversary Collection
", "abstract": "Inclination of unpatterned, linearly polarized illumination in the plane of the electric field oscillation effected increased directional feature alignment and decreased off-axis order in Se\u2013Te deposits generated by inorganic phototropic growth relative to that produced using normal incidence. Optically based growth simulations reproduced the experimental results indicating a photonic basis for the morphology change. Modeling of the light scattering at the growth interface revealed that illumination inclination enhances scattering that localizes the optical field along the polarization plane and suppresses cooperativity in defect-driven scattering. Thus, the symmetry of the deposited structures increased as the asymmetry of the illumination increased, as measured by the inclination of the illumination incidence away from the surface normal.
", "date": "2023-10", "date_type": "published", "publication": "Materials Horizons", "volume": "10", "number": "10", "publisher": "Royal Society of Chemistry", "pagerange": "4251-4255", "issn": "2051-6347", "official_url": "https://authors.library.caltech.edu/records/9xae2-2b037", "funders": { "items": [ { "grant_number": "DMR-1905963" }, { "grant_number": "NSF Graduate Research Fellowship" }, { "grant_number": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1039/d3mh00839h", "primary_object": { "basename": "d3mh00839h1.pdf", "url": "https://authors.library.caltech.edu/records/9xae2-2b037/files/d3mh00839h1.pdf" }, "resource_type": "article", "pub_year": "2023", "author_list": "Meier, Madeline C.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/79c0g-6br20", "eprint_status": "archive", "datestamp": "2023-12-12 17:31:10", "lastmod": "2023-12-12 17:31:10", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ifkovits-Zachary-P", "name": { "family": "Ifkovits", "given": "Zachary P." }, "orcid": "0000-0003-2538-0794" }, { "id": "Reed-Jillian-T", "name": { "family": "Reed", "given": "Jillian T." }, "orcid": "0009-0005-2814-8415" }, { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "Paul A." }, "orcid": "0000-0003-3909-1790" }, { "id": "Meier-Madeline-C", "name": { "family": "Meier", "given": "Madeline C." }, "orcid": "0000-0003-1608-0810" }, { "id": "Byrne-Sean-T", "name": { "family": "Byrne", "given": "Sean T." }, "orcid": "0000-0002-5466-3112" }, { "id": "Lin-Shaoyang", "name": { "family": "Lin", "given": "Shaoyang" }, "orcid": "0000-0003-4108-7299" }, { "id": "Ye-Alexandre-Z", "name": { "family": "Ye", "given": "Alexandre Z." }, "orcid": "0009-0003-4895-0160" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Spontaneous mesostructure formation produces optically transmissive Ni\u2013P films that are catalytically active for the photoelectrochemical hydrogen evolution reaction", "ispublished": "pub", "full_text_status": "public", "keywords": "Energy Engineering and Power Technology; Fuel Technology; Renewable Energy, Sustainability and the Environment", "note": "\u00a9 The Royal Society of Chemistry 2023.
\n\nThis work was supported by U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, and under Award Number DE-SC0022087. XPS and UV-Vis data were collected at the Molecular Materials Resource Center of the Beckman Institute of the California Institute of Technology. M. C. M. acknowledges the Resnick Sustainability Institute at Caltech for fellowship support.
\n\nNSL is a scientific founder of and consultant to a company, H2U Technologies, that is developing catalysts and electrolyzers for the production of hydrogen.
", "abstract": "Ni\u2013P films that are catalytically active for the hydrogen-evolution reaction were electrodeposited onto photoactive Si substrates between 20 \u00b0C and 80 \u00b0C from an aqueous solution. Ni\u2013P films deposited at 20 \u00b0C and exposed to acidic environments spontaneously developed deep cracks. A substantial increase in optical transmission to the semiconducting substrate resulted without affecting the catalytic performance of the film. In contrast, Ni\u2013P films deposited at 80 \u00b0C only developed minor surface-level cracks and did not exhibit a substantial increase in optical transmission. During electrodeposition of the Ni\u2013P films at low temperatures, the uptake of parasitically evolved hydrogen generated partially defective Ni\u2013P, causing crack formation. Increases in the temperature of the electrodeposition bath increased the faradaic efficiency of Ni\u2013P deposition and consequently reduced the uptake of parasitically generated hydrogen. The defective Ni\u2013P films were converted to a crack-resistant material by thermally desorbing the excess hydrogen that was absorbed during the low-temperature electrodeposition process.
", "date": "2023-09-21", "date_type": "published", "publication": "Sustainable Energy & Fuels", "volume": "7", "number": "18", "publisher": "Royal Society of Chemistry", "pagerange": "4401-4406", "issn": "2398-4902", "official_url": "https://authors.library.caltech.edu/records/79c0g-6br20", "funders": { "items": [ { "grant_number": "DE-SC0004993" }, { "grant_number": "DE-SC0022087" }, { "grant_number": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1039/d3se00378g", "primary_object": { "basename": "d3se00378g1.pdf", "url": "https://authors.library.caltech.edu/records/79c0g-6br20/files/d3se00378g1.pdf" }, "resource_type": "article", "pub_year": "2023", "author_list": "Ifkovits, Zachary P.; Reed, Jillian T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2wq8x-nwd98", "eprint_id": 118942, "eprint_status": "archive", "datestamp": "2023-08-22 18:26:43", "lastmod": "2023-10-24 23:46:13", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ifkovits-Zachary-P", "name": { "family": "Ifkovits", "given": "Zachary P." }, "orcid": "0000-0003-2538-0794" }, { "id": "Evans-Jake-M", "name": { "family": "Evans", "given": "Jake M." }, "orcid": "0000-0002-8721-5316" }, { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "Paul A." }, "orcid": "0000-0003-3909-1790" }, { "id": "Morla-Maureen-B", "name": { "family": "Morla", "given": "Maureen B." }, "orcid": "0000-0002-2520-9543" }, { "id": "Pham-Kim-H", "name": { "family": "Pham", "given": "Kim H." } }, { "id": "Dowling-Jacqueline-A", "name": { "family": "Dowling", "given": "Jacqueline A." }, "orcid": "0000-0001-5642-8960" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Powdered Mn_(y)Sb_(1-y)O_(x) Catalysts for Cerium-Mediated Oxygen Evolution in Acidic Environments", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Energy Engineering and Power Technology; Fuel Technology; Renewable Energy, Sustainability and the Environment; Chemistry (miscellaneous)", "note": "This work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award number DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, and under award DE-SC0022087 from the Basic Energy Sciences Office of the DOE. XPS and DRS data were collected at the Molecular Materials Resource Center of the Beckman Institute of the California Institute of Technology. ICP-MS instrumentation at the Resnick Sustainability Institute's Water and Environment Lab at the California Institute of Technology was used in this work. We thank Madeline C. Meier for assistance with illustrations and schematic design and Dr. Nathan Dalleska for assistance with the ICP-MS.", "abstract": "Mn_(y)Sb_(1-y)O_(x) powders with a series of compositions were evaluated as catalysts for chemical water oxidation in aqueous perchloric, sulfuric, or methanesulfonic acid. O\u2082(g) evolved spontaneously over Mn_(y)Sb_(1-y)O_(x) catalyst powders that had been suspended in solutions that were pre-loaded with Ce\u2074\u207a ions. The rate of O\u2082 evolution depended on the amount, as well as the oxidation state, of the Mn in the powder. The highest O\u2082 evolution rate was observed from the most Mn-rich catalyst, which had an effective surface oxidation state of Mn\u00b2\u22c5\u2079\u207a in its rest state. The facile synthetic accessibility of such catalysts in powder form constitutes a step toward replacing Ir or Ru in Ce-mediated oxygen evolution in decoupled water splitting systems, as well as toward developing inks of earth-abundant catalysts for preparation of catalyst-coated membranes used in conventional proton-exchange membrane electrolyzers.", "date": "2022-12-09", "date_type": "published", "publication": "ACS Energy Letters", "volume": "7", "number": "12", "publisher": "American Chemical Society", "pagerange": "4258-4264", "id_number": "CaltechAUTHORS:20230125-514893900.22", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230125-514893900.22", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0022087" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acsenergylett.2c01754", "resource_type": "article", "pub_year": "2022", "author_list": "Ifkovits, Zachary P.; Evans, Jake M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dw6nm-tbd73", "eprint_id": 117307, "eprint_status": "archive", "datestamp": "2023-08-22 17:43:50", "lastmod": "2023-10-24 22:28:53", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Koskela-Kristopher-M", "name": { "family": "Koskela", "given": "Kristopher M." }, "orcid": "0000-0001-6002-6737" }, { "id": "Mora-Perez-Carlos", "name": { "family": "Mora Perez", "given": "Carlos" }, "orcid": "0000-0001-8840-5093" }, { "id": "Eremin-Dmitry-B", "name": { "family": "Eremin", "given": "Dmitry B." }, "orcid": "0000-0003-2946-5293" }, { "id": "Evans-Jake-M", "name": { "family": "Evans", "given": "Jake M." }, "orcid": "0000-0002-8721-5316" }, { "id": "Strumolo-Marissa-J", "name": { "family": "Strumolo", "given": "Marissa J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Prezhdo-Oleg-V", "name": { "family": "Prezhdo", "given": "Oleg V." }, "orcid": "0000-0002-5140-7500" }, { "id": "Brutchey-Richard-L", "name": { "family": "Brutchey", "given": "Richard L." }, "orcid": "0000-0002-7781-5596" } ] }, "title": "Polymorphic Control of Solution-Processed Cu\u2082SnS\u2083 Films with Thiol-Amine Ink Formulation", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; General Chemical Engineering; General Chemistry", "note": "\u00a9 2022 The Authors. Published by American Chemical Society. Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/). \n\nThis work was supported by the National Science Foundation under awards DMR-1904719 to R.L.B. and CHE-2154367 to O.V.P. XPS experiments were carried out at the Molecular Materials Resource Center (MMRC) of the Beckman Institute of the California Institute of Technology with financial support from Award No. DE-SC0022087 from the Basic Energy Sciences Office of the DOE to N.S.L. D.B.E. acknowledges the support of Agilent Technologies through an Agilent Fellowship. \n\nThe authors declare no competing financial interest.\n\nPublished - cm2c01612.pdf
Supplemental Material - cm2c01612_si_001.pdf
", "abstract": "There is increasing demand for tailored molecular inks that produce phase-pure solution-processed semiconductor films. Within the Cu\u2013Sn\u2013S phase space, Cu\u2082SnS\u2083 belongs to the I\u2082\u2013IV\u2013VI\u2083 class of semiconductors that crystallizes in several different polymorphs. We report the ability of thiol\u2013amine solvent mixtures to dissolve inexpensive bulk Cu\u2082S and SnO precursors to generate free-flowing molecular inks. Upon mild annealing, polymorphic control over phase-pure tetragonal (I4\u03052m) and orthorhombic (Cmc2\u2081) Cu\u2082SnS\u2083 films was realized simply by switching the identity of the thiol (i.e., 1,2-ethanedithiol vs 2-mercaptoethanol, respectively). Polymorph control is dictated by differences in the resulting molecular metal\u2013thiolate complexes and their subsequent decomposition profiles, which likely seed distinct Cu\u2082\u208b\u2093S phases that template the ternary sulfide sublattice. The p-type tetragonal and orthorhombic Cu\u2082SnS\u2083 films possess similar experimental direct optical band gaps of 0.94 and 0.88 eV, respectively, and strong photoelectrochemical current responses. Understanding how ink formulation dictates polymorph choice should inform the development of other thiol\u2013amine inks for solution-processed films.", "date": "2022-09-21", "date_type": "published", "publication": "Chemistry of Materials", "volume": "34", "number": "19", "publisher": "American Chemical Society", "pagerange": "8654-8663", "id_number": "CaltechAUTHORS:20221010-454096500.23", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221010-454096500.23", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1904719" }, { "agency": "NSF", "grant_number": "CHE-2154367" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0022087" }, { "agency": "Agilent Technologies" } ] }, "doi": "10.1021/acs.chemmater.2c01612", "primary_object": { "basename": "cm2c01612.pdf", "url": "https://authors.library.caltech.edu/records/dw6nm-tbd73/files/cm2c01612.pdf" }, "related_objects": [ { "basename": "cm2c01612_si_001.pdf", "url": "https://authors.library.caltech.edu/records/dw6nm-tbd73/files/cm2c01612_si_001.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Koskela, Kristopher M.; Mora Perez, Carlos; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7ebct-w0d84", "eprint_id": 115555, "eprint_status": "archive", "datestamp": "2023-08-22 17:12:32", "lastmod": "2023-10-24 16:34:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Evans-Jake-M", "name": { "family": "Evans", "given": "Jake M." }, "orcid": "0000-0002-8721-5316" }, { "id": "Lee-Kyra-S", "name": { "family": "Lee", "given": "Kyra S." } }, { "id": "Yan-Ellen-X", "name": { "family": "Yan", "given": "Ellen X." }, "orcid": "0000-0003-3252-790X" }, { "id": "Thompson-Annelise-C", "name": { "family": "Thompson", "given": "Annelise C." }, "orcid": "0000-0003-2414-7050" }, { "id": "Morla-Maureen-B", "name": { "family": "Morla", "given": "Maureen B." }, "orcid": "0000-0002-2520-9543" }, { "id": "Meier-Madeline-C", "name": { "family": "Meier", "given": "Madeline C." }, "orcid": "0000-0003-1608-0810" }, { "id": "Ifkovits-Zachary-P", "name": { "family": "Ifkovits", "given": "Zachary P." }, "orcid": "0000-0003-2538-0794" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Demonstration of a Sensitive and Stable Chemical Gas Sensor Based on Covalently Functionalized MoS\u2082", "ispublished": "pub", "full_text_status": "public", "keywords": "Electron density, Functional groups, Functionalization, Sensors, Volatile organic compounds; General Materials Science; Biomedical Engineering; General Chemical Engineering", "note": "\u00a9 2022 American Chemical Society. \n\nReceived: April 26, 2022; Accepted: June 21, 2022; Published: July 13, 2022. \n\nThis work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under award no. DE-FG02-03-ER15483. XPS data and vapor sensor measurements were obtained using the facilities and support of the Molecular Materials Resource Center of the Beckman Institute of the California Institute of Technology. M.C.M. acknowledges Graduate Research Fellowship from the National Science Foundation. M.C.M. also acknowledges the Resnick Sustainability Institute at Caltech for fellowship support. \n\nAuthor Contributions: J.M.E., K.S.L., and E.X.Y. contributed equally to this work. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - tz2c00372_si_001.pdf
", "abstract": "Chemically exfoliated MoS\u2082 was covalently functionalized and characterized as a chemically sensitive vapor sensor using changes in dc electrical resistance to detect a variety of volatile organic compounds (VOCs). Regardless of the polarity of the functionality introduced to the surface, sensors derived from functionalized MoS\u2082 showed high sensitivity for polar and nonpolar VOCs. Additionally, MoS\u2082 functionalized with trifluoromethyl benzyl bromide exhibited a very high sensitivity to polar and nonpolar organic vapors relative to the electrical resistance response of 2H MoS\u2082, 1T\u2032 MoS\u2082, or carbon black/polymer composite chemiresistive vapor sensors. Chemically functionalized MoS\u2082 sensors retained >70% of their initial responsiveness to test analytes after at least 72 h in air.", "date": "2022-08-01", "date_type": "published", "publication": "ACS Materials Letters", "volume": "4", "number": "8", "publisher": "American Chemical Society", "pagerange": "1475-1480", "id_number": "CaltechAUTHORS:20220714-369435000", "issn": "2639-4979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220714-369435000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03-ER15483" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1021/acsmaterialslett.2c00372", "primary_object": { "basename": "tz2c00372_si_001.pdf", "url": "https://authors.library.caltech.edu/records/7ebct-w0d84/files/tz2c00372_si_001.pdf" }, "resource_type": "article", "pub_year": "2022", "author_list": "Evans, Jake M.; Lee, Kyra S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ckqjx-89a34", "eprint_id": 115030, "eprint_status": "archive", "datestamp": "2023-08-22 16:18:14", "lastmod": "2023-10-24 15:17:32", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yu-Weilai", "name": { "family": "Yu", "given": "Weilai" }, "orcid": "0000-0002-9420-0702" }, { "id": "Buabthong-Pakpoom", "name": { "family": "Buabthong", "given": "Pakpoom" }, "orcid": "0000-0001-5538-138X" }, { "id": "Young-James-L", "name": { "family": "Young", "given": "James L." } }, { "id": "Ifkovits-Zachary-P", "name": { "family": "Ifkovits", "given": "Zachary P." }, "orcid": "0000-0003-2538-0794" }, { "id": "Byrne-Sean-T", "name": { "family": "Byrne", "given": "Sean T." }, "orcid": "0000-0002-5466-3112" }, { "id": "Steiner-Myles-A", "name": { "family": "Steiner", "given": "Myles A." }, "orcid": "0000-0003-1643-9766" }, { "id": "Deutsch-Todd-G", "name": { "family": "Deutsch", "given": "Todd G." }, "orcid": "0000-0001-6577-1226" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Failure Modes of Platinized pn\u207a-GaInP Photocathodes for Solar-Driven H\u2082 Evolution", "ispublished": "pub", "full_text_status": "public", "keywords": "photoelectrochemistry; III\u2212V semiconductor; water splitting; failure mode; solar fuels; General Materials Science", "note": "\u00a9 2022 American Chemical Society. \n\nReceived 29 January 2022. Accepted 13 May 2022. Published online 6 June 2022. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993 and by award DE-SC0022087 from the DOE Office of Basic Energy Sciences. Research was in part carried out at the Molecular Materials Research Center (MMRC) of the Beckman Institute of the California Institute of Technology. Dr. Nathan Dalleska is thanked for assistance with ICP-MS analysis. The authors from NREL acknowledge research support from the HydroGEN Advanced Water Splitting Materials Consortium, established as part of the Energy Materials Network under the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office, under Award Number DE-EE-0008084. This work was authored in part by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy under Contract Number DE-AC36-08GO28308. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes. Jake Evans is thanked for assistance with experiments. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - am2c01845_si_001.pdf
", "abstract": "The long-term stability for the hydrogen-evolution reaction (HER) of homojunction pn\u207a-Ga_(0.52)In_(0.48)P photocathodes (band gap = 1.8 eV) with an electrodeposited Pt catalyst (pn\u207a-GaInP/Pt) has been systematically evaluated in both acidic and alkaline electrolytes. Electrode dissolution during chronoamperometry was correlated with changes over time in the current density-potential (J\u2013E) behavior to reveal the underlying failure mechanism. Pristine pn\u207a-GaInP/Pt photocathodes yielded an open-circuit photopotential (Eoc) as positive as >1.0 V vs the potential of the reversible hydrogen electrode (RHE) and a light-limited current density (J\u209a\u2095) of >12 mA cm\u207b\u00b2 (1-sun illumination). However, E\u2092\ua700 and J\u209a\u2095 gradually degraded at either pH 0 or pH 14. The performance degradation was attributed to three different failure modes: (1) gradual thinning of the n\u207a-emitter layer due to GaInP dissolution in acid; (2) active corrosion of the underlying GaAs substrate at positive potentials causing delamination of the upper GaInP epilayers; and (3) direct GaAs/electrolyte contact compromising the operational stability of the device. This work reveals the importance of both substrate stability and structural integrity of integrated photoelectrodes toward stable solar fuel generation.", "date": "2022-06-15", "date_type": "published", "publication": "ACS Applied Materials & Interfaces", "volume": "14", "number": "23", "publisher": "American Chemical Society", "pagerange": "26622-26630", "id_number": "CaltechAUTHORS:20220606-736144000", "issn": "1944-8244", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220606-736144000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0022087" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-EE-0008084" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC36-08GO28308" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acsami.2c01845", "primary_object": { "basename": "am2c01845_si_001.pdf", "url": "https://authors.library.caltech.edu/records/ckqjx-89a34/files/am2c01845_si_001.pdf" }, "resource_type": "article", "pub_year": "2022", "author_list": "Yu, Weilai; Buabthong, Pakpoom; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fsknh-f7q63", "eprint_id": 115044, "eprint_status": "archive", "datestamp": "2023-08-22 15:57:29", "lastmod": "2023-10-24 15:17:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" }, "orcid": "0000-0002-2955-9671" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan" }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Numerical Simulation and Modeling of Hydrogen Gas Evolution on Planar and Microwire Array Electrodes", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Electrochemistry; Surfaces, Coatings and Films; Condensed Matter Physics; Renewable Energy, Sustainability and the Environment; Electronic, Optical and Magnetic Materials", "note": "\u00a9 2022 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. \n\nReceived 4 February 2022. Revised 24 May 2022. Accepted 31 May 2022. Accepted Manuscript online 1 June 2022. \n\nThis work was supported in part by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award number DE-SC0022087. This work was also supported in part by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award number DE-SC0004993. We are grateful to participate in this special issue to acknowledge on his 100th birthday the seminal contributions and extraordinary collegiality of Prof John Goodenough over decades of inspirational service to electrochemical societies, research, technology and electrochemists.\n\nPublished - Chen_2022_J._Electrochem._Soc._169_066510.pdf
Accepted Version - Chen+et+al_2022_J._Electrochem._Soc._10.1149_1945-7111_ac751e.pdf
Supplemental Material - jesac751esupp1.pdf
", "abstract": "The impact of gas evolution on the electrochemical characteristics of planar electrodes and microwire array electrodes has been analyzed using modeling and simulation. The impacts can mainly be broken into three phenomena: a) a shift in the local reversible hydrogen electrode potential; b) hyperpolarization; and c) an increase in the solution resistance of the electrolyte. The local reversible hydrogen electrode potential shift was found to play the most important role, constituting >40% of the total potential drop between the cathode and reference electrode, following correction for cell resistance. Compared to planar electrodes, a microwire array structure reduces the impact of bubbles on the solution conductance, but the shift in the local reversible hydrogen electrode potential varies with distance from the actual electrode surface.", "date": "2022-06", "date_type": "published", "publication": "Journal of the Electrochemical Society", "volume": "169", "number": "6", "publisher": "Electrochemical Society", "pagerange": "Art. No. 066510", "id_number": "CaltechAUTHORS:20220606-736390000", "issn": "0013-4651", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220606-736390000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0022087" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1149/1945-7111/ac751e", "primary_object": { "basename": "Chen+et+al_2022_J._Electrochem._Soc._10.1149_1945-7111_ac751e.pdf", "url": "https://authors.library.caltech.edu/records/fsknh-f7q63/files/Chen+et+al_2022_J._Electrochem._Soc._10.1149_1945-7111_ac751e.pdf" }, "related_objects": [ { "basename": "Chen_2022_J._Electrochem._Soc._169_066510.pdf", "url": "https://authors.library.caltech.edu/records/fsknh-f7q63/files/Chen_2022_J._Electrochem._Soc._169_066510.pdf" }, { "basename": "jesac751esupp1.pdf", "url": "https://authors.library.caltech.edu/records/fsknh-f7q63/files/jesac751esupp1.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Chen, Yikai and Lewis, Nathan" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sya21-9q476", "eprint_id": 113758, "eprint_status": "archive", "datestamp": "2023-08-22 15:49:44", "lastmod": "2023-10-23 19:49:08", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kennedy-Kathleen-M", "name": { "family": "Kennedy", "given": "Kathleen M." }, "orcid": "0000-0002-7125-4871" }, { "id": "Ruggles-Tyler-H", "name": { "family": "Ruggles", "given": "Tyler H." }, "orcid": "0000-0002-6643-2047" }, { "id": "Rinaldi-Katherine-Z", "name": { "family": "Rinaldi", "given": "Katherine" }, "orcid": "0000-0002-0746-2852" }, { "id": "Dowling-Jacqueline-A", "name": { "family": "Dowling", "given": "Jacqueline A." }, "orcid": "0000-0001-5642-8960" }, { "id": "Duan-Lei", "name": { "family": "Duan", "given": "Lei" }, "orcid": "0000-0002-6540-1847" }, { "id": "Caldeira-Ken", "name": { "family": "Caldeira", "given": "Ken" }, "orcid": "0000-0002-4591-643X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "The role of concentrated solar power with thermal energy storage in least-cost highly reliable electricity systems fully powered by variable renewable energy", "ispublished": "pub", "full_text_status": "public", "keywords": "Macro-energy modeling; Concentrated solar power; Thermal energy storage; Renewables; Energy systems", "note": "\u00a9 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license\n(http://creativecommons.org/licenses/by-nc-nd/4.0/) \n\nThis work was supported by a gift from Gates Ventures LLC to the Carnegie Institution of Science and a fellowship from SoCalGas in support of Low Carbon Energy Science and Policy. \n\nCRediT authorship contribution statement: Kathleen M. Kennedy: Conceptualization, Formal analysis, Investigation, Writing \u2013 original draft, Visualization. Tyler H. Ruggles: Methodology, Writing \u2013 review & editing. Katherine Rinaldi: Writing \u2013 review & editing. Jacqueline A. Dowling: Writing \u2013 review & editing. Lei Duan: Methodology, Data curation, Writing \u2013 review & editing. Ken Caldeira: Conceptualization, Methodology, Writing \u2013 review & editing, Funding acquisition. Nathan S. Lewis: Conceptualization, Writing \u2013 review & editing, Funding acquisition. \n\nThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\n\nPublished - 1-s2.0-S2666792422000099-main.pdf
Supplemental Material - 1-s2.0-S2666792422000099-mmc1.pdf
", "abstract": "Policies in the US increasingly stipulate the use of variable renewable energy sources, which must be able to meet electricity demand reliably and affordably despite variability. The value of grid services provided by additional marginal capacity and storage in existing grids is likely very different than their value in a 100% variable renewable electricity system under such policies. Consequently, the role of concentrated solar power (CSP) and thermal energy storage (TES) relative to photovoltaics (PV) and batteries has not been clearly evaluated or established for such highly reliable, 100% renewable systems. Electricity generation by CSP is currently more costly than by PV, but TES is much less costly than chemical battery storage. Herein, we analyze the role of CSP and TES compared to PV and batteries in an idealized least-cost solar/wind/storage electricity system using a macro-scale energy model with real-world historical demand and hourly weather data across the contiguous United States. We find that CSP does not compete directly with PV. Instead, TES competes with short-duration storage from batteries, with the coupled CSP+TES system providing reliability in the absence of other grid flexibility mechanisms. Without TES, little CSP generation is built in this system because CSP and PV have similar generation profiles, but PV is currently cheaper on a dollar-per-kWh basis than CSP. However, CSP with TES can provide grid flexibility in the modeled least-cost system under some circumstances due to the low cost of TES compared to batteries. Cost-sensitivity analysis shows that penetration of CSP with TES is primarily limited by high CSP generation costs. These results provide a framework for researchers and decision-makers to assess the role of CSP with TES in future electricity systems.", "date": "2022-06", "date_type": "published", "publication": "Advances in Applied Energy", "volume": "6", "publisher": "Elsevier", "pagerange": "Art. No. 100091", "id_number": "CaltechAUTHORS:20220304-60934000", "issn": "2666-7924", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220304-60934000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Gates Ventures LLC" }, { "agency": "SoCalGas" } ] }, "doi": "10.1016/j.adapen.2022.100091", "primary_object": { "basename": "1-s2.0-S2666792422000099-main.pdf", "url": "https://authors.library.caltech.edu/records/sya21-9q476/files/1-s2.0-S2666792422000099-main.pdf" }, "related_objects": [ { "basename": "1-s2.0-S2666792422000099-mmc1.pdf", "url": "https://authors.library.caltech.edu/records/sya21-9q476/files/1-s2.0-S2666792422000099-mmc1.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Kennedy, Kathleen M.; Ruggles, Tyler H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3yw1a-mtp69", "eprint_id": 114177, "eprint_status": "archive", "datestamp": "2023-08-22 15:12:47", "lastmod": "2023-11-16 00:22:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hamann-Kathryn-R", "name": { "family": "Hamann", "given": "Kathryn R." }, "orcid": "0000-0003-1163-7173" }, { "id": "Meier-Madeline-C", "name": { "family": "Meier", "given": "Madeline C." }, "orcid": "0000-0003-1608-0810" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" } ] }, "title": "Plastic Morphological Response to Spectral Shifts during Inorganic Phototropic Growth", "ispublished": "pub", "full_text_status": "public", "keywords": "photoelectrodeposition photoelectrochemistry; mesostructure; template-free; maskless; optical", "note": "\u00a9 2022 The Authors. Published by American Chemical Society. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0).\n\nReceived 31 December 2021. Accepted 4 March 2022. Revised 3 March 2022. Published online 4 April 2022. \n\nThis work was supported by the National Science Foundation, Directorate for Mathematical & Physical Sciences, Division of Materials Research under Award No. DMR-1905963. The authors gratefully acknowledge J.R. Thompson for insightful discussions, E.D. Simonoff and S. Yalamanchili for assistance with substrate preparation, and R. Gerhart, N. Hart, and B. Markowicz for assistance with photoelectrochemical cell fabrication. KRH and MCM acknowledge Graduate Research Fellowships from the National Science Foundation. MCM also acknowledges the Resnick Institute at Caltech for fellowship support. \n\nThe authors declare no competing financial interest.\n\nPublished - au1c00588.pdf
Supplemental Material - au1c00588_si_001.pdf
", "abstract": "Plants exhibit phototropism in which growth is directed toward sunlight and demonstrate morphological plasticity in response to changes in the spectral distribution of the incident illumination. Inorganic phototropic growth via template-free, light-directed electrochemical deposition of semiconductor material can spontaneously generate highly ordered mesostructures with anisotropic, nanoscale lamellar features that exhibit a pitch proportional to the wavelength (\u03bb) of the stimulating illumination. In this work, Se\u2013Te films were generated via a two-step inorganic phototropic growth process using a series of narrowband light-emitting diode sources with discrete output wavelengths (\u03bb\u2080 \u2260 \u03bb\u2081). Analogous to the plasticity observed in plants, changes in illumination wavelength from \u03bb\u2080 to \u03bb\u2081 resulted in morphological changes including feature branching, termination, and/or fusion along the growth direction. The interfacial feature pitch changed with the growth duration, in some cases in a notably nonmonotonic fashion, and eventually matched that obtained for growth using only \u03bb\u2081. Simulated morphologies generated by modeling light\u2013material interactions at the growth interface closely matched the evolved structures observed experimentally, indicating that the characteristics of the optical stimulation produce the observed plastic response during inorganic phototropic growth. Examination of the interfacial electric field modulation for \u03bb1 illumination of simplified structures, representative of those generated experimentally, revealed the interfacial light scattering and concentration behavior that directed phototropic growth away from equilibrium, as well as the emergent nature of the phenomena that reestablish equilibrium.", "date": "2022-04-06", "date_type": "published", "publication": "JACS Au", "volume": "2", "number": "4", "publisher": "American Chemical Society", "pagerange": "865-874", "id_number": "CaltechAUTHORS:20220406-400053753", "issn": "2691-3704", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220406-400053753", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1905963" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1021/jacsau.1c00588", "pmcid": "PMC9088297", "primary_object": { "basename": "au1c00588.pdf", "url": "https://authors.library.caltech.edu/records/3yw1a-mtp69/files/au1c00588.pdf" }, "related_objects": [ { "basename": "au1c00588_si_001.pdf", "url": "https://authors.library.caltech.edu/records/3yw1a-mtp69/files/au1c00588_si_001.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Hamann, Kathryn R.; Meier, Madeline C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/71m5j-q8w49", "eprint_id": 113912, "eprint_status": "archive", "datestamp": "2023-08-22 14:42:33", "lastmod": "2023-11-16 16:20:44", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Thompson-Annelise-C", "name": { "family": "Thompson", "given": "Annelise C." }, "orcid": "0000-0003-2414-7050" }, { "id": "Lee-Kyra-S", "name": { "family": "Lee", "given": "Kyra S." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Strain-Based Chemiresistive Polymer-Coated Graphene Vapor Sensors", "ispublished": "pub", "full_text_status": "public", "keywords": "Sensors, Pyridines, Two dimensional materials, Monolayers, Polymers; General Chemical Engineering; General Chemistry", "note": "\u00a9 2022 The Authors. Published by American Chemical Society. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) \n\nReceived: January 26, 2022; Accepted: February 28, 2022;\nPublished: March 15, 2022.\n\nThis work was supported by the Department of Energy (DOE) Basic Energy Sciences, grant DE-FG02-03-ER15483. Fabrication was performed in the Kavli Nanoscience Institute (KNI) at Caltech, and the authors thank the KNI staff for their assistance during fabrication. A.C.T. acknowledges a National Science Foundation Graduate Research Fellowship. \n\nAuthor Contributions. A.C.T. and K.S.L. contributed equally. \n\nThe authors declare no competing financial interest.\n\nPublished - acsomega.2c00543.pdf
Supplemental Material - ao2c00543_si_001.pdf
", "abstract": "Suspended chemiresistive graphene sensors have been fabricated using well-established nanofabrication techniques to generate sensors that are highly sensitive to pyridine and with excellent discrimination between polar and nonpolar analytes. When coated with a polymer surface layer and suspended on 3-D patterned glass electrodes, a hybrid combination of polymer and graphene yields chemiresistive vapor sensors. Expansion and contraction of the polymer layer produces strain on the suspended graphene (Gr). Hence, when organic vapors permeate into the polymer layer, the high gauge factor of the graphene induces substantial electrical resistive changes as folds and creases are induced in the graphene. The hybrid suspended polymer/Gr sensor exhibits substantial responses to polar organic vapors, especially pyridine, while also exhibiting reversibility and increased discrimination between polar and nonpolar analytes compared to previous approaches. This sensor design also allows for potential tunability in the types of polymers used for the reactive surface layer, allowing for use in a variety of potential applications.", "date": "2022-03-29", "date_type": "published", "publication": "ACS Omega", "volume": "7", "number": "12", "publisher": "American Chemical Society", "pagerange": "10765-10774", "id_number": "CaltechAUTHORS:20220315-625938000", "issn": "2470-1343", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220315-625938000", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03-ER15483" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acsomega.2c00543", "pmcid": "PMC8973036", "primary_object": { "basename": "acsomega.2c00543.pdf", "url": "https://authors.library.caltech.edu/records/71m5j-q8w49/files/acsomega.2c00543.pdf" }, "related_objects": [ { "basename": "ao2c00543_si_001.pdf", "url": "https://authors.library.caltech.edu/records/71m5j-q8w49/files/ao2c00543_si_001.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Thompson, Annelise C.; Lee, Kyra S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ppn6p-w4f28", "eprint_id": 112157, "eprint_status": "archive", "datestamp": "2023-08-20 07:15:24", "lastmod": "2023-10-23 20:56:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Mazza-Michael-F", "name": { "family": "Mazza", "given": "Michael F." }, "orcid": "0000-0003-3995-3100" }, { "id": "Cab\u00e1n-Acevedo-Miguel", "name": { "family": "Cab\u00e1n-Acevedo", "given": "Miguel" }, "orcid": "0000-0003-0054-8044" }, { "id": "Fu-Harold-J", "name": { "family": "Fu", "given": "Harold J." }, "orcid": "0000-0001-9738-209X" }, { "id": "Meier-Madeline-C", "name": { "family": "Meier", "given": "Madeline C." }, "orcid": "0000-0003-1608-0810" }, { "id": "Thompson-Annelise-C", "name": { "family": "Thompson", "given": "Annelise C." }, "orcid": "0000-0003-2414-7050" }, { "id": "Ifkovits-Zachary-P", "name": { "family": "Ifkovits", "given": "Zachary P." }, "orcid": "0000-0003-2538-0794" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Selective-Area, Water-Free Atomic Layer Deposition of Metal Oxides on Graphene Defects", "ispublished": "pub", "full_text_status": "public", "keywords": "atomic layer deposition, graphene, defect driven reactivity, defect passivation, device integration", "note": "\u00a9 2021 The Authors. Published by American Chemical Society. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). \n\nReceived 20 September 2021. Accepted 11 November 2021. Revised 9 November 2021. Published online 19 November 2021. \n\nM.F.M. and N.S.L. acknowledge support from the U.S. Department of Energy under Award DE-FG02-04ER15483. M.C. acknowledges support from the Ford Foundation under the Postdoctoral Scholar Fellowship program. M.C. acknowledges support from the National Science Foundation CCI Solar Fuels Program under Grant No. CHE-1305124. A.C.T. and M.C.M. acknowledge support from National Science Foundation graduate research fellowships. M.C.M. also acknowledges the Resnick Sustainability Institute at Caltech for fellowship support. Research was in part carried out at the Molecular Materials Research Center in the Beckman Institute at the California Institute of Technology. \n\nThe authors declare no competing financial interest.\n\nPublished - acsmaterialsau.1c00049.pdf
Supplemental Material - mg1c00049_si_001.pdf
", "abstract": "Passivating defective regions on monolayer graphene with metal oxides remains an active area of research for graphene device integration. To effectively passivate these regions, a water-free atomic layer deposition (ALD) recipe was developed and yielded selective-area ALD (sa-ALD) of mixed-metal oxides onto line defects in monolayer graphene. The anisotropically deposited film targeted high-energy defect sites that were formed during synthesis or transfer of the graphene layer. The passivating layer exceeded 10 nm thickness with minimal deposition onto the basal plane of graphene. The mixed-metal oxide film was of comparable quality to films deposited using nonselective water-based ALD methods, as shown by X-ray photoelectron spectroscopy. The development of sa-ALD techniques to target defect regions on the graphene sheet, while keeping the basal plane intact, will provide a new mechanism to passivate graphene defects and modify the electronic and physical properties of graphene.", "date": "2022-03-09", "date_type": "published", "publication": "ACS Materials Au", "volume": "2", "number": "2", "publisher": "American Chemical Society", "pagerange": "74-78", "id_number": "CaltechAUTHORS:20211201-231211106", "issn": "2694-2461", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211201-231211106", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-04ER15483" }, { "agency": "Ford Foundation" }, { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/acsmaterialsau.1c00049", "pmcid": "PMC9888651", "primary_object": { "basename": "acsmaterialsau.1c00049.pdf", "url": "https://authors.library.caltech.edu/records/ppn6p-w4f28/files/acsmaterialsau.1c00049.pdf" }, "related_objects": [ { "basename": "mg1c00049_si_001.pdf", "url": "https://authors.library.caltech.edu/records/ppn6p-w4f28/files/mg1c00049_si_001.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Mazza, Michael F.; Cab\u00e1n-Acevedo, Miguel; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/a7yjw-hha82", "eprint_id": 113472, "eprint_status": "archive", "datestamp": "2023-08-22 14:06:55", "lastmod": "2023-10-23 23:04:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yan-Ellen-X", "name": { "family": "Yan", "given": "Ellen" }, "orcid": "0000-0003-3252-790X" }, { "id": "Balgley-Renata", "name": { "family": "Balgley", "given": "Renata" } }, { "id": "Morla-Maureen-B", "name": { "family": "Morla", "given": "Maureen B." }, "orcid": "0000-0002-2520-9543" }, { "id": "Kwon-Soonho", "name": { "family": "Kwon", "given": "Soonho" }, "orcid": "0000-0002-9225-3018" }, { "id": "Musgrave-Charles-B-III", "name": { "family": "Musgrave", "given": "Charles B." }, "orcid": "0000-0002-3432-0817" }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A., III" }, "orcid": "0000-0003-0097-5716" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Experimental and Theoretical Comparison of Potential-dependent Methylation on Chemically Exfoliated WS\u2082 and MoS\u2082", "ispublished": "pub", "full_text_status": "public", "keywords": "density functional theory; grand canonical electrocatalysis; transition metal dichalcogenide; surface functionalization; potential-dependent reaction; General Materials Science", "note": "\u00a9 2022 American Chemical Society. \n\nReceived: October 29, 2021;\nAccepted: January 19, 2022;\nPublished: February 11, 2022.\n\nThis work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under award DE-FG02-03ER15483. E.X.Y. would also like to thank Bill Ling for assistance with DLS measurements. R.B. is an Awardee of the Weizmann Institute of Science\u2500National Postdoctoral Award Program for Advancing Women in Science and the Zuckerman STEM Leadership Program. Research was possible only with the use of instrumentation maintained in the Molecular Materials Resource Center of the Beckman Institute of the California Institute of Technology. The computations presented here were conducted on a Caltech high-performance cluster, partially supported by a grant from the Gordon and Betty Moore Foundation. S.K., C.B.M., W.A.G., and the H.P.C. calculations were supported by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub, under award number DE-SC0021266. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - am1c20949_si_001.pdf
", "abstract": "Reductant-activated functionalization is shown to enhance the methylation of chemically exfoliated MoS\u2082 (ceMoS\u2082) and ceWS\u2082 by introducing excess negative charge to facilitate a nucleophilic attack reaction. Relative to methylation in the absence of a reductant, the reaction produces a twofold increase in coverage of ceWS\u2082, from 25 to 52% coverage per WS\u2082. However, at every potential, the methyl coverage on ceWS\u2082 was \u223c20% lower than that on ceMoS\u2082. We applied grand canonical density functional theory to show that at constant potential, more negative charge is present on 1T\u2032-MoS\u2082 than on 1T\u2032-WS\u2082, making methylation both thermodynamically and kinetically more favorable for 1T\u2032-MoS\u2082 than 1T\u2032-WS\u2082. This effect was moderated when the reactions were compared at constant charge, emphasizing the importance of comparing the reactivity of materials at nominally identical electrode potentials.", "date": "2022-02-23", "date_type": "published", "publication": "ACS Applied Materials & Interfaces", "volume": "14", "number": "7", "publisher": "American Chemical Society", "pagerange": "9744-9753", "id_number": "CaltechAUTHORS:20220216-289231016", "issn": "1944-8244", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220216-289231016", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "Weizmann Institute of Science" }, { "agency": "Zuckerman STEM Leadership Program" }, { "agency": "Gordon and Betty Moore Foundation" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0021266" } ] }, "other_numbering_system": { "items": [ { "id": "1534", "name": "WAG" } ] }, "local_group": { "items": [ { "id": "Liquid-Sunlight-Alliance" } ] }, "doi": "10.1021/acsami.1c20949", "primary_object": { "basename": "am1c20949_si_001.pdf", "url": "https://authors.library.caltech.edu/records/a7yjw-hha82/files/am1c20949_si_001.pdf" }, "resource_type": "article", "pub_year": "2022", "author_list": "Yan, Ellen; Balgley, Renata; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2h146-mr664", "eprint_id": 112325, "eprint_status": "archive", "datestamp": "2023-09-22 22:34:56", "lastmod": "2023-10-23 23:23:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Fu-Harold-J", "name": { "family": "Fu", "given": "Harold J." }, "orcid": "0000-0001-9738-209X" }, { "id": "Buabthong-Pakpoom", "name": { "family": "Buabthong", "given": "Pakpoom" }, "orcid": "0000-0001-5538-138X" }, { "id": "Ifkovits-Zachary-P", "name": { "family": "Ifkovits", "given": "Zachary Philip" }, "orcid": "0000-0003-2538-0794" }, { "id": "Yu-Weilai", "name": { "family": "Yu", "given": "Weilai" }, "orcid": "0000-0002-9420-0702" }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Catalytic open-circuit passivation by thin metal oxide films of p-Si anodes in aqueous alkaline electrolytes", "ispublished": "pub", "full_text_status": "public", "keywords": "Pollution; Nuclear Energy and Engineering; Renewable Energy, Sustainability and the Environment; Environmental Chemistry", "note": "\u00a9 The Royal Society of Chemistry 2022. \n\nSubmitted 28 Sep 2021. Accepted 26 Nov 2021. First published 29 Nov 2021. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award number DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, and under award DE-SC0022087 from the Basic Energy Sciences Office of the DOE. Research was in part performed at the Molecular Materials Resource Center of the Beckman Institute.\n\nSupplemental Material - d1ee03040j1.pdf__ga=2.248598279.1627782830.1639070284-494341399.1632163545
", "abstract": "Ni and NiO\u2093-based protective thin films are shown to catalyze the oxidation of Si in the presence of O\u2082 in strongly alkaline KOH(aq) even in the absence of illumination. The O\u2082 in solution drove the open-circuit potential of the electrode to >0.4 V, which is positive of the Si passivation potential. The elevated electrochemical potential of the surface promoted formation of passive oxides on exposed Si regions of Si/Ni electrodes. Catalytic passivation of Si extended the durability of an np\u207a-Si(100)/NiO\u2093 photoanode to >400 h while operating under simulated day/night cycles. In contrast, electrodes without a Ni(O\u2093) layer and/or without O\u2082 in solution displayed direct etching of the Si and corrosion pitting during non-illuminated, simulated nighttime episodes of day/night cycling. The O\u2082-derived catalyzed passivation of Si using thin films can be generalized to multiple phases of NiO\u2093 as well as to materials other than Ni. Relative to operation in aqueous alkaline conditions, decreasing the pH of the electrolyte decreased the dissolution rate of the protective oxide layer formed by the catalyzed passivation process, and consequently increased the durability of the photoanode, but yielded lower photoelectrode fill factors for water oxidation due to the relatively large kinetic overpotentials for the electrocatalyzed oxygen-evolution reaction at near-neutral pH.", "date": "2022-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "15", "number": "1", "publisher": "Royal Society of Chemistry", "pagerange": "334-345", "id_number": "CaltechAUTHORS:20211209-456392000", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211209-456392000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0022087" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/d1ee03040j", "primary_object": { "basename": "d1ee03040j1.pdf", "url": "https://authors.library.caltech.edu/records/2h146-mr664/files/d1ee03040j1.pdf" }, "resource_type": "article", "pub_year": "2022", "author_list": "Fu, Harold J.; Buabthong, Pakpoom; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/g72fr-qzy96", "eprint_id": 112063, "eprint_status": "archive", "datestamp": "2023-08-22 12:44:34", "lastmod": "2023-10-23 20:52:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yu-Weilai", "name": { "family": "Yu", "given": "Weilai" }, "orcid": "0000-0002-9420-0702" }, { "id": "Young-James-L", "name": { "family": "Young", "given": "James L." } }, { "id": "Deutsch-Todd-G", "name": { "family": "Deutsch", "given": "Todd G." }, "orcid": "0000-0001-6577-1226" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Understanding the Stability of Etched or Platinized p-GaInP Photocathodes for Solar-Driven H\u2082 Evolution", "ispublished": "pub", "full_text_status": "public", "keywords": "photoelectrode; electrodeposition; semiconductor; hydrogen-evolution reaction; tandem solar-fuel generators; General Materials Science", "note": "\u00a9 2021 American Chemical Society. \n\nReceived: September 23, 2021; Accepted: November 8, 2021; Published: November 25, 2021. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993 and under award DE-SC0022087 from the Basic Energy Sciences Office of the DOE. Research was in part performed at the Molecular Materials Research Center (MMRC) of the Beckman Institute of the California Institute of Technology. Dr. Nathan Dalleska is thanked for assistance with ICP\u2013MS analysis. Dr. Myles Steiner is thanked for assistance with material fabrication. The authors acknowledge research support from the HydroGEN Advanced Water Splitting Materials Consortium, established as part of the Energy Materials Network under the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office, under Award Number DE-EE-0008084. This work was authored in part by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy under Contract Number DE-AC36-08GO28308. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes. \\\n\nThe authors declare no competing financial interest.\n\nSupplemental Material - am1c18243_si_001.pdf
", "abstract": "The long-term stability in acidic or alkaline aqueous electrolytes of p-Ga_(0.52)In_(0.48)P photocathodes, with a band gap of \u223c1.8 eV, for the solar-driven hydrogen-evolution reaction (HER) has been evaluated from a thermodynamic, kinetic, and mechanistic perspective. At either pH 0 or pH 14, etched p-GaInP electrodes corroded cathodically under illumination and formed metallic In0 on the photoelectrode surface. In contrast, under the same conditions, electrodeposition of Pt facilitated the HER kinetics and stabilized p-GaInP/Pt photoelectrodes against such cathodic decomposition. When held at 0 V versus the reversible hydrogen electrode, p-GaInP/Pt electrodes in either pH = 0 or pH = 14 exhibited stable current densities (J) of \u223c\u22129 mA cm\u207b\u00b2 for hundreds of hours under simulated 1 sun illumination. During the stability tests, the current density\u2013potential (J\u2013E) characteristics of the p-GaInP/Pt photoelectrodes degraded due to pH-dependent changes in the surface chemistry of the photocathode. This work provides a fundamental understanding of the stability and corrosion mechanisms of p-GaInP photocathodes that constitute a promising top light absorber for tandem solar-fuel generators.", "date": "2021-12-08", "date_type": "published", "publication": "ACS Applied Materials & Interfaces", "volume": "13", "number": "48", "publisher": "American Chemical Society", "pagerange": "57350-57361", "id_number": "CaltechAUTHORS:20201129-123456789", "issn": "1944-8244", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201129-123456789", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0022087" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-EE-0008084" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC36-08GO28308" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acsami.1c18243", "primary_object": { "basename": "am1c18243_si_001.pdf", "url": "https://authors.library.caltech.edu/records/g72fr-qzy96/files/am1c18243_si_001.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Yu, Weilai; Young, James L.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/b8ae7-8e028", "eprint_id": 112442, "eprint_status": "archive", "datestamp": "2023-08-22 11:55:12", "lastmod": "2023-10-23 22:32:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dowling-Jacqueline-A", "name": { "family": "Dowling", "given": "Jacqueline A." }, "orcid": "0000-0001-5642-8960" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Long-duration energy storage for reliable renewable electricity: The realistic possibilities", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Long-duration energy storage; pumped hydro; hydrogen energy storage; compressed air energy storage; pumped thermal storage; Political Science and International Relations", "note": "\u00a9 2021 Bulletin of the Atomic Scientists. \n\nNo potential conflict of interest was reported by the author(s). \n\nThe authors thank Tyler H. Ruggles and Katherine Z. Rinaldi for reviewing this piece. This work was supported by a fellowship from SoCalGas in support of Low Carbon Energy Science and Policy and a gift from Gates Ventures LLC to the Carnegie Institution for Science. \n\nNo potential conflict of interest was reported by the author(s).", "abstract": "Several American states mandate zero-carbon electricity systems based primarily on renewable technologies such as wind and solar power. Reliable and affordable electricity systems based on these variable resources may depend on the ability to store large quantities of low-cost energy over long timescales. Long-duration storage technologies (that is, those that provide from 10 to hundreds of hours of storage) have much cheaper energy storage capital costs than lithium-ion batteries. Long-duration storage plays unique roles, such as seasonal and multi-year storage, that increase the affordability of electricity from variable renewable energy. We compare realistic options for seasonal energy storage, including underground hydrogen, pumped hydro, pumped thermal, and compressed air systems. To make 100 percent renewable electricity reliable and more affordable, such long-duration storage technologies can be employed.", "date": "2021-11-02", "date_type": "published", "publication": "Bulletin of the Atomic Scientists", "volume": "77", "number": "6", "publisher": "Educational Foundation for Nuclear Science, Inc.", "pagerange": "281-284", "id_number": "CaltechAUTHORS:20211214-82844000", "issn": "0096-3402", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211214-82844000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "SoCalGas" }, { "agency": "Gates Ventures LLC" } ] }, "doi": "10.1080/00963402.2021.1989191", "resource_type": "article", "pub_year": "2021", "author_list": "Dowling, Jacqueline A. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2xpwh-x1m66", "eprint_id": 111916, "eprint_status": "archive", "datestamp": "2023-08-20 05:52:37", "lastmod": "2023-10-23 20:48:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yu-Weilai", "name": { "family": "Yu", "given": "Weilai" }, "orcid": "0000-0002-9420-0702" }, { "id": "Richter-Matthias-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Buabthong-Pakpoom", "name": { "family": "Buabthong", "given": "Pakpoom" }, "orcid": "0000-0001-5538-138X" }, { "id": "Moreno-Hernandez-Ivan-A", "name": { "family": "Moreno-Hernandez", "given": "Ivan A." }, "orcid": "0000-0001-6461-9214" }, { "id": "Read-Carlos-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Simonoff-Ethan", "name": { "family": "Simonoff", "given": "Ethan" }, "orcid": "0000-0002-2156-8602" }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Investigations of the stability of etched or platinized p-InP(100) photocathodes for solar-driven hydrogen evolution in acidic or alkaline aqueous electrolytes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 The Royal Society of Chemistry 2021. \n\nSubmitted 09 Sep 2021; Accepted 23 Sep 2021; First published 30 Sep 2021. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the office of Science of the U.S. Department of Energy under Award Number DE-SC0004993 and under award DE-SC0022087 from the Basic Energy Sciences Office of the DOE. Research was in part carried out at the Molecular Materials Resource Center (MMRC) of the Beckman Institute of the California Institute of Technology. W. Yu and C. G. Read acknowledge the Resnick Sustainability Institute (RSI) at Caltech for fellowship support. I. A. Moreno-Hernandez acknowledges a National Science Foundation Graduate Research Fellowship (Grant No. DGE-1144469). Prof. Dr Hans-Joachim Lewerenz, Dr Ke Sun and Dr Chengxiang Xiang are gratefully acknowledged for inspiring discussions. Dr Kimberly M. Papadantonakis is thanked for assistance with manuscript editing. Dr Nathan Dalleska is thanked for assistance with ICP-MS analyses. Ryan Jones is acknowledged for assistance with the design of the compression cell. Sean Byrne and Heng Dong are acknowledged for assistance with experiments. \n\nThere are no conflicts to declare.\n\nSupplemental Material - d1ee02809j1.pdf
", "abstract": "The stability of p-InP photocathodes performing the hydrogen-evolution reaction (HER) has been evaluated in contact with either 1.0 M H\u2082SO\u2084 (aq) or 1.0 M KOH(aq), with a focus on identifying corrosion mechanisms. Stability for the solar-driven HER was evaluated using p-InP electrodes that were either etched or coated with an electrodeposited Pt catalyst (p-InP/Pt). Variables such as trace O\u2082 were systematically controlled during the measurements. Changes in surface characteristics after exposure to electrochemical conditions as well as electrode dissolution processes were monitored using X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometry (ICP-MS). In either H\u2082SO\u2084 or KOH, etched p-InP photoelectrodes corroded cathodically under illumination, forming metallic In\u2070 at the electrode surface. In contrast, electrodeposition of Pt kinetically stabilized illuminated p-InP photocathodes in both H\u2082SO\u2084 and KOH by inhibiting the cathodic corrosion pathway. Notably, when held at 0 V vs. the reversible hydrogen electrode (RHE) in 1.0 M H\u2082SO\u2084 (aq), p-InP/Pt exhibited a stable current density (J) of \u223c\u221218 mA cm\u207b\u00b2 for >285 h under simulated 1 Sun illumination. The long-term current density vs. potential (J\u2013E) behavior at pH 0 and pH 14 of p-InP/Pt photocathodes correlated with changes in the surface chemistry as well as the dissolution of p-InP. In acidic media, the J\u2013E behavior of p-InP/Pt photocathodes remained nearly constant with time, but the surface of a p-InP/Pt electrodes gradually turned P-rich via a slow and continuous leaching of In ions. In alkaline electrolyte, the surface of p-InP/Pt electrodes was passivated by formation of an InO_x layer that exhibited negligible dissolution but led to a substantial degradation in the J\u2013E characteristics. Consequently, changes in the catalytic kinetics and surface stoichiometry are both important considerations for determining the corrosion chemistry and the long-term operational stability of InP photoelectrodes.", "date": "2021-11-01", "date_type": "published", "publication": "Energy & Environmental Science", "volume": "14", "number": "11", "publisher": "Royal Society of Chemistry", "pagerange": "6007-6020", "id_number": "CaltechAUTHORS:20211117-163656680", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211117-163656680", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0022087" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1144469" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1039/d1ee02809j", "primary_object": { "basename": "d1ee02809j1.pdf", "url": "https://authors.library.caltech.edu/records/2xpwh-x1m66/files/d1ee02809j1.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Yu, Weilai; Richter, Matthias H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9dkp8-dt670", "eprint_id": 111310, "eprint_status": "archive", "datestamp": "2023-08-20 05:44:10", "lastmod": "2023-10-23 20:30:39", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yu-Weilai", "name": { "family": "Yu", "given": "Weilai" }, "orcid": "0000-0002-9420-0702" }, { "id": "Richter-Matthias-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Simonoff-Ethan", "name": { "family": "Simonoff", "given": "Ethan" }, "orcid": "0000-0002-2156-8602" }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Investigations of the stability of GaAs for photoelectrochemical H\u2082 evolution in acidic or alkaline aqueous electrolytes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 The Royal Society of Chemistry 2021. \n\nSubmitted 17 May 2021. Accepted 22 Sep 2021. First published\t22 Sep 2021. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993 and by award DE-SC0022087 from the DOE Office of Basic Energy Sciences. Research was in part performed in the Molecular Materials Resource Center (MMRC) of the Beckman Institute of the California Institute of Technology. Phil Jahelka and Dr Chengxiang Xiang are gratefully acknowledged for fruitful discussions. Dr Nathan Dalleska provided assistance with ICP-MS analysis and Dr Pakpoom Buabthong assisted with XPS analysis. \n\nThere are no conflicts to declare.\n\nSupplemental Material - d1ta04145b1.pdf
", "abstract": "The long-term stability of p-GaAs photocathodes has been investigated for the hydrogen-evolution reaction (HER) in contact with either 1.0 M H\u2082SO\u2084(aq) or 1.0 M KOH(aq). Stability for the HER was evaluated using p-GaAs electrodes that were either etched or coated with active HER catalysts (Pt and CoP). Changes in surface characteristics of GaAs after exposure to electrochemical conditions were monitored by X-ray photoelectron spectroscopy (XPS), and electrode dissolution processes were evaluated by inductively coupled plasma mass spectrometry (ICP-MS). Consistent with thermodynamic predictions, after operation of the HER at pH 0 or pH 14, illuminated etched p-GaAs electrodes exhibited minimal dissolution while preserving a nearly stoichiometric surface. Electrodeposition or sputtering of Pt on the p-GaAs surface promoted the formation of excess As\u2070 via an interfacial reaction during the HER. The resulting non-stoichiometric As\u2070-rich surface of p-GaAs/Pt electrodes caused a loss in photoactivity as well as substantial cathodic dark current. In contrast, p-GaAs electrodes coated with thin-film CoP catalysts did not display an increase in surficial As\u2070 after operation of the HER in acidic electrolytes. Minimization of deleterious interfacial reactions is thus critical to obtain extended stability in conjunction with high performance from p-GaAs photocathodes.", "date": "2021-10-28", "date_type": "published", "publication": "Journal of Materials Chemistry A", "volume": "9", "number": "40", "publisher": "Royal Society of Chemistry", "pagerange": "22958-22972", "id_number": "CaltechAUTHORS:20211008-224606577", "issn": "2050-7488", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211008-224606577", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0022087" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/d1ta04145b", "primary_object": { "basename": "d1ta04145b1.pdf", "url": "https://authors.library.caltech.edu/records/9dkp8-dt670/files/d1ta04145b1.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Yu, Weilai; Richter, Matthias H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0d7vj-kkr88", "eprint_id": 111670, "eprint_status": "archive", "datestamp": "2023-08-22 11:39:03", "lastmod": "2023-10-23 19:38:13", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tong-Dan", "name": { "family": "Tong", "given": "Dan" }, "orcid": "0000-0003-3787-0707" }, { "id": "Farnham-David-J", "name": { "family": "Farnham", "given": "David J." }, "orcid": "0000-0002-6690-4251" }, { "id": "Duan-Lei", "name": { "family": "Duan", "given": "Lei" }, "orcid": "0000-0002-6540-1847" }, { "id": "Zhang-Qiang", "name": { "family": "Zhang", "given": "Qiang" }, "orcid": "0000-0002-8376-131X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Caldeira-Ken", "name": { "family": "Caldeira", "given": "Ken" }, "orcid": "0000-0002-4591-643X" }, { "id": "Davis-Steven-J", "name": { "family": "Davis", "given": "Steven J." }, "orcid": "0000-0002-9338-0844" } ] }, "title": "Geophysical constraints on the reliability of solar and wind power worldwide", "ispublished": "pub", "full_text_status": "public", "keywords": "Climate change; Climate-change mitigation; Renewable energy", "note": "\u00a9 The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived 24 February 2021; Accepted 24 September 2021; Published 22 October 2021. \n\nThis work was supported by the National Natural Science Foundation of China (41921005). D.T., D.J.F., L.D., and K.C. were supported by the Carnegie Institution for Science endowment and a gift from Gates Ventures, Inc. S.J.D. was supported by the US National Science Foundation (Innovations at the Nexus of Food, Energy and Water Systems (INFEWS) grant EAR 1639318). \n\nData availability: The electricity demand, solar, and wind capacity factors data generated for this study have been deposited in Dantong2021/Geophysical_constraints: Data of electricity demand, solar and wind capacity factors (v1.0). Zenodo. https://doi.org/10.5281/zenodo.5463202. \n\nCode availability: The Macro Electricity Model (MEM) code is available on GitHub via https://github.com/ClabEnergyProject/MEM. \n\nAuthor Contributions: K.C., N.S.L., S.J.D., and D.T. designed the study. D.T. performed the analyses, with support from D.J.F. on simulations and L.D. on resources estimates, and from S.J.D., Q.Z., N.S.L., and K.C. on analytical approaches. D.T. and S.J.D. led the writing with input from all coauthors. \n\nThe authors declare no competing interests. \n\nPeer review information: Nature Communications thanks Jesse Jenkin and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.\n\nPublished - s41467-021-26355-z.pdf
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", "abstract": "If future net-zero emissions energy systems rely heavily on solar and wind resources, spatial and temporal mismatches between resource availability and electricity demand may challenge system reliability. Using 39 years of hourly reanalysis data (1980\u20132018), we analyze the ability of solar and wind resources to meet electricity demand in 42 countries, varying the hypothetical scale and mix of renewable generation as well as energy storage capacity. Assuming perfect transmission and annual generation equal to annual demand, but no energy storage, we find the most reliable renewable electricity systems are wind-heavy and satisfy countries' electricity demand in 72\u201391% of hours (83\u201394% by adding 12\u2009h of storage). Yet even in systems which meet >90% of demand, hundreds of hours of unmet demand may occur annually. Our analysis helps quantify the power, energy, and utilization rates of additional energy storage, demand management, or curtailment, as well as the benefits of regional aggregation.", "date": "2021-10-22", "date_type": "published", "publication": "Nature Communications", "volume": "12", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 6146", "id_number": "CaltechAUTHORS:20211028-165534518", "issn": "2041-1723", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211028-165534518", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "National Natural Science Foundation of China", "grant_number": "41921005" }, { "agency": "Carnegie Institution" }, { "agency": "Gates Ventures, Inc." }, { "agency": "NSF", "grant_number": "EAR-1639318" } ] }, "doi": "10.1038/s41467-021-26355-z", "pmcid": "PMC8536784", "primary_object": { "basename": "41467_2021_26355_MOESM3_ESM.pdf", "url": "https://authors.library.caltech.edu/records/0d7vj-kkr88/files/41467_2021_26355_MOESM3_ESM.pdf" }, "related_objects": [ { "basename": "41467_2021_26355_MOESM4_ESM.xlsx", "url": "https://authors.library.caltech.edu/records/0d7vj-kkr88/files/41467_2021_26355_MOESM4_ESM.xlsx" }, { "basename": "41467_2021_26355_MOESM6_ESM.xlsx", "url": "https://authors.library.caltech.edu/records/0d7vj-kkr88/files/41467_2021_26355_MOESM6_ESM.xlsx" }, { "basename": "41467_2021_26355_MOESM7_ESM.xlsx", "url": "https://authors.library.caltech.edu/records/0d7vj-kkr88/files/41467_2021_26355_MOESM7_ESM.xlsx" }, { "basename": "41467_2021_26355_MOESM8_ESM.xlsx", "url": "https://authors.library.caltech.edu/records/0d7vj-kkr88/files/41467_2021_26355_MOESM8_ESM.xlsx" }, { "basename": "41467_2021_26355_MOESM9_ESM.xlsx", "url": "https://authors.library.caltech.edu/records/0d7vj-kkr88/files/41467_2021_26355_MOESM9_ESM.xlsx" }, { "basename": "s41467-021-26355-z.pdf", "url": "https://authors.library.caltech.edu/records/0d7vj-kkr88/files/s41467-021-26355-z.pdf" }, { "basename": "41467_2021_26355_MOESM2_ESM.pdf", "url": "https://authors.library.caltech.edu/records/0d7vj-kkr88/files/41467_2021_26355_MOESM2_ESM.pdf" }, { "basename": "41467_2021_26355_MOESM5_ESM.xlsx", "url": "https://authors.library.caltech.edu/records/0d7vj-kkr88/files/41467_2021_26355_MOESM5_ESM.xlsx" }, { "basename": "41467_2021_26355_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/0d7vj-kkr88/files/41467_2021_26355_MOESM1_ESM.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Tong, Dan; Farnham, David J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6mc22-s2d96", "eprint_id": 111322, "eprint_status": "archive", "datestamp": "2023-08-20 05:33:08", "lastmod": "2023-10-23 20:31:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Buabthong-Pakpoom", "name": { "family": "Buabthong", "given": "Pakpoom" }, "orcid": "0000-0001-5538-138X" }, { "id": "Evans-Jake-M", "name": { "family": "Evans", "given": "Jake M." }, "orcid": "0000-0002-8721-5316" }, { "id": "Rinaldi-Katherine-Z", "name": { "family": "Rinaldi", "given": "Katherine Z." }, "orcid": "0000-0002-0746-2852" }, { "id": "Kennedy-Kathleen-M", "name": { "family": "Kennedy", "given": "Kathleen M." }, "orcid": "0000-0002-7125-4871" }, { "id": "Fu-Harold-J", "name": { "family": "Fu", "given": "Harold J." }, "orcid": "0000-0001-9738-209X" }, { "id": "Ifkovits-Zachary-P", "name": { "family": "Ifkovits", "given": "Zachary P." }, "orcid": "0000-0003-2538-0794" }, { "id": "Kuo-Tai-Jung", "name": { "family": "Kuo", "given": "Tai-Jung" } }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "GaAs Microisland Anodes Protected by Amorphous TiO\u2082 Films Mitigate Corrosion Spreading During Water Oxidation in Alkaline Electrolytes", "ispublished": "pub", "full_text_status": "public", "keywords": "Electrochemistry, Layers, Electrodes, Defects, Gallium arsenide", "note": "\u00a9 2021 American Chemical Society. \n\nReceived 7 June 2021. Accepted 20 September 2021. Published online 27 September 2021. Published in issue 8 October 2021. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993 and under award DE-SC0022087 from the Basic Energy Sciences Office of the DOE. We gratefully acknowledge a gift from the Lam Research Unlock Ideas program. P.B. is grateful to Toy Jatuporn Leksut for assistance with illustrations and visualization of the data. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nz1c01174_si_001.pdf
", "abstract": "Microisland structures of \u223c200 \u03bcm diameter GaAs circles were fabricated and used to spatially isolate defects during electrochemical operation as an anode in aqueous alkaline electrolytes. The microisland structures allowed one to measure the rate and distribution of the pinhole formation on electrodes protected by 110 nm-thick amorphous titanium dioxide (a-TiO\u2082) films formed by atomic layer deposition. Although no crystalline regions were detected by Raman spectroscopy, a limited number of defects were present in the a-TiO2 layer and developed into new microscopic pinholes within the first 20 h of electrochemical operation. The film dissolved at a rate of <13 nm per day, and hence, intrinsic film dissolution was not the primary mode of pinhole formation during this first 20 h of operation. The fabrication processes presented herein only utilized chemical etching and mechanical polishing and, consequently, should be readily transferable to the fabrication of the more complicated np\u207a-GaAs structures.", "date": "2021-10-08", "date_type": "published", "publication": "ACS Energy Letters", "volume": "6", "number": "10", "publisher": "American Chemical Society", "pagerange": "3709-3714", "id_number": "CaltechAUTHORS:20211008-224620533", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211008-224620533", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0022087" }, { "agency": "Lam Research Unlock Ideas" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acsenergylett.1c01174", "primary_object": { "basename": "nz1c01174_si_001.pdf", "url": "https://authors.library.caltech.edu/records/6mc22-s2d96/files/nz1c01174_si_001.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Buabthong, Pakpoom; Evans, Jake M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ztj05-21j03", "eprint_id": 110397, "eprint_status": "archive", "datestamp": "2023-08-20 04:58:42", "lastmod": "2023-10-23 19:38:19", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ifkovits-Zachary-P", "name": { "family": "Ifkovits", "given": "Zachary P." }, "orcid": "0000-0003-2538-0794" }, { "id": "Evans-Jake-M", "name": { "family": "Evans", "given": "Jake M." }, "orcid": "0000-0002-8721-5316" }, { "id": "Meier-Madeline-C", "name": { "family": "Meier", "given": "Madeline C." }, "orcid": "0000-0003-1608-0810" }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Decoupled electrochemical water-splitting systems: a review and perspective", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 The Royal Society of Chemistry 2021. \n\nSubmitted 24 Apr 2021; Accepted 02 Jul 2021; First published 07 Jul 2021. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. MCM acknowledges a Graduate Research Fellowship from the National Science Foundation. MCM also acknowledges the Resnick Sustainability Institute at Caltech for fellowship support. \n\nConflicts of interest: NSL may become a consultant and equity holder in a future potential corporation that is seeking funding to focus on commercial development of catalysts and systems for the production and use of hydrogen.", "abstract": "Electrochemical water splitting is a promising technology to renewably generate hydrogen fuel from water. One particular drawback of conventional water splitting is that the hydrogen-forming reduction reaction is tightly coupled, both spatially and temporally, to the oxygen-forming oxidation reaction. This coupling poses challenges in both conventional and direct-solar-powered electrolysis systems, including gas crossover and separator degradation, sometimes necessitating the use of precious metal catalysts. In decoupled water splitting, the conventional electrolysis reactions are separated spatially, temporally, or both, via coupling to an intermediate redox mediator. Decoupled water-splitting systems are flexible and modular by nature, with other proposed benefits including facile coupling to renewable power sources, utilization of earth-abundant catalysts, and intrinsically safe operation. Here we review recent advances in decoupled water splitting and related fields, mainly categorizing decoupled systems by mediator phase and standard potential. We offer insight to how decoupling may be advantageous, and which tradeoffs need to be considered for practical implementation. We conclude our review with discussion of known technological hurdles and note opportunities for future discovery.", "date": "2021-09-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "14", "number": "9", "publisher": "Royal Society of Chemistry", "pagerange": "4740-4759", "id_number": "CaltechAUTHORS:20210823-225400426", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210823-225400426", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1039/d1ee01226f", "resource_type": "article", "pub_year": "2021", "author_list": "Ifkovits, Zachary P.; Evans, Jake M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ka7z0-6j108", "eprint_id": 109682, "eprint_status": "archive", "datestamp": "2023-08-22 10:54:53", "lastmod": "2023-10-23 18:07:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ruggles-Tyler-H", "name": { "family": "Ruggles", "given": "Tyler H." } }, { "id": "Dowling-Jacqueline-A", "name": { "family": "Dowling", "given": "Jacqueline A." }, "orcid": "0000-0001-5642-8960" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Caldeira-Ken", "name": { "family": "Caldeira", "given": "Ken" }, "orcid": "0000-0002-4591-643X" } ] }, "title": "Opportunities for flexible electricity loads such as hydrogen production from curtailed generation", "ispublished": "pub", "full_text_status": "public", "keywords": "Curtailment; Hydrogen; Flexible load; Electricity costs; System flexibility; Variable renewable energy", "note": "\u00a9 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). \n\nReceived 20 June 2021, Revised 23 June 2021, Accepted 23 June 2021, Available online 25 June 2021. \n\nWe would like to thank Lei Duan of the Carnegie Institution for Science, Department of Global Ecology for calculation of the solar and wind capacity factors used in this study. We would also like to thank Enrico Antonini of the Carnegie Institution for Science, Department of Global Ecology for performing the wind and solar resource aggregation comparison. We would also like to thank the reviewers for their thorough review and thoughtful comments that resulted in an improved manuscript. This work is funded by a gift to the Carnegie Institution for Science from Gates Ventures, Inc. This work is also supported by the Fund for Innovative Climate and Energy Research. J.A.D. acknowledges a fellowship from SoCalGas in support of Low Carbon Energy Science and Policy. \n\nData and code availability: In the interest of transparency and reproducibility, all model code, input data, and analysis results are publicly available and documented at https://github.com/carnegie/SEM_public/tree/Ruggles_et_al_2021. \n\nCRediT authorship contribution statement: Tyler H. Ruggles: Conceptualization, Methodology, Formal analysis, Writing - original draft, Writing - review & editing. Jacqueline A. Dowling: Formal analysis, Resources, Writing - review & editing. Nathan S. Lewis: Conceptualization, Methodology, Writing - review & editing. Ken Caldeira: Conceptualization, Methodology, Writing - review & editing, Funding acquisition. \n\nThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\n\nPublished - 1-s2.0-S2666792421000433-main.pdf
Supplemental Material - 1-s2.0-S2666792421000433-mmc1.pdf
", "abstract": "Variable, low-cost, low-carbon electricity that would otherwise be curtailed may provide a substantial economic opportunity for entities that can flexibly adapt their electricity consumption. We used historical hourly weather data over the contiguous U.S. to model the characteristics of least-cost electricity systems dominated by variable renewable generation that powered firm and flexible electricity demands (loads). Scenarios evaluated included variable wind and solar power, battery storage, and dispatchable natural gas with carbon capture and storage, with electrolytic hydrogen representing a prototypical flexible load. When flexible loads were small, excess generation capacity was available during most hours, allowing flexible loads to operate at high capacity factors. Expanding the flexible loads allowed the least-cost systems to more fully utilize the generation capacity built to supply firm loads, and thus reduced the average cost of delivered electricity. The macro-scale energy model indicated that variable renewable electricity systems optimized to supply firm loads at current costs could supply ~25% or more additional flexible load with minimal capacity expansion, while resulting in reduced average electricity costs (~10% or less capacity expansion and ~10% to 20% reduction in costs in our modeled scenarios). These results indicate that adding flexible loads to electricity systems will likely allow more full utilization of generation assets across a wide range of system architectures, thus providing new energy services with infrastructure that is already needed to supply firm electricity loads.", "date": "2021-08-25", "date_type": "published", "publication": "Advances in Applied Energy", "volume": "3", "publisher": "Elsevier", "pagerange": "Art. No. 100051", "id_number": "CaltechAUTHORS:20210630-203017608", "issn": "2666-7924", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210630-203017608", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Gates Ventures, Inc." }, { "agency": "Fund for Innovative Climate and Energy Research" }, { "agency": "Southern California Gas Company" } ] }, "doi": "10.1016/j.adapen.2021.100051", "primary_object": { "basename": "1-s2.0-S2666792421000433-main.pdf", "url": "https://authors.library.caltech.edu/records/ka7z0-6j108/files/1-s2.0-S2666792421000433-main.pdf" }, "related_objects": [ { "basename": "1-s2.0-S2666792421000433-mmc1.pdf", "url": "https://authors.library.caltech.edu/records/ka7z0-6j108/files/1-s2.0-S2666792421000433-mmc1.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Ruggles, Tyler H.; Dowling, Jacqueline A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/xcj09-vkg35", "eprint_id": 110630, "eprint_status": "archive", "datestamp": "2023-08-20 04:44:40", "lastmod": "2023-10-23 19:46:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nunez-Paul-D", "name": { "family": "Nunez", "given": "Paul" }, "orcid": "0000-0001-7039-0516" }, { "id": "Cab\u00e1n-Acevedo-Miguel", "name": { "family": "Cab\u00e1n-Acevedo", "given": "Miguel" }, "orcid": "0000-0003-0054-8044" }, { "id": "Yu-Weilai", "name": { "family": "Yu", "given": "Weilai" }, "orcid": "0000-0002-9420-0702" }, { "id": "Richter-Matthias-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Kennedy-Kathleen-M", "name": { "family": "Kennedy", "given": "Kathleen" }, "orcid": "0000-0002-7125-4871" }, { "id": "Molina-Villarino-Andr\u00e9s", "name": { "family": "Molina Villarino", "given": "Andr\u00e9s" }, "orcid": "0000-0003-3272-5156" }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Origin of the Electrical Barrier in Electrolessly Deposited Platinum Nanoparticles on p-Si Surfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "Platinum, Layers, Electrodes, Deposition, X-ray photoelectron spectroscopy", "note": "\u00a9 2021 American Chemical Society. \n\nReceived 6 April 2021. Revised 10 June 2021. Published online 6 August 2021. Published in issue 19 August 2021. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under Award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. P.N. acknowledges support from the National Science Foundation for graduate research fellowships. Research was in part carried out at the Molecular Materials Resource Center of the Beckman Institute and at the Microanalysis Center of the California Institute of Technology. The authors thank Dr. K. Papadantonakis for assistance with editing this manuscript, and B.S.B. thanks Dr. S. Maldonado for helpful discussions. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - jp1c03072_si_001.pdf
", "abstract": "Pt deposited by either sputtering or electron-beam (e-beam) evaporation on p-Si forms an ohmic contact, with zero photovoltage and very little photogenerated charge-carrier collection. However, electro- or electroless deposition of Pt onto p-Si produces a rectifying junction that generates a photovoltage of \u223c300 mV under simulated 1 sun illumination. To explain these differences, we have characterized junctions formed by electroless or e-beam deposition of Pt onto H-terminated or oxide-coated p-Si substrates using impedance spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electrochemical current density vs potential (J\u2013E) characteristics. When Pt was deposited electrolessly, XPS and TEM measurements revealed a thin interfacial SiO_x layer of 1\u20136 nm thickness under the Pt overlayer. Moreover, open-circuit potential measurements under illumination on electrolessly deposited Pt on a p-Si electrode showed that the junction was a function of the Nernstian potential of the contacting electrolyte solution. Creating an analogous junction by e-beam deposition of Pt required oxidation of the Si surface prior to Pt deposition, followed by etching in HF to remove oxide on the exposed Si surface. The resulting structure has both an interfacial SiO_x layer under the Pt and a H-terminated Si surface on the bare areas. Additionally, under a H\u2082 atmosphere, Pt can adsorb hydrogen that can diffuse to the SiO_x/Pt interface and produce a dipole layer. This information allowed formulation of a model for the charge transfer across p-Si/SiO_x/Pt interfaces. When in contact with a solution having a kinetically facile redox couple, the current is carried across the Si/electrolyte interface, and the electrode has the properties of a semiconductor/liquid junction. In contrast, when in contact with a solution with a large kinetic barrier to interfacial charge transfer, such as the hydrogen evolution reaction, the current instead passes predominantly through the SiO_x layer to the Pt and then reacts with protons in the solution. In this situation, the junction to the semiconductor is buried and occurs at the Si/SiO_x/Pt interface. The Si/SiO_x/Pt contact displays an increase in barrier height due to the hydrogen-induced dipoles. Consequently, the barrier height for an electrode made by electroless deposition of Pt onto Si is determined by the pathway that the electrons traverse to reach the solution.", "date": "2021-08-19", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "125", "number": "32", "publisher": "American Chemical Society", "pagerange": "17660-17670", "id_number": "CaltechAUTHORS:20210830-230029107", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210830-230029107", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acs.jpcc.1c03072", "primary_object": { "basename": "jp1c03072_si_001.pdf", "url": "https://authors.library.caltech.edu/records/xcj09-vkg35/files/jp1c03072_si_001.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Nunez, Paul; Cab\u00e1n-Acevedo, Miguel; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/eamm1-9a070", "eprint_id": 108900, "eprint_status": "archive", "datestamp": "2023-08-20 03:11:16", "lastmod": "2023-10-23 17:24:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Simonoff-Ethan", "name": { "family": "Simonoff", "given": "Ethan" }, "orcid": "0000-0002-2156-8602" }, { "id": "Thompson-Jonathan-R", "name": { "family": "Thompson", "given": "Jonathan R." } }, { "id": "Meier-Madeline-C", "name": { "family": "Meier", "given": "Madeline C." }, "orcid": "0000-0003-1608-0810" }, { "id": "Kennedy-Kathleen-M", "name": { "family": "Kennedy", "given": "Kathleen M." }, "orcid": "0000-0002-7125-4871" }, { "id": "Hamann-Kathryn-R", "name": { "family": "Hamann", "given": "Kathryn R." }, "orcid": "0000-0003-1163-7173" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Preseeded Optical Scatterers as a Template for Enhancing Order in Inorganic Phototropic Growth", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2021 American Chemical Society. \n\nReceived: April 5, 2021; Revised: April 8, 2021; Published: April 22, 2021. \n\nThis work was supported by the National Science Foundation under Award Number DMR1905963. M.C.M. and K.R.H. acknowledge Graduate Research Fellowships from the National Science Foundation. M.C.M. also acknowledges the Resnick Sustainability Institute at Caltech for fellowship support. \n\nAuthor Contributions: E.S. and J.R.T. contributed equally. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - jp1c02746_si_001.pdf
", "abstract": "Lithographically patterned substrates were used as templates of optical scatterers that seeded the inorganic phototropic growth of Se\u2013Te. Relative to films grown on nominally featureless substrates, films grown on substrates having patterned optical scatterers demonstrated much improved Se\u2013Te pattern fidelities and a narrower distribution of film pattern spatial periods, as quantified by Fourier spectrum analysis. Full-wave electromagnetic modeling and Monte Carlo simulations of Se\u2013Te film growth on substrates with patterned optical scatterers were in good agreement with the patterns observed experimentally. Additional simulations were performed to investigate the limits to pattern period confinement. Simulations revealed that films deposited onto templated substrates can exhibit pattern periods as low as \u223c80% and as high as \u223c160% of the pattern period observed for films deposited on nontemplated substrates.", "date": "2021-05-06", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "125", "number": "17", "publisher": "American Chemical Society", "pagerange": "9571-9581", "id_number": "CaltechAUTHORS:20210430-103304262", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210430-103304262", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1905963" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1021/acs.jpcc.1c02746", "primary_object": { "basename": "jp1c02746_si_001.pdf", "url": "https://authors.library.caltech.edu/records/eamm1-9a070/files/jp1c02746_si_001.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Simonoff, Ethan; Thompson, Jonathan R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/r3007-tg461", "eprint_id": 108642, "eprint_status": "archive", "datestamp": "2023-10-03 22:41:38", "lastmod": "2023-10-24 15:32:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Rinaldi-Katherine-Z", "name": { "family": "Rinaldi", "given": "Katherine Z." }, "orcid": "0000-0002-0746-2852" }, { "id": "Dowling-Jacqueline-A", "name": { "family": "Dowling", "given": "Jacqueline A." }, "orcid": "0000-0001-5642-8960" }, { "id": "Ruggles-Tyler-H", "name": { "family": "Ruggles", "given": "Tyler H." }, "orcid": "0000-0002-6643-2047" }, { "id": "Caldeira-Ken", "name": { "family": "Caldeira", "given": "Ken" }, "orcid": "0000-0002-4591-643X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Wind and Solar Resource Droughts in California Highlight the Benefits of Long-Term Storage and Integration with the Western Interconnect", "ispublished": "pub", "full_text_status": "public", "keywords": "California electricity system, variable renewable energy, zero-carbon electricity, macro-energy model, wind energy,\nsolar energy, interannual variability", "note": "\u00a9 2021 American Chemical Society. \n\nReceived: November 19, 2020; Revised: March 19, 2021; Accepted: March 19, 2021; Published: April 6, 2021. \n\nThis work was supported by fellowships at Caltech from SoCalGas in support of Low Carbon Energy Science and Policy, and by a gift from Gates Ventures LLC to the Carnegie Institution for Science. The authors thank Lei Duan and David J. Farnham for providing wind, solar, and demand input data. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - es0c07848_si_001.pdf
", "abstract": "As reliance on wind and solar power for electricity generation increases, so does the importance of understanding how variability in these resources affects the feasible, cost-effective ways of supplying energy services. We use hourly weather data over multiple decades and historical electricity demand data to analyze the gaps between wind and solar supply and electricity demand for California (CA) and the Western Interconnect (WECC). We quantify the occurrence of resource droughts when the daily power from each resource was less than half of the 39-year daily mean for that day of the year. Averaged over 39 years, CA experienced 6.6 days of solar and 48 days of wind drought per year, compared to 0.41 and 19 for WECC. Using a macro-scale electricity model, we evaluate the potential for both long-term storage and more geographically diverse generation resources to minimize system costs. For wind-solar-battery electricity systems, meeting California demand with WECC generation resources reduces the cost by 9% compared to constraining resources entirely to California. Adding long-duration storage lowers system costs by 21% when treating California as an island. This data-driven analysis quantifies rare weather-related events and provides an understanding that can be used to inform stakeholders in future electricity systems.", "date": "2021-05-04", "date_type": "published", "publication": "Environmental Science and Technology", "volume": "55", "number": "9", "publisher": "American Chemical Society", "pagerange": "6214-6226", "id_number": "CaltechAUTHORS:20210407-082224233", "issn": "0013-936X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210407-082224233", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech" }, { "agency": "Southern California Gas Company" }, { "agency": "Gates Ventures LLC" } ] }, "doi": "10.1021/acs.est.0c07848", "primary_object": { "basename": "es0c07848_si_001.pdf", "url": "https://authors.library.caltech.edu/records/r3007-tg461/files/es0c07848_si_001.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Rinaldi, Katherine Z.; Dowling, Jacqueline A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/726pw-pv947", "eprint_id": 108796, "eprint_status": "archive", "datestamp": "2023-08-20 02:50:39", "lastmod": "2023-10-23 17:19:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Johnson-Samantha-I", "name": { "family": "Johnson", "given": "Samantha I." }, "orcid": "0000-0001-6495-9892" }, { "id": "Blakemore-James-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-4453-9716" }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A., III" }, "orcid": "0000-0003-0097-5716" }, { "id": "Persson-Petter", "name": { "family": "Persson", "given": "Petter" }, "orcid": "0000-0001-7600-3230" } ] }, "title": "Design of robust 2,2\u2032-bipyridine ligand linkers for the stable immobilization of molecular catalysts on silicon(111) surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 the Owner Societies 2021. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. \n\nSubmitted 05 Feb 2021; Accepted 06 Apr 2021; First published 06 Apr 2021. \n\nResearch at Caltech was supported by the National Science Foundation Center for Chemical Innovation Solar Fuels (NSF CHE-1305124). S. I. J. was supported by a National Science Foundation Graduate Research Fellowship (Grant No. DGE-1144469), a National Science Foundation Graduate Research Opportunities Worldwide Grant, and by the generous support of the Resnick Sustainability Institute. S. I. J. and P. P. were supported by the Swedish Research Council (VR). W. A. G. was partially supported by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under Award Number DE-SC0021266. P. P. acknowledges the Swedish Energy Agency (STEM) as well as the Swedish supercomputing facilities LUNARC and NSC for support. S. I. J. thanks Drs. Robert J. Nielsen and Noah Plymale for helpful discussions. S. I. J. and P. P. thank Drs. Lisa A. Fredin and Marta Galynska for helpful discussions. \n\nThere are no conflicts to declare.\n\nPublished - d1cp00545f.pdf
Supplemental Material - d1cp00545f1.pdf
Supplemental Material - d1cp00545f2.xyz
", "abstract": "The attachment of the 2,2\u2032-bipyridine (bpy) moieties to the surface of planar silicon(111) (photo)electrodes was investigated using ab initio simulations performed on a new cluster model for methyl-terminated silicon. Density functional theory (B3LYP) with implicit solvation techniques indicated that adventitious chlorine atoms, when present in the organic linker backbone, led to instability at very negative potentials of the surface-modified electrode. In prior experimental work, chlorine atoms were present as a trace surface impurity due to required surface processing chemistry, and thus could plausibly result in the observed surface instability of the linker. Free energy calculations for the Cl-atom release process with model silyl-linker constructs revealed a modest barrier (14.9 kcal mol\u207b\u00b9) that decreased as the electrode potential became more negative. A small library of new bpy-derived structures has additionally been explored computationally to identify strategies that could minimize chlorine-induced linker instability. Structures with fluorine substituents are predicted to be more stable than their chlorine analogues, whereas fully non-halogenated structures are predicted to exhibit the highest stability. The behavior of a hydrogen-evolving molecular catalyst Cp*Rh(bpy) (Cp* = pentamethylcyclopentadienyl) immobilized on a silicon(111) cluster was explored theoretically to evaluate differences between the homogeneous and surface-attached behavior of this species in a tautomerization reaction observed under reductive conditions for catalytic H\u2082 evolution. The calculated free energy difference between the tautomers is small, hence the results suggest that use of reductively stable linkers can enable robust attachment of catalysts while maintaining chemical behavior on the electrode similar to that exhibited in homogeneous solution.", "date": "2021-04-28", "date_type": "published", "publication": "Physical Chemistry Chemical Physics", "volume": "23", "number": "16", "publisher": "Royal Society of Chemistry", "pagerange": "9921-9929", "id_number": "CaltechAUTHORS:20210421-170248147", "issn": "1463-9076", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210421-170248147", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1144469" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "Swedish Research Council" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0021266" } ] }, "other_numbering_system": { "items": [ { "id": "1427", "name": "WAG" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1039/d1cp00545f", "primary_object": { "basename": "d1cp00545f.pdf", "url": "https://authors.library.caltech.edu/records/726pw-pv947/files/d1cp00545f.pdf" }, "related_objects": [ { "basename": "d1cp00545f1.pdf", "url": "https://authors.library.caltech.edu/records/726pw-pv947/files/d1cp00545f1.pdf" }, { "basename": "d1cp00545f2.xyz", "url": "https://authors.library.caltech.edu/records/726pw-pv947/files/d1cp00545f2.xyz" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Johnson, Samantha I.; Blakemore, James D.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sy8kc-v7d12", "eprint_id": 108391, "eprint_status": "archive", "datestamp": "2023-08-20 02:21:16", "lastmod": "2023-10-23 16:59:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Meier-Madeline-C", "name": { "family": "Meier", "given": "Madeline C." }, "orcid": "0000-0003-1608-0810" }, { "id": "Kennedy-Kathleen-M", "name": { "family": "Kennedy", "given": "Kathleen M." }, "orcid": "0000-0002-7125-4871" }, { "id": "Richter-Matthias-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Hamann-Kathryn-R", "name": { "family": "Hamann", "given": "Kathryn R." }, "orcid": "0000-0003-1163-7173" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Assessing Effects of Near-Field Synergistic Light Absorption on Ordered Inorganic Phototropic Growth", "ispublished": "pub", "full_text_status": "public", "keywords": "Morphology, Light absorption, Absorption, Toxicological synergy, Deposition", "note": "\u00a9 2021 American Chemical Society. \n\nReceived: December 18, 2020;\nPublished: March 8, 2021.\n\nThis work was supported by the National Science Foundation, Directorate for Mathematical & Physical Sciences, Division of Materials Research under Award Number DMR 1905963. The authors gratefully acknowledge J. R. Thompson and W.-H. Cheng for insightful discussions and R. Gerhart and N. Hart for assistance with photoelectrochemical cell fabrication. M.C.M. and K.R.H. acknowledge Graduate Research Fellowships from the National Science Foundation. M.C.M. also acknowledges the Resnick Sustainability Institute at Caltech for fellowship support. \n\nAuthor Contributions: A.I.C. and M.C.M. contributed equally. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - ja0c13085_si_001.pdf
", "abstract": "We report herein that synergistic light absorption in the optical near-field enables nanoscale self-organization during inorganic phototropic growth. Se\u2013Te was grown electrochemically under illumination from an incoherent, unstructured light source in geometrically constrained, wavelength scale areas. Despite the limited dimensions, with as few as two discrete features produced in a single sub-micron dimension, the deposit morphology exhibited defined order and anisotropy. Computer modeling analysis of light absorption in simulated structures revealed a synergy wherein light capture in a nanoscale feature was enhanced by the presence of additional adjacent features, with the synergistic effect originating predominantly from nearest neighbor contributions. Modeling moreover indicated that synergistic absorption is produced by scattering of the incident illumination by individual nanoscale features, leading to a local increase in the near-field intensity and consequently increasing the absorption in neighboring features. The interplay between these optical processes establishes the basis for spontaneous order generation via inorganic phototropic growth.", "date": "2021-03-17", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "143", "number": "10", "publisher": "American Chemical Society", "pagerange": "3693-3696", "id_number": "CaltechAUTHORS:20210311-085247183", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210311-085247183", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1905963" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1021/jacs.0c13085", "primary_object": { "basename": "ja0c13085_si_001.pdf", "url": "https://authors.library.caltech.edu/records/sy8kc-v7d12/files/ja0c13085_si_001.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Carim, Azhar I.; Meier, Madeline C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kh8r9-5a478", "eprint_id": 108282, "eprint_status": "archive", "datestamp": "2023-10-03 22:38:02", "lastmod": "2023-10-24 15:31:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jiang-Sheng", "name": { "family": "Jiang", "given": "S." }, "orcid": "0000-0002-0381-3846" }, { "id": "Link-A-James", "name": { "family": "Link", "given": "A." } }, { "id": "Canning-David", "name": { "family": "Canning", "given": "D." }, "orcid": "0000-0001-9576-2013" }, { "id": "Fooks-Julie-A", "name": { "family": "Fooks", "given": "J. A." }, "orcid": "0000-0002-3445-4727" }, { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "P. A." }, "orcid": "0000-0003-3909-1790" }, { "id": "Kerr-S", "name": { "family": "Kerr", "given": "S." } }, { "id": "Kim-Joohwan", "name": { "family": "Kim", "given": "J." }, "orcid": "0000-0002-5188-7815" }, { "id": "Krieger-M", "name": { "family": "Krieger", "given": "M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Wallace-R", "name": { "family": "Wallace", "given": "R." } }, { "id": "Williams-Gerald-Jackson", "name": { "family": "Williams", "given": "G. J." }, "orcid": "0000-0002-6495-5696" }, { "id": "Yalamanchili-Sisir", "name": { "family": "Yalamanchili", "given": "S." } }, { "id": "Chen-Hui", "name": { "family": "Chen", "given": "Hui" }, "orcid": "0000-0002-0181-1695" } ] }, "title": "Enhancing positron production using front surface target structures", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2021 Published under license by AIP Publishing. \n\nSubmitted: 19 November 2020; Accepted: 8 February 2021; Published Online: 2 March 2021. \n\nWe thank the OMEGA EP team for laser operation and technical support. This work was performed under the auspices of the U.S. DOE by LLNL under Contract No. DEAC5207NA27344, and funded by LDRD (No. 17ERD010). The fabrication of Si microwire arrays was supported through the Office of Science of the U.S. Department of Energy under Award No. DE- SC0004993. Additional support for this work was provided by the Lockheed Martin Corporation (Award No. 4103810021). We thank the staff at the Kavli Nanoscience Institute at Caltech for their technical assistance with fabrication. \n\nData Availability: The data that support the findings of this study are available from the corresponding author upon reasonable request.\n\nPublished - 094101_1_online.pdf
", "abstract": "We report a target design which produced a substantial gain in relativistic electron-positron pair production using high-intensity lasers and targets with large-scale micro-structures on their surface. Comparing to an unstructured target, a selected Si microwire array target yielded a near 100% increase in the laser-to-positron conversion efficiency and produced a 10\u2009MeV increase in the average emitted positron energy under nominally the same experimental conditions. We had established a multi-scale particle-in-cell simulation scheme to simulate both the laser absorption and the subsequent pair productions in a thick metal target. The experimental results are supported by the simulations demonstrating the performance increase is due to a higher conversion efficiency of laser energy into electrons with kinetic energies greater than 10\u2009MeV due to enhanced direct laser acceleration of electrons enabled by the microwire array.", "date": "2021-03-01", "date_type": "published", "publication": "Applied Physics Letters", "volume": "118", "number": "9", "publisher": "American Institute of Physics", "pagerange": "Art. No. 094101", "id_number": "CaltechAUTHORS:20210303-071742285", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210303-071742285", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC52-07NA27344" }, { "agency": "Los Alamos National Laboratory", "grant_number": "17ERD010" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Lockheed Martin", "grant_number": "4103810021" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1063/5.0038222", "primary_object": { "basename": "094101_1_online.pdf", "url": "https://authors.library.caltech.edu/records/kh8r9-5a478/files/094101_1_online.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Jiang, S.; Link, A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hb6vt-pe660", "eprint_id": 108060, "eprint_status": "archive", "datestamp": "2023-08-20 01:56:19", "lastmod": "2023-10-23 16:26:13", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Richter-Matthias-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Cheng-Wen-Hui", "name": { "family": "Cheng", "given": "Wen-Hui" }, "orcid": "0000-0003-3233-4606" }, { "id": "Crumlin-Ethan-J", "name": { "family": "Crumlin", "given": "Ethan J." }, "orcid": "0000-0003-3132-190X" }, { "id": "Drisdell-Walter-S", "name": { "family": "Drisdell", "given": "Walter S." }, "orcid": "0000-0002-8693-4562" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Schmei\u00dfer-Dieter", "name": { "family": "Schmei\u00dfer", "given": "Dieter" }, "orcid": "0000-0002-7560-2634" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" } ] }, "title": "X-ray Photoelectron Spectroscopy and Resonant X-ray Spectroscopy Investigations of Interactions between Thin Metal Catalyst Films and Amorphous Titanium Dioxide Photoelectrode Protection Layers", "ispublished": "pub", "full_text_status": "public", "keywords": "Oxides, Interfaces, Transition metals, Metals, Gold", "note": "\u00a9 2021 American Chemical Society. \n\nReceived: October 15, 2020; Revised: January 25, 2021; Published: February 11, 2021. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. Research was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE AC02 05CH11231. E.J.C. was partially supported by an Early Career Award in the Condensed Phase and Interfacial Molecular Science Program in the Chemical Sciences, Geosciences, and Biosciences Division of the Office of Basic Energy Sciences of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. M.H.R. and W.H.C. carried out the investigation; E.J.C., W.S.D., H.A.A., and D.S. provided support for synchrotron studies and general discussion. M.H.R., W.H.C., N.S.L., and B.S.B. wrote the manuscript; and N.S.L. and B.S.B supervised the study. \n\nAuthor Contributions: M.H.R. and W.H.C. contributed equally to this work. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - cm0c04043_si_001.pdf
", "abstract": "The use of electrochemistry, X-ray photoelectron spectroscopy, and resonant X-ray spectroscopy has unlocked the paradox of interfacial hole conduction through amorphous TiO\u2082 (a-TiO\u2082) to deposited Ni, Ir, and Au metal catalysts. Although electrocatalysts for the oxygen-evolution reaction derived from metallic Ir and Ni have mutually similar overpotentials in alkaline media, Si/a-TiO\u2082/Ir interfaces exhibit higher overpotentials than Si/a-TiO\u2082/Ni interfaces. The data allow formulation of full band energy diagrams for n-Si/a-TiO\u2082/metal interfaces for M = Ni, Ir, or Au. Although both Ni and Ir produce band bending in a-TiO\u2082 favoring hole conduction, only Ni creates multiple states within the a-TiO\u2082 band gap at the a-TiO\u2082/Ni interface, which produces a quasi-metallic interface at the a-TiO\u2082/Ni junction. Au, however, produces a flat-band interface that limits hole conduction without any new band gap states.", "date": "2021-02-23", "date_type": "published", "publication": "Chemistry of Materials", "volume": "33", "number": "4", "publisher": "American Chemical Society", "pagerange": "1265-1275", "id_number": "CaltechAUTHORS:20210216-100602720", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210216-100602720", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1021/acs.chemmater.0c04043", "primary_object": { "basename": "cm0c04043_si_001.pdf", "url": "https://authors.library.caltech.edu/records/hb6vt-pe660/files/cm0c04043_si_001.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Richter, Matthias H.; Cheng, Wen-Hui; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8z5cx-46068", "eprint_id": 107416, "eprint_status": "archive", "datestamp": "2023-08-22 08:36:51", "lastmod": "2023-10-23 15:52:08", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kennedy-Kathleen-M", "name": { "family": "Kennedy", "given": "Kathleen M." }, "orcid": "0000-0002-7125-4871" }, { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "Paul Andrew" }, "orcid": "0000-0003-3909-1790" }, { "id": "Cab\u00e1n-Acevedo-Miguel", "name": { "family": "Cab\u00e1n-Acevedo", "given": "Miguel" }, "orcid": "0000-0003-0054-8044" }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Primary Corrosion Processes for Polymer-Embedded Free-Standing or Substrate-Supported Silicon Microwire Arrays in Aqueous Alkaline Electrolytes", "ispublished": "pub", "full_text_status": "public", "keywords": "microwires; corrosion; solar fuels; membrane-embedded", "note": "\u00a9 2021 American Chemical Society. \n\nReceived: October 27, 2020; Revised: December 18, 2020; Published: January 6, 2021. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy-Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. We gratefully acknowledge the critical support and infrastructure provided for this work by the Kavli Nanoscience Institute at Caltech. \n\nAuthor Contributions: K.M.K. and P.K. conceived the idea and designed the study. P.K. fabricated the microwire arrays and contributed to figure design. K.M.K. performed the corrosion experiments, optical and SEM characterization, and wrote the text. M.C.A. performed the FIB studies and contributed substantially to the intellectual understanding of the corrosion process. K.M.P. wrote the Matlab code used to analyze the optical images and generate statistics. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nl0c04298_si_001.pdf
", "abstract": "Solar fuel devices have shown promise as a sustainable source of chemical fuels. However, long-term stability of light absorbing materials remains a substantial barrier to practical devices. Herein, multiple corrosion pathways in 1 M KOH(aq) have been defined for TiO\u2082-protected Si microwire arrays in a polymer membrane either attached to a substrate or free-standing. Top-down corrosion was observed in both morphologies through defects in the TiO\u2082 coating. For the substrate-based samples, bottom-up corrosion was observed through the substrate and up the adjacent wires. In the free-standing samples, uniform bottom-up corrosion was observed through the membrane with all wire material corroded within 10 days of immersion in the dark in 1 M KOH(aq).", "date": "2021-01-27", "date_type": "published", "publication": "Nano Letters", "volume": "21", "number": "2", "publisher": "American Chemical Society", "pagerange": "1056-1061", "id_number": "CaltechAUTHORS:20210112-091401361", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210112-091401361", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acs.nanolett.0c04298", "primary_object": { "basename": "nl0c04298_si_001.pdf", "url": "https://authors.library.caltech.edu/records/8z5cx-46068/files/nl0c04298_si_001.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Kennedy, Kathleen M.; Kempler, Paul Andrew; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qz1zk-egz88", "eprint_id": 106496, "eprint_status": "archive", "datestamp": "2023-08-20 01:29:06", "lastmod": "2023-10-20 23:33:05", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Banin-U", "name": { "family": "Banin", "given": "U." }, "orcid": "0000-0003-1698-2128" }, { "id": "Waiskopf-N", "name": { "family": "Waiskopf", "given": "N" } }, { "id": "Hammarstr\u00f6m-L", "name": { "family": "Hammarstr\u00f6m", "given": "L." }, "orcid": "0000-0002-9933-9084" }, { "id": "Boschloo-G", "name": { "family": "Boschloo", "given": "G." } }, { "id": "Freitag-M", "name": { "family": "Freitag", "given": "M." } }, { "id": "Johansson-E-M-J", "name": { "family": "Johansson", "given": "E. M. J." } }, { "id": "S\u00e1-J", "name": { "family": "S\u00e1", "given": "J." }, "orcid": "0000-0003-2124-9510" }, { "id": "Tian-Haining", "name": { "family": "Tian", "given": "H." }, "orcid": "0000-0001-6897-2808" }, { "id": "Johnston-M-B", "name": { "family": "Johnston", "given": "M. B." }, "orcid": "0000-0002-0301-8033" }, { "id": "Herz-L-M", "name": { "family": "Herz", "given": "L. M." }, "orcid": "0000-0001-9621-334X" }, { "id": "Milot-R-L", "name": { "family": "Milot", "given": "R. L." } }, { "id": "Kanatzidis-M-G", "name": { "family": "Kanatzidis", "given": "M. G." }, "orcid": "0000-0003-2037-4168" }, { "id": "Ke-W", "name": { "family": "Ke", "given": "W." } }, { "id": "Spanopoulos-I", "name": { "family": "Spanopoulos", "given": "I." } }, { "id": "Kohlstedt-K-L", "name": { "family": "Kohlstedt", "given": "K. L." }, "orcid": "0000-0001-8045-0930" }, { "id": "Schatz-G-C", "name": { "family": "Schatz", "given": "G. C." }, "orcid": "0000-0001-5837-4740" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N." }, "orcid": "0000-0001-5245-0538" }, { "id": "Meyer-T", "name": { "family": "Meyer", "given": "T." }, "orcid": "0000-0002-7006-2608" }, { "id": "Nozik-A-J", "name": { "family": "Nozik", "given": "A. J." }, "orcid": "0000-0001-7176-7645" }, { "id": "Beard-M-C", "name": { "family": "Beard", "given": "M. C." }, "orcid": "0000-0002-2711-1355" }, { "id": "Armstrong-F", "name": { "family": "Armstrong", "given": "F." }, "orcid": "0000-0001-8041-2491" }, { "id": "Megarity-C-F", "name": { "family": "Megarity", "given": "C. F." } }, { "id": "Schmuttenmaer-C-A", "name": { "family": "Schmuttenmaer", "given": "C. A." }, "orcid": "0000-0001-9992-8578" }, { "id": "Batista-V-S", "name": { "family": "Batista", "given": "V. S." }, "orcid": "0000-0002-3262-1237" }, { "id": "Brudvig-G-W", "name": { "family": "Brudvig", "given": "G. W." }, "orcid": "0000-0002-7040-1892" } ] }, "title": "Nanotechnology for catalysis and solar energy conversion", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 The Author(s). Published by IOP Publishing Ltd.\nOriginal content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. \n\nReceived 11 May 2020; Revised 11 September 2020; Accepted 30 September 2020; Published 5 November 2020. \n\nThis work was supported by the Israel Science Foundation (Grant No. 1867/17). U B thanks the Alfred & Erica Larisch memorial chair. \n\nThis work was supported by ONR Grant N00014-20-1-2725. \n\nThe authors acknowledge the support by the Center for Light Energy Activated Redox Processes (LEAP) Energy Frontier Research Center under the award DE-SC0001059. \n\nThe Department of Energy, Office of Basic Energy Sciences, grant DE-FG02-03ER15483, and the Department of Energy, Office of Science, through the Joint Center for Artificial Photosynthesis, award SC-0004993, are acknowledged for support that made preparation of this manuscript possible. \n\nSupport from the Solar Photochemistry program within the Division of Chemical Sciences, Geosciences, and Biosciences in the Office of Basic Energy of the Department of Energy is acknowledged. DOE funding was provided to NREL through Contract DE-AC36-086038308. \n\nC F M and F A A are supported by a grant (CF 327) from the EPA Cephalosporin Fund.\n\nPublished - Banin_2021_Nanotechnology_32_042003.pdf
", "abstract": "This roadmap on Nanotechnology for Catalysis and Solar Energy Conversion focuses on the application of nanotechnology in addressing the current challenges of energy conversion: 'high efficiency, stability, safety, and the potential for low-cost/scalable manufacturing' to quote from the contributed article by Nathan Lewis. This roadmap focuses on solar-to-fuel conversion, solar water splitting, solar photovoltaics and bio-catalysis. It includes dye-sensitized solar cells (DSSCs), perovskite solar cells, and organic photovoltaics. Smart engineering of colloidal quantum materials and nanostructured electrodes will improve solar-to-fuel conversion efficiency, as described in the articles by Waiskopf and Banin and Meyer. Semiconductor nanoparticles will also improve solar energy conversion efficiency, as discussed by Boschloo et al in their article on DSSCs. Perovskite solar cells have advanced rapidly in recent years, including new ideas on 2D and 3D hybrid halide perovskites, as described by Spanopoulos et al 'Next generation' solar cells using multiple exciton generation (MEG) from hot carriers, described in the article by Nozik and Beard, could lead to remarkable improvement in photovoltaic efficiency by using quantization effects in semiconductor nanostructures (quantum dots, wires or wells). These challenges will not be met without simultaneous improvement in nanoscale characterization methods. Terahertz spectroscopy, discussed in the article by Milot et al is one example of a method that is overcoming the difficulties associated with nanoscale materials characterization by avoiding electrical contacts to nanoparticles, allowing characterization during device operation, and enabling characterization of a single nanoparticle. Besides experimental advances, computational science is also meeting the challenges of nanomaterials synthesis. The article by Kohlstedt and Schatz discusses the computational frameworks being used to predict structure\u2013property relationships in materials and devices, including machine learning methods, with an emphasis on organic photovoltaics. The contribution by Megarity and Armstrong presents the 'electrochemical leaf' for improvements in electrochemistry and beyond. In addition, biohybrid approaches can take advantage of efficient and specific enzyme catalysts. These articles present the nanoscience and technology at the forefront of renewable energy development that will have significant benefits to society.", "date": "2021-01-22", "date_type": "published", "publication": "Nanotechnology", "volume": "32", "number": "4", "publisher": "IOP", "pagerange": "Art. No. 042003", "id_number": "CaltechAUTHORS:20201106-130122089", "issn": "0957-4484", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201106-130122089", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Israel Science Foundation", "grant_number": "1867/17" }, { "agency": "Alfred and Erica Larisch memorial chair" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-20-1-2725" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001059" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC36-086038308" }, { "agency": "EPA Cephalosporin Fund", "grant_number": "CF 327" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1088/1361-6528/abbce8", "primary_object": { "basename": "Banin_2021_Nanotechnology_32_042003.pdf", "url": "https://authors.library.caltech.edu/records/qz1zk-egz88/files/Banin_2021_Nanotechnology_32_042003.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Banin, U.; Waiskopf, N; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zaj0j-qem58", "eprint_id": 107175, "eprint_status": "archive", "datestamp": "2023-08-20 01:21:38", "lastmod": "2023-10-23 15:37:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shen-Xin", "name": { "family": "Shen", "given": "Xin" } }, { "id": "Yao-Maoqing", "name": { "family": "Yao", "given": "Maoqing" } }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Zhao-Tianshuo", "name": { "family": "Zhao", "given": "Tianshuo" } }, { "id": "He-Yulian", "name": { "family": "He", "given": "Yulian" } }, { "id": "Chi-Chun-Yung", "name": { "family": "Chi", "given": "Chun-Yung" } }, { "id": "Zhou-Chongwu", "name": { "family": "Zhou", "given": "Chongwu" }, "orcid": "0000-0001-8448-8450" }, { "id": "Dapkus-Paul-D", "name": { "family": "Dapkus", "given": "Paul Daniel" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" } ] }, "title": "Defect-Tolerant TiO\u2082-Coated and Discretized Photoanodes for >600 h of Stable Photoelectrochemical Water Oxidation", "ispublished": "pub", "full_text_status": "public", "keywords": "Photonics, Oxides, Absorption, Nanowires, Gallium arsenide", "note": "\u00a9 2020 American Chemical Society. \n\nReceived: December 3, 2020; Accepted: December 9, 2020; Published: December 16, 2020. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, and under Award Number DE-SC0001013 to the Center for Energy Nanoscience, an Energy Frontier Research Center (EFRC). We thank the Materials Characterization Core at Yale West Campus for SEM characterization. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nz0c02521_si_001.pdf
", "abstract": "Arrays of GaAs nanowires have been grown by selective-area metal\u2013organic chemical-vapor deposition (MOCVD) onto photoactive planar Si substrates. This tandem, vertical-wire-array-on-planar absorber was then coated by atomic layer deposition (ALD) of an amorphous TiO\u2082 (a-TiO\u2082) stabilization layer, followed by deposition of a NiO_x electrocatalyst layer. The tandem planar Si/nanowire GaAs/a-TiO\u2082/NiO_x photoanodes exhibited continuous solar-driven water oxidation in 1.0 M KOH(aq) for over 600 h without substantial photocurrent decay. The preservation of the nanowire morphology and structural integrity during >600 h of photoanodic operation confirms the benefits of mitigating and isolating nanoscale defects via the architecture of discretized absorbers on a self-passivating and insulating substrate. Nanoscale morphology and compositions of the photoanode after 600 h of testing were characterized to reveal the self-limiting corrosion behavior. It provides a promising approach to develop efficient but otherwise unstable absorbers such as III\u2013V materials into defect-tolerant, corrosion-resistant photoanodes.", "date": "2021-01-08", "date_type": "published", "publication": "ACS Energy Letters", "volume": "6", "number": "1", "publisher": "American Chemical Society", "pagerange": "193-200", "id_number": "CaltechAUTHORS:20201217-143607686", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201217-143607686", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001013" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acsenergylett.0c02521", "primary_object": { "basename": "nz0c02521_si_001.pdf", "url": "https://authors.library.caltech.edu/records/zaj0j-qem58/files/nz0c02521_si_001.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Shen, Xin; Yao, Maoqing; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/np129-58b77", "eprint_id": 106813, "eprint_status": "archive", "datestamp": "2023-08-20 01:19:34", "lastmod": "2023-10-20 23:49:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "Paul A." }, "orcid": "0000-0003-3909-1790" }, { "id": "Ifkovits-Zachary-P", "name": { "family": "Ifkovits", "given": "Zachary P." } }, { "id": "Yu-Weilai", "name": { "family": "Yu", "given": "Weilai" }, "orcid": "0000-0002-9420-0702" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Optical and electrochemical effects of H\u2082 and O\u2082 bubbles at upward-facing Si photoelectrodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 The Royal Society of Chemistry. \n\nSubmitted 31 Aug 2020; Accepted 12 Nov 2020; First published\t12 Nov 2020. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. Silicon microwire arrays were fabricated in the Kavli Nanoscience Institute (KNI) at Caltech; we thank the KNI staff for their assistance with fabrication. We are grateful to Rick Gerhart for assistance in fabricating glassware for solar simulations. Additional instrumentation was provided by the Molecular Materials Research Center in the Beckman Institute at Caltech. We appreciate Bruce Brunschwig for providing helpful feedback on the manuscript. \n\nAuthor contributions: Si-\u03bcW Fabrication, P. A. K., Metallization, Z. P. I., Atomic Layer Deposition, W. Y., Scanning-Electron Microscopy, A. I. C., Investigation, P. A. K.; Writing \u2013 Original Draft, P. A. K. and N. S. L., Writing \u2013 Review and Editing, P. A. K., N. S. L., Z. P. I., W. Y., A. I. C., Funding Acquisition, N. S. L. Supervision, N. S. L. \n\nThe authors declare no competing interests.\n\nSupplemental Material - d0ee02796k1.pdf
Supplemental Material - d0ee02796k2.mp4
Supplemental Material - d0ee02796k3.mp4
", "abstract": "The effects of the size, contact-angle, and coverage of gas bubbles on solar fuels devices were characterized at cm-scale, upward-facing planar and microwire-array Si photoelectrodes in stagnant electrolytes. Experimental measurements were supported by ray-tracing simulations of surface attached gas bubble films. A dilute, redox-active tracer allowed for the quantification of the mass-transport effects of bubble coverage during photoanodic O\u2082 (g) evolution at upward-facing photoanodes in 1.0 M KOH(aq.). Measurements of the gas coverage at upward-facing p-Si photocathodes in 0.50 M H\u2082SO\u2084 (aq.) allowed for the nucleation rate and contact angle of H\u2082 (g) bubbles to be evaluated for systems having various surface free energies. Under simulated solar illumination, the rapid departure of small O\u2082 (g) bubbles produced stable photocurrents at upward-facing oxygen-evolving Si photoanodes and yielded increased mass-transport velocities relative to a stagnant electrolyte, indicating that bubbles can provide a net benefit to the photoelectrochemical performance of an upward-facing photoanode in solar fuels devices.", "date": "2021-01-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "14", "number": "1", "publisher": "Royal Society of Chemistry", "pagerange": "414-423", "id_number": "CaltechAUTHORS:20201124-121041867", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201124-121041867", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/d0ee02796k", "primary_object": { "basename": "d0ee02796k2.mp4", "url": "https://authors.library.caltech.edu/records/np129-58b77/files/d0ee02796k2.mp4" }, "related_objects": [ { "basename": "d0ee02796k3.mp4", "url": "https://authors.library.caltech.edu/records/np129-58b77/files/d0ee02796k3.mp4" }, { "basename": "d0ee02796k1.pdf", "url": "https://authors.library.caltech.edu/records/np129-58b77/files/d0ee02796k1.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Kempler, Paul A.; Ifkovits, Zachary P.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7yq0c-jr491", "eprint_id": 107151, "eprint_status": "archive", "datestamp": "2023-08-22 07:56:25", "lastmod": "2023-10-23 15:35:33", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yuan-Mengyao", "name": { "family": "Yuan", "given": "Mengyao" }, "orcid": "0000-0002-5923-4085" }, { "id": "Tong-Fan", "name": { "family": "Tong", "given": "Fan" }, "orcid": "0000-0003-4661-3956" }, { "id": "Duan-Lei", "name": { "family": "Duan", "given": "Lei" } }, { "id": "Dowling-Jacqueline-A", "name": { "family": "Dowling", "given": "Jacqueline A." }, "orcid": "0000-0001-5642-8960" }, { "id": "Davis-Steven-J", "name": { "family": "Davis", "given": "Steven J." }, "orcid": "0000-0002-9338-0844" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Caldeira-Ken", "name": { "family": "Caldeira", "given": "Ken" }, "orcid": "0000-0002-4591-643X" } ] }, "title": "Would firm generators facilitate or deter variable renewable energy in a carbon-free electricity system?", "ispublished": "pub", "full_text_status": "public", "keywords": "Net-zero electricity systems; Firm carbon-free electricity generation; Variable renewable energy", "note": "\u00a9 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). \n\nReceived 12 June 2020; Received in revised form 23 August 2020; Accepted 25 August 2020. \n\nThe authors would like to thank Mehdi Shahriari for early contributions to the model code, David J. Farnham for providing helpful insights, and Leslie Willoughby for editing the manuscript. We acknowledge support from a gift from Gates Ventures LLC, United States to the Carnegie Institution for Science. \n\nCRediT authorship contribution statement: Mengyao Yuan: Formal analysis, Methodology, Writing - original draft, Writing - review & editing. Fan Tong: Methodology, Writing - review & editing. Lei Duan: Methodology, Writing - review & editing. Jacqueline A. Dowling: Writing - review & editing. Steven J. Davis: Writing - review & editing. Nathan S. Lewis: Conceptualization, Writing - review & editing. Ken Caldeira: Conceptualization, Methodology, Funding acquisition, Supervision, Writing - review & editing. \n\nThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\n\nPublished - 1-s2.0-S0306261920312733-main.pdf
", "abstract": "To reduce atmospheric carbon dioxide emissions and mitigate impacts of climate change, countries across the world have mandated quotas for renewable electricity. But a question has remained largely unexplored: would low-cost, firm, zero-carbon electricity generation technologies enhance\u2014or would they displace\u2014deployment of variable renewable electricity generation technologies, i.e., wind and solar photovoltaics, in a least-cost, fully reliable, and deeply decarbonized electricity system? To address this question, we modeled idealized electricity systems based on historical weather data and considered only technoeconomic factors. We did not apply a predetermined use model. We found that cost reductions in firm generation technologies (starting at current costs, ramping down to nearly zero) uniformly resulted in increased penetration of the firm technologies and decreased penetration of variable renewable electricity generation, in electricity systems where technology deployment is primarily driven by relative costs, and across a wide array of future technology cost assumptions. Similarly, reduced costs of variable renewable electricity (starting at current costs, ramping down to nearly zero) drove out firm generation technologies. Yet relative to deployment of \"must-run\" firm generation technologies, and when the studied firm technologies have high fixed costs relative to variable costs, the addition of flexibility to firm generation technologies had only limited impacts on the system cost, less than a 9% system cost reduction in our idealized model. These results reveal that policies and funding that support particular technologies for low- or zero-carbon electricity generation can inhibit the development of other low- or zero-carbon alternatives.", "date": "2020-12-01", "date_type": "published", "publication": "Applied Energy", "volume": "279", "publisher": "Elsevier", "pagerange": "Art. No. 115789", "id_number": "CaltechAUTHORS:20201217-103829489", "issn": "0306-2619", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201217-103829489", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Gates Ventures LLC" } ] }, "doi": "10.1016/j.apenergy.2020.115789", "primary_object": { "basename": "1-s2.0-S0306261920312733-main.pdf", "url": "https://authors.library.caltech.edu/records/7yq0c-jr491/files/1-s2.0-S0306261920312733-main.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Yuan, Mengyao; Tong, Fan; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0v5gm-mgt86", "eprint_id": 106587, "eprint_status": "archive", "datestamp": "2023-08-20 00:29:39", "lastmod": "2023-10-20 23:36:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Simonoff-Ethan", "name": { "family": "Simonoff", "given": "Ethan" }, "orcid": "0000-0002-2156-8602" }, { "id": "Van-Mu\u00f1oz-L-X", "name": { "family": "Van Mu\u00f1oz", "given": "Lorenzo X." }, "orcid": "0000-0003-0807-5034" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Increased spatial randomness and disorder of nucleates in dark-phase electrodeposition lead to increased spatial order and pattern fidelity in phototropically grown Se\u2013Te electrodeposits", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 The Royal Society of Chemistry. \n\nSubmitted 23 Oct 2020; Accepted 27 Oct 2020; First published\t30 Oct 2020. \n\nThis work was supported by the National Science Foundation under Award Number DMR1905963. The authors acknowledge Kathryn R. Hamann for assistance with image collection. L. X. V. M. acknowledges financial support from the Richard H. Cox SURF Fellowship. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - d0nr07617a1.pdf
", "abstract": "The role of nucleation was investigated during phototropic growth of Se\u2013Te. Under low levels of mass deposition (mass equivalent of \u22123.75 mC cm\u207b\u00b2 of charge passed) that produced small nucleate spacings, patterns in photoelectrochemically deposited Se\u2013Te films converged at relatively earlier levels of mass deposition and ultimately exhibited higher pattern fidelity throughout pattern development as compared to pattern formation from larger initial nucleate spacings. Consistently, use of an applied striking potential during very early levels of mass deposition produced more spatially random dark-phase electrodeposited nucleates and led to phototropic Se\u2013Te photoelectrodeposited films that exhibited improved pattern fidelity relative to depositions performed with no striking step. Collectively, the data indicate that increases in randomness and spatial disorder of the dispersion of the initial nucleates produces increases in the fidelity and spatial order in the resulting phototropically grown electrodeposits.", "date": "2020-11-28", "date_type": "published", "publication": "Nanoscale", "volume": "12", "number": "44", "publisher": "Royal Society of Chemistry", "pagerange": "22478-22486", "id_number": "CaltechAUTHORS:20201110-101255735", "issn": "2040-3364", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201110-101255735", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1905963" }, { "agency": "Caltech Summer Undergraduate Research Fellowship (SURF)" } ] }, "doi": "10.1039/d0nr07617a", "primary_object": { "basename": "d0nr07617a1.pdf", "url": "https://authors.library.caltech.edu/records/0v5gm-mgt86/files/d0nr07617a1.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Simonoff, Ethan; Van Mu\u00f1oz, Lorenzo X.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zkxdz-e5z50", "eprint_id": 106643, "eprint_status": "archive", "datestamp": "2023-08-20 00:28:42", "lastmod": "2023-10-20 23:39:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hamann-Kathryn-R", "name": { "family": "Hamann", "given": "Kathryn R." }, "orcid": "0000-0003-1163-7173" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Meier-Madeline-C", "name": { "family": "Meier", "given": "Madeline C." }, "orcid": "0000-0003-1608-0810" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Path-Dependent Morphological Evolution of Se\u2013Te Mesostructures Prepared by Inorganic Phototropic Growth", "ispublished": "pub", "full_text_status": "public", "keywords": "Morphology, Crystallization, Absorption, Deposition, Quantum mechanics", "note": "\u00a9 2020 American Chemical Society. \n\nReceived: September 13, 2020;\nPublished: November 11, 2020.\n\nThis work was supported by the \"Light-Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-SC0001293 and was also supported by the National Science Foundation, Directorate for Mathematical & Physical Sciences, Division of Materials Research, under Award Number DMR 1905963. The authors gratefully acknowledge J. Thompson for insightful discussions, E. Simonoff and S. Yalamanchili for assistance with substrate preparation, and R. Gerhart, N. Hart, and B. Markowicz for assistance with photoelectrochemical cell fabrication. K.R.H. and M.C.M. acknowledge Graduate Research Fellowships from the National Science Foundation. M.C.M. also acknowledges the Resnick Sustainability Institute at Caltech for fellowship support. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - ja0c09798_si_001.pdf
", "abstract": "We describe herein a path-dependent \"history\" effect wherein the film morphology generated in the second step of a two-step inorganic phototropic growth process depends on a preexisting structure that has been first grown under different optical stimulation conditions. Se\u2013Te generated with static illumination exhibited a highly anisotropic lamellar morphology with a characteristic feature pitch proportional to the input wavelength. Growth using first a short wavelength of light, followed by growth using a longer wavelength, resulted in the second-stage morphology exhibiting termination of lamellae formed during the first growth step. The lamellar pitch at the end of the second growth step was larger than that effected in the first step. In contrast, use of the same input wavelengths but in the opposite order produced no change in the feature pitch but rather only linear feature extension. Analysis of light absorption in simulated structures, in tandem with the empirical data, indicated that the history effect and asymmetric path dependence are a result of emergent nanophotonic processes at the growth interface that dynamically shape the optical field and direct morphological evolution of the photodeposit in a continuous feedback loop.", "date": "2020-11-25", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "142", "number": "47", "publisher": "American Chemical Society", "pagerange": "19840-19843", "id_number": "CaltechAUTHORS:20201112-103612027", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201112-103612027", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "NSF", "grant_number": "DMR-1905963" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1021/jacs.0c09798", "primary_object": { "basename": "ja0c09798_si_001.pdf", "url": "https://authors.library.caltech.edu/records/zkxdz-e5z50/files/ja0c09798_si_001.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Hamann, Kathryn R.; Carim, Azhar I.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/d9826-7xc92", "eprint_id": 104651, "eprint_status": "archive", "datestamp": "2023-08-20 00:20:18", "lastmod": "2023-10-20 20:41:53", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" }, "orcid": "0000-0002-2955-9671" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" } ] }, "title": "Modeling the Performance of A Flow-Through Gas Diffusion Electrode for Electrochemical Reduction of CO or CO\u2082", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 The Electrochemical Society (\"ECS\"). Published on behalf of ECS by IOP Publishing Limited. \n\nReceived 15 January 2020; Accepted Manuscript online 1 June 2020; Published 1 July 2020. \n\nThis material is based on work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.\n\nPublished - Chen_2020_J._Electrochem._Soc._167_114503.pdf
Supplemental Material - JES_167_11_114503_suppdata.pdf
", "abstract": "A flow-through gas diffusion electrode (GDE) consisting of agglomerate catalysts for CO or CO\u2082 reduction, gas channels for reactants, aqueous electrolytes for ionic transport, and metallic current collectors was simulated and evaluated using a numerical model. The geometric partial current densities and Faradaic Efficiencies (FE) for CH\u2084, C\u2082H\u2084 and H\u2082 generation in GDEs were calculated and compared to the behavior of analogous aqueous-based planar electrodes. The pH-dependent kinetics for CH\u2084 and C\u2082H\u2084 generation were used to represent the intrinsic catalytic characteristics for the agglomerate catalyst. The modeling indicated that relative to planar electrodes for either CO reduction (COR) or CO\u2082 reduction (CO\u2082R), substantial increases in electrochemical reduction rates and Faradaic efficiencies are expected when flow-through GDEs are used. The spatially resolved pH and reaction rates within the flow-through GDEs were also simulated for two different operating pHs, and the resulting transport losses were analyzed quantitatively. For CO\u2082 reduction, substantial loss of CO\u2082 via chemical reaction with the locally alkaline electrolyte was observed due to the increased pH in operating GDEs.", "date": "2020-11-11", "date_type": "published", "publication": "Journal of The Electrochemical Society", "volume": "167", "number": "11", "publisher": "The Electrochemical Society", "pagerange": "Art. No. 114503", "id_number": "CaltechAUTHORS:20200730-073238681", "issn": "1945-7111", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200730-073238681", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1149/1945-7111/ab987a", "primary_object": { "basename": "Chen_2020_J._Electrochem._Soc._167_114503.pdf", "url": "https://authors.library.caltech.edu/records/d9826-7xc92/files/Chen_2020_J._Electrochem._Soc._167_114503.pdf" }, "related_objects": [ { "basename": "JES_167_11_114503_suppdata.pdf", "url": "https://authors.library.caltech.edu/records/d9826-7xc92/files/JES_167_11_114503_suppdata.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Chen, Yikai; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cwck3-r7h84", "eprint_id": 106114, "eprint_status": "archive", "datestamp": "2023-08-20 00:12:26", "lastmod": "2023-10-20 23:06:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Fu-Harold-J", "name": { "family": "Fu", "given": "Harold J." }, "orcid": "0000-0001-9738-209X" }, { "id": "Moreno-Hernandez-I-A", "name": { "family": "Moreno-Hernandez", "given": "Ivan A." }, "orcid": "0000-0001-6461-9214" }, { "id": "Buabthong-Pakpoom", "name": { "family": "Buabthong", "given": "Pakpoom" }, "orcid": "0000-0001-5538-138X" }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Enhanced stability of silicon for photoelectrochemical water oxidation through self-healing enabled by an alkaline protective electrolyte", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 Royal Society of Chemistry 2020. \n\nSubmitted 16 Jul 2020; Accepted 06 Oct 2020; First published 06 Oct 2020. \n \nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. Research was in part carried out at the Molecular Materials Resource Center of the Beckman Institute. We thank M. H. Richter for assistance in automating day/night cycles. \n\nThere are no conflicts to declare.\n\nSupplemental Material - d0ee02250k1.pdf
", "abstract": "Alkaline electrolytes impede the corrosion of Si photoanodes under positive potentials and/or illumination, due to the formation of a SiO_x layer that etches 2\u20133 orders of magnitude more slowly than Si. Hence during water oxidation under illumination, pinholes in protection layers on Si photoanodes result in the local formation of a protective, stabilizing passive oxide on the Si surface. However, operation under natural diurnal insolation cycles additionally requires protection strategies that minimize the dark corrosive etching rate of Si at pinholes. We show herein that addition of [Fe(CN)\u2086]\u00b3\u207b to 1.0 M KOH(aq) results in a self-healing process that extends the lifetime to >280 h of an np\u207a-Si(100) photoanode patterned with an array of Ni catalyst islands operated under simulated day/night cycles. The self-healing [Fe(CN)\u2086]\u00b3\u207b additive caused the exposed Si(100) surface to etch >180 times slower than the Si etch rate in 1.0 M KOH(aq) alone. No appreciable difference in etch rate or facet preference was observed between Si(100) and Si(111) surfaces in 1.0 M KOH(aq) with [Fe(CN)\u2086]\u00b3\u207b, indicating that the surface conformally oxidized before Si dissolved. The presence of [Fe(CN)\u2086]\u00b3\u207b minimally impacted the faradaic efficiency or overpotential of p\u207a-Si/Ni electrodes for the oxygen-evolution reaction.", "date": "2020-11-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "13", "number": "11", "publisher": "Royal Society of Chemistry", "pagerange": "4132-4141", "id_number": "CaltechAUTHORS:20201016-131847563", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201016-131847563", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/d0ee02250k", "primary_object": { "basename": "d0ee02250k1.pdf", "url": "https://authors.library.caltech.edu/records/cwck3-r7h84/files/d0ee02250k1.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Fu, Harold J.; Moreno-Hernandez, Ivan A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/na9zw-j5x42", "eprint_id": 105852, "eprint_status": "archive", "datestamp": "2023-08-20 00:12:17", "lastmod": "2023-10-20 22:29:31", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Buabthong-Pakpoom", "name": { "family": "Buabthong", "given": "Pakpoom" }, "orcid": "0000-0001-5538-138X" }, { "id": "Ifkovits-Zachary-P", "name": { "family": "Ifkovits", "given": "Zachary P." } }, { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "Paul A." }, "orcid": "0000-0003-3909-1790" }, { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" }, "orcid": "0000-0002-2955-9671" }, { "id": "Nunez-Paul-D", "name": { "family": "Nunez", "given": "Paul D." }, "orcid": "0000-0001-7039-0516" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Failure modes of protection layers produced by atomic layer deposition of amorphous TiO\u2082 on GaAs anodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 The Royal Society of Chemistry. \n\nSubmitted 26 Jun 2020; Accepted 23 Sep 2020; First published 23 Sep 2020. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. We gratefully acknowledge a gift from the Lam Research Unlock Ideas program. Deposition of a-TiO\u2082 in a cleanroom was performed in the Kavli Nanoscience Institute (KNI) at Caltech, and we thank the KNI staff for their assistance during fabrication. \n\nThere are no conflicts of interest to declare.\n\nSupplemental Material - d0ee02032j1.pdf
", "abstract": "Amorphous titanium dioxide (a-TiO\u2082) films formed by atomic layer deposition can serve as protective coatings for semiconducting photoanodes in water-splitting cells using strongly alkaline aqueous electrolytes. Herein, we experimentally examine the mechanisms of failure for p\u207a-GaAs anodes coated with a-TiO\u2082 films (GaAs/a-TiO\u2082). Galvanic displacement of exposed GaAs by Au allowed imaging of pinholes in the a-TiO\u2082 coatings, and enabled collection of quantitative and statistical data associated with pinhole defects. A combination of imaging, electrochemical measurements, and quantitative analyses of corrosion products indicated that extrinsic pinholes were present in the a-TiO\u2082 films before electrochemical operation. During electrochemical operation these pinholes led to pitting corrosion of the underlying GaAs substrate. The dominant source of pinholes was the presence of atmospheric particulate matter on the GaAs surface during deposition of the a-TiO\u2082 layer. The pinhole density decreased substantially when the thickness of the a-TiO\u2082 coating increased beyond 45 nm, and approached zero when the thickness of the film exceeded 112 nm. The density of pinholes in films thinner than 45 nm decreased when the a-TiO\u2082 coating was deposited in an environmentally controlled cleanroom. Pinhole-free GaAs/a-TiO\u2082 devices were also tested via chronoamperometry to quantify the rate of pinhole formation during electrochemistry. The time-to-failure increased with thickness, suggesting that the failure mechanism may involve diffusion or migration through the film. However, other mechanisms may also contribute to the degradation of thicker films (>112 nm). Nevertheless, as previously hypothesized, extrinsic pinhole defects formed during deposition and testing control the short-term protective performance of the a-TiO\u2082 film for GaAs anodes evolving O\u2082 from water.", "date": "2020-11-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "13", "number": "11", "publisher": "Royal Society of Chemistry", "pagerange": "4269-4279", "id_number": "CaltechAUTHORS:20201007-073929719", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201007-073929719", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/d0ee02032j", "primary_object": { "basename": "d0ee02032j1.pdf", "url": "https://authors.library.caltech.edu/records/na9zw-j5x42/files/d0ee02032j1.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Buabthong, Pakpoom; Ifkovits, Zachary P.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0cyx0-8rq40", "eprint_id": 104974, "eprint_status": "archive", "datestamp": "2023-08-19 23:43:48", "lastmod": "2023-10-20 21:01:05", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yu-Weilai", "name": { "family": "Yu", "given": "Weilai" }, "orcid": "0000-0002-9420-0702" }, { "id": "Buabthong-Pakpoom", "name": { "family": "Buabthong", "given": "Pakpoom" }, "orcid": "0000-0001-5538-138X" }, { "id": "Read-Carlos-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Dalleska-N-F", "name": { "family": "Dalleska", "given": "Nathan F." }, "orcid": "0000-0002-2059-1587" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Lewerenz-Hans-Joachim", "name": { "family": "Lewerenz", "given": "Hans-Joachim" }, "orcid": "0000-0001-8433-9471" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-4453-9716" }, { "id": "Brinkert-Katharina", "name": { "family": "Brinkert", "given": "Katharina" }, "orcid": "0000-0002-3593-5047" } ] }, "title": "Cathodic NH\u2084\u207a leaching of nitrogen impurities in CoMo thin-film electrodes in aqueous acidic solutions", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 The Royal Society of Chemistry. \n\nSubmitted 01 May 2020; Accepted 05 Aug 2020; First published 05 Aug 2020. \n\nK. B. acknowledges funding from the fellowship program of the German National Academy of Sciences \u2013 Leopoldina, grant LPDS 2016-06. Acknowledgment is made to the donors of The American Chemical Society Petroleum Research Fund for partial support of this research. Sample preparation and analyses were performed at the Joint Center for Artificial Photosynthesis, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993, which also provided support for N. S. L., W. Y., P. B. and C. G. R. We acknowledge use of instrumentation in the Molecular Materials Research Center of the Beckman Institute at Caltech. N. F. D. is grateful to the Linde Center for support. The Environmental Analysis Center is supported by the Beckman Institute at Caltech. W. Y. and C. G. R. acknowledge the Resnick Sustainability Institute at Caltech for fellowship support. Dr Fabai Wu and Prof. Victoria Orphan are acknowledged for providing the \u00b9\u2075NH\u2084Cl standard reagent for UPLC-MS analysis. Mr Christopher Kenseth is thanked for assistance with UPLC-MS analysis. Dr Yuanlong Huang is acknowledged for assistance with chemiluminescence analysis. All authors would like to acknowledge the reviewers for their valuable comments in the first round. \n\nThere are no conflicts to declare.\n\nSupplemental Material - d0se00674b1.pdf
", "abstract": "Electrocatalytic reduction of dinitrogen (N\u2082) to ammonium (NH\u2084\u207a) in acidic aqueous solutions was investigated at ambient temperature and pressure using a cobalt\u2013molybdenum (CoMo) thin-film electrode prepared by magnetron reactive sputtering. Increased concentrations of ammonium ions (NH\u2084\u207a) were consistently detected in the electrolyte using ion chromatography (IC) after constant-potential electrolysis at various potentials (\u2264\u22120.29 V vs. RHE). Using a newly developed analytical method based on ammonia derivatization, performing the experiments with \u00b9\u2075N\u2082-labelled gas led however to the detection of increased \u00b9\u2074NH\u2084\u207a concentrations instead of \u00b9\u2075NH\u2084\u207a. X-ray photoelectron spectroscopic (XPS) analysis of the electrode surface revealed the presence of Mo N and Mo\u2013NH_x species. Several contamination sources were identified that led to substantial increases in the concentration of ammonium ions, including \u00b9\u2075NH\u2083 impurities in \u00b9\u2075N\u2082 gas. The observed ammonium concentrations can be consistently ascribed to leaching of nitrogen (\u00b9\u2074N) impurities incorporated in the CoMo film during the sputtering process. Researchers in the field are therefore urged to adopt extended protocols to identify and eliminate sources of ammonia contamination and to very carefully monitor the ammonium concentrations in each experimental step.", "date": "2020-10-01", "date_type": "published", "publication": "Sustainable Energy and Fuels", "volume": "4", "number": "10", "publisher": "Royal Society of Chemistry", "pagerange": "5080-5087", "id_number": "CaltechAUTHORS:20200817-095314564", "issn": "2398-4902", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200817-095314564", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Deutsche Akademie der Naturforscher Leopoldina", "grant_number": "LPDS 2016-06" }, { "agency": "American Chemical Society Petroleum Research Fund" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1039/d0se00674b", "primary_object": { "basename": "d0se00674b1.pdf", "url": "https://authors.library.caltech.edu/records/0cyx0-8rq40/files/d0se00674b1.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Yu, Weilai; Buabthong, Pakpoom; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fb56a-jst04", "eprint_id": 104233, "eprint_status": "archive", "datestamp": "2023-08-19 23:30:04", "lastmod": "2023-10-20 19:11:53", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hamann-Kathryn-R", "name": { "family": "Hamann", "given": "Kathryn R." }, "orcid": "0000-0003-1163-7173" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Meier-Madeline-C", "name": { "family": "Meier", "given": "Madeline C." }, "orcid": "0000-0003-1608-0810" }, { "id": "Thompson-Jonathan-R", "name": { "family": "Thompson", "given": "Jonathan R." } }, { "id": "Batara-Nicolas-A", "name": { "family": "Batara", "given": "Nicolas A." } }, { "id": "Yermolenko-Ian-S", "name": { "family": "Yermolenko", "given": "Ivan S." } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Optically tunable mesoscale CdSe morphologies via inorganic phototropic growth", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 The Royal Society of Chemistry. \n\nSubmitted 01 May 2020; Accepted 22 Jun 2020; First published\t22 Jun 2020. \n\nThis work was supported by the \"Light\u2013Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001293 and was also supported by the National Science Foundation, Directorate for Mathematical & Physical Sciences, Division of Materials Research under Award Number DMR 1905963. Research was in part carried out at the Molecular Materials Research Center in the Beckman Institute of Caltech. The authors gratefully acknowledge R. Gerhart for assistance with photoelectrochemical cell fabrication and W.-H. Cheng and M. Richter for assistance with computer simulations. KRH, AIC, and MCM acknowledge graduate research fellowships from the National Science Foundation. MCM also acknowledges the Resnick Sustainability Institute at Caltech for fellowship support. \n\nThere are no conflicts of interest to declare.\n\nSupplemental Material - d0tc02126a1.pdf
", "abstract": "Inorganic phototropic growth using only spatially conformal illumination generated Se\u2013Cd films that exhibited precise light-defined mesoscale morphologies including highly ordered, anisotropic, and periodic ridge and trench nanotextures over entire macroscopic substrates. Growth was accomplished via a light-induced electrochemical method using an optically and chemically isotropic solution, an unpatterned substrate, and unstructured, incoherent, low-intensity illumination in the absence of chemical directing agents or physical templates and masks. The morphologies were defined by the illumination inputs: the nanotexture long axes aligned parallel to the optical E-field vector, and the feature sizes and periods scaled with the wavelength. Optically based modeling of the growth closely reproduced the experimental results, confirming the film morphologies were fully determined by the light\u2013matter interactions during growth. Solution processing of the Se\u2013Cd films resulted in stoichiometric, crystalline CdSe films that also exhibited ordered nanotextures, demonstrating that inorganic phototropic growth can effect tunable, template-free generation of ordered CdSe nanostructures over macroscopic length scales.", "date": "2020-09-28", "date_type": "published", "publication": "Journal of Materials Chemistry C", "volume": "8", "number": "36", "publisher": "Royal Society of Chemistry", "pagerange": "12412-12417", "id_number": "CaltechAUTHORS:20200706-150753170", "issn": "2050-7526", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200706-150753170", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "NSF", "grant_number": "DMR-1905963" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1039/d0tc02126a", "primary_object": { "basename": "d0tc02126a1.pdf", "url": "https://authors.library.caltech.edu/records/fb56a-jst04/files/d0tc02126a1.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Hamann, Kathryn R.; Carim, Azhar I.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ha8zy-k5n68", "eprint_id": 105480, "eprint_status": "archive", "datestamp": "2023-08-22 06:27:59", "lastmod": "2023-10-20 22:02:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tong-Fan", "name": { "family": "Tong", "given": "Fan" }, "orcid": "0000-0003-4661-3956" }, { "id": "Yuan-Mengyao", "name": { "family": "Yuan", "given": "Mengyao" }, "orcid": "0000-0002-5923-4085" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Davis-S-J", "name": { "family": "Davis", "given": "Steven J." }, "orcid": "0000-0002-9338-0844" }, { "id": "Caldeira-K", "name": { "family": "Caldeira", "given": "Ken" }, "orcid": "0000-0002-4591-643X" } ] }, "title": "Effects of Deep Reductions in Energy Storage Costs on Highly Reliable Wind and Solar Electricity Systems", "ispublished": "pub", "full_text_status": "public", "keywords": "Energy Resources; Energy Policy; Energy Engineering", "note": "\u00a9 2020 The Author(s). This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). \n\nReceived 4 December 2019, Revised 14 June 2020, Accepted 17 August 2020, Available online 20 August 2020. Published: September 25, 2020. \n\nWe thank Jacqueline A. Dowling, Lei Duan, Patrick T. Brown, Dan Tong, Yixuan Zheng, and David J. Farnham for their insightful inputs. This work was supported by a gift from Gates Ventures LLC. \n\nAuthor Contributions: F.T., N.S.L., and K.C. designed the study; F.T., M.Y., and K.C. developed the model with inputs from N.S.L. and S.J.D.; F.T. and K.C. performed the analysis with inputs from M.Y., N.S.L., and S.J.D.; F.T. drafted the manuscript; F.T., M.Y., N.S.L., S.J.D., and K.C. edited the manuscript. \n\nThe authors declare no competing interests.\n\nPublished - 1-s2.0-S2589004220306763-main.pdf
Supplemental Material - 1-s2.0-S2589004220306763-mmc1.pdf
", "abstract": "We use 36 years (1980\u20132015) of hourly weather data over the contiguous United States (CONUS) to assess the impact of low-cost energy storage on highly reliable electricity systems that use only variable renewable energy (VRE; wind and solar photovoltaics). Even assuming perfect transmission of wind and solar generation aggregated over CONUS, energy storage costs would need to decrease several hundred-fold from current costs (to \u223c$1/kWh) in fully VRE electricity systems to yield highly reliable electricity without extensive curtailment of VRE generation. The role of energy storage changes from high-cost storage competing with curtailment to fill short-term gaps between VRE generation and hourly demand to near-free storage serving as seasonal storage for VRE resources. Energy storage faces \"double penalties\" in VRE/storage systems: with increasing capacity, (1) the additional storage is used less frequently and (2) hourly electricity costs would become less volatile, thus reducing price arbitrage opportunities for the additional storage.", "date": "2020-09-25", "date_type": "published", "publication": "iScience", "volume": "23", "number": "9", "publisher": "Elsevier", "pagerange": "Art. No. 101484", "id_number": "CaltechAUTHORS:20200922-152836539", "issn": "2589-0042", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200922-152836539", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Gates Ventures LLC" } ] }, "doi": "10.1016/j.isci.2020.101484", "primary_object": { "basename": "1-s2.0-S2589004220306763-mmc1.pdf", "url": "https://authors.library.caltech.edu/records/ha8zy-k5n68/files/1-s2.0-S2589004220306763-mmc1.pdf" }, "related_objects": [ { "basename": "1-s2.0-S2589004220306763-main.pdf", "url": "https://authors.library.caltech.edu/records/ha8zy-k5n68/files/1-s2.0-S2589004220306763-main.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Tong, Fan; Yuan, Mengyao; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9djjb-yxd48", "eprint_id": 104772, "eprint_status": "archive", "datestamp": "2023-08-22 06:24:59", "lastmod": "2023-10-20 20:49:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dowling-Jacqueline-A", "name": { "family": "Dowling", "given": "Jacqueline A." }, "orcid": "0000-0001-5642-8960" }, { "id": "Rinaldi-Katherine-Z", "name": { "family": "Rinaldi", "given": "Katherine Z." }, "orcid": "0000-0002-0746-2852" }, { "id": "Ruggles-Tyler-H", "name": { "family": "Ruggles", "given": "Tyler H." }, "orcid": "0000-0002-6643-2047" }, { "id": "Davis-Steven-J", "name": { "family": "Davis", "given": "Steven J." }, "orcid": "0000-0002-9338-0844" }, { "id": "Yuan-Mengyao", "name": { "family": "Yuan", "given": "Mengyao" }, "orcid": "0000-0002-5923-4085" }, { "id": "Tong-Fan", "name": { "family": "Tong", "given": "Fan" }, "orcid": "0000-0003-4661-3956" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Caldeira-Ken", "name": { "family": "Caldeira", "given": "Ken" }, "orcid": "0000-0002-4591-643X" } ] }, "title": "Role of Long-Duration Energy Storage in Variable Renewable Electricity Systems", "ispublished": "pub", "full_text_status": "public", "keywords": "long-duration energy storage; renewable energy; zero-carbon electricity; electricity cost; macro-energy model; wind energy; solar energy; batteries; storage technologies; long-term energy storage", "note": "\u00a9 2020 Elsevier Inc. \n\nReceived 14 May 2020, Revised 21 May 2020, Accepted 9 July 2020, Available online 6 August 2020. \n\nJ.A.D. acknowledges fellowship support from the Resnick Sustainability Institute at Caltech. This work was also supported by the Gordon and Betty Moore Foundation, a fellowship from SoCalGas in support of Low Carbon Energy Science and Policy, and a gift from Gates Ventures LLC to the Carnegie Institution for Science. The authors thank Lei Duan, and David Farnham for providing wind, solar, and demand input data. J.A.D. thanks Eric Ewing for technical assistance during manuscript preparation. \n\nAuthor Contributions: N.S.L. and K.C. conceived this study. J.A.D., K.C., and N.S.L. designed the analyses with contributions from K.Z.R., T.H.R., M.Y., and F.T. K.C., F.T., M.Y., and J.A.D. developed and tested the version of the model used in this study. K.Z.R. assisted with literature review, T.H.R. compiled various technology costs, and S.J.D. improved the figures and main text. J.A.D. performed the analyses and wrote the manuscript with interactive feedback from N.S.L., K.C., K.Z.R., T.H.R., S.J.D., M.Y., and F.T. All authors edited the manuscript and provided helpful discussions. \n\nThe authors declare no competing interests.\n\nSupplemental Material - 1-s2.0-S2542435120303251-mmc1.pdf
", "abstract": "Reliable and affordable electricity systems based on variable energy sources, such as wind and solar may depend on the ability to store large quantities of low-cost energy over long timescales. Here, we use 39 years of hourly U.S. weather data, and a macro-scale energy model to evaluate capacities and dispatch in least cost, 100% reliable electricity systems with wind and solar generation supported by long-duration storage (LDS; 10 h or greater) and battery storage. We find that the introduction of LDS lowers total system costs relative to wind-solar-battery systems, and that system costs are twice as sensitive to reductions in LDS costs as to reductions in battery costs. In least-cost systems, batteries are used primarily for intra-day storage and LDS is used primarily for inter-season and multi-year storage. Moreover, dependence on LDS increases when the system is optimized over more years. LDS technologies could improve the affordability of renewable electricity.", "date": "2020-09-16", "date_type": "published", "publication": "Joule", "volume": "4", "number": "9", "publisher": "Cell Press", "pagerange": "1907-1928", "id_number": "CaltechAUTHORS:20200806-090232377", "issn": "2542-4351", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200806-090232377", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Resnick Sustainability Institute" }, { "agency": "Gordon and Betty Moore Foundation" }, { "agency": "Southern California Gas Company" }, { "agency": "Gates Ventures LLC" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1016/j.joule.2020.07.007", "primary_object": { "basename": "1-s2.0-S2542435120303251-mmc1.pdf", "url": "https://authors.library.caltech.edu/records/9djjb-yxd48/files/1-s2.0-S2542435120303251-mmc1.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Dowling, Jacqueline A.; Rinaldi, Katherine Z.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sbanf-s8t86", "eprint_id": 104264, "eprint_status": "archive", "datestamp": "2023-08-19 22:56:39", "lastmod": "2023-10-20 19:14:00", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "Paul A." }, "orcid": "0000-0003-3909-1790" }, { "id": "Richter-Matthias-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Cheng-Wen-Hui", "name": { "family": "Cheng", "given": "Wen-Hui" }, "orcid": "0000-0003-3233-4606" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Si Microwire-Array Photocathodes Decorated with Cu Allow CO\u2082 Reduction with Minimal Parasitic Absorption of Sunlight", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 American Chemical Society. \n\nReceived: June 21, 2020; Accepted: July 7, 2020; Published: July 7, 2020. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. Fabrication of the Si microwire arrays was performed in the Kavli Nanoscience Institute (KNI) at Caltech, and we thank the KNI staff for their assistance during fabrication. XPS data were collected at the Molecular Materials Resource Center of the Beckman Institute. \n\nAuthor Contributions: Si \u03bcW sample fabrication, P.A.K.; Cu foil preparation, M.H.R.; investigation, P.A.K., M.H.R., and W.H.C.; writing, P.A.K., M.H.R., B.S.B., and N.S.L.; funding acquisition, N.S.L. and B.S.B.; supervision, N.S.L. and B.S.B. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nz0c01334_si_001.pdf
", "abstract": "High loadings of Cu were integrated on the light-facing side of Si microwire arrays used under simulated sunlight for the photoelectrochemical reduction of CO\u2082 (aq) to hydrocarbons in 0.10 M KHCO\u2083 (aq). Radial-junction n\u207ap-Si microwire arrays decorated with Cu exhibited absolute photocurrent densities comparable to an uncovered Si surface. Moreover, with respect to a Cu foil electrode, the positive shift in the onset potential for hydrocarbon formation at n\u207ap-Si/Cu microwire arrays was equal to or greater than the photovoltage of the semiconductor alone. Selective electrodeposition of Cu on the tips and sidewalls of Si microwires was responsible for the minimal parasitic reflection and absorption exhibited by the catalyst, such that light-limited, absolute current densities >25 mA\u00b7cm\u207b\u00b2 were sustained for 48 h under simulated sunlight. Photoelectrodes prepared from semiconductors with low diode quality factors and electrocatalysts with large Tafel slopes are shown to benefit from increased microstructured surface area. Si microwire arrays are thus suitable for photoelectrochemical reactions requiring high loadings of metallic and reflective electrocatalysts.", "date": "2020-08-14", "date_type": "published", "publication": "ACS Energy Letters", "volume": "5", "number": "8", "publisher": "American Chemical Society", "pagerange": "2528-2534", "id_number": "CaltechAUTHORS:20200707-161346609", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200707-161346609", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acsenergylett.0c01334", "primary_object": { "basename": "nz0c01334_si_001.pdf", "url": "https://authors.library.caltech.edu/records/sbanf-s8t86/files/nz0c01334_si_001.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Kempler, Paul A.; Richter, Matthias H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5htrq-kjp09", "eprint_id": 104162, "eprint_status": "archive", "datestamp": "2023-08-19 22:34:15", "lastmod": "2023-10-20 19:08:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Cab\u00e1n-Acevedo-M", "name": { "family": "Cab\u00e1n-Acevedo", "given": "Miguel" } }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Surface Passivation and Positive Band-Edge Shift of p-Si(111) Surfaces Functionalized with Mixed Methyl/Trifluoromethylphenylacetylene Overlayers", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 American Chemical Society. \n\nReceived: March 9, 2020; Revised: June 29, 2020; Published: June 30, 2020. \n\nM.C. acknowledges support from the Ford Foundation under the Postdoctoral Scholar Fellowship program. B.S.B. and M.C. acknowledge support from the National Science Foundation CCI Solar Fuels Program under grant no. CHE-1305124. N.S.L. and M.C. acknowledges support from the National Science Foundation under grant no. CHE-1808599. Instrumentation support was provided by the Molecular Materials Resource Center of the Beckman Institute at the California Institute of Technology. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - jp0c02017_si_001.pdf
", "abstract": "Chemical functionalization of semiconductor surfaces can provide high-efficiency photoelectrochemical devices through molecular-level control of the energetics, surface dipole, surface electronic defects, and chemical reactivity at semiconductor/electrolyte junctions. We describe the covalent functionalization by nucleophilic addition chemistry of p-Si(111) surfaces to produce mixed overlayers of trifluoromethylphenylacetylene (TFMPA) and methyl moieties. Functionalization of Cl-terminated Si(111) surfaces with TFMPA moieties introduced a positive surface molecular dipole that in contact with CH\u2083CN or Hg produced a positive band-edge shift of the semiconductor relative to junctions with CH\u2083-Si(111) surfaces. Methylation of the Cl/TFMPA surfaces using methylmagnesium chloride resulted in the degradation of the TFMPA moieties, whereas methylation using methylzinc chloride allowed controlled production of mixed TFMPA/methyl-terminated surfaces and permitted reversal of the order of the functionalization steps so that nucleophilic addition of TFMPA could be accomplished after methylation of Cl\u2013Si(111) surfaces. Mixed TFMPA/methyl functionalization resulted in a Si(111) surface with surface recombination velocities of 2 \u00d7 10\u00b2 cm s\u207b\u00b9 that exhibited an \u223c150 mV positive band-edge shift relative to CH\u2083\u2013Si(111) surfaces.", "date": "2020-07-30", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "124", "number": "30", "publisher": "American Chemical Society", "pagerange": "16338-16349", "id_number": "CaltechAUTHORS:20200630-105347382", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200630-105347382", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Ford Foundation" }, { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "NSF", "grant_number": "CHE-1808599" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/acs.jpcc.0c02017", "primary_object": { "basename": "jp0c02017_si_001.pdf", "url": "https://authors.library.caltech.edu/records/5htrq-kjp09/files/jp0c02017_si_001.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Cab\u00e1n-Acevedo, Miguel; Papadantonakis, Kimberly M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5y8dd-5x714", "eprint_id": 104358, "eprint_status": "archive", "datestamp": "2023-08-19 22:33:12", "lastmod": "2023-10-20 19:20:42", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yang-Fan", "name": { "family": "Yang", "given": "Fan" } }, { "id": "Zhou-Xinghao", "name": { "family": "Zhou", "given": "Xinghao" }, "orcid": "0000-0001-9229-7670" }, { "id": "Plymale-N-T", "name": { "family": "Plymale", "given": "Noah T." }, "orcid": "0000-0003-2564-8009" }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Evaluation of sputtered nickel oxide, cobalt oxide and nickel\u2013cobalt oxide on n-type silicon photoanodes for solar-driven O\u2082(g) evolution from water", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 The Royal Society of Chemistry. \n\nReceived 8th April 2020; Accepted 26th June 2020; First published 30 Jun 2020. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award DE-SC0004993 to the Joint Center for Artificial Photosynthesis (JCAP), a DOE funded Energy Innovation Hub. UV-vis absorption and Atomic Force Microscope studies were performed at the Molecular Materials Resource Center (MMRC) in the Beckman Institute at the California Institute of Technology. Paul Kempler and Weilai Yu are thanked for assistance with editing the manuscript. \n\nThere are no conflicts to declare.\n\nSupplemental Material - d0ta03725g1.pdf
", "abstract": "Thin films of nickel oxide (NiO_x), cobalt oxide (CoO_x) and nickel\u2013cobalt oxide (NiCoO_x) were sputtered onto n-Si(111) surfaces to produce a series of integrated, protected Si photoanodes that did not require deposition of a separate heterogeneous electrocatalyst for water oxidation. The p-type transparent conductive oxides (p-TCOs) acted as multi-functional transparent, antireflective, electrically conductive, chemically stable coatings that also were active electrocatalysts for the oxidation of water to O\u2082(g). Relative to the formal potential for water oxidation to O\u2082, E^(o\u2032)(O\u2082/H\u2082O), under simulated Air Mass (AM)1.5 illumination the p-TCO-coated n-Si(111) photoanodes produced mutually similar open-circuit potentials of \u2212270 \u00b1 20 mV, but different photocurrent densities at E^(o\u2032)(O\u2082/H\u2082O), of 28 \u00b1 0.3 mA cm\u207b\u00b2 for NiO_x, 18 \u00b1 0.3 mA cm\u207b\u00b2 for CoO_x and 24 \u00b1 0.5 mA cm\u207b\u00b2 for NiCoO_x. The p-TCOs all provided protection from oxide growth for extended time periods, and produced stable photocurrent densities from n-Si in 1.0 M KOH(aq) (ACS grade) under potential control at E^(o\u2032)(O\u2082/H\u2082O) for >400 h of continuous operation under 100 mW cm\u22122 of simulated AM1.5 illumination.", "date": "2020-07-28", "date_type": "published", "publication": "Journal of Materials Chemistry A", "volume": "8", "number": "28", "publisher": "Royal Society of Chemistry", "pagerange": "13955-13963", "id_number": "CaltechAUTHORS:20200713-130247847", "issn": "2050-7488", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200713-130247847", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/d0ta03725g", "primary_object": { "basename": "d0ta03725g1.pdf", "url": "https://authors.library.caltech.edu/records/5y8dd-5x714/files/d0ta03725g1.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Yang, Fan; Zhou, Xinghao; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/yncck-x6j92", "eprint_id": 104339, "eprint_status": "archive", "datestamp": "2023-08-19 22:24:10", "lastmod": "2023-10-20 19:19:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yu-Weilai", "name": { "family": "Yu", "given": "Weilai" }, "orcid": "0000-0002-9420-0702" }, { "id": "Fu-Harold-J", "name": { "family": "Fu", "given": "Harold J." }, "orcid": "0000-0001-9738-209X" }, { "id": "Mueller-Thomas", "name": { "family": "Mueller", "given": "Thomas" } }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Atomic force microscopy: Emerging illuminated and operando techniques for solar fuel research", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 Published under license by AIP Publishing. \n\nSubmitted: 6 April 2020; Accepted: 5 June 2020; Published Online: 10 July 2020. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. The authors would like to thank the Beckman Institute at the California Institute of Technology for continuous support. \n\nAuthors' Contributions: W.Y. and H.J.F. contributed equally to this work. \n\nData Availability: The data that support the findings of this study are available within the article.\n\nPublished - 5.0009858.pdf
", "abstract": "Integrated photoelectrochemical devices rely on the synergy between components to efficiently generate sustainable fuels from sunlight. The micro- and/or nanoscale characteristics of the components and their interfaces often control critical processes of the device, such as charge-carrier generation, electron and ion transport, surface potentials, and electrocatalysis. Understanding the spatial properties and structure\u2013property relationships of these components can provide insight into designing scalable and efficient solar fuel components and systems. These processes can be probed ex situ or in situ with nanometer-scale spatial resolution using emerging scanning-probe techniques based on atomic force microscopy (AFM). In this Perspective, we summarize recent developments of AFM-based techniques relevant to solar fuel research. We review recent progress in AFM for (1) steady-state and dynamic light-induced surface photovoltage measurements; (2) nanoelectrical conductive measurements to resolve charge-carrier heterogeneity and junction energetics; (3) operando investigations of morphological changes, as well as surface electrochemical potentials, currents, and photovoltages in liquids. Opportunities for research include: (1) control of ambient conditions for performing AFM measurements; (2) in situ visualization of corrosion and morphological evolution of electrodes; (3) operando AFM techniques to allow nanoscale mapping of local catalytic activities and photo-induced currents and potentials.", "date": "2020-07-14", "date_type": "published", "publication": "Journal of Chemical Physics", "volume": "153", "number": "2", "publisher": "American Institute of Physics", "pagerange": "Art. No. 020902", "id_number": "CaltechAUTHORS:20200710-151813992", "issn": "0021-9606", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200710-151813992", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1063/5.0009858", "primary_object": { "basename": "5.0009858.pdf", "url": "https://authors.library.caltech.edu/records/yncck-x6j92/files/5.0009858.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Yu, Weilai; Fu, Harold J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8aks8-76f41", "eprint_id": 103312, "eprint_status": "archive", "datestamp": "2023-08-19 21:44:14", "lastmod": "2023-10-20 15:54:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "Paul A." }, "orcid": "0000-0003-3909-1790" }, { "id": "Coridan-Robert-H", "name": { "family": "Coridan", "given": "Robert H." }, "orcid": "0000-0003-1916-4446" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Effects of bubbles on the electrochemical behavior of hydrogen-evolving Si microwire arrays oriented against gravity", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 The Royal Society of Chemistry. \n\nSubmitted 03 Feb 2020; Accepted 08 Apr 2020; First published 08 Apr 2020. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. High-speed microscopy experiments were supported by the National Science Foundation under Grant No. 1732096 (R. H. C.). Fabrication of the Si microwire arrays was performed in the Kavli Nanoscience Institute (KNI) at Caltech, and we thank the KNI staff for their assistance during fabrication. We thank K. M. P. and B. S. B. for helpful discussions on experimental design. \n\nAuthor contributions: Conceptualization, P. A. K., and N. S. L.; Methodology, P. A. K., Investigation, P. A. K. and R. H. C.; Writing\u2014Original Draft, P. A. K. and N. S. L.; Writing\u2014Review & Editing, N. S. L., P. A. K., R. H. C.; Funding Acquisition, N. S. L. and R. H. C.; Supervision, N. S. L. \n\nThe authors declare no competing interests.\n\nSupplemental Material - d0ee00356e1.mp4
Supplemental Material - d0ee00356e2.pdf
Supplemental Material - d0ee00356e3.mp4
", "abstract": "The size-distribution, coverage, electrochemical impedance, and mass-transport properties of H\u2082 gas-bubble films were measured for both planar and microwire-array platinized n\u207a-Si cathodes performing the hydrogen-evolution reaction in 0.50 M H\u2082SO\u2084 (aq). Inverted, planar n\u207a-Si/Ti/Pt cathodes produced large, stationary bubbles which contributed to substantial increases in ohmic potential drops. In contrast, regardless of orientation, microwire array n\u207a-Si/Ti/Pt cathodes exhibited a smaller layer of bubbles on the surface, and the formation of bubbles did not substantially increase the steady-state overpotential for H\u2082 (g) production. Experiments using an electroactive tracer species indicated that even when oriented against gravity, bubbles enhanced mass transport at the electrode surface. Microconvection due to growing and coalescing bubbles dominated effects due to macroconvection of gliding bubbles on Si microwire array cathodes. Electrodes that maintained a large number of small bubbles on the surface simultaneously exhibited low concentrations of dissolved hydrogen and small ohmic potential drops, thus exhibiting the lowest steady-state overpotentials. The results indicate that microstructured electrodes can operate acceptably for unassisted solar-driven water splitting in the absence of external convection and can function regardless of the orientation of the electrode with respect to the gravitational force vector.", "date": "2020-06-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "13", "number": "6", "publisher": "Royal Society of Chemistry", "pagerange": "1808-1817", "id_number": "CaltechAUTHORS:20200519-103638391", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200519-103638391", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "CBET-1732096" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/d0ee00356e", "primary_object": { "basename": "d0ee00356e1.mp4", "url": "https://authors.library.caltech.edu/records/8aks8-76f41/files/d0ee00356e1.mp4" }, "related_objects": [ { "basename": "d0ee00356e2.pdf", "url": "https://authors.library.caltech.edu/records/8aks8-76f41/files/d0ee00356e2.pdf" }, { "basename": "d0ee00356e3.mp4", "url": "https://authors.library.caltech.edu/records/8aks8-76f41/files/d0ee00356e3.mp4" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Kempler, Paul A.; Coridan, Robert H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/yxbvn-61w10", "eprint_id": 102940, "eprint_status": "archive", "datestamp": "2023-08-19 21:26:41", "lastmod": "2023-10-20 00:38:52", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Moreno-Hernandez-I-A", "name": { "family": "Moreno-Hernandez", "given": "Ivan A." }, "orcid": "0000-0001-6461-9214" }, { "id": "Yalamanchili-S", "name": { "family": "Yalamanchili", "given": "Sisir" } }, { "id": "Fu-Harold-J", "name": { "family": "Fu", "given": "Harold J." }, "orcid": "0000-0001-9738-209X" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Conformal SnO_x heterojunction coatings for stabilized photoelectrochemical water oxidation using arrays of silicon microcones", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 The Royal Society of Chemistry 2020. \n\nReceived 29th January 2020. Accepted 19th April 2020. First published 30 Apr 2020. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, and in part by the National Science Foundation (NSF) and the Department of Energy (DOE) under NSF CA No. EEC-1041895. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect those of NSF or DOE. Fabrication was performed in Kavli Nanoscience Institute (KNI) at Caltech, and we thank KNI staff for their assistance during fabrication. I. M. H acknowledges a National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469. We thank C. Garland for assistance with transmission-electron microscopy measurements. \n\nThere are no conflicts to declare.\n\nSupplemental Material - d0ta01144d1.pdf
", "abstract": "The efficiency of photoelectrodes towards fuel-forming reactions is strongly affected by surface-based charge recombination, charge-transfer losses, and parasitic light absorption by electrocatalysts. We report a protective tin oxide (SnO_x) layer formed by atomic-layer deposition that limits surface recombination at n-Si/SnO_x heterojunctions and produces \u223c620 mV of photovoltage on planar n-Si photoanodes. The SnO_x layer can be deposited conformally on high aspect-ratio three-dimensional structures such as Si microcone arrays. Atomic-level control of the SnO_x thickness enabled highly conductive contacts to electrolytes, allowing the direct electrodeposition of NiFeOOH, CoO_x, and IrO_x electrocatalysts for photoelectrochemical water oxidation with minimal parasitic absorption losses. SnO_x-coated n-Si microcone arrays coupled to electrodeposited catalysts exhibited photocurrent densities of \u223c42 mA cm\u207b\u00b2 and a photovoltage of \u223c490 mV under 100 mW cm\u207b\u00b2 of simulated solar illumination. The SnO_x layer can be integrated with amorphous TiO\u2082 to form a protective SnO_x/TiO\u2082 bilayer that exhibits the beneficial properties of both materials. Photoanodes coated with SnO_x/TiO\u2082 exhibited a similar photovoltage to that of SnO_x-coated photoanodes, and showed >480 h of stable photocurrent for planar photoelectrodes and >140 h of stable photocurrent for n-Si microcone arrays under continuous simulated solar illumination in alkaline electrolytes.", "date": "2020-05-14", "date_type": "published", "publication": "Journal of Materials Chemistry A", "volume": "8", "number": "18", "publisher": "Royal Society of Chemistry", "pagerange": "9292-9301", "id_number": "CaltechAUTHORS:20200430-151239546", "issn": "2050-7488", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200430-151239546", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "EEC-1041895" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1144469" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/d0ta01144d", "primary_object": { "basename": "d0ta01144d1.pdf", "url": "https://authors.library.caltech.edu/records/yxbvn-61w10/files/d0ta01144d1.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Moreno-Hernandez, Ivan A.; Yalamanchili, Sisir; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4cezq-9je74", "eprint_id": 102594, "eprint_status": "archive", "datestamp": "2023-08-19 21:24:26", "lastmod": "2023-10-20 00:19:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yu-Weilai", "name": { "family": "Yu", "given": "Weilai" }, "orcid": "0000-0002-9420-0702" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Dalleska-N-F", "name": { "family": "Dalleska", "given": "Nathan F." }, "orcid": "0000-0002-2059-1587" } ] }, "title": "Isotopically Selective Quantification by UPLC-MS of Aqueous Ammonia at Submicromolar Concentrations Using Dansyl Chloride Derivatization", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 American Chemical Society. \n\nReceived: March 2, 2020; Accepted: April 6, 2020; Published: April 16, 2020. \n\nAcknowledgement is made to the donors of The American Chemical Society Petroleum Research Fund for partial support of this research. This work was also supported by the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. N.F.D. is grateful to the Linde Center for support. The Environmental Analysis Center is grateful for support from the Beckman Institute at Caltech. Dr. Fabai Wu and Prof. Victoria Orphan are thanked for providing the \u00b9\u2075NH\u2084Cl standard sample. Mr. Christopher Kenseth is thanked for assistance with UPLC-MS analysis. Dr. Yuanlong Huang is thanked for fruitful discussions. \n\nViews expressed in this Viewpoint are those of the authors and\nnot necessarily the views of ACS. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nz0c00496_si_001.pdf
", "abstract": "Ammonia (NH\u2083) is essential for food production and is commercially synthesized from nitrogen (N\u2082) and hydrogen (H\u2082) using the Haber\u2013Bosch process. Enormous amounts of ammonia are made every year in a reaction that requires high temperatures and pressures, with the Haber\u2013Bosch accounting for \u223c1.6% of total annual global energy consumption. Electrocatalysts are also being explored to convert in an environmentally friendly manner N\u2082 to NH\u2083 at ambient temperature and pressure.", "date": "2020-05-08", "date_type": "published", "publication": "ACS Energy Letters", "volume": "5", "number": "5", "publisher": "American Chemical Society", "pagerange": "1532-1536", "id_number": "CaltechAUTHORS:20200417-094556803", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200417-094556803", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "American Chemical Society Petroleum Research Fund" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Ronald And Maxine Linde Center for Global Environmental Science" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/acsenergylett.0c00496", "primary_object": { "basename": "nz0c00496_si_001.pdf", "url": "https://authors.library.caltech.edu/records/4cezq-9je74/files/nz0c00496_si_001.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Yu, Weilai; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3vefm-jhr06", "eprint_id": 102116, "eprint_status": "archive", "datestamp": "2023-08-19 20:55:11", "lastmod": "2023-10-19 23:51:41", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Mazza-M-F", "name": { "family": "Mazza", "given": "Michael F." } }, { "id": "Cab\u00e1n-Acevedo-M", "name": { "family": "Cab\u00e1n-Acevedo", "given": "Miguel" } }, { "id": "Wiensch-J-D", "name": { "family": "Wiensch", "given": "Joshua D." }, "orcid": "0000-0002-8235-6937" }, { "id": "Thompson-A-C", "name": { "family": "Thompson", "given": "Annelise C." }, "orcid": "0000-0003-2414-7050" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Defect-Seeded Atomic Layer Deposition of Metal Oxides on the Basal Plane of 2D Layered Materials", "ispublished": "pub", "full_text_status": "public", "keywords": "Defect driven growth, atomic layer deposition, dislocation networks, 2D\nlayered materials", "note": "\u00a9 2020 American Chemical Society. \n\nReceived: January 14, 2020; Revised: February 28, 2020; Published: March 25, 2020. \n\nM.C. acknowledges support from the Ford Foundation under the Postdoctoral Scholar Fellowship program. M.C. acknowledges support from the National Science Foundation CCI Solar Fuels Program under Grant No. CHE-1305124. M.F.M, J.D.W., and N.S.L. acknowledge support from the U.S. Department of Energy under award DE-FG02-03ER15483. A.C.T. acknowledges support from the Graduate Research Fellowship Program of the National Science Foundation. Research was in part carried out at the Molecular Materials Research Center in the Beckman Institute at the California Institute of Technology. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nl0c00179_si_001.pdf
", "abstract": "Atomic layer deposition (ALD) on mechanically exfoliated 2D layered materials spontaneously produces network patterns of metal oxide nanoparticles in triangular and linear deposits on the basal surface. The network patterns formed under a range of ALD conditions and were independent of the orientation of the substrate in the ALD reactor. The patterns were produced on MoS2 or HOPG when either tetrakis(dimethylamido)titanium or bis(ethylcyclopentadienyl)manganese were used as precursors, suggesting that the phenomenon is general for 2D materials. Transmission electron microscopy revealed the presence, prior to deposition, of dislocation networks along the basal plane of mechanically exfoliated 2D flakes, indicating that periodical basal plane defects related to disruptions in the van der Waals stacking of layers, such as perfect line dislocations and triangular extended stacking faults networks, introduce a surface reactivity landscape that leads to the emergence of patterned deposition.", "date": "2020-04-08", "date_type": "published", "publication": "Nano Letters", "volume": "20", "number": "4", "publisher": "American Chemical Society", "pagerange": "2632-2638", "id_number": "CaltechAUTHORS:20200326-084207099", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200326-084207099", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Ford Foundation" }, { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/acs.nanolett.0c00179", "primary_object": { "basename": "nl0c00179_si_001.pdf", "url": "https://authors.library.caltech.edu/records/3vefm-jhr06/files/nl0c00179_si_001.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Mazza, Michael F.; Cab\u00e1n-Acevedo, Miguel; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7s8vj-hpt40", "eprint_id": 101944, "eprint_status": "archive", "datestamp": "2023-08-19 20:54:31", "lastmod": "2023-10-19 23:40:32", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Richter-M-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Lublow-M", "name": { "family": "Lublow", "given": "Michael" } }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Lewerenz-H-J", "name": { "family": "Lewerenz", "given": "Hans-Joachim" }, "orcid": "0000-0001-8433-9471" } ] }, "title": "Genesis and Propagation of Fractal Structures During Photoelectrochemical Etching of n-Silicon", "ispublished": "pub", "full_text_status": "public", "keywords": "Fractal structures, Silicon, Photoelectrochemistry, Photoelectron spectroscopy", "note": "\u00a9 2020 American Chemical Society. \n\nReceived: December 18, 2019; Accepted: March 16, 2020; Published: March 16, 2020. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. HJL is grateful for support by DFG project Le1192-4. Research was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. Dedicated to the memory of Hans-Joachim Lewerenz. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - am9b22900_si_001.pdf
Supplemental Material - am9b22900_si_002.mp4
", "abstract": "The genesis, propagation, and dimensions of fractal-etch patterns that form anodically on front- or back-illuminated n-Si(100) photoelectrodes in contact with 11.9 M NH\u2084F(aq) has been investigated during either linear-sweep voltammetry or when the electrode was held at a constant potential (E = +6.0 V versus Ag/AgCl). Optical images collected in situ during electrochemical experiments revealed the location and underlying mechanism of initiation and propagation of the structures on the surface. X-ray photoelectron spectroscopic (XPS) data collected for samples emersed from the electrolyte at varied times provided detailed information about the chemistry of the surface during fractal etching. The fractal structure was strongly influenced by the orientation of the crystalline Si sample. The etch patterns were initially generated at points along the circumference of bubbles that formed upon immersion of n-Si(100) samples in the electrolyte, most likely due to the electrochemical and electronic isolation of areas beneath bubbles. XPS data showed the presence of a tensile-stressed silicon surface throughout the etching process as well as the presence of SiO_xF_y on the surface. The two-dimensional fractal dimension D_(f,2D) of the patterns increased with etching time to a maximum observed value of D_(f,2D)=1.82. Promotion of fractal etching near etch masks that electrochemically and electronically isolated areas of the photoelectrode surface enabled the selective placement of highly branched structures at desired locations on an electrode surface.", "date": "2020-04-08", "date_type": "published", "publication": "ACS Applied Materials & Interfaces", "volume": "12", "number": "14", "publisher": "American Chemical Society", "pagerange": "17018-17028", "id_number": "CaltechAUTHORS:20200317-132013328", "issn": "1944-8244", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200317-132013328", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Deutsche Forschungsgemeinschaft (DFG)", "grant_number": "Le1192-4" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acsami.9b22900", "primary_object": { "basename": "am9b22900_si_001.pdf", "url": "https://authors.library.caltech.edu/records/7s8vj-hpt40/files/am9b22900_si_001.pdf" }, "related_objects": [ { "basename": "am9b22900_si_002.mp4", "url": "https://authors.library.caltech.edu/records/7s8vj-hpt40/files/am9b22900_si_002.mp4" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Richter, Matthias H.; Lublow, Michael; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/gv2ea-wzs75", "eprint_id": 101218, "eprint_status": "archive", "datestamp": "2023-08-19 20:32:41", "lastmod": "2023-10-19 22:33:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Thompson-A-C", "name": { "family": "Thompson", "given": "Annelise C." }, "orcid": "0000-0003-2414-7050" }, { "id": "Simpson-B-H", "name": { "family": "Simpson", "given": "Burton H." }, "orcid": "0000-0002-3990-6892" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Macroscale and Nanoscale Photoelectrochemical Behavior of p-Type Si(111) Covered by a Single Layer of Graphene or Hexagonal Boron Nitride", "ispublished": "pub", "full_text_status": "public", "keywords": "2D material, graphene, hexagonal boron nitride, photoelectrochemistry, semiconductor/liquid junction, scanning electrochemical cell microscopy", "note": "\u00a9 2020 American Chemical Society. \n\nReceived: November 20, 2019; Accepted: February 10, 2020; Published: February 10, 2020. \n\nThis work was supported by the Department of Energy, Basic Energy Sciences, grant DE-FG02-03ER15483. A.C.T. acknowledges the National Science Foundation for a graduate fellowship. SECCM, UV\u2013vis, and XPS data were collected at the Molecular Materials Research Center in the Beckman Institute of the California Institute of Technology. We gratefully acknowledge the critical support and infrastructure provided for this work by The Kavli Nanoscience Institute at Caltech. \n\nAuthor Contributions: The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. A.C.T. and B.H.S. contributed equally. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - am9b21134_si_001.pdf
", "abstract": "Two-dimensional (2D) materials may enable a general approach to the introduction of a dipole at a semiconductor surface as well as control over other properties of the double layer at a semiconductor/liquid interface. Vastly different properties can be found in the 2D materials currently studied due in part to the range of the distribution of density-of-states. In this work, the open-circuit voltage (V_(oc)) of p-Si\u2013H, p-Si/Gr (graphene), and p-Si/h-BN (hexagonal boron nitride) in contact with a series of one-electron outer-sphere redox couples was investigated by macroscale measurements as well as by scanning electrochemical cell microscopy (SECCM). The band gaps of Gr and h-BN (0\u20135.97 eV) encompass the wide range of band gaps for 2D materials, so these interfaces (p-Si/Gr and p-Si/h-BN) serve as useful references to understand the behavior of 2D materials more generally. The value of V_(oc) shifted with respect to the effective potential of the contacting solution, with slopes (\u0394V_(oc)/\u0394E_(Eff)) of \u22120.27 and \u22120.38 for p-Si/Gr and p-Si/h-BN, respectively, indicating that band bending at the p-Si/h-BN and p-Si/Gr interfaces responds at least partially to changes in the electrochemical potential of the contacting liquid electrolyte. Additionally, SECCM is shown to be an effective method to interrogate the nanoscale photoelectrochemical behavior of an interface, showing little spatial variance over scales exceeding the grain size of the CVD-grown 2D materials in this work. The measurements demonstrated that the polycrystalline nature of the 2D materials had little effect on the results and confirmed that the macroscale measurements reflected the junction behavior at the nanoscale.", "date": "2020-03-11", "date_type": "published", "publication": "ACS Applied Materials & Interfaces", "volume": "12", "number": "10", "publisher": "American Chemical Society", "pagerange": "11551-11561", "id_number": "CaltechAUTHORS:20200211-081431977", "issn": "1944-8244", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200211-081431977", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acsami.9b21134", "primary_object": { "basename": "am9b21134_si_001.pdf", "url": "https://authors.library.caltech.edu/records/gv2ea-wzs75/files/am9b21134_si_001.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Thompson, Annelise C.; Simpson, Burton H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/xkgyb-xyf43", "eprint_id": 100432, "eprint_status": "archive", "datestamp": "2023-08-19 19:51:42", "lastmod": "2023-10-18 19:57:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yan-Ellen-X", "name": { "family": "Yan", "given": "Ellen X." }, "orcid": "0000-0003-3252-790X" }, { "id": "Cab\u00e1n-Acevedo-M", "name": { "family": "Cab\u00e1n-Acevedo", "given": "Miguel" } }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Reductant-Activated, High-Coverage, Covalent Functionalization of 1T\u2032-MoS\u2082", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 American Chemical Society. \n\nReceived: June 27, 2019; Accepted: December 20, 2019; Published: December 20, 2019. \n\nThis work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences under award no. DE-FG02-03ER15483. E.X.Y. gratefully acknowledges Dr. Sonjong Hwang at the Caltech Solid-State NMR Facility for discussions and NMR spectra. Research was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. Computations were performed with assistance from the Goddard group at Caltech. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - tz9b00241_si_001.pdf
", "abstract": "Recently developed covalent functionalization chemistry for MoS\u2082 in the 1T\u2032 phase enables the formation of covalent chalcogenide\u2013carbon bonds from alkyl halides and aryl diazonium salts. However, the coverage of functional groups using this method has been limited by the amount of negative charge stored in the exfoliated MoS\u2082 sheets to <25\u201330% per MoS\u2082 unit. We report, herein, a reductant-activated functionalization, wherein one-electron metallocene reductants, such as nickelocene, octamethylnickelocene, and cobaltocene, are introduced during functionalization with methyl and propyl halides to tune the coverage of the alkyl groups. The reductant-activated functionalization yields functional group coverages up to 70%, \u223c1.5\u20132 times higher than the previous limit, and enables functionalization by weak electrophiles, such as 1-chloropropane, that are otherwise unreactive with chemically exfoliated MoS\u2082. We also explored the dependence of coverage on the strength of the leaving group and the steric hindrance of the alkyl halide in the absence of reductants and showed that functionalization was ineffective for chloride leaving groups and for secondary and tertiary alkyl iodides. These results demonstrate a substantial increase in coverage compared to functionalization without reductants, and may impact the performance of these materials in applications reliant on surface interactions. Furthermore, this method may be applicable to the covalent functionalization of similar layered materials and metal chalcogenides.", "date": "2020-02-03", "date_type": "published", "publication": "ACS Materials Letters", "volume": "2", "number": "2", "publisher": "American Chemical Society", "pagerange": "133-139", "id_number": "CaltechAUTHORS:20191224-093208052", "issn": "2639-4979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191224-093208052", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" } ] }, "doi": "10.1021/acsmaterialslett.9b00241", "primary_object": { "basename": "tz9b00241_si_001.pdf", "url": "https://authors.library.caltech.edu/records/xkgyb-xyf43/files/tz9b00241_si_001.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Yan, Ellen X.; Cab\u00e1n-Acevedo, Miguel; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7pe2g-q5j41", "eprint_id": 100276, "eprint_status": "archive", "datestamp": "2023-08-19 19:31:28", "lastmod": "2023-10-18 19:48:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yalamanchili-Sisir", "name": { "family": "Yalamanchili", "given": "Sisir" } }, { "id": "Verlage-Erik", "name": { "family": "Verlage", "given": "Erik" } }, { "id": "Cheng-Wen-Hui", "name": { "family": "Cheng", "given": "Wen-Hui" }, "orcid": "0000-0003-3233-4606" }, { "id": "Fountaine-Katherine-T", "name": { "family": "Fountaine", "given": "Katherine T." }, "orcid": "0000-0002-0414-8227" }, { "id": "Jahelka-Philip-R", "name": { "family": "Jahelka", "given": "Philip R." }, "orcid": "0000-0002-1460-7933" }, { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "Paul A." }, "orcid": "0000-0003-3909-1790" }, { "id": "Saive-Rebecca", "name": { "family": "Saive", "given": "Rebecca" }, "orcid": "0000-0001-7420-9155" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "High Broadband Light Transmission for Solar Fuels Production Using Dielectric Optical Waveguides in TiO\u2082 Nanocone Arrays", "ispublished": "pub", "full_text_status": "public", "keywords": "dielectric nanocone, broadband transmission, nanophotonic, optoelectronic, photoelectrochemical, photovoltaic", "note": "\u00a9 2019 American Chemical Society. \n\nReceived: October 12, 2019; Revised: November 29, 2019; Published: December 10, 2019. \n\nThe fabrication and assessment of photoanodes for the oxygen-evolution reaction was supported through the Office of Science of the U. S. Department of Energy under Award No. DE-SC0004993 for the Joint Center for Artificial Photosynthesis and used facilities of the Kavli Nanoscience Institute at Caltech, a DOE Energy Innovation Hub; the development of simulations was supported by the National Science Foundation under award No. EEC-1041895. \n\nAuthor Contributions: S.Y., E.V., and W.H.C. contributed equally. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nl9b04225_si_001.pdf
", "abstract": "We describe the fabrication and use of arrays of TiO\u2082 nanocones to yield high optical transmission into semiconductor photoelectrodes covered with high surface loadings of light-absorbing electrocatalysts. Covering over 50% of the surface of a light absorber with an array of high-refractive-index TiO\u2082 nanocones imparted antireflective behavior (< 5% reflectance) to the surface and allowed > 85% transmission of broadband light to the underlying Si, even when thick metal contacts or opaque catalyst coatings were deposited on areas of the light-facing surface that were not directly beneath a nanocone. Three-dimensional full-field electromagnetic simulations for the 400 \u2013 1100 nm spectral range showed that incident broadband illumination couples to multiple waveguide modes in the TiO\u2082 nanocones, reducing interactions of the light with the metal layer. A proof-of-concept experimental demonstration of light-driven water oxidation was performed using a p\u207an-Si photoanode decorated with an array of TiO\u2082 nanocones additionally having a Ni catalyst layer electrodeposited onto the areas of the p\u207an-Si surface left uncovered by the TiO\u2082 nanocones. This photoanode produced a light-limited photocurrent density of ~ 28 mA cm\u207b\u00b2 under 100 mW cm\u207b\u00b2 of simulated Air Mass 1.5 illumination, equivalent to the photocurrent density expected for a bare planar Si surface even though 54% of the front surface of the Si was covered by an ~ 70 nm thick Ni metal layer.", "date": "2020-01-08", "date_type": "published", "publication": "Nano Letters", "volume": "20", "number": "1", "publisher": "American Chemical Society", "pagerange": "502-508", "id_number": "CaltechAUTHORS:20191212-105210937", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191212-105210937", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "EEC-1041895" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acs.nanolett.9b04225", "primary_object": { "basename": "nl9b04225_si_001.pdf", "url": "https://authors.library.caltech.edu/records/7pe2g-q5j41/files/nl9b04225_si_001.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Yalamanchili, Sisir; Verlage, Erik; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/58whj-0gn64", "eprint_id": 100159, "eprint_status": "archive", "datestamp": "2023-08-19 19:28:31", "lastmod": "2023-10-18 19:08:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "Paul A." }, "orcid": "0000-0003-3909-1790" }, { "id": "Fu-Harold-J", "name": { "family": "Fu", "given": "Harold J." }, "orcid": "0000-0001-9738-209X" }, { "id": "Ifkovits-Zachary-P", "name": { "family": "Ifkovits", "given": "Zachary P." } }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Spontaneous Formation of >90% Optically Transmissive, Electrochemically Active CoP Films for Photoelectrochemical Hydrogen Evolution", "ispublished": "pub", "full_text_status": "public", "keywords": "Photoelectrochemistry, Solar Fuels, Catalysts, Photocathode, Phosphides", "note": "\u00a9 2019 American Chemical Society. \n\nReceived: October 3, 2019; Accepted: December 2, 2019; Published: December 2, 2019. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. AFM measurements were performed in the Molecular Materials Resource Center, supported by the Beckmann Institute at the California Institute of Technology. We thank T. Tiwald for helpful discussions on models for effective medium approximations and N. Dalleska for assistance with ICP-MS. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - jz9b02926_si_001.pdf
", "abstract": "Earth-abundant catalysts for the hydrogen-evolution reaction require increased mass loadings, relative to Pt films, to achieve comparable activity and stability in acidic electrolytes. We report herein that spontaneous nanostructuring of opaque, electrodeposited CoP films, 40\u2013120 nm in thickness, leads to transparent electrocatalyst films that exhibit up to 90% optical transmission in the visible spectrum. The photocurrent density under simulated sunlight at a representative n+p-Si(100)/CoP photocathode increases by 200% after exposure to 0.50 M H\u2082SO\u2084 (aq) and remains stable for 12 h of continuous operation. Atomic force microscopy and scanning electron microscopy of the film before and after exposure to 0.50 M H\u2082SO\u2084 (aq) validate an optical model for transparent CoP films as probed with spectroscopic ellipsometry.", "date": "2020-01-02", "date_type": "published", "publication": "Journal of Physical Chemistry Letters", "volume": "11", "number": "1", "publisher": "American Chemical Society", "pagerange": "14-20", "id_number": "CaltechAUTHORS:20191203-081242656", "issn": "1948-7185", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191203-081242656", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Caltech Beckman Institute" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acs.jpclett.9b02926", "primary_object": { "basename": "jz9b02926_si_001.pdf", "url": "https://authors.library.caltech.edu/records/58whj-0gn64/files/jz9b02926_si_001.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Kempler, Paul A.; Fu, Harold J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ham6d-jhk46", "eprint_id": 99536, "eprint_status": "archive", "datestamp": "2023-08-19 19:02:05", "lastmod": "2023-10-18 18:32:39", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Giesbrecht-P-K", "name": { "family": "Giesbrecht", "given": "Patrick K." }, "orcid": "0000-0003-2039-4791" }, { "id": "M\u00fcller-A-M", "name": { "family": "M\u00fcller", "given": "Astrid M." }, "orcid": "0000-0002-2785-6808" }, { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Holdcroft-S", "name": { "family": "Holdcroft", "given": "Steven" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Freund-M-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" } ] }, "title": "Vapor-fed electrolysis of water using earth-abundant catalysts in Nafion or in bipolar Nafion/poly(benzimidazolium) membranes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 The Royal Society of Chemistry. \n\nThe article was received on 17 Aug 2019, accepted on 23 Oct 2019 and first published on 28 Oct 2019. \n\nSupport for this work was provided by the United States National Science Foundation (NSF) under the CCI Solar Fuels Program, Grant No. CHE-1305124, the Natural Sciences and Engineering Research Council of Canada (NSERC), as well as the Canada Foundation for Innovation (CFI). We are grateful to Kimberly Papadantonakis for helpful comments and technical editing of the manuscript. \n\nThere are no conflicts to declare.\n\nSupplemental Material - c9se00672a1_si.pdf
", "abstract": "Vapor-fed electrolysis of water has been performed using membrane-electrode assemblies (MEAs) incorporating earth-abundant catalysts and bipolar membranes (BPMs). Catalyst films containing CoP nanoparticles, carbon black, and Nafion were synthesized, characterized, and integrated into cathodes of MEAs. The CoP-containing MEAs exhibited stable (>16 h) vapor-fed electrolysis of water at room temperature at a current density of 10 mA cm\u207b\u00b2 with 350 mV of additional overvoltage relative to MEA's formed from Pt/C cathodic electrocatalysts due to slower hydrogen-evolution reaction kinetics under vapor-fed conditions and fewer available triple-phase boundaries in the catalyst film. Additionally, catalyst films containing a [NiFe]-layered double hydroxide ([NiFe]-LDH) as well as a hydroxide ion conductor, hexamethyl-p-terphenyl poly(benzimidazolium) (HMT-PMBI), were synthesized, characterized, and integrated into the anodes of the MEAs. The [NiFe]-LDH-containing MEAs exhibited overvoltages at 10 mA cm\u207b\u00b2 that were similar to those of IrO_x-containing MEAs for vapor-fed electrolysis of water at room temperature. A BPM was formed by pairing Nafion with HMT-PMBI, resulting in a locally alkaline environment of HMT-PMBI to stabilize the [NiFe]-LDH and a locally acidic environment to stabilize the CoP. BPM-based MEAs were stable (>16 h) for vapor-fed electrolysis of water at room temperature at a current density of 10 mA cm\u207b\u00b2, with a change in the pH gradient of 1 unit over 16 h of electrolysis for IrOx-containing MEAs. The stability of [NiFe]-LDH-based MEAs under vapor-fed conditions was dependent on the catalyst film morphology and resulting BPM interface, with stable operation at 10 mA cm\u207b\u00b2 achieved for 16 h. All MEAs exhibited a drift in the operating voltage over time associated with dehydration. These results demonstrate that earth-abundant catalysts and BPMs can be incorporated into stable, room-temperature, vapor-fed water-splitting cells operated at 10 mA cm\u207b\u00b2.", "date": "2019-12-01", "date_type": "published", "publication": "Sustainable Energy and Fuels", "volume": "3", "number": "12", "publisher": "Royal Society of Chemistry", "pagerange": "3611-3626", "id_number": "CaltechAUTHORS:20191029-113947239", "issn": "2398-4902", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191029-113947239", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "Canada Foundation for Innovation" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1039/c9se00672a", "primary_object": { "basename": "c9se00672a1_si.pdf", "url": "https://authors.library.caltech.edu/records/ham6d-jhk46/files/c9se00672a1_si.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Giesbrecht, Patrick K.; M\u00fcller, Astrid M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hcahh-x0586", "eprint_id": 99735, "eprint_status": "archive", "datestamp": "2023-08-19 18:48:54", "lastmod": "2023-10-18 18:43:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Meier-Madeline-C", "name": { "family": "Meier", "given": "Madeline C." }, "orcid": "0000-0003-1608-0810" }, { "id": "Cheng-Wen-Hui", "name": { "family": "Cheng", "given": "Wen-Hui" }, "orcid": "0000-0003-3233-4606" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" } ] }, "title": "Inorganic Phototropism in Electrodeposition of Se-Te", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 American Chemical Society. \n\nReceived: October 1, 2019; Published: November 7, 2019. \n\nThis work was supported by the National Science Foundation under Award Number DMR1905963. The authors gratefully acknowledge K. Hamann for insightful discussions and R. Gerhart, N. Hart, and B. Markowicz for assistance with photoelectrochemical cell fabrication. MCM acknowledges a Graduate Research Fellowship from the National Science Foundation. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - ja9b10579_si_001.pdf
", "abstract": "Photoelectrochemical deposition of Se\u2013Te on isolated Au islands using an unstructured, incoherent beam of light produces growth of Se\u2013Te alloy toward the direction of the incident light beam. Full-wave electromagnetic simulations of light absorption indicated that the induced spatial growth anisotropy was a function of asymmetric absorption in the evolving deposit. Inorganic phototropic growth is analogous to biological systems such as palm trees that exhibit phototropic growth wherein physical extension of the plant guides the crown toward the time-averaged position of the sun, to maximize solar harvesting.", "date": "2019-11-27", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "141", "number": "47", "publisher": "American Chemical Society", "pagerange": "18658-18661", "id_number": "CaltechAUTHORS:20191107-105009380", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191107-105009380", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1905963" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1021/jacs.9b10579", "primary_object": { "basename": "ja9b10579_si_001.pdf", "url": "https://authors.library.caltech.edu/records/hcahh-x0586/files/ja9b10579_si_001.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Meier, Madeline C.; Cheng, Wen-Hui; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kx8dc-mbg83", "eprint_id": 98204, "eprint_status": "archive", "datestamp": "2023-08-19 17:54:55", "lastmod": "2023-10-18 17:08:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bhattacharyya-D", "name": { "family": "Bhattacharyya", "given": "Dhritiman" }, "orcid": "0000-0001-6761-8655" }, { "id": "Montenegro-A", "name": { "family": "Montenegro", "given": "Angelo" } }, { "id": "Plymale-N-T", "name": { "family": "Plymale", "given": "Noah T." }, "orcid": "0000-0003-2564-8009" }, { "id": "Dutta-Chayan", "name": { "family": "Dutta", "given": "Chayan" }, "orcid": "0000-0003-4839-2245" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Benderskii-A-V", "name": { "family": "Benderskii", "given": "Alexander V." }, "orcid": "0000-0001-7031-2630" } ] }, "title": "Vibrational Sum Frequency Generation (VSFG) Spectroscopy Measurement of the Rotational Barrier of Methyl Groups on Methyl-Terminated Silicon(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 American Chemical Society. \n\nReceived: May 23, 2019;\nAccepted: August 23, 2019;\nPublished: August 23, 2019.\n\nThis research was supported by AFOSR Grant No. FA9550-15-1-0184. N.T.P. and N.S.L. acknowledge support from the National Science Foundation Grant No. CHE-1808599. D.B. acknowledges support from the Burg Teaching Fellowship from Anton Burg Foundation.\n\nThe authors declare no competing financial interest.\n\nSupplemental Material - jz9b01487_si_001.pdf
", "abstract": "The methyl-terminated Si(111) surface possesses a 3-fold in-plane symmetry, with the methyl groups oriented perpendicular to the substrate. The propeller-like rotation of the methyl groups is hindered at room temperature and proceeds via 120\u00b0 jumps between three isoenergetic minima in registry with the crystalline Si substrate. We have used line-shape analysis of polarization-selected vibrational sum frequency generation spectroscopy to determine the rotational relaxation rate of the surface methyl groups and have measured the temperature dependence of the relaxation rate between 20 and 120 \u00b0C. By fitting the measured rate to an Arrhenius dependence, we extracted an activation energy (the rotational barrier) of 830 \u00b1 360 cm^(\u20131) and an attempt frequency of (2.9 \u00b1 4.2) \u00d7 10^(13) s^(\u20131) for the methyl rotation process. Comparison with the harmonic frequency of a methyl group in a 3-fold cosine potential suggests that the hindered rotation occurs via uncorrelated jumps of single methyl groups rather than concerted gear-like rotation.", "date": "2019-09-19", "date_type": "published", "publication": "Journal of Physical Chemistry Letters", "volume": "10", "number": "18", "publisher": "American Chemical Society", "pagerange": "5434-5439", "id_number": "CaltechAUTHORS:20190826-085041693", "issn": "1948-7185", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190826-085041693", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-15-1-0184" }, { "agency": "NSF", "grant_number": "CHE-1808599" }, { "agency": "Anton Burg Foundation" } ] }, "doi": "10.1021/acs.jpclett.9b01487", "primary_object": { "basename": "jz9b01487_si_001.pdf", "url": "https://authors.library.caltech.edu/records/kx8dc-mbg83/files/jz9b01487_si_001.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Bhattacharyya, Dhritiman; Montenegro, Angelo; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hcf4g-2wn91", "eprint_id": 97497, "eprint_status": "archive", "datestamp": "2023-08-19 17:51:11", "lastmod": "2023-10-18 16:00:10", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ardo-S", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Santori-E-A", "name": { "family": "Santori", "given": "Elizabeth A." } }, { "id": "Emmer-H-S", "name": { "family": "Emmer", "given": "Hal S." } }, { "id": "Grimm-R-L", "name": { "family": "Grimm", "given": "Ronald L." }, "orcid": "0000-0003-0407-937X" }, { "id": "Bierman-M-J", "name": { "family": "Bierman", "given": "Matthew J." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Enhanced Stability and Efficiency for Photoelectrochemical Iodide Oxidation by Methyl Termination and Electrochemical Pt Deposition of n-Si Microwire Arrays", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 American Chemical Society. \n\nReceived: July 17, 2019; Accepted: July 24, 2019; Published: July 25, 2019. \n\nThis work was supported by the National Science Foundation (NSF) Center for Chemical Innovation (CCI) Powering the Planet grants (Grants CHE-0802907, CHE-0947829, and NSF-ACCF) and made use of the Molecular Materials Resource Center of the Beckman Institute at Caltech and the Kavli Nanoscience Institute at Caltech. S.A. acknowledges support from a U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under the EERE Fuel Cell Technologies Program. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nz9b01529_si_001.pdf
", "abstract": "Arrays of Si microwires doped n-type (n-Si) and surface-functionalized with methyl groups have been used, with or without deposition of Pt electrocatalysts, to photoelectrochemically oxidize I\u2013(aq) to I_3\u2013(aq) in 7.6 M HI(aq). Under conditions of iodide oxidation, methyl-terminated n-Si microwire arrays exhibited stable short-circuit photocurrents over a time scale of days, albeit with low energy-conversion efficiencies. In contrast, electrochemical deposition of Pt onto methyl-terminated n-Si microwire arrays consistently yielded energy-conversion efficiencies of \u223c2% for iodide oxidation, with an open-circuit photovoltage of \u223c400 mV and a short-circuit photocurrent density of \u223c10 mA cm^(\u20132) under 100 mW cm^(\u20132) of simulated air mass 1.5G solar illumination. Platinized electrodes were stable for >200 h of continuous operation, with no discernible loss of Si or Pt. Pt deposited using electron-beam evaporation also resulted in stable photoanodic operation of the methyl-terminated n-Si microwire arrays but yielded substantially lower photovoltages than when Pt was deposited electrochemically.", "date": "2019-09-13", "date_type": "published", "publication": "ACS Energy Letters", "volume": "4", "number": "9", "publisher": "American Chemical Society", "pagerange": "2308-2314", "id_number": "CaltechAUTHORS:20190729-153032767", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190729-153032767", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "NSF", "grant_number": "CHE-0947829" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Kavli Nanoscience Institute" }, { "agency": "Department of Energy (DOE)" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acsenergylett.9b01529", "primary_object": { "basename": "nz9b01529_si_001.pdf", "url": "https://authors.library.caltech.edu/records/hcf4g-2wn91/files/nz9b01529_si_001.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Ardo, Shane; Santori, Elizabeth A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pf1a4-zd677", "eprint_id": 96018, "eprint_status": "archive", "datestamp": "2023-08-19 17:42:39", "lastmod": "2023-10-20 20:48:21", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yalamanchili-Sisir", "name": { "family": "Yalamanchili", "given": "Sisir" } }, { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "Paul A." }, "orcid": "0000-0003-3909-1790" }, { "id": "Papadantonakis-K-M", "name": { "family": "Papadantonakis", "given": "Kimberly\u00a0M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Integration of electrocatalysts with silicon microcone arrays for minimization of optical and overpotential losses during sunlight-driven hydrogen evolution", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 The Royal Society of Chemistry 2019. \n\nReceived 10th May 2019. Accepted 13th May 2019. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, as follows: electrochemical measurements for all devices, and fabrication of p-Si/Co\u2013P devices was supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993; the development and fabrication of p-Si and n^+p-Si/Pt \u03bc-cone arrays and reflection measurements were supported by the National Science Foundation (NSF) under NSF CA No. EEC-1041895. Additional support for this work was provided by the Lockheed Martin Corporation (Award 4103810021). Fabrication of Si \u03bc-cones was performed in the Kavli Nanoscience Institute (KNI) at Caltech, and we thank the KNI staff for their assistance during fabrication.\n\nSupplemental Material - c9se00294d1.pdf
", "abstract": "Microstructured photoelectrode morphologies can advantageously facilitate integration of optically absorbing electrocatalysts with semiconducting light absorbers, to maintain low overpotentials for fuel production without producing a substantial loss in photocurrent density. We report herein the use of arrays of antireflective, high-aspect-ratio Si microcones (\u03bc-cones), coupled with light-blocking Pt and Co\u2013P catalysts, as photocathodes for H_2 evolution. Thick (\u223c16 nm) layers of Pt or Co\u2013P deposited onto Si \u03bc-cone arrays yielded absolute light-limited photocurrent densities of \u223c32 mA cm^(\u22122), representing a reduction in light-limited photocurrent density of 6% relative to bare Si \u03bc-cone-array photocathodes, while maintaining high fill factors and low overpotentials for H_2 production from 0.50 M H_2SO_4(aq). The Si \u03bc-cone arrays were embedded in a flexible polymeric membrane and removed from the Si substrate, to yield flexible photocathodes consisting of polymer-embedded arrays of free-standing \u03bc-cones that evolved hydrogen from 0.50 M H_2SO_4(aq).", "date": "2019-09-01", "date_type": "published", "publication": "Sustainable Energy and Fuels", "volume": "3", "number": "9", "publisher": "Royal Society of Chemistry", "pagerange": "2227-2236", "id_number": "CaltechAUTHORS:20190531-151359075", "issn": "2398-4902", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190531-151359075", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "EEC-1041895" }, { "agency": "Lockheed Martin", "grant_number": "4103810021" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/c9se00294d", "primary_object": { "basename": "c9se00294d1.pdf", "url": "https://authors.library.caltech.edu/records/pf1a4-zd677/files/c9se00294d1.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Yalamanchili, Sisir; Kempler, Paul A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6xwga-55241", "eprint_id": 96580, "eprint_status": "archive", "datestamp": "2023-08-19 17:25:14", "lastmod": "2023-10-20 21:19:25", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nunez-P-D", "name": { "family": "Nunez", "given": "Paul" }, "orcid": "0000-0001-7039-0516" }, { "id": "Richter-M-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Piercy-B-D", "name": { "family": "Piercy", "given": "Brandon D." }, "orcid": "0000-0002-9943-6773" }, { "id": "Roske-C-W", "name": { "family": "Roske", "given": "Christopher W." } }, { "id": "Cab\u00e1n-Acevedo-M", "name": { "family": "Cab\u00e1n-Acevedo", "given": "Miguel" }, "orcid": "0000-0003-0054-8044" }, { "id": "Losego-M-D", "name": { "family": "Losego", "given": "Mark D." }, "orcid": "0000-0002-9810-9834" }, { "id": "Konezny-S-J", "name": { "family": "Konezny", "given": "Steven J." }, "orcid": "0000-0003-1487-0931" }, { "id": "Fermin-D-J", "name": { "family": "Fermin", "given": "David J." }, "orcid": "0000-0002-0376-5506" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Characterization of Electronic Transport through Amorphous TiO_2 Produced by Atomic-Layer Deposition", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 American Chemical Society. \n\nReceived: May 9, 2019; Revised: June 14, 2019; Published: June 19, 2019. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. P.D.N. and C.W.R. thank the National Science Foundation for graduate research fellowships. C.W.R. also thanks the Link Energy Foundation for a graduate research fellowship. Research was in part carried out at the Molecular Materials Resource Center of the Beckman Institute and at the Microanalysis Center of the California Institute of Technology. D.J.F. acknowledges the financial support by the UK Engineering and Physical Sciences Research Council through the PVTEAM programme (EP/L017792/1). We thank Dr. Y. Guan for SIMS measurements, Dr. Angelo Di Bilio and Dr. Paul H. Oyala for EPR measurements, and K. Papadantonakis for assistance with editing this manuscript. S.H. and S.J.K. acknowledge the start-up support from the Tomkat Foundation. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - jp9b04434_si_001.pdf
", "abstract": "Electrical transport in amorphous titanium dioxide (a-TiO_2) thin films, deposited by atomic layer deposition (ALD), and across heterojunctions of p+-Si|a-TiO_2|metal substrates that had various top metal contacts has been characterized by ac conductivity, temperature-dependent dc conductivity, space-charge-limited current spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, X-ray photoelectron spectroscopy, and current density versus voltage (J\u2013V) characteristics. Amorphous TiO_2 films were fabricated using either tetrakis(dimethylamido)-titanium with a substrate temperature of 150 \u00b0C or TiCl_4 with a substrate temperature of 50, 100, or 150 \u00b0C. EPR spectroscopy of the films showed that the Ti^(3+) concentration varied with the deposition conditions and increases in the concentration of Ti^(3+) in the films correlated with increases in film conductivity. Valence band spectra for the a-TiO_2 films exhibited a defect-state peak below the conduction band minimum (CBM) and increases in the intensity of this peak correlated with increases in the Ti^(3+) concentration measured by EPR as well as with increases in film conductivity. The temperature-dependent conduction data showed Arrhenius behavior at room temperature with an activation energy that decreased with decreasing temperature, suggesting that conduction did not occur primarily through either the valence or conduction bands. The data from all of the measurements are consistent with a Ti^(3+) defect-mediated transport mode involving a hopping mechanism with a defect density of 10^(19) cm^(\u20133), a 0.83 wide defect band centered 1.47 eV below the CBM, and a free-electron concentration of 10^(16) cm^(\u20133). The data are consistent with substantial room-temperature anodic conductivity resulting from the introduction of defect states during the ALD fabrication process as opposed to charge transport intrinsically associated with the conduction band of TiO_2.", "date": "2019-08-22", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "123", "number": "33", "publisher": "American Chemical Society", "pagerange": "20116-20129", "id_number": "CaltechAUTHORS:20190620-093003082", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190620-093003082", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Link Foundation" }, { "agency": "Engineering and Physical Sciences Research Council (EPSRC)", "grant_number": "EP/L017792/1" }, { "agency": "Tomkat Foundation" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acs.jpcc.9b04434", "primary_object": { "basename": "jp9b04434_si_001.pdf", "url": "https://authors.library.caltech.edu/records/6xwga-55241/files/jp9b04434_si_001.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Nunez, Paul; Richter, Matthias H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/v8qf2-nsk37", "eprint_id": 95415, "eprint_status": "archive", "datestamp": "2023-08-22 01:34:14", "lastmod": "2023-10-20 20:12:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Borgwardt-Mario", "name": { "family": "Borgwardt", "given": "Mario" }, "orcid": "0000-0002-1693-7047" }, { "id": "Omelchenko-Stefan-T", "name": { "family": "Omelchenko", "given": "Stefan T." }, "orcid": "0000-0003-1104-9291" }, { "id": "Favaro-Marco", "name": { "family": "Favaro", "given": "Marco" } }, { "id": "Plate-Paul", "name": { "family": "Plate", "given": "Paul" } }, { "id": "H\u00f6hn-Christian", "name": { "family": "H\u00f6hn", "given": "Christian" }, "orcid": "0000-0002-2043-598X" }, { "id": "Abou-Ras-Daniel", "name": { "family": "Abou-Ras", "given": "Daniel" } }, { "id": "Schwarzburg-Klaus", "name": { "family": "Schwarzburg", "given": "Klaus" } }, { "id": "van-de-Krol-Roel", "name": { "family": "van de Krol", "given": "Roel" }, "orcid": "0000-0003-4399-399X" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Eichberger-Rainer", "name": { "family": "Eichberger", "given": "Rainer" }, "orcid": "0000-0001-9521-0024" }, { "id": "Friedrich-Dennis", "name": { "family": "Friedrich", "given": "Dennis" }, "orcid": "0000-0003-4844-368X" } ] }, "title": "Femtosecond time-resolved two-photon photoemission studies of ultrafast carrier relaxation in Cu_2O photoelectrodes", "ispublished": "pub", "full_text_status": "public", "keywords": "Chemical physics; Energy; Photocatalysis", "note": "\u00a9 2019 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived 09 November 2018; Accepted 23 April 2019; Published\n08 May 2019. \n\nData availability: The source data underlying Figs. 2a\u2013d and 3 are available in Zenodo, https://doi.org/10.5281/zenodo.2628238. The source data for the Supplementary Figures are available from the corresponding author upon reasonable request. \n\nM.B., R.E. and D.F. thank P. Sippel for discussions. M.B. acknowledges funding from the Helmholtz Association through the Excellence network UniSysCat (ExNet-0024-1). This work was supported in part (S.T.O., H.A.A. and N.S.L.) through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. D.F. acknowledges support by the German Research Foundation (DFG), project numbers PAK 981/1 and FR 4025/2-1. \n\nAuthor Contributions: M.B., D.F. and R.E. designed the experiments on samples provided by S.T.O, H.A.A., and N.S.L. M.B. and D.F. carried out the laser experiments and analyzed the data with the help of R. vdK and R.E. M.B., M.F., P.P., C.H. and D.F. performed the LEED and XPS measurements and analyzed the data. D.A.-R. performed the SEM/EDX experiments. K.S. performed the AFM measurements. M.B., R.E. and D.F. prepared the paper. All authors discussed the results and commented on the paper. \n\nThe authors declare no competing interests.\n\nPublished - s41467-019-10143-x.pdf
Supplemental Material - 41467_2019_10143_MOESM1_ESM.pdf
Supplemental Material - 41467_2019_10143_MOESM2_ESM.pdf
", "abstract": "Cuprous oxide (Cu_2O) is a promising material for solar-driven water splitting to produce hydrogen. However, the relatively small accessible photovoltage limits the development of efficient Cu_2O based photocathodes. Here, femtosecond time-resolved two-photon photoemission spectroscopy has been used to probe the electronic structure and dynamics of photoexcited charge carriers at the Cu_2O surface as well as the interface between Cu_2O and a platinum (Pt) adlayer. By referencing ultrafast energy-resolved surface sensitive spectroscopy to bulk data we identify the full bulk to surface transport dynamics for excited electrons rapidly localized within an intrinsic deep continuous defect band ranging from the whole crystal volume to the surface. No evidence of bulk electrons reaching the surface at the conduction band level is found resulting into a substantial loss of their energy through ultrafast trapping. Our results uncover main factors limiting the energy conversion processes in Cu_2O and provide guidance for future material development.", "date": "2019-05-08", "date_type": "published", "publication": "Nature Communications", "volume": "10", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 2106", "id_number": "CaltechAUTHORS:20190513-072232965", "issn": "2041-1723", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190513-072232965", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Helmholtz Association", "grant_number": "ExNet-0029-1" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Deutsche Forschungsgemeinschaft (DFG)", "grant_number": "PAK 981/1" }, { "agency": "Deutsche Forschungsgemeinschaft (DFG)", "grant_number": "FR 4025/2-1" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1038/s41467-019-10143-x", "pmcid": "PMC6506537", "primary_object": { "basename": "41467_2019_10143_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/v8qf2-nsk37/files/41467_2019_10143_MOESM1_ESM.pdf" }, "related_objects": [ { "basename": "41467_2019_10143_MOESM2_ESM.pdf", "url": "https://authors.library.caltech.edu/records/v8qf2-nsk37/files/41467_2019_10143_MOESM2_ESM.pdf" }, { "basename": "s41467-019-10143-x.pdf", "url": "https://authors.library.caltech.edu/records/v8qf2-nsk37/files/s41467-019-10143-x.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Borgwardt, Mario; Omelchenko, Stefan T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0raf9-cy352", "eprint_id": 94034, "eprint_status": "archive", "datestamp": "2023-08-19 15:24:28", "lastmod": "2023-10-20 17:37:10", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ho-Alec", "name": { "family": "Ho", "given": "Alec" } }, { "id": "Zhou-Xinghao", "name": { "family": "Zhou", "given": "Xinghao" }, "orcid": "0000-0001-9229-7670" }, { "id": "Han-Lihao", "name": { "family": "Han", "given": "Lihao" }, "orcid": "0000-0002-0452-3381" }, { "id": "Sullivan-Ian", "name": { "family": "Sullivan", "given": "Ian" }, "orcid": "0000-0003-0632-4607" }, { "id": "Karp-C-L", "name": { "family": "Karp", "given": "Christoph" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" } ] }, "title": "Decoupling H_2(g) and O_2(g) Production in Water Splitting by a Solar-Driven V^(3+/2)+(aq,H_2SO_4)|KOH(aq) Cell", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 American Chemical Society. \n\nReceived: February 4, 2019; Accepted: March 21, 2019; Published: March 21, 2019. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993, as well as the Gordon and Betty Moore Foundation. The authors thank Caltech's SURF Board for a Summer Undergraduate Research Fellowship and acknowledge Caltech's Federal Work-Study program. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nz9b00278_si_001.pdf
", "abstract": "A solar-driven V^(3+/2+)(aq,H_2SO_4)|KOH(aq) cell, consisting of a carbon-cloth cathode in 2.0 M H_2SO_4(aq) with 0.36 M V_2(SO_4)_3 (pH \u22120.16), a Ni mesh anode in 2.5 M KOH(aq) (pH 14.21) for the oxygen-evolution reaction (OER), and a bipolar membrane that sustained the pH differentials between the catholyte and anolyte, enabled water splitting with spatial and temporal decoupling of the hydrogen evolution reaction (HER) from the OER and produced H_2(g) locally under pressure upon demand. Over a range of potentials and charging depths, V^(3+) was selectively reduced with >99.8% faradic efficiency. The V^(2+) species produced in the catholyte was then passed subsequently on demand over a MoCx-based HER catalyst to produce H_2(g) and regenerate V^(3+) for subsequent reduction. Under a base hydrogen pressure of 1, 10, and 100 atm, the discharge efficiency of the V^(3+) to hydrogen was 83%, 65.2%, and 59.8%, respectively. In conjunction with a solar tracker and a photovoltaic device, the V^(3+/2+)(aq,H_2SO_4)|KOH(aq) cell was charged outdoors under sunlight and discharged at night with a daily averaged diurnal solar-to-hydrogen (STH) energy conversion efficiency of 3.7% and a STH conversion efficiency of 5.8% during daylight operation.", "date": "2019-04-12", "date_type": "published", "publication": "ACS Energy Letters", "volume": "4", "number": "4", "publisher": "American Chemical Society", "pagerange": "968-976", "id_number": "CaltechAUTHORS:20190321-152633678", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190321-152633678", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Gordon and Betty Moore Foundation" }, { "agency": "Caltech Summer Undergraduate Research Fellowship (SURF)" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acsenergylett.9b00278", "primary_object": { "basename": "nz9b00278_si_001.pdf", "url": "https://authors.library.caltech.edu/records/0raf9-cy352/files/nz9b00278_si_001.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Ho, Alec; Zhou, Xinghao; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/09h6b-rfv12", "eprint_id": 93864, "eprint_status": "archive", "datestamp": "2023-08-19 15:17:53", "lastmod": "2023-10-20 17:28:52", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Moreno-Hernandez-I-A", "name": { "family": "Moreno-Hernandez", "given": "Ivan A." }, "orcid": "0000-0001-6461-9214" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Crystalline nickel, cobalt, and manganese antimonates as electrocatalysts for the chlorine evolution reaction", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 The Royal Society of Chemistry. \n\nReceived 19th December 2018, Accepted 7th March 2019, First published on 12th March 2019. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. I. A. M.-H. acknowledges a National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469. We thank Dr K. Papadantonakis for assistance with editing the manuscript, and C. Finke for assistance with iodometric measurements. \n\nThere are no conflicts to declare.\n\nSupplemental Material - c8ee03676d1_si.pdf
", "abstract": "The chlorine-evolution reaction (CER) is a common, commercially valuable electrochemical reaction, and is practiced at industrial scale globally. A precious metal solid solution of RuO_2 or IrO_2 with TiO_2 is the predominant electrocatalyst for the CER. Herein we report that materials comprised only of non-precious metal elements, specifically crystalline transition-metal antimonates (TMAs) such as NiSb_2O_x, CoSb_2O_x, and MnSb_2O_x, are moderately active, stable catalysts for the electrochemical oxidation of chloride to chlorine under conditions relevant to the commercial chlor-alkali process. Specifically, CoSb2Ox exhibited a galvanostatic potential of 1.804 V vs. NHE at 100 mA cm^(\u22122) of Cl_2(g) production from aqueous pH = 2.0, 4.0 M NaCl after 250 h of operation. Studies of the bulk and surface of the electrocatalyst and the composition of the electrolyte before and after electrolysis indicated minimal changes in the surface structure and intrinsic activity of CoSb_2O_x as a result of Cl2(g) evolution under these conditions.", "date": "2019-04-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "12", "number": "4", "publisher": "Royal Society of Chemistry", "pagerange": "1241-1248", "id_number": "CaltechAUTHORS:20190315-102720320", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190315-102720320", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1144469" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/c8ee03676d", "primary_object": { "basename": "c8ee03676d1_si.pdf", "url": "https://authors.library.caltech.edu/records/09h6b-rfv12/files/c8ee03676d1_si.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Moreno-Hernandez, Ivan A.; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/09hxv-zzq35", "eprint_id": 94107, "eprint_status": "archive", "datestamp": "2023-08-19 15:10:11", "lastmod": "2023-10-20 17:41:20", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yu-Weilai", "name": { "family": "Yu", "given": "Weilai" }, "orcid": "0000-0002-9420-0702" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Probing the material corrosion chemistry at the semiconductor/electrolyte interface for sustainable solar fuel generation", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2019 American Chemical Society.", "abstract": "Stability is one of the crit. aspects that greatly influence the future pathway of large-scale industrial application of integrated solar fuel generators. While a variety III-V semiconductors (GaAs, InP and GaP, etc.) with suitable band gaps can be employed in a tandem light-absorber device design, their material robustness under solar water-splitting conditions (pH=0 or pH=14) always remains a question. Thus, a fundamental and comprehensive understanding over the corrosion chem. of these technol.-important semiconductor materials is urgently required, which should be evaluated at exact conditions for hydrogen/oxygen evolution reactions. Herein, we systematically investigate this sophisticated material corrosion chem. in both strong acidic and basic electrolyte. Various techniques including inductively coupled plasma mass spectroscopy (ICP-MS), scanning electron microscope (SEM), XPS and at.-force microscopy (AFM) are all employed to reveal the phys. and chem. transformations occurring at the semiconductor/electrolyte interface. Combined with theor. considerations of thermodn. pourbaix diagrams, their diverse corrosion behaviors can be understood under varying conditions (under light/dark, with voltage bias/open-circuit, etc.). Eventually, rational strategies are designed to protect these semiconductors from rapid corrosion and achieve prolonged lifetime suitable for practical and sustained solar fuel generation.", "date": "2019-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190325-093202729", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190325-093202729", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2019", "author_list": "Yu, Weilai and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/06bt2-cem33", "eprint_id": 94086, "eprint_status": "archive", "datestamp": "2023-08-19 15:07:55", "lastmod": "2023-10-20 17:39:43", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Fu-Harold-J", "name": { "family": "Fu", "given": "Harold J." }, "orcid": "0000-0001-9738-209X" }, { "id": "Ardo-S", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Transparent, mixed proton/electron conducting Nafion-PEDOT:PSS composite for tandem microwire array solar water splitting devices", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2019 American Chemical Society.", "abstract": "One proposed integrated solar water splitting device involves two ion-exchange membrane-embedded, semiconducting micro-/nanowire arrays elec. connected as a tandem. Such an elec. connection must be optically transparent, ion permeable, and adhere to each membrane-embedded array. A composite Nafion-Poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) film possesses excellent adhesion and charge transport properties while being more transparent than PEDOT:PSS alone. Understanding the phase-sepn. behavior between conductive and non-conductive domains via PeakForce Tunneling Atomic Force Microscopy (PF-TUNA) enables insight towards the Nafion-PEDOT interactions that explain bulk elec. properties. A percolative network of conductive PEDOT domains held by a Nafion/PSS bulk enable electron conduction while maintaining the mech. stability and proton conducting properties of Nafion. Addn. of DMSO reduces these domain sizes from mm to nm scale, producing a dramatic >10^4 fold increase in lateral cond. Nanoscale current-voltage sweeps probe the spatial variations of ohmic behavior that lead to macroscale\ncontact resistance at composite/p-Si interfaces. The measured composite properties are input into a sensitivity anal. that guides device design via load-line anal. of a model tandem water splitting device.", "date": "2019-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190325-082415070", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190325-082415070", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2019", "author_list": "Fu, Harold J.; Ardo, Shane; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1rrja-84h70", "eprint_id": 92504, "eprint_status": "archive", "datestamp": "2023-08-19 14:18:22", "lastmod": "2023-10-20 15:46:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Simonoff-Ethan", "name": { "family": "Simonoff", "given": "Ethan" }, "orcid": "0000-0002-2156-8602" }, { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Influence of Substrates on the Long-Range Order of Photoelectrodeposited Se-Te Nanostructures", "ispublished": "pub", "full_text_status": "public", "keywords": "Electrodeposition, photoelectrochemistry, photodeposition, nanopatterning, interface, chalcogenide", "note": "\u00a9 2019 American Chemical Society. \n\nReceived: December 6, 2018; Revised: January 21, 2019; Published: January 28, 2019. \n\nThis work is part of the 'Light-Material Interactions in Energy Conversion' Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0001293. XPS and UPS data were collected at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nl8b04891_si_001.pdf
", "abstract": "The long-range order of anisotropic phototropic Se\u2013Te films grown electrochemically at room temperature under uniform-intensity, polarized, incoherent, near-IR illumination has been investigated using crystalline (111)-oriented Si substrates doped degenerately with either p- or n-type dopants. Fourier-transform (FT) analysis was performed on large-area images obtained with a scanning electron microscope, and peak shapes in the FT spectra were used to determine the pattern fidelity in the deposited Se\u2013Te films. Under nominally identical illumination conditions, phototropic films grown on p^+-Si(111) exhibited a higher degree of anisotropy and a more well-defined pattern period than phototropic films grown on n+-Si(111). Similar differences in the phototropic Se\u2013Te deposit morphology and pattern fidelity on p^+-Si versus n^+-Si were observed when the deposition rate and current densities were controlled for by adjusting the deposition parameters and illumination conditions. The doping-related effects of the Si substrate on the pattern fidelity of the phototropic Se\u2013Te deposits are ascribable to an electrical effect produced by the different interfacial junction energetics between Se\u2013Te and p^+-Si versus n^+-Si that influences the dynamic behavior during phototropic growth at the Se\u2013Te/Si interface.", "date": "2019-02-13", "date_type": "published", "publication": "Nano Letters", "volume": "19", "number": "2", "publisher": "American Chemical Society", "pagerange": "1295-1300", "id_number": "CaltechAUTHORS:20190128-155030817", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190128-155030817", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" } ] }, "doi": "10.1021/acs.nanolett.8b04891", "primary_object": { "basename": "nl8b04891_si_001.pdf", "url": "https://authors.library.caltech.edu/records/1rrja-84h70/files/nl8b04891_si_001.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Simonoff, Ethan; Lichterman, Michael F.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hx2gy-15624", "eprint_id": 92144, "eprint_status": "archive", "datestamp": "2023-08-19 13:45:17", "lastmod": "2023-10-20 00:00:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A prospective on Energy and Environmental Science", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2018 The Royal Society of Chemistry. \n\nThe article was received on 14 Dec 2018, accepted on 14 Dec 2018 and first published on 08 Jan 2019.", "abstract": "This Editorial commemorates the first\ndecade of Energy & Environmental Science\n(EES), reviewing its remarkable success\nas well as outlook for the future. In the\npast ten years, EES filled a void by fostering\nresearch and development in energy and\nenvironmental science. The success of\nEES can be attributed to several factors:\nat initiation, EES was the only high-profile\njournal to rapidly publish only the\nhighest quality energy-related research;\na growing global community of vibrant\nenergy researchers who initiated Gordon\nResearch Conferences, international meetings,\netc.; energy research becoming important\nin the eyes of the public, due to high\noil prices and environmental issues; a\ngeneration of scientists, especially junior\nresearchers and students, eager to embrace\nthe challenge of a transition to net-zero\nemissions energy systems; increased funding\nfor energy research internationally as\nwell as in the U.S. at the National Science\nFoundation and Department of Energy.\nEES became the preferred option to publish\nhigh-quality, high-impact energy\nresearch, with success reflected by a\nrecord-setting impact factor for a full-featured\njournal.", "date": "2019-01-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "12", "number": "1", "publisher": "Royal Society of Chemistry", "pagerange": "16-18", "id_number": "CaltechAUTHORS:20190108-140553260", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190108-140553260", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1039/c8ee90070a", "resource_type": "article", "pub_year": "2019", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8p281-9rt86", "eprint_id": 91853, "eprint_status": "archive", "datestamp": "2023-08-19 13:45:01", "lastmod": "2023-10-19 23:46:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Finke-Cody-E", "name": { "family": "Finke", "given": "Cody E." }, "orcid": "0000-0002-1343-1737" }, { "id": "Omelchenko-Stefan-T", "name": { "family": "Omelchenko", "given": "Stefan T." }, "orcid": "0000-0003-1104-9291" }, { "id": "Jasper-Justin-T", "name": { "family": "Jasper", "given": "Justin T." }, "orcid": "0000-0002-2461-5283" }, { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Read-Carlos-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Hoffmann-M-R", "name": { "family": "Hoffmann", "given": "Michael R." }, "orcid": "0000-0001-6495-1946" } ] }, "title": "Enhancing the activity of oxygen-evolution and chlorine-evolution electrocatalysts by atomic layer deposition of TiO\u2082", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 The Royal Society of Chemistry. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. \n\nThe article was received on 12 Aug 2018, accepted on 26 Nov 2018 and first published on 14 Dec 2018. \n\nSupporting data referenced above may be found in the ESI. This work was supported by the Bill and Melinda Gates Foundation (BMGF RTTC Grants OPP1111246 and OPP1149755). Research was in part carried out at the Molecular Materials Resource Center of the Beckman Institute of the California Institute of Technology. Funding was provided to C. E. F., J. T. J., and C. G. R. by the Resnick Institute for Sustainability at Caltech. In part, this material is based upon work by S. T. O. and N. S. L. performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. C. E. F. was the primary concept generator for this work, led electrocatalyst activity, E_(ZC), and AFM data collection and analysis, and helped fabricate and characterize the electrocatalysts. S. T. O. helped to generate the concept for this work, fabricated and characterized the electrocatalysts, and helped with data analysis and experimental design. J. T. J. helped generate the concept of this work, helped design the electrochemical methodology, and helped collect electrochemical data. M. F. L. collected the XPS data and assisted in the fitting and analysis of XPS and impedance spectroscopy data. C. G. R. lead TEM characterization of the electro catalysts. C. E. F., S. T. O., and J. T. J. prepared the manuscript and N. S. L., M. R. H., M. F. L., and C. G. R. helped with its editing. All authors reviewed and contributed to the final manuscript. We would like to acknowledge Dr Katharina Urmann and Sisir Yalamanchili for help dicing Si wafers, Jingjing Jiang for help analyzing AFM data, and Azhar Carim for help with SEM, and Laleh Majari Kasmaee for help with E_(ZC) analysis. We acknowledge Prof. Stefan Zweifel and his group for foundational mentoring as well as Prof. Gretchen Hofmeister and Prof. Matt Whited for foundational chemical insight. \n\nConflicts of interest: The authors' institution (California Institute of Technology) has filed a U.S. patent application directly relating to the work described in the paper (patent application no. US20180087164A1, filed on Sept. 28, 2017).\n\nPublished - c8ee02351d.pdf
Supplemental Material - c8ee02351d1_si.pdf
", "abstract": "We report that TiO\u2082 coatings formed via atomic layer deposition (ALD) may tune the activity of IrO\u2082, RuO\u2082, and FTO for the oxygen-evolution and chlorine-evolution reactions (OER and CER). Electrocatalysts exposed to \u223c3\u201330 ALD cycles of TiO\u2082 exhibited overpotentials at 10 mA cm\u207b\u00b2 of geometric current density that were several hundred millivolts lower than uncoated catalysts, with correspondingly higher specific activities. For example, the deposition of TiO\u2082 onto IrO\u2082 yielded a 9-fold increase in the OER-specific activity in 1.0 M H\u2082SO\u2084 (0.1 to 0.9 mA cm_(ECSA)\u207b\u00b2 at 350 mV overpotential). The oxidation state of titanium and the potential of zero charge were also a function of the number of ALD cycles, indicating a correlation between oxidation state, potential of zero charge, and activity of the tuned electrocatalysts.", "date": "2019-01-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "12", "number": "1", "publisher": "Royal Society of Chemistry", "pagerange": "358-365", "id_number": "CaltechAUTHORS:20181217-085437866", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181217-085437866", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Bill and Melinda Gates Foundation", "grant_number": "OPP1111246" }, { "agency": "Bill and Melinda Gates Foundation", "grant_number": "OPP1149755" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1039/c8ee02351d", "pmcid": "PMC7680952", "primary_object": { "basename": "c8ee02351d.pdf", "url": "https://authors.library.caltech.edu/records/8p281-9rt86/files/c8ee02351d.pdf" }, "related_objects": [ { "basename": "c8ee02351d1_si.pdf", "url": "https://authors.library.caltech.edu/records/8p281-9rt86/files/c8ee02351d1_si.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Finke, Cody E.; Omelchenko, Stefan T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/trwxy-v4y42", "eprint_id": 91847, "eprint_status": "archive", "datestamp": "2023-08-19 13:00:55", "lastmod": "2023-10-19 23:46:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shen-Heping", "name": { "family": "Shen", "given": "Heping" }, "orcid": "0000-0002-8409-8839" }, { "id": "Omelchenko-Stefan-T", "name": { "family": "Omelchenko", "given": "Stefan T." }, "orcid": "0000-0003-1104-9291" }, { "id": "Jacobs-Daniel-A", "name": { "family": "Jacobs", "given": "Daniel A." }, "orcid": "0000-0002-6267-9827" }, { "id": "Yalamanchili-Sisir", "name": { "family": "Yalamanchili", "given": "Sisir" } }, { "id": "Wan-Yimao", "name": { "family": "Wan", "given": "Yimao" }, "orcid": "0000-0003-2999-2464" }, { "id": "Yan-Di", "name": { "family": "Yan", "given": "Di" }, "orcid": "0000-0003-2179-3188" }, { "id": "Phang-Pheng", "name": { "family": "Phang", "given": "Pheng" } }, { "id": "Duong-The", "name": { "family": "Duong", "given": "The" } }, { "id": "Wu-Yiliang", "name": { "family": "Wu", "given": "Yiliang" }, "orcid": "0000-0002-5369-2130" }, { "id": "Yin-Yanting", "name": { "family": "Yin", "given": "Yanting" }, "orcid": "0000-0003-0379-1816" }, { "id": "Samundsett-Christian", "name": { "family": "Samundsett", "given": "Christian" } }, { "id": "Peng-Jun", "name": { "family": "Peng", "given": "Jun" } }, { "id": "Wu-Nandi", "name": { "family": "Wu", "given": "Nandi" } }, { "id": "White-Thomas-P", "name": { "family": "White", "given": "Thomas P." }, "orcid": "0000-0001-8493-9450" }, { "id": "Andersson-Gunther-G", "name": { "family": "Andersson", "given": "Gunther G." }, "orcid": "0000-0001-5742-3037" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Catchpole-Kylie-R", "name": { "family": "Catchpole", "given": "Kylie R." }, "orcid": "0000-0003-4858-1820" } ] }, "title": "In situ recombination junction between p-Si and TiO_2 enables high-efficiency monolithic perovskite/Si tandem cells", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). \n\nSubmitted 1 August 2018; Accepted 15 November 2018; Published 14 December 2018. \n\nWe would like to thank S. Surve for the mask fabrication and D. Sheng for the STEM results discussion. We greatly appreciate T. Lu and Y. Liu for help with the AFM measurement, D. Walter and T. Kho for discussion about the passivation of Si solar cells, P. Zhang, Y. Zhang, and L. Wang for coordination of the EQE measurement, W. Liang for optimization of the texturing process, and H. T. Nguyen for optical analysis. The electron spectroscopy apparatus was built with a grant from the Australian Research Council (LE0989068). We acknowledge the equipment and support provided by the Australian Microscopy and Microanalysis Research Facility (AMMRF) and the Australian National Fabrication Facility (ANFF) at the South Australian nodes of the AMMRF and ANFF under the National Collaborative Research Infrastructure Strategy. \n\nThis work was supported by the Australian Government through the Australian Renewable Energy Agency (ARENA), grant MG005, and the Australian Research Council through grant FT13010916. Responsibility for the views, information, or advice expressed herein is not accepted by the Australian Government. Part of the experiment was performed at ANFF ACT Node at the Australian National University. The conception and experimental realization of the TiO_2 deposition and ohmic contact behavior in the tandem solid-state device structure are based on work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under award no. DE-SC0004993. \n\nAuthor contributions: N.S.L. and K.R.C. supervised the research and coordinated the collaboration. N.S.L., S.T.O., and S.Y. were instrumental in generating the concept for this work. H.S. designed experiments as well as fabricated and characterized devices. D.A.J. helped with data analysis, provided the physical theory, and performed simulations. S.T.O., S.Y., N.W., and Y. Wa. contributed to preparing different TiO2 materials and the design of experiments to characterize the TiO_2/Si contacts. Y. Wa., Y. Wu, T.D., and T.P.W. supplied expertise in tandem design. P.P., C.S., Y. Wu, and D.Y. helped with Si solar cell design and fabrication. T.D. and J.P. assisted in perovskite device fabrication and device stability analysis. Y.Y. and G.G.A. were responsible for the energy level characterization of the ALD-TiO2 layer. H.S. and D.A.J. prepared the manuscript, and N.S.L, K.R.C., S.T.O., and S.Y. helped with its editing. All authors reviewed and contributed to the final manuscript. \n\nCompeting interests: S.T.O., S.Y., and N.S.L. are inventors on a provisional U.S. patent application related to this work filed by the California Institute of Technology (no. 62/662,852, filed 26 April 2018). The authors declare that there are no other competing interests. \n\nData and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.\n\nPublished - eaau9711.full.pdf
Supplemental Material - aau9711_SM.pdf
", "abstract": "Increasing the power conversion efficiency of silicon (Si) photovoltaics is a key enabler for continued reductions in the cost of solar electricity. Here, we describe a two-terminal perovskite/Si tandem design that increases the Si cell's output in the simplest possible manner: by placing a perovskite cell directly on top of the Si bottom cell. The advantageous omission of a conventional interlayer eliminates both optical losses and processing steps and is enabled by the low contact resistivity attainable between n-type TiO_2 and Si, established here using atomic layer deposition. We fabricated proof-of-concept perovskite/Si tandems on both homojunction and passivating contact heterojunction Si cells to demonstrate the broad applicability of the interlayer-free concept. Stabilized efficiencies of 22.9 and 24.1% were obtained for the homojunction and passivating contact heterojunction tandems, respectively, which could be readily improved by reducing optical losses elsewhere in the device. This work highlights the potential of emerging perovskite photovoltaics to enable low-cost, high-efficiency tandem devices through straightforward integration with commercially relevant Si solar cells.", "date": "2018-12", "date_type": "published", "publication": "Science Advances", "volume": "4", "number": "12", "publisher": "American Association for the Advancement of Science", "pagerange": "Art. No. eaau9711", "id_number": "CaltechAUTHORS:20181217-073539652", "issn": "2375-2548", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181217-073539652", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Australian Research Council", "grant_number": "LE0989068" }, { "agency": "Australian Renewable Energy Agency", "grant_number": "MG005" }, { "agency": "Australian Research Council", "grant_number": "FT13010916" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1126/sciadv.aau9711", "pmcid": "PMC6294601", "primary_object": { "basename": "aau9711_SM.pdf", "url": "https://authors.library.caltech.edu/records/trwxy-v4y42/files/aau9711_SM.pdf" }, "related_objects": [ { "basename": "eaau9711.full.pdf", "url": "https://authors.library.caltech.edu/records/trwxy-v4y42/files/eaau9711.full.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Shen, Heping; Omelchenko, Stefan T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kkmk9-n1557", "eprint_id": 87651, "eprint_status": "archive", "datestamp": "2023-09-22 22:14:30", "lastmod": "2023-10-23 23:22:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Moreno-Hernandez-I-A", "name": { "family": "Moreno-Hernandez", "given": "Ivan A." }, "orcid": "0000-0001-6461-9214" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Tin Oxide as a Protective Heterojunction with Silicon for Efficient Photoelectrochemical Water Oxidation in Strongly Acidic or Alkaline Electrolytes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 WILEY\u2010VCH. \n\nReceived: April 16, 2018. Revised: May 26, 2018. Version of Record online: 01 July 2018. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE\u2010SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. I.A.M.\u2010H. acknowledges a National Science Foundation Graduate Research Fellowship under Grant No. DGE\u20101144469. The authors thank C. Garland for assistance with transmission\u2010electron microscopy. \n\nThe authors declare no conflict of interest.\n\nSupplemental Material - downloadSupplement_doi=10.1002_2Faenm.201801155_file=aenm201801155-sup-0001-S1.pdf
", "abstract": "Photoelectrodes without a p\u2013n junction are often limited in efficiency by charge recombination at semiconductor surfaces and slow charge transfer to electrocatalysts. This study reports that tin oxide (SnO_x) layers applied to n\u2010Si wafers after forming a thin chemically oxidized SiO_x layer can passivate the Si surface while producing \u2248620 mV photovoltage under 100 mW cm^(\u22122) of simulated sunlight. The SnO_x layer makes ohmic contacts to Ni, Ir, or Pt films that act as precatalysts for the oxygen\u2010evolution reaction (OER) in 1.0 m KOH(aq) or 1.0 m H_2SO_4(aq). Ideal regenerative solar\u2010to\u2010O_2(g) efficiencies of 4.1% and 3.7%, respectively, are obtained in 1.0 m KOH(aq) with Ni or in 1.0 m H2_SO_4(aq) with Pt/IrO_x layers as OER catalysts. Stable photocurrents for >100 h are obtained for electrodes with patterned catalyst layers in both 1.0 m KOH(aq) and 1.0 m H_2SO_4(aq).", "date": "2018-08-27", "date_type": "published", "publication": "Advanced Energy Materials", "volume": "8", "number": "24", "publisher": "Wiley", "pagerange": "Art. No. 1801155", "id_number": "CaltechAUTHORS:20180709-131016014", "issn": "1614-6832", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180709-131016014", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE\u20101144469" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1002/aenm.201801155", "primary_object": { "basename": "10.1002:aenm.201801155.pdf", "url": "https://authors.library.caltech.edu/records/kkmk9-n1557/files/10.1002:aenm.201801155.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Moreno-Hernandez, Ivan A.; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/778zx-rqb92", "eprint_id": 87092, "eprint_status": "archive", "datestamp": "2023-08-19 11:04:22", "lastmod": "2023-10-18 20:51:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Francis-Sonja-A", "name": { "family": "Francis", "given": "Sonja A." } }, { "id": "Velazquez-Jesus-M", "name": { "family": "Velazquez", "given": "Jesus M." } }, { "id": "Ferrer-Ivonne-M", "name": { "family": "Ferrer", "given": "Ivonne M." } }, { "id": "Torelli-Daniel-A", "name": { "family": "Torelli", "given": "Daniel A." }, "orcid": "0000-0002-6222-817X" }, { "id": "Guevarra-Dan-W", "name": { "family": "Guevarra", "given": "Dan" }, "orcid": "0000-0002-9592-3195" }, { "id": "McDowell-Matthew-T", "name": { "family": "McDowell", "given": "Matthew T." }, "orcid": "0000-0001-5552-3456" }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Zhou-Xinghao", "name": { "family": "Zhou", "given": "Xinghao" }, "orcid": "0000-0001-9229-7670" }, { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "John-Jimmy", "name": { "family": "John", "given": "Jimmy" }, "orcid": "0000-0002-8772-8939" }, { "id": "Richter-Matthias-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Hyler-Forrest-P", "name": { "family": "Hyler", "given": "Forrest P." } }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Reduction of aqueous CO_2 to 1-Propanol at MoS_2 electrodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 American Chemical Society. \n\nReceived: October 20, 2017; Revised: June 12, 2018; Published: June 13, 2018. \n\nWe thank Dr. Nathan Dalleska and Dr. David VanderVelde of the Environmental Analysis Center and High Resolution NMR Facility, respectively, for many useful discussions and instrumental access and assistance. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award DE-SC0004993. S.A.F. acknowledges the Resnick Sustainability Institute at Caltech for a Postdoctoral Fellowship. J.M.V. acknowledges support through an NRC Ford Foundation Postdoctoral Fellowship and UC Davis startup funds. D.A.T. acknowledges support through a Graduate Research Fellowship from the National Science Foundation. \n\nAuthor Contributions: S.A.F. and J.M.V. contributed equally. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - cm7b04428_si_001.pdf
", "abstract": "Reduction of carbon dioxide in aqueous electrolytes at single-crystal MoS_2 or thin-film MoS_2 electrodes yields 1-propanol as the major CO_2 reduction product, along with hydrogen from water reduction as the predominant reduction process. Lower levels of formate, ethylene glycol, and t-butanol were also produced. At an applied potential of \u22120.59 V versus a reversible hydrogen electrode, the Faradaic efficiencies for reduction of CO_2 to 1-propanol were \u223c3.5% for MoS2single crystals and \u223c1% for thin films with low edge-site densities. Reduction of CO_2 to 1-propanol is a kinetically challenging reaction that requires the overall transfer of 18 e\u2013 and 18 H+ in a process that involves the formation of 2 C\u2013C bonds. NMR analyses using ^(13)CO_2 showed the production of ^(13)C-labeled 1-propanol. In all cases, the vast majority of the Faradaic current resulted in hydrogen evolution via water reduction. H_2S was detected qualitatively when single-crystal MoS_2 electrodes were used, indicating that some desulfidization of single crystals occurred under these conditions.", "date": "2018-08-14", "date_type": "published", "publication": "Chemistry of Materials", "volume": "30", "number": "15", "publisher": "American Chemical Society", "pagerange": "4902-4908", "id_number": "CaltechAUTHORS:20180613-162202390", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180613-162202390", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "National Research Council" }, { "agency": "Ford Foundation" }, { "agency": "University of California, Davis" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1021/acs.chemmater.7b04428", "primary_object": { "basename": "cm7b04428_si_001.pdf", "url": "https://authors.library.caltech.edu/records/778zx-rqb92/files/cm7b04428_si_001.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Francis, Sonja A.; Velazquez, Jesus M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fm9vc-7ex47", "eprint_id": 87478, "eprint_status": "archive", "datestamp": "2023-08-19 09:56:00", "lastmod": "2023-10-18 21:12:31", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Davis-S-J", "name": { "family": "Davis", "given": "Steven J." }, "orcid": "0000-0002-9338-0844" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Net-zero emissions energy systems", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 American Association for the Advancement of Science. This is an article distributed under the terms of the Science Journals Default License. \n\nReceived 11 January 2018; accepted 25 May 2018. \n\nThe authors extend a special acknowledgment to M.I.H. for inspiration on the 20th anniversary of publication of (1). The authors also thank M. Dyson, L. Fulton, L. Lynd, G. Janssens-Maenhout, M. McKinnon, J. Mueller, G. Pereira, M. Ziegler, and M. Wang for helpful input. This Review stems from an Aspen Global Change Institute meeting in July 2016 convened with support from NASA, the Heising-Simons Foundation, and the Fund for Innovative Climate and Energy Research. S.J.D. and J.B. also acknowledge support of the U.S. National Science Foundation (INFEWS grant EAR 1639318). D.A., B.H., and B-M.H. acknowledge Alliance for Sustainable Energy, the manager and operator of the National Renewable Energy Laboratory for the U.S. Department of Energy (DOE) under contract DE-AC36-08GO28308. Funding was in part provided by the DOE Office of Energy Efficiency and Renewable Energy. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. government. The U.S. government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. government purposes.\n\nCorrection (29 June 2018): Figure 2 has been revised; \"Other industry\" has been correctly labeled \"14%\".\n\nSupplemental Material - aas9793-Davis-SM.pdf
", "abstract": "Some energy services and industrial processes\u2014such as long-distance freight transport, air travel, highly reliable electricity, and steel and cement manufacturing\u2014are particularly difficult to provide without adding carbon dioxide (CO2) to the atmosphere. Rapidly growing demand for these services, combined with long lead times for technology development and long lifetimes of energy infrastructure, make decarbonization of these services both essential and urgent. We examine barriers and opportunities associated with these difficult-to-decarbonize services and processes, including possible technological solutions and research and development priorities. A range of existing technologies could meet future demands for these services and processes without net addition of CO2 to the atmosphere, but their use may depend on a combination of cost reductions via research and innovation, as well as coordinated deployment and integration of operations across currently discrete energy industries.", "date": "2018-06-29", "date_type": "published", "publication": "Science", "volume": "360", "number": "6396", "publisher": "American Association for the Advancement of Science", "pagerange": "Art. No. eaas9793", "id_number": "CaltechAUTHORS:20180629-133032793", "issn": "0036-8075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180629-133032793", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" }, { "agency": "Heising-Simons Foundation" }, { "agency": "Fund for Innovative Climate and Energy Research (FICER)" }, { "agency": "NSF", "grant_number": "EAR-1639318" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC36-08GO28308" } ] }, "doi": "10.1126/science.aas9793", "primary_object": { "basename": "aas9793-Davis-SM.pdf", "url": "https://authors.library.caltech.edu/records/fm9vc-7ex47/files/aas9793-Davis-SM.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Davis, Steven J. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/tpre5-hge40", "eprint_id": 86732, "eprint_status": "archive", "datestamp": "2023-08-19 09:44:38", "lastmod": "2023-10-18 19:56:42", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Landers-A-T", "name": { "family": "Landers", "given": "Alan T." } }, { "id": "Fields-M", "name": { "family": "Fields", "given": "Meredith" } }, { "id": "Torelli-D-A", "name": { "family": "Torelli", "given": "Daniel A." }, "orcid": "0000-0002-6222-817X" }, { "id": "Xiao-Jianping", "name": { "family": "Xiao", "given": "Jianping" }, "orcid": "0000-0003-1779-6140" }, { "id": "Hellstern-T-R", "name": { "family": "Hellstern", "given": "Thomas R." } }, { "id": "Francis-S-A", "name": { "family": "Francis", "given": "Sonja A." } }, { "id": "Tsai-Charlie", "name": { "family": "Tsai", "given": "Charlie" } }, { "id": "Kibsgaard-J", "name": { "family": "Kibsgaard", "given": "Jakob" }, "orcid": "0000-0002-9219-816X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Chan-Karen", "name": { "family": "Chan", "given": "Karen" }, "orcid": "0000-0002-6897-1108" }, { "id": "Hahn-C", "name": { "family": "Hahn", "given": "Christopher" }, "orcid": "0000-0002-2772-6341" }, { "id": "Jaramillo-T-F", "name": { "family": "Jaramillo", "given": "Thomas F." }, "orcid": "0000-0001-9900-0622" } ] }, "title": "The Predominance of Hydrogen Evolution on Transition Metal Sulfides and Phosphides under CO_2 Reduction Conditions: An Experimental and Theoretical Study", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 American Chemical Society. \n\nReceived: February 9, 2018; Accepted: April 20, 2018; Publication Date (Web): May 31, 2018. \n\nThis material is based, in part, on work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy, under Award No. DE-SC0004993. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy (under Contract No. DE-AC02-05CH11231). Part of this work was performed at the Stanford Nano Shared Facilities (SNSF) and the Stanford Nanofabrication Facility (SNF), supported by the National Science Foundation under Award ECCS-1542152. We also acknowledge assistance from the Stanford NMR Facility. M.F. and D.A.T. acknowledge a graduate fellowship through the National Science Foundation. S.A.F. acknowledges the Resnick Sustainability Institute at Caltech for a postdoctoral fellowship. The authors also thank J. Chance Crompton for assistance in synthesizing the nanoparticle electrocatalysts. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nz8b00237_si_001.pdf
", "abstract": "A combination of experiment and theory has been used to understand the relationship between the hydrogen evolution reaction (HER) and CO_2 reduction (CO_2R) on transition metal phosphide and transition metal sulfide catalysts. Although multifunctional active sites in these materials could potentially improve their CO_2R activity relative to pure transition metal electrocatalysts, under aqueous testing conditions, these materials showed a high selectivity for the HER relative to CO_2R. Computational results supported these findings, indicating that a limitation of the metal phosphide catalysts is that the HER is favored thermodynamically over CO_2R. On Ni-MoS_2, a limitation is the kinetic barrier for the proton\u2013electron transfer to *CO. These theoretical and experimental results demonstrate that selective CO_2R requires electrocatalysts that possess both favorable thermodynamic pathways and surmountable kinetic barriers.", "date": "2018-06-08", "date_type": "published", "publication": "ACS Energy Letters", "volume": "3", "number": "6", "publisher": "American Chemical Society", "pagerange": "1450-1457", "id_number": "CaltechAUTHORS:20180601-080239556", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180601-080239556", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" }, { "agency": "NSF", "grant_number": "ECCS-1542152" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1021/acsenergylett.8b00237", "primary_object": { "basename": "nz8b00237_si_001.pdf", "url": "https://authors.library.caltech.edu/records/tpre5-hge40/files/nz8b00237_si_001.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Landers, Alan T.; Fields, Meredith; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/936x2-ap062", "eprint_id": 91656, "eprint_status": "archive", "datestamp": "2023-08-19 09:37:00", "lastmod": "2023-10-19 23:36:41", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Omelchenko-S-T", "name": { "family": "Omelchenko", "given": "Stefan T." }, "orcid": "0000-0003-1104-9291" }, { "id": "Wong-Joeson", "name": { "family": "Wong", "given": "Joeson" }, "orcid": "0000-0002-6304-7602" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Effects of Sub-gap Absorption on Photovoltaic Performance", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "detailed balance, Shockley-Queisser limit Urbach tail, sub-gap absorption", "note": "\u00a9 2018 IEEE.", "abstract": "The theoretical maximum photovoltaic efficiency is bounded by the Shockley-Queisser model which assumes that the photovoltaic material has step-function like absorptance, with zero absorption below its bandgap and perfect absorption above. However, typical photovoltaic materials exhibit absorption with an exponential dependence below its bandgap, known as the\"Urbach tail\" whose steepness is dependent on the Urbach parameter. Using a modified detailed balance model that accounts for sub-gap absorption we show that photovoltaic performance is strongly affected by the magnitude of the Urbach parameter.", "date": "2018-06", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "1837-1840", "id_number": "CaltechAUTHORS:20181210-140401951", "isbn": "9781538685297", "book_title": "2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181210-140401951", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1109/pvsc.2018.8547909", "resource_type": "book_section", "pub_year": "2018", "author_list": "Omelchenko, Stefan T.; Wong, Joeson; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nwqnf-c0z44", "eprint_id": 91655, "eprint_status": "archive", "datestamp": "2023-08-19 09:36:53", "lastmod": "2023-10-19 23:36:35", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yalamanchili-S", "name": { "family": "Yalamanchili", "given": "Sisir" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Role of Doping Dependent Radiative and Non-radiative Recombination in Determining the Limiting Efficiencies of Silicon Solar Cells", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "silicon, photovoltaic cells, limiting efficiency", "note": "\u00a9 2018 IEEE. \n\nThis material is based upon work supported in part by the National Science Foundation (NSF) and the Department of Energy (DOE) under NSF CA No. EEC-1041895. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect those of NSF or DOE. The authors would like to thank Phil Jahelka and Colton Bukowsky for productive discussions.", "abstract": "We show that increasing the bulk doping in a silicon based solar cell can increase the fraction of photo generated carriers that recombine radiatively at open circuit condition. This increases the maximum achievable open circuit voltage (Voc) in a solar cell At higher doping levels auger recombination and band gap narrowing effects dominate leading to a reduction in Voc. Therefore radiative and non-radiative recombinations at Voc determines the optimum doping of the bulk to maximize the performance especially in thin solar cells with increased surface area due to surface texturing.", "date": "2018-06", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "3223-3226", "id_number": "CaltechAUTHORS:20181210-140401859", "isbn": "9781538685297", "book_title": "2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181210-140401859", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "EEC-1041895" }, { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1109/pvsc.2018.8547758", "resource_type": "book_section", "pub_year": "2018", "author_list": "Yalamanchili, Sisir; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8xe3a-q2739", "eprint_id": 86333, "eprint_status": "archive", "datestamp": "2023-08-19 09:23:10", "lastmod": "2023-10-18 19:28:49", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Hamann-Kathryn-R", "name": { "family": "Hamann", "given": "Kathryn R." }, "orcid": "0000-0003-1163-7173" }, { "id": "Batara-Nicolas-A", "name": { "family": "Batara", "given": "Nicolas A." } }, { "id": "Thompson-Jonathan-R", "name": { "family": "Thompson", "given": "Jonathan R." } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Template-Free Synthesis of Periodic Three-Dimensional PbSe Nanostructures via Photoelectrodeposition", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 American Chemical Society. \n\nReceived: March 15, 2018; Published: May 9, 2018. \n\nThis work was supported by the \"Light-Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award No. DE-SC0001293. The authors gratefully acknowledge R. Gerhart for assistance with photoelectrochemical cell fabrication and M. Meier and S. Yalamanchili for assistance with computer simulations. A.I.C. acknowledges a Graduate Research Fellowship from the National Science Foundation. \n\nAuthor Contributions: A.I.C. and K.R.H. contributed equally. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - ja8b02931_si_001.pdf
", "abstract": "Highly periodic, geometrically directed, anisotropic Se\u2013Pb films have been synthesized at room temperature from an isotropic aqueous solution without the use of physical templates by photoelectrodeposition using a series of discrete input illumination polarizations and wavelengths from an unstructured, uncorrelated, incoherent light source. Dark growth did not generate deposits with substantial long-range order, but growth using unpolarized illumination resulted in an ordered, nanoscale, mesh-type morphology. Linearly polarized illumination generated Se\u2013Pb deposits that displayed an ordered, highly anisotropic lamellar pattern wherein the long axes of the lamellae were aligned parallel to the light polarization vector. The pitch of the lamellar features was proportional to the input light wavelength, as confirmed by Fourier analysis. Full-wave electromagnetic and Monte Carlo growth simulations that incorporated only the fundamental light\u2013matter interactions during growth successfully reproduced the experimentally observed morphologies and quantitatively matched the pattern periodicities. Electrochemical postprocessing of the as-deposited Se\u2013Pb structures resulted in the generation of stoichiometric, crystalline PbSe while preserving the nanopatterned morphology, thus broadening the genus of materials that can be prepared with controlled three-dimensional morphologies through maskless photoelectrodeposition.", "date": "2018-05-30", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "140", "number": "21", "publisher": "American Chemical Society", "pagerange": "6536-6539", "id_number": "CaltechAUTHORS:20180510-105817632", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180510-105817632", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1021/jacs.8b02931", "primary_object": { "basename": "ja8b02931_si_001.pdf", "url": "https://authors.library.caltech.edu/records/8xe3a-q2739/files/ja8b02931_si_001.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Carim, Azhar I.; Hamann, Kathryn R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/etbm7-cz134", "eprint_id": 86213, "eprint_status": "archive", "datestamp": "2023-08-19 09:22:28", "lastmod": "2023-10-18 19:22:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Roberts-E-J", "name": { "family": "Roberts", "given": "Emily J." } }, { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Brutchey-R-L", "name": { "family": "Brutchey", "given": "Richard L." }, "orcid": "0000-0002-7781-5596" } ] }, "title": "Phase Directing Ability of an Ionic Liquid Solvent for the Synthesis of HER-Active Ni_2P Nanocrystals", "ispublished": "pub", "full_text_status": "public", "keywords": "ionic liquid, nickel phosphide, nanocrystal, electrocatalyst, hydrogen evolution reaction", "note": "\u00a9 2018 American Chemical Society. \n\nReceived: February 13, 2018; Accepted: May 3, 2018; Published: May 3, 2018. \n\nR.L.B. acknowledges NSF for supporting the synthetic chemistry under CMMI-1728649. N.S.L. acknowledges NSF for supporting the electrochemical characterization work under the NSF CCI Solar Fuels Program CHE-1305124. C.G.R. acknowledges the Resnick Sustainability Institute for a postdoctral fellowship. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - ae8b00213_si_001.pdf
", "abstract": "An ionic liquid (IL) solvent was used to synthesize small, phase-pure nickel phosphide (Ni_2P) nanocrystals. In contrast, under analogous reaction conditions, substitution of the IL for the common high-boiling organic solvent 1-octadecene (ODE) results in phase-impure nanocrystals. The 5 nm Ni_2P nanocrystals prepared in IL were electrocatalytically active toward the hydrogen evolution reaction. The synthesis in IL was also extended to alloyed Ni_(2\u2013x)Co_xP nanocrystals, where 0.5 \u2264 x \u2264 1.5.", "date": "2018-05-29", "date_type": "published", "publication": "ACS Applied Energy Materials", "volume": "1", "number": "5", "publisher": "American Chemical Society", "pagerange": "1823-1827", "id_number": "CaltechAUTHORS:20180503-144511877", "issn": "2574-0962", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180503-144511877", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CMMI-1728649" }, { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1021/acsaem.8b00213", "primary_object": { "basename": "ae8b00213_si_001.pdf", "url": "https://authors.library.caltech.edu/records/etbm7-cz134/files/ae8b00213_si_001.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Roberts, Emily J.; Read, Carlos G.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dtcd9-sfj08", "eprint_id": 85483, "eprint_status": "archive", "datestamp": "2023-08-19 09:05:48", "lastmod": "2023-10-18 18:15:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Ritzert-N-L", "name": { "family": "Ritzert", "given": "Nicole L." } }, { "id": "John-Jimmy", "name": { "family": "John", "given": "Jimmy" }, "orcid": "0000-0002-8772-8939" }, { "id": "Tan-Haiyan", "name": { "family": "Tan", "given": "Haiyan" } }, { "id": "Hale-W-G", "name": { "family": "Hale", "given": "William G." } }, { "id": "Jiang-Jingjing", "name": { "family": "Jiang", "given": "Jingjing" } }, { "id": "Moreno-Hernandez-I-A", "name": { "family": "Moreno-Hernandez", "given": "Ivan" }, "orcid": "0000-0001-6461-9214" }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Moffat-T-P", "name": { "family": "Moffat", "given": "Thomas P." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Performance and failure modes of Si anodes patterned with thin-film Ni catalyst islands for water oxidation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 Royal Society of Chemistry 2018. \n\nThe article was received on 05 Dec 2017, accepted on 03 Mar 2018 and first published on 06 Mar 2018. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under award no. DE-SC0004993. UV-vis spectroscopy was performed at the Molecular Materials Research Center (MMRC) in the Beckman Institute at the California Institute of Technology. This work was also supported by the Gordon and Betty Moore Foundation under award no. GBMF1225. We thank A. Carim, M. Shaner, F. Saadi, J. Velazquez, and C. Xiang from Caltech for stimulating discussions. We also thank K. Walczak (Lawrence Berkeley National Laboratory) for preparation of the ion-implanted Si n^+np^+ substrates. The NIST work was supported by the American Recovery and Reinvestment funds. N. L. R. acknowledges the National Institute of Standards and Technology-National Research Council research associateship program for a postdoctoral fellowship. \n\nAuthor contributions: K. S. and N. S. L designed research; K. S., N. R., J. J., H. T., W. G. H., J. J., I. A. M., and T. P. M. performed experiments; K. S., N. R., J. J., H. T., K. M. P., T. P. M., B. S. B., and N. S. L. analyzed data; and K. S., N. R., K. M. P., T. P. M., B. S. B., and N. S. L. wrote the paper. \n\nThere are no conflicts to declare.\n\nSupplemental Material - c7se00583k1.pdf
", "abstract": "Silicon photoanodes patterned with thin-film Ni catalyst islands exhibited stable oxygen evolution for over 240 h of continuous operation in 1.0 mol L^(\u22121) KOH under simulated sunlight conditions. Buried-junction np^+-Si(111) photoanodes with an 18.0% filling fraction of a square array of Ni microelectrodes, np^+-Si(111)|Ni\u03bcE_(18.0%), demonstrated performance equivalent to a Ni anode in series with a photovoltaic device having an open-circuit voltage of 538 \u00b1 20 mV, a short-circuit current density of 20.4 \u00b1 1.3 mA cm^(\u22122), and a photovoltaic efficiency of 6.7 \u00b1 0.9%. For the np^+-Si(111)|Ni\u03bcE_(18.0%) samples, the photocurrent density at the equilibrium potential for oxygen evolution was 12.7 \u00b1 0.9 mA cm^(\u22122), yielding an ideal regenerative cell solar-to-oxygen conversion efficiency of 0.47 \u00b1 0.07%. The photocurrent passed exclusively through the Ni catalyst islands to evolve O_2 with nearly 100% faradaic efficiency, while a passivating, insulating surface layer of SiO_x formed in situ on areas of the Si in direct contact with the electrolyte. The (photo)electrochemical behavior of Si electrodes patterned with varying areal filling fractions of Ni catalyst islands was also investigated. The stability and efficiency of the patterned-catalyst Si electrodes were affected by the filling fraction of the Ni catalyst, the orientation and dopant type of the substrates, and the measurement conditions. The electrochemical behavior at different stages of operation, including Ni catalyst activation, Si passivation, stable operation, and device failure, was affected by the dynamic processes of anodic formation and isotropic dissolution of SiO_x on the exposed Si. Ex situ and operando microscopic and spectroscopic studies revealed that these processes were three-dimensional and spatially non-uniform across the surface of the substrate, and occurred near the active catalyst islands. The patterned catalyst/substrate electrodes serve as a model system for accelerated studies of failure mechanisms in photoanodes protected by multifunctional catalytic coatings or other hole-conductive thin-film coatings that contain defects.", "date": "2018-05-01", "date_type": "published", "publication": "Sustainable Energy and Fuels", "volume": "2", "number": "5", "publisher": "Royal Society of Chemistry", "pagerange": "983-998", "id_number": "CaltechAUTHORS:20180328-133308643", "issn": "2398-4902", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180328-133308643", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" }, { "agency": "American Recovery and Reinvestment Act (ARRA)" }, { "agency": "National Institute of Standards and Technology (NIST)" }, { "agency": "National Research Council" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/C7SE00583K", "primary_object": { "basename": "c7se00583k1.pdf", "url": "https://authors.library.caltech.edu/records/dtcd9-sfj08/files/c7se00583k1.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Sun, Ke; Ritzert, Nicole L.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/d83mc-eef70", "eprint_id": 86307, "eprint_status": "archive", "datestamp": "2023-08-19 08:34:29", "lastmod": "2023-10-20 21:53:42", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shaner-M-R", "name": { "family": "Shaner", "given": "Matthew R." }, "orcid": "0000-0003-4682-9757" }, { "id": "Davis-S-J", "name": { "family": "Davis", "given": "Steven J." }, "orcid": "0000-0002-9338-0844" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Caldeira-K", "name": { "family": "Caldeira", "given": "Ken" } } ] }, "title": "Geophysical constraints on the reliability of solar and wind power in the United States", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 The Royal Society of Chemistry. \n\nThe article was received on 21 Oct 2017, accepted on 14 Feb 2018 and first published on 27 Feb 2018. \n\nFunding was provided by Near Zero and the Fund for Innovative Climate and Energy Research (FICER). N. S. L. acknowledges the Gordon and Betty Moore Foundation for funding. SJD was partially supported by NSF INFEWS Grant EAR 1639318. We thank Grayson Badgley and Seth Nickell for help with data processing and analysis. We also thank Michael Mastrandrea, Karen Fries, Daniel Sanchez, Danny Cullenward and Mason Inman for helpful discussions throughout the analysis and writing processes. \n\nThere are no conflicts to declare.\n\nSupplemental Material - c7ee03029k1_si.pdf
Erratum - c8ee90019a_corr.pdf
", "abstract": "We analyze 36 years of global, hourly weather data (1980\u20132015) to quantify the covariability of solar and wind resources as a function of time and location, over multi-decadal time scales and up to continental length scales. Assuming minimal excess generation, lossless transmission, and no other generation sources, the analysis indicates that wind-heavy or solar-heavy U.S.-scale power generation portfolios could in principle provide \u223c80% of recent total annual U.S. electricity demand. However, to reliably meet 100% of total annual electricity demand, seasonal cycles and unpredictable weather events require several weeks' worth of energy storage and/or the installation of much more capacity of solar and wind power than is routinely necessary to meet peak demand. To obtain \u223c80% reliability, solar-heavy wind/solar generation mixes require sufficient energy storage to overcome the daily solar cycle, whereas wind-heavy wind/solar generation mixes require continental-scale transmission to exploit the geographic diversity of wind. Policy and planning aimed at providing a reliable electricity supply must therefore rigorously consider constraints associated with the geophysical variability of the solar and wind resource\u2014even over continental scales.", "date": "2018-04", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "11", "number": "4", "publisher": "Royal Society of Chemistry", "pagerange": "914-925", "id_number": "CaltechAUTHORS:20180509-093355674", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180509-093355674", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Fund for Innovative Climate and Energy Research (FICER)" }, { "agency": "Gordon and Betty Moore Foundation" }, { "agency": "NSF", "grant_number": "EAR-1639318" }, { "agency": "Near Zero" } ] }, "doi": "10.1039/c7ee03029k", "primary_object": { "basename": "c7ee03029k1_si.pdf", "url": "https://authors.library.caltech.edu/records/d83mc-eef70/files/c7ee03029k1_si.pdf" }, "related_objects": [ { "basename": "c8ee90019a_corr.pdf", "url": "https://authors.library.caltech.edu/records/d83mc-eef70/files/c8ee90019a_corr.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Shaner, Matthew R.; Davis, Steven J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/33v7a-p2m55", "eprint_id": 84894, "eprint_status": "archive", "datestamp": "2023-08-19 08:17:24", "lastmod": "2023-10-18 16:56:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "Paul A." }, "orcid": "0000-0003-3909-1790" }, { "id": "Gonzalez-Miguel-A", "name": { "family": "Gonzalez", "given": "Miguel A." } }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Hydrogen Evolution with Minimal Parasitic Light Absorption by Dense Co\u2013P Catalyst Films on Structured p-Si Photocathodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 American Chemical Society. \n\nReceived: January 9, 2018; Accepted: February 8, 2018; Published: February 8, 2018. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.\n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nz8b00034_si_001.pdf
", "abstract": "Planar and three-dimensionally structured p-Si devices, consisting of an electrodeposited Co\u2013P catalyst on arrays of Si microwires or Si micropyramids, were used as photocathodes for solar-driven hydrogen evolution in 0.50 M H_2SO_4(aq) to assess the effects of electrode structuring on parasitic absorption by the catalyst. Without the use of an emitter layer, p-Si/Co\u2013P microwire arrays produced a photocurrent density of \u221210 mA cm^(\u20132) at potentials that were 130 mV more positive than those of optimized planar p-Si/Co\u2013P devices. Champion p-Si/Co\u2013P microwire array devices exhibited ideal regenerative cell solar-to-hydrogen efficiencies of >2.5% and were primarily limited by the photovoltage of the p-Si/Co\u2013P junction. The vertical sidewalls of the Si microwire photoelectrodes thus minimized effects due to parasitic absorption at high loadings of catalyst for device structures with or without emitters.", "date": "2018-03-09", "date_type": "published", "publication": "ACS Energy Letters", "volume": "3", "number": "3", "publisher": "American Chemical Society", "pagerange": "612-617", "id_number": "CaltechAUTHORS:20180220-133422256", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180220-133422256", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acsenergylett.8b00034", "primary_object": { "basename": "nz8b00034_si_001.pdf", "url": "https://authors.library.caltech.edu/records/33v7a-p2m55/files/nz8b00034_si_001.pdf" }, "resource_type": "article", "pub_year": "2018", "author_list": "Kempler, Paul A.; Gonzalez, Miguel A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qds76-xyx13", "eprint_id": 84666, "eprint_status": "archive", "datestamp": "2023-08-19 08:11:45", "lastmod": "2023-10-20 21:51:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "McFarland-Eric-W", "name": { "family": "McFarland", "given": "Eric W." } } ] }, "title": "Relative costs of transporting electrical and chemical energy", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 Royal Society of Chemistry. \n\nReceived 17th July 2017. Accepted 22nd January 2018. First published on 29th January 2018. \n\nSupport for this work was provided by a graduate fellowship for F. H. S. from the Dow Centre for Sustainable Engineering Innovation at the University of Queensland, Australia. Additional support was provided by U.S. Department of Energy under Award Numbers DEFG02-89ER14048 (E. W. M.), and DE-SC0004993 (N. S. L.). \n\nThere are no conflicts to declare.\n\nPublished - c7ee01987d.pdf
Erratum - C8EE90006J.pdf
", "abstract": "Transportation costs of energy resources are important when determining the overall economics of future energy infrastructure. The majority of long distance energy transmission occurs via merchant ships and pipelines carrying oil or natural gas. In contrast, future energy scenarios often envision vastly altered energy transportation scenarios including very high degrees of grid electrification and widespread installation of hydrogen pipelines. The unit cost of energy transportation varies by over two orders of magnitude. In particular, the costs of electricity and hydrogen transmission are substantially higher than the cost of oil and natural gas transportation. If carbon pricing is to be used to incentivize alternative energy systems, these differences in costs will need to be reduced and used when making meaningful technology comparisons.", "date": "2018-03-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "11", "number": "3", "publisher": "Royal Society of Chemistry", "pagerange": "469-475", "id_number": "CaltechAUTHORS:20180205-084607037", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180205-084607037", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "University of Queensland" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-89ER14048" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c7ee01987d", "primary_object": { "basename": "C8EE90006J.pdf", "url": "https://authors.library.caltech.edu/records/qds76-xyx13/files/C8EE90006J.pdf" }, "related_objects": [ { "basename": "c7ee01987d.pdf", "url": "https://authors.library.caltech.edu/records/qds76-xyx13/files/c7ee01987d.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Saadi, Fadl H.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dragq-x2968", "eprint_id": 85854, "eprint_status": "archive", "datestamp": "2023-08-19 08:05:52", "lastmod": "2023-10-18 18:53:02", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Moreno-Hernandez-I-A", "name": { "family": "Moreno-Hernandez", "given": "Ivan A." }, "orcid": "0000-0001-6461-9214" }, { "id": "MacFarland-C-A", "name": { "family": "MacFarland", "given": "Clara A." }, "orcid": "0000-0002-9570-948X" }, { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly" }, "orcid": "0000-0002-9900-5500" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Catalysis of the oxygen evolution reaction in strongly acidic electrolytes with earth-abundant crystalline nickel-manganese antimonate", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "Many technologies that store renewable energy in chem. bonds rely on the oxygen evolution reaction (OER) to produce a\nrenewable oxidant. In systems with an alk. electrolyte the OER is catalyzed by earth-abundant oxyhydroxides of the first-row\ntransition metals, whereas systems with acidic electrolytes rely on noble metal oxides such as RuO_2 or IrO_2. The discrepancy in\nearth-abundance of OER catalysts in alk. and acidic electrolytes corresponds to the thermodn. instability of many first-row\ntransition metal binary oxides in acidic conditions. Understanding how to stabilize first-row transition metals in acidic\nelectrolytes while retaining catalytic activity towards the OER is a key milestone towards the development of scalable renewable\nenergy technologies. We report herein a nickel-manganese antimonate OER electrocatalysts with a rutile-type crystal structure.\nThe crystallinity of the nickel-manganese antimonate catalyst prevents dissoln. of Ni and Mn under operating conditions and at\nopen circuit. The nickel-manganese antimonate catalyst operates at an initial overpotential of 672 \u00b1 9 mV at 10 mA cm^(-2) of\ngeometric c.d., and operates at an overpotential below 745 mV for 168 of continuous operation at 10 mA cm^(-2). The electrode\nsurface, electrode bulk, and electrolyte were characterized with XPS, TEM, SEM, and ICP-MS. Surface and electrolyte\nmeasurements indicate initial preferential leaching of Mn from the electrocatalyst, followed by a leach rate of zero for Ni, Mn,\nand Sb after 120 h of continuous operation. The observations suggest an approach towards the development of earth-abundant,\nhighly-activate electrocatalysts for the oxygen evolution reaction in strongly acidic conditions.", "date": "2018-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20180413-154320340", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180413-154320340", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2018", "author_list": "Moreno-Hernandez, Ivan A.; MacFarland, Clara A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sev7n-ce135", "eprint_id": 85776, "eprint_status": "archive", "datestamp": "2023-08-19 08:03:08", "lastmod": "2023-10-18 18:47:01", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos" } }, { "id": "Buabthong-Pakpoom", "name": { "family": "Buabthong", "given": "Pai" }, "orcid": "0000-0001-5538-138X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan" }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Growth and characterization of single-crystalline oxynitride materials for solar fuels production", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "A complete photoelectrochem. device requires many components, all working together at optimal efficiencies for\nprolonged periods of time. Unfortunately, to date the performance and stability of many of the available\nmaterials is less than desired, esp. under the extreme alk. or acidic environments required for a com. viable\nsolar fuels platform. Recent reports have identified transition metal oxynitrides as one of the few classes of\nsemiconductor materials capable of direct overall water splitting under visible-light irradn. However, poor\nmaterials quality, low performances (<1%) and modest stabilities still hinder their in-depth study. Here, we\npresent our recent work on the development of new synthetic methods for the prodn. of high-quality singlecrystals\nof a series of perovskite-type oxynitrides, as well as their application as efficient photoanodes for water\noxidn. In addn., we cover the effects that various co-catalysts and surface protection layers have on the\nelectronic band structure, activity, and stability of these systems.", "date": "2018-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20180412-095052506", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180412-095052506", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2018", "author_list": "Read, Carlos; Buabthong, Pai; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0k07w-tn747", "eprint_id": 85857, "eprint_status": "archive", "datestamp": "2023-08-19 08:06:14", "lastmod": "2023-10-18 18:53:19", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Rinaldi-Katherine-Z", "name": { "family": "Rinaldi", "given": "Katherine Z." }, "orcid": "0000-0002-0746-2852" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Operando Raman interrogation of the synthesis and activation of a CoSe HER catalyst", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "A highly active cobalt selenide electrocatalyst for the hydrogen-evolution reaction (HER) in acidic media was electrochem.\nsynthesized using a two-step process consisting of potentiostatic electrodeposition from aq. soln. followed by galvanostatic\nconditioning in the HER potential regime. Ex-situ Raman spectroscopy and energy-dispersive X-Ray spectroscopy indicated that\nthe initial deposition step generated a material contg. CoSe as well as Se in multiple phases. Operando Raman anal. during the\ninitial galvanostatic operation indicated a structural evolution of the Se phases including the partial elimination of one phase.\nDespite operating in the HER regime, the faradaic efficiency towards hydrogen evolution was low until this structural change\nwas complete, demonstrating the in situ realization of the active catalytic material. This resulting catalyst required an\noverpotential (\u03b7) < 150 mV to drive the benchmark c.d. of -10 mA cm^(-2) in 0.5 M H_2SO_4. Stability anal. including continuous\ngalvnostatic operation as well as simulated intermittent operation indicated significant electrochem. robustness in the acidic\noperating environment.", "date": "2018-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20180413-160048649", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180413-160048649", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2018", "author_list": "Rinaldi, Katherine Z.; Carim, Azhar I.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0s3tq-w2p23", "eprint_id": 87779, "eprint_status": "archive", "datestamp": "2023-08-19 08:09:35", "lastmod": "2023-10-18 21:26:01", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Roberts-E-J", "name": { "family": "Roberts", "given": "Emily J." } }, { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Brutchey-R-L", "name": { "family": "Brutchey", "given": "Richard L." }, "orcid": "0000-0002-7781-5596" } ] }, "title": "Phase directing ability of an ionic liquid solvent for the synthesis of colloidal Ni_2P nanocrystals", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "In the past decade, nickel phosphide (Ni_2P) has garnered considerable interest due to the earth abundance of its constituent elements, its stability in alk. and acidic media, and its comparable catalytic activity to precious metal catalysts for the hydrodeoxygenation of biomass, hydrodesulfurization of petrol, and the hydrogen evolution reaction. However, current methods of synthesizing high-quality colloidal Ni_2P nanocrystals typically use flammable org. solvents. Ionic liqs. (ILs) are attractive candidates for use as solvents as a result of their nonflammable nature and high thermal and chem. stability. In addn., the low interfacial tension possessed by ILs tends to result in fast nucleation rates in the context of nanocrystal syntheses, which generally produces smaller particles with higher surface-area-to-vol. ratios. Herein, we report the high-temp. synthesis of Ni_2P nanocrystals using a 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM-Tf_2N) IL solvent in combination with triphenylphosphine (PPh_3) as a low-cost and less-reactive phosphine source, yielding smaller, phase-pure Ni_2P nanocrystals in shorter times and lower temps. compared to the std. reported methods. When the IL solvent was replaced with the prototypical high-boiling org. solvent 1-octadecene under otherwise identical reaction conditions, mixed-phased products contg. the undesired nickel-rich Ni_(12)P_5 and the target Ni_2P were obtained. We will discuss the viability of the resulting Ni_2P nanocrystals synthesized in IL for the hydrogen evolution reaction, and extension of the synthesis method to the prepn. of Ni_(2-xCox)P nanocrystals.", "date": "2018-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20180711-154948117", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180711-154948117", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2018", "author_list": "Roberts, Emily J.; Read, Carlos G.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zjvkh-xhn86", "eprint_id": 85850, "eprint_status": "archive", "datestamp": "2023-08-19 08:05:23", "lastmod": "2023-10-18 18:52:43", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kempler-Paul-A", "name": { "family": "Kempler", "given": "Paul" }, "orcid": "0000-0003-3909-1790" }, { "id": "Gonzalez-Miguel-A", "name": { "family": "Gonzalez", "given": "Miguel" } }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly" }, "orcid": "0000-0002-9900-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Structured Si/Co-P photocathodes: Designs for efficient light absorption in earth abundant solar fuels devices", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "Designs for solar fuels devices frequently employ electrocatalysts integrated directly on the light-absorbing surfaces of\nsemiconductors. Improvements that are gained in catalytic efficiency can be offset by the losses in light-conversion efficiency\nthat result from parasitic absorption by the catalyst. We report two methods of circumventing parasitic absorption in these\nsystems, using silicon light-absorbers decorated with electrodeposited Co-P catalyst as model integrated photocathodes. (1)\nCo-P catalyst films on planar silicon were restructured during operation to form nanoscale catalyst islands, which led to a\ndoubling of the max. AM1.5 power conversion from 0.56 mW/cm^2 to 1.1 mW/cm^2\u2022 (2) Higher loadings of Co-Pon structured\nn+p-Si photocathodes achieved greater photon conversion efficiencies due to sepn. of the regions responsible for light\nabsorption from regions contg. opaque catalyst. High-aspect-ratio microwires, \u03bcWs, supported on a planar photoactive\nsubstrate exhibited a short circuit c.d., Jsc, of -24 \u00b1 4 mA/cm^2\u2022 Top performing \u03bcW-on-planar n+p-S/Co-P devices achieved\nideal regenerative cell efficiencies of 3.9%, and reached an operating c.d. of -10 mA/cm^2 at a potential +310 mV vs. a\nreversible hydrogen electrode. These devices achieved high performance for two figures of merit that are typically anticorrelated\nfor single-junction, all earth-abundant photoelectrodes and demonstrate important design principles for solar fuels\ndevices.", "date": "2018-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20180413-150847835", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180413-150847835", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2018", "author_list": "Kempler, Paul; Gonzalez, Miguel; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/yq8v0-wr360", "eprint_id": 85853, "eprint_status": "archive", "datestamp": "2023-08-19 08:05:45", "lastmod": "2023-10-18 18:52:57", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Sunlight-driven hydrogen formation by membrane-supported photoelectrochemical water splitting", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2018 American Chemical Society.", "abstract": "We are developing an artificial photosynthetic system that will utilize sunlight and water as inputs and will produce hydrogen\nand oxygen as outputs using a modular, parallel development approach in which the three distinct primary components-the\nphotoanode, the photocathode, and the product-sepg. but ion-conducting membrane-are fabricated and optimized sep. before\nassembly into a water-splitting system. The design principles incorporate two sep., photosensitive semiconductor/liq. junctions\nthat will collectively generate the 1.7-1.9 Vat open circuit to support both the oxidn. of H2_O (or OH-) and the redn. of H+ (or\nH_2O). The photoanode and photocathode will consist of rod-like semiconductor components, with attached heterogeneous multielectron\ntransfer catalysts, needed to drive the oxidn. or redn. reactions at low overpotentials. The high aspect-ratio\nsemiconductor rod electrode architecture allows for the use of low cost, earth abundant materials without sacrificing energy\nconversion efficiency due to orthogonalization of light absorption and charge-carrier collection. Addnl., the high surface-area\ndesign of the rod-based semiconductor array electrode inherently lowers the flux of charge carriers over the rod array surface\nrelative to the projected geometric surface of the photoelectrode, lowering the photocurrent d. at the solid/liq. junction and\nthereby relaxing demands on the activity (and cost) of any electrocatalysts. Flexible composite polymer film will allow for\nelectron and ion conduction between the photoanode and photocathode while simultaneously preventing mixing of the gaseous\nproducts. Sep. polymeric materials will be used to make elec. contact between the anode and cathode and also provide\nstructural support. Interspersed patches of an ion conducting polymer will maintain charge balance between the two half-cells.\nThe modularity design approach allows each piece to be independently modified, tested, and improved, as future advances in\nsemiconductor, polymeric, and catalytic materials are made. This work will demonstrate a feasible and functional prototype and\nblueprint for an artificial photosynthetic system, composed of inexpensive, earth-abundant materials while simultaneously\nefficient, durable, manufacturably scalable, and readily upgradeable.", "date": "2018-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20180413-153323263", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180413-153323263", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "JCAP" } ] }, "resource_type": "conference_item", "pub_year": "2018", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0f51p-7sw75", "eprint_id": 83062, "eprint_status": "archive", "datestamp": "2023-08-19 06:17:10", "lastmod": "2023-10-17 22:53:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shing-Amanda-M", "name": { "family": "Shing", "given": "Amanda M." } }, { "id": "Tolstova-Y", "name": { "family": "Tolstova", "given": "Yulia" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Effects of surface condition on the work function and valence-band position of ZnSnN_2", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 Springer-Verlag GmbH Germany. \n\nReceived: 17 May 2017; Accepted: 27 October 2017; First Online: 07 November 2017. \n\nWe gratefully acknowledge support from the Dow Chemical Company under the earth-abundant semiconductor project. We also acknowledge the Joint Center for Artificial Photosynthesis and the Molecular Materials Research Center of the Beckman Institute at Caltech for instrument access. The authors thank Bruce Brunschwig and Kimberly Papadantonakis for guidance. \n\nCompliance with ethical standards. \n\nFunding: Dow Chemical Company, Caltech Molecular Materials Research Center.\n\nSupplemental Material - 339_2017_1341_MOESM1_ESM.docx
", "abstract": "ZnSnN_2 is an emerging wide band gap earth-abundant semiconductor with potential applications in photonic devices such as solar cells, LEDs, and optical sensors. We report the characterization by ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy of reactively radio-frequency sputtered II\u2013IV-nitride ZnSnN_2 thin films. For samples transferred in high vacuum, the ZnSnN2 surface work function was 4.0\u2009\u00b1\u20090.1 eV below the vacuum level, with a valence-band onset of 1.2\u2009\u00b1\u20090.1 eV below the Fermi level. The resulting band diagram indicates that the degenerate bulk Fermi level position in ZnSnN_2 shifts to mid-gap at the surface due to band bending that results from equilibration with delocalized surface states within the gap. Brief (<\u200910 s) exposures to air, a nitrogen-plasma treatment, or argon-ion sputtering caused significant chemical changes at the surface, both in surface composition and interfacial energetics. The relative band positioning of the n-type semiconductor against standard redox potentials indicated that ZnSnN_2 has an appropriate energy band alignment for use as a photoanode to effect the oxygen-evolution reaction.", "date": "2017-12", "date_type": "published", "publication": "Applied Physics A: Materials Science and Processing", "volume": "123", "number": "12", "publisher": "Springer", "pagerange": "Art. No. 735", "id_number": "CaltechAUTHORS:20171108-094950631", "issn": "0947-8396", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171108-094950631", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Dow Chemical Company" }, { "agency": "Caltech Beckman Institute" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1007/s00339-017-1341-3", "primary_object": { "basename": "339_2017_1341_MOESM1_ESM.docx", "url": "https://authors.library.caltech.edu/records/0f51p-7sw75/files/339_2017_1341_MOESM1_ESM.docx" }, "resource_type": "article", "pub_year": "2017", "author_list": "Shing, Amanda M.; Tolstova, Yulia; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8f0vz-b5s56", "eprint_id": 80732, "eprint_status": "archive", "datestamp": "2023-08-21 22:17:25", "lastmod": "2023-10-17 17:07:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Buabthong-Pakpoom", "name": { "family": "Buabthong", "given": "Pakpoom" }, "orcid": "0000-0001-5538-138X" }, { "id": "Becerra-Stasiewicz-N", "name": { "family": "Becerra-Stasiewicz", "given": "Natalie" } }, { "id": "Mitrovic-S", "name": { "family": "Mitrovic", "given": "Slobodan" }, "orcid": "0000-0001-8913-8505" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Vanadium, niobium and tantalum by XPS", "ispublished": "pub", "full_text_status": "public", "keywords": "XPS; vanadium; niobium; tantalum", "note": "\u00a9 2017 American Vacuum Society. \n\nReceived 16 March 2017; accepted 20 June 2017; published 22 August 2017. Published Online: August 2017 Accepted: June 2017. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innova:on Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.\n\nPublished - 1_2E4998018.pdf
", "abstract": "We present high-resolution XPS spectra of elemental vanadium, niobium and tantalum sputter-cleaned by Ar^+ ions. The energy scales are shown without applying any corrections, and the position of the Fermi level was verified to be at zero binding energy within better than 0.1 eV, as determined from the Fermi edge measurement.", "date": "2017-12", "date_type": "published", "publication": "Surface Science Spectra", "volume": "24", "number": "2", "publisher": "American Vacuum Society", "pagerange": "Art. No. 024001", "id_number": "CaltechAUTHORS:20170823-130557839", "issn": "1055-5269", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170823-130557839", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "collection": "CaltechAUTHORS", "doi": "10.1116/1.4998018", "primary_object": { "basename": "1_2E4998018.pdf", "url": "https://authors.library.caltech.edu/records/8f0vz-b5s56/files/1_2E4998018.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Buabthong, Pakpoom; Becerra-Stasiewicz, Natalie; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/y85rf-07v48", "eprint_id": 78588, "eprint_status": "archive", "datestamp": "2023-08-21 22:14:34", "lastmod": "2023-10-26 00:12:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jiang-Jingjing", "name": { "family": "Jiang", "given": "Jingjing" } }, { "id": "Huang-Zhuangqun", "name": { "family": "Huang", "given": "Zhuangqun" } }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Poddar-R", "name": { "family": "Poddar", "given": "Rakesh" } }, { "id": "Lewerenz-H-J", "name": { "family": "Lewerenz", "given": "Hans-Joachim" }, "orcid": "0000-0001-8433-9471" }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan" }, "orcid": "0000-0001-5245-0538" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce" }, "orcid": "0000-0002-6135-6727" } ] }, "title": "Nanoelectrical and Nanoelectrochemical Imaging of Pt/p-Si and Pt/p+-Si Electrodes", "ispublished": "pub", "full_text_status": "public", "keywords": "afm; electrochemistry; energy conversion; interface; secm", "note": "\u00a9 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. \n\nIssue online: 23 November 2017; Version of record online: 7 August 2017; Accepted manuscript online: 21 June 2017; Manuscript Revised: 19 June 2017; Manuscript Received: 22 May 2017. \n\nFunded by: \nU.S. Department of Energy. Grant Number: DE-SC0004993;\nGordon and Betty Moore Foundation. Grant Number: GBMF1225.\n\nSupplemental Material - cssc201700893-sup-0001-SI1.pdf
", "abstract": "The interfacial properties of electrolessly deposited Pt nanoparticles (Pt-NP) on p-Si and p+-Si electrodes have been resolved on the nanometer scale using a combination of scanning probe methods. Atomic-force microscopy (AFM) showed highly dispersed Pt nanoparticles. Conductive AFM measurements showed that only about half of the particles exhibited measurable contact currents, with a factor of 10^3 difference in current. Local current-voltage measurements revealed a rectifying junction with a resistance of \u2265 10 M\u03a9 at the Pt-NP/p-Si interface, while Pt-NP/p+-Si samples formed an Ohmic junction with a local resistance of \u2265 1 M\u03a9. The particles were strongly attached to the sample surface in air. However in contact with an electrolyte, the adhesion of the particles to the surface was substantially lower. Scanning electrochemical microscopy (SECM) showed smaller, but more uniform electrochemical currents for the particles relative to the currents observed in conductive AFM measurements. In accord with the conductive AFM measurements, SECM measurements showed conductance through the substrate for only a minority of the particles. These results suggest that the electrochemical performance of the electrolessly deposited Pt nanoparticles on Si is ascribable to: 1) the high resistance of the contact between the particles and the substrate; 2) the low (<50%) fraction of particles that support high currents; and 3) the low adhesion of the particles to the surface in the electrolyte.", "date": "2017-11-23", "date_type": "published", "publication": "ChemSusChem", "volume": "10", "number": "22", "publisher": "Wiley", "pagerange": "4657-4663", "id_number": "CaltechAUTHORS:20170627-075439064", "issn": "1864-5631", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170627-075439064", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1002/cssc.201700893", "primary_object": { "basename": "cssc201700893-sup-0001-SI1.pdf", "url": "https://authors.library.caltech.edu/records/y85rf-07v48/files/cssc201700893-sup-0001-SI1.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Jiang, Jingjing; Huang, Zhuangqun; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/h0akd-0vb06", "eprint_id": 76835, "eprint_status": "archive", "datestamp": "2023-08-21 22:03:20", "lastmod": "2023-10-25 16:54:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Richter-M-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Lewerenz-H-J", "name": { "family": "Lewerenz", "given": "Hans-Joachim" }, "orcid": "0000-0001-8433-9471" } ] }, "title": "Operando X-ray photoelectron spectroscopic investigations of the electrochemical double layer at Ir/KOH(aq) interfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "Electrochemical double layer; Operando XPS; Solid/liquid interface", "note": "\u00a9 2017 Elsevier B.V. \n\nReceived 11 November 2016, Revised 19 February 2017, Accepted 17 March 2017, Available online 18 March 2017.", "abstract": "Tender X-ray operando photoemission spectroscopy has been used to directly analyze the energetics of the double layer at a metal-water interface in a dilute electrolyte having a Debye length of several nanometers. The data are compared to a theoretical evaluation of the potential of the solution near the electrode. Due to its noble nature, Ir was chosen as a working electrode material, and KOH(aq) at varied concentrations and thicknesses constituted the electrolyte. Shifts in peak width and binding energy of the water O 1s core level were analyzed by modeling based on Debye-H\u00fcckel approximations. The data are consistent with electrochemical formulations of the double layer that provide a foundation to electrochemistry.", "date": "2017-11", "date_type": "published", "publication": "Journal of Electron Spectroscopy and Related Phenomena", "volume": "221", "publisher": "Elsevier", "pagerange": "99-105", "id_number": "CaltechAUTHORS:20170424-080421711", "issn": "0368-2048", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170424-080421711", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1016/j.elspec.2017.03.011", "resource_type": "article", "pub_year": "2017", "author_list": "Lichterman, Michael F.; Richter, Matthias H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/bdphm-9mf52", "eprint_id": 81242, "eprint_status": "archive", "datestamp": "2023-08-19 05:37:04", "lastmod": "2023-10-17 19:41:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Wiensch-J-D", "name": { "family": "Wiensch", "given": "Joshua D." }, "orcid": "0000-0002-8235-6937" }, { "id": "John-Jimmy", "name": { "family": "John", "given": "Jimmy" }, "orcid": "0000-0002-8772-8939" }, { "id": "Velazquez-J-M", "name": { "family": "Velazquez", "given": "Jesus M." } }, { "id": "Torelli-D-A", "name": { "family": "Torelli", "given": "Daniel A." }, "orcid": "0000-0002-6222-817X" }, { "id": "Pieterick-A-P", "name": { "family": "Pieterick", "given": "Adam P." } }, { "id": "McDowell-M-T", "name": { "family": "McDowell", "given": "Matthew T." }, "orcid": "0000-0001-5552-3456" }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Zhao-Xinghao", "name": { "family": "Zhao", "given": "Xinghao" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparative Study in Acidic and Alkaline Media of the Effects of pH and Crystallinity on the Hydrogen-Evolution Reaction on MoS_2 and MoSe_2", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 American Chemical Society. \n\nReceived: August 4, 2017; Accepted: August 28, 2017; Published: September 6, 2017. \n\nJ.J. thanks the Camille and Henry Dreyfus Foundation for support through its postdoctoral fellowship program in environmental chemistry. This material is based upon work supported by the U.S. Department of Energy, Office of Basic Energy Sciences under Award No. DE-FG02-03ER15483. J.M.V. acknowledges support through an NRC Ford Foundation Postdoctoral Fellowship. D.A.T. acknowledges support through the NSF Graduate Research Fellowships Program. Single-crystal MoS2 growth and sputtering of Mo was performed at the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. X-ray photoelectron spectroscopy was performed at the Molecular Materials Research Center of the Beckman Institute at Caltech.\n\nSupplemental Material - nz7b00700_si_001.pdf
", "abstract": "Single crystals of n-type MoS_2 and n-MoSe_2 showed higher electrocatalytic activity for the evolution of H_2(g) in alkaline solutions than in acidic solutions. The overpotentials required to drive hydrogen evolution at \u221210 mA cm^(\u20132) of current density for MoS^2 samples were \u22120.76 \u00b1 0.13 and \u22121.03 \u00b1 0.21 V when in contact with 1.0 M NaOH(aq) and 1.0 M H_2SO_4(aq), respectively. For MoSe_2 samples, the overpotentials at \u221210 mA cm^(\u20132) were \u22120.652 \u00b1 0.050 and \u22120.709 \u00b1 0.073 V in contact with 1.0 M KOH(aq) and 1.0 M H_2SO_4(aq), respectively. Single crystals from two additional sources were also tested, and the absolute values of the measured overpotentials were consistently less (by 460 \u00b1 250 mV) in alkaline solutions than in acidic solutions. When electrochemical etching was used to create edge sites on the single crystals, the kinetics improved in acid but changed little in alkaline media. The overpotentials measured for polycrystalline thin films (PTFs) and amorphous forms of MoS_2 showed less sensitivity to pH and edge density than was observed for single crystals and showed enhanced kinetics in acid when compared to alkaline solutions. These results suggest that the active sites for hydrogen evolution on MoS_2 and MoSe_2 are different in alkaline and acidic media. Thus, while edges are known to serve as active sites in acidic media, in alkaline media it is more likely that terraces function in this role.", "date": "2017-10-13", "date_type": "published", "publication": "ACS Energy Letters", "volume": "2", "number": "10", "publisher": "American Chemical Society", "pagerange": "2234-2238", "id_number": "CaltechAUTHORS:20170907-124508456", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170907-124508456", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "NRC Ford Foundation Postdoctoral Fellowship" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acsenergylett.7b00700", "primary_object": { "basename": "nz7b00700_si_001.pdf", "url": "https://authors.library.caltech.edu/records/bdphm-9mf52/files/nz7b00700_si_001.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Wiensch, Joshua D.; John, Jimmy; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/px460-w3x39", "eprint_id": 79526, "eprint_status": "archive", "datestamp": "2023-08-19 05:32:59", "lastmod": "2023-10-26 16:16:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ulissi-Z-W", "name": { "family": "Ulissi", "given": "Zachary W." }, "orcid": "0000-0002-9401-4918" }, { "id": "Tang-Michael-T", "name": { "family": "Tang", "given": "Michael T." } }, { "id": "Xiao-Jianping", "name": { "family": "Xiao", "given": "Jianping" }, "orcid": "0000-0003-1779-6140" }, { "id": "Liu-Xinyan", "name": { "family": "Liu", "given": "Xinyan" } }, { "id": "Torelli-D-A", "name": { "family": "Torelli", "given": "Daniel A." }, "orcid": "0000-0002-6222-817X" }, { "id": "Karamad-M", "name": { "family": "Karamad", "given": "Mohammadreza" } }, { "id": "Cummins-K-D", "name": { "family": "Cummins", "given": "Kyle" } }, { "id": "Hahn-C", "name": { "family": "Hahn", "given": "Christopher" }, "orcid": "0000-0002-2772-6341" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Jaramillo-T-F", "name": { "family": "Jaramillo", "given": "Thomas F." }, "orcid": "0000-0001-9900-0622" }, { "id": "Chan-Karen", "name": { "family": "Chan", "given": "Karen" }, "orcid": "0000-0002-6897-1108" }, { "id": "Norskov-J-K", "name": { "family": "Norskov", "given": "Jens K." } } ] }, "title": "Machine-Learning Methods Enable Exhaustive Searches for Active Bimetallic Facets and Reveal Active Site Motifs for CO_2 Reduction", "ispublished": "pub", "full_text_status": "public", "keywords": "density functional theory, bimetallic facets, machine learning, catalysis, electrochemistry, CO2 reduction,\nmachine learning, DFT, energy", "note": "\u00a9 2017 American Chemical Society. \n\nReceived: May 20, 2017; Revised: July 17, 2017; Published: July 27, 2017.\n\n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. D.A.T. and M.T acknowledge graduate fellowships through the National Science Foundation Graduate Research Fellowship under Grant No. DGE-114747.\n\nThe authors declare no competing financial interests.\n\nSupplemental Material - cs7b01648_si_001.pdf
", "abstract": "Bimetallic catalysts are promising for the most difficult thermal and electrochemical reactions, but modeling the many diverse active sites on polycrystalline samples is an open challenge. We present a general framework for addressing this complexity in a systematic and predictive fashion. Active sites for every stable low-index facet of a bimetallic crystal are enumerated and cataloged, yielding hundreds of possible active sites. The activity of these sites is explored in parallel using a neural-network-based surrogate model to share information between the many density functional theory (DFT) relaxations, resulting in activity estimates with an order of magnitude fewer explicit DFT calculations. Sites with interesting activity were found and provide targets for follow-up calculations. This process was applied to the electrochemical reduction of CO_2 on nickel gallium bimetallics and indicated that most facets had similar activity to Ni surfaces, but a few exposed Ni sites with a very favorable on-top CO configuration. This motif emerged naturally from the predictive modeling and represents a class of intermetallic CO_2 reduction catalysts. These sites rationalize recent experimental reports of nickel gallium activity and why previous materials screens missed this exciting material. Most importantly these methods suggest that bimetallic catalysts will be discovered by studying facet reactivity and diversity of active sites more systematically.", "date": "2017-10-06", "date_type": "published", "publication": "ACS Catalysis", "volume": "7", "number": "10", "publisher": "American Chemical Society", "pagerange": "6600-6608", "id_number": "CaltechAUTHORS:20170728-081606737", "issn": "2155-5435", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170728-081606737", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-114747" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acscatal.7b01648", "primary_object": { "basename": "cs7b01648_si_001.pdf", "url": "https://authors.library.caltech.edu/records/px460-w3x39/files/cs7b01648_si_001.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Ulissi, Zachary W.; Tang, Michael T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rdtkq-g8k55", "eprint_id": 81265, "eprint_status": "archive", "datestamp": "2023-08-19 05:29:28", "lastmod": "2023-10-17 19:42:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Moreno-Hernandez-I-A", "name": { "family": "Moreno-Hernandez", "given": "Ivan A." }, "orcid": "0000-0001-6461-9214" }, { "id": "MacFarland-C-A", "name": { "family": "MacFarland", "given": "Clara A." }, "orcid": "0000-0002-9570-948X" }, { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Crystalline nickel manganese antimonate as a stable water-oxidation catalyst in aqueous 1.0 M H_2SO_4", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 Royal Society of Chemistry. \n\nThe article was received on 28 May 2017, accepted on 10 Aug 2017 and first published on 10 Aug 2017. \n\nThis work is supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. I. M. H. acknowledges a National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469. This work was also supported by the Gordon and Betty Moore Foundation under Award No. GBMF1225. C. G. R. acknowledges the Resnick Sustainability Institute for a post-doctoral fellowship. We thank N. Dalleska and P. Buabthong for assistance with mass spectroscopy measurements and X-ray photoelectron spectroscopy measurements, respectively.\n\nSupplemental Material - c7ee01486d1.pdf
", "abstract": "Water oxidation is a required half-reaction for electrochemical water splitting. To date, the only well-established active oxygen-evolution catalysts stable under operating conditions and at rest in acidic aqueous media contain Ru or Ir, two of the scarcest non-radioactive elements on Earth. We report herein a nickel-manganese antimonate electrocatalyst with a rutile-type crystal structure that requires an initial voltammetric overpotential of 672 \u00b1 9 mV to catalyze the oxidation of water to O_2(g) at a rate corresponding to 10 mA cm^(\u22122) of current density when operated in contact with 1.0 M sulfuric acid. Under galvanostatic control, the overpotential initially rose from 670 mV but was then stable at 735 \u00b1 10 mV for 168 h of continuous operation at 10 mA cm^(\u22122). We additionally provide an in-depth evaluation of the stability of the nickel-manganese antimonate electrocatalyst, including elemental characterization of the surface, bulk, and electrolyte before and after electrochemical operation.", "date": "2017-10-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "2017", "number": "10", "publisher": "Royal Society of Chemistry", "pagerange": "2103-2108", "id_number": "CaltechAUTHORS:20170908-102102710", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170908-102102710", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1144469" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1039/C7EE01486D", "primary_object": { "basename": "c7ee01486d1.pdf", "url": "https://authors.library.caltech.edu/records/rdtkq-g8k55/files/c7ee01486d1.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Moreno-Hernandez, Ivan A.; MacFarland, Clara A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/e9r5r-at880", "eprint_id": 81704, "eprint_status": "archive", "datestamp": "2023-08-19 05:10:43", "lastmod": "2023-10-17 21:10:52", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shing-Amanda-M", "name": { "family": "Shing", "given": "Amanda M." } }, { "id": "Tolstova-Yulia", "name": { "family": "Tolstova", "given": "Yulia" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Growth of Epitaxial ZnSn_xGe_(1\u2212x)N_2 Alloys by MBE", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived: 15 June 2017. Accepted: 06 September 2017. Published online: 20 September 2017. \n\nWe gratefully acknowledge support from the Dow Chemical Company under the earth-abundant semiconductor project, the NSF-DOE Quantum Energy and Sustainable Solar Technologies Engineering Research Center, and the Molecular Materials Resource Center of the Beckman Institute at Caltech. We also acknowledge the Joint Center for Artificial Photosynthesis and the Molecular Materials Resource Center of the Beckman Institute at Caltech for instrument access. The authors thank Bruce Brunschwig and Kimberly Papadantonakis for guidance, and Carol Garland for TEM assistance. \n\nAuthor Contributions: A.S. performed fabrication and measurements. Y.T. provided consultation. N.S.L. and H.A.A. were the PIs. All authors reviewed the manuscript. \n\nThe authors declare that they have no competing interests. \n\nPublisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.\n\nPublished - s41598-017-12357-9.pdf
", "abstract": "ZnSn_xGe_(1\u2212x)N_2 alloys are chemically miscible semiconductor compounds with potential application as earth-abundant alternatives to In_xGa_(1\u2212x)N. Preparation of ZnSn_xGe_(1\u2212x)N_2 thin-films by reactive RF sputter deposition yield low-mobility, nanocrystalline films. In contrast, the growth of ZnSn_xGe_(1\u2212x)N_2 films by molecular-beam epitaxy (MBE) on c-plane sapphire and GaN templates is described herein. Epitaxial films exhibited 3D growth on sapphire and 2D single-crystal quality on GaN, exhibiting substantial improvements in epitaxy and crystallinity relative to nanocrystalline sputtered films. Films on sapphire were n-type with electronic mobilities as high as 18\u2009cm^2\u2009V^(\u22121) s^(\u22121), an order of magnitude greater than the 2\u2009cm^2\u2009V^(\u22121) s^(\u22121) average mobility observed in this work for sputtered films. Mobility differences potentially arise from strain or surface effects originating from growth techniques, or from differences in film thicknesses. In general, MBE growth has provided desired improvements in electronic mobility, epitaxy, and crystal quality that provide encouragement for the continued study of ZnSn_xGe_(1\u2212x)N_2 alloys.", "date": "2017-09-20", "date_type": "published", "publication": "Scientific Reports", "volume": "7", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 11990", "id_number": "CaltechAUTHORS:20170921-145038630", "issn": "2045-2322", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170921-145038630", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Dow Chemical Company" }, { "agency": "NSF" }, { "agency": "Department of Energy (DOE)" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1038/s41598-017-12357-9", "pmcid": "PMC5607306", "primary_object": { "basename": "s41598-017-12357-9.pdf", "url": "https://authors.library.caltech.edu/records/e9r5r-at880/files/s41598-017-12357-9.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Shing, Amanda M.; Tolstova, Yulia; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6t5ab-dff07", "eprint_id": 80895, "eprint_status": "archive", "datestamp": "2023-08-19 05:10:14", "lastmod": "2023-10-17 18:34:44", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Drisdell-Walter-S", "name": { "family": "Drisdell", "given": "Walter S." }, "orcid": "0000-0002-8693-4562" }, { "id": "Gul-Sheraz", "name": { "family": "Gul", "given": "Sheraz" }, "orcid": "0000-0001-8920-8737" }, { "id": "Baricuatro-Jack-H", "name": { "family": "Baricuatro", "given": "Jack H." } }, { "id": "Yano-Junko", "name": { "family": "Yano", "given": "Junko" }, "orcid": "0000-0001-6308-9071" }, { "id": "Soriaga-M-P", "name": { "family": "Soriaga", "given": "Manuel P." }, "orcid": "0000-0002-0077-6226" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Operando Spectroscopic Analysis of CoP Films Electrocatalyzing the Hydrogen-Evolution Reaction", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 American Chemical Society. \n\nReceived: July 20, 2017; Published: August 28, 2017. \n\nThis work was based on work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the U.S. Department of Energy Office of Science under Award Number DE-SC0004993. Synchrotron measurements were performed at beamlines 7-3 and 14-3 at the Stanford Synchrotron Radiation Lightsource at SLAC National Accelerator Laboratory, which is operated by Stanford University for the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-76SF00515, and supported by the Office of Biological and Environmental Research, and by the NIH including P41GM103393. A.I.C. acknowledges a Graduate Research Fellowship from the National Science Foundation. The authors gratefully acknowledge R. Jones and Dr. K. Walczak for assistance with spectroelectrochemical cell fabrication. \n\nThe authors declare no competing financial interests.\n\nSupplemental Material - ja7b07606_si_001.pdf
", "abstract": "Transition metal phosphides exhibit high catalytic activity towards the electrochemical hydrogen-evolution reaction (HER) and resist chemical corrosion in acidic solutions. For example, an electrodeposited CoP catalyst exhibited an overpotential, \u03b7, of -\u03b7 < 100 mV at a current density of -10 mA cm^(-2) in 0.500 M H_2SO_4(aq). To obtain a chemical description of the material as-prepared and also while effecting the HER in acidic media, such electrocatalyst films were investigated using Raman spectroscopy and X-ray absorption spectroscopy both ex-situ as well as under in-situ and operando conditions in 0.500 M H_2SO_4(aq). Ex-situ analysis using the tandem spectroscopies indicated the presence of multiple ordered and disordered phases that contained both near-zero valent and oxidized Co species, in addition to reduced and oxygenated P species. Operando analysis indicated that the active electrocatalyst was primarily amorphous and predominantly consisted of near-zero-valent Co as well as reduced P.", "date": "2017-09-20", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "139", "number": "37", "publisher": "American Chemical Society", "pagerange": "12927-12930", "id_number": "CaltechAUTHORS:20170829-095313751", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170829-095313751", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-76SF00515" }, { "agency": "NIH", "grant_number": "P41GM103393" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/jacs.7b07606", "primary_object": { "basename": "ja7b07606_si_001.pdf", "url": "https://authors.library.caltech.edu/records/6t5ab-dff07/files/ja7b07606_si_001.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Saadi, Fadl H.; Carim, Azhar I.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cd461-wvq31", "eprint_id": 80464, "eprint_status": "archive", "datestamp": "2023-08-19 04:44:16", "lastmod": "2023-10-17 16:01:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Matheu-R", "name": { "family": "Matheu", "given": "Roc" }, "orcid": "0000-0001-8601-5219" }, { "id": "Moreno-Hernandez-I-A", "name": { "family": "Moreno-Hernandez", "given": "Ivan A." }, "orcid": "0000-0001-6461-9214" }, { "id": "Sala-X", "name": { "family": "Sala", "given": "Xavier" } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Llobet-A", "name": { "family": "Llobet", "given": "Antoni" }, "orcid": "0000-0002-6176-5272" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemical Behavior of a Molecular Ru-Based Water-Oxidation Catalyst Bound to TiO_2-Protected Si Photoanodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 American Chemical Society. \n\nReceived: June 30, 2017; Published: August 7, 2017. \n\nThe National Science Foundation under NSF Center CHE-1305124 provided support for H.B.G., I.M.H., N.S.L., B.S.B., and R.M. and for supplies at Caltech, I.M.H. was supported by a NSF Graduate Research Fellowship (Grant No. DGE-1144469). Instrumentation support was also provided by the Molecular Materials Resource Center of the Beckman Institute at California Institute of Technology. R.M., A.L., and X.S. acknowledge MINECO and FEDER (CTQ2016-80058-R, CTQ2015-64261-R, SEV 2013-0319, ENE2016-82025-REDT, CTQ2016-81923-REDC), AGAUR (2014-SGR-915), and \"La Caixa\" foundation. We acknowledge Dr. K. Sun for helpful discussions. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - ja7b06800_si_001.pdf
", "abstract": "A hybrid photoanode based on a molecular water oxidation precatalyst was prepared from TiO_2-protected n- or p+-Si coated with multiwalled carbon nanotubes (CNT) and the ruthenium-based water oxidation precatalyst [Ru^(IV)(tda)(py-pyr)_2(O)], 1(O) (tda^(2\u2013) is [2,2\u2032:6\u2032,2\u2033-terpyridine]-6,6\u2033-dicarboxylato and py-pir is 4-(pyren-1-yl)-N-(pyridin-4-ylmethyl)butanamide). The Ru complex was immobilized by \u03c0\u2013\u03c0 stacking onto CNTs that had been deposited by drop casting onto Si electrodes coated with 60 nm of amorphous TiO_2 and 20 nm of a layer of sputtered C. At pH = 7 with 3 Sun illumination, the n-Si/TiO_2/C/CNT/[1+1(O)] electrodes exhibited current densities of 1 mA cm^(\u20132) at 1.07 V vs NHE. The current density was maintained for >200 min at a constant potential while intermittently collecting voltammograms that indicated that over half of the Ru was still in molecular form after O_2 evolution.", "date": "2017-08-23", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "139", "number": "33", "publisher": "American Chemical Society", "pagerange": "11345-11348", "id_number": "CaltechAUTHORS:20170816-083201966", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170816-083201966", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1144469" }, { "agency": "Ministerio de Econom\u00eda y Competitividad (MINECO)", "grant_number": "CTQ2016-80058-R" }, { "agency": "Ministerio de Econom\u00eda y Competitividad (MINECO)", "grant_number": "CTQ2015-64261-R" }, { "agency": "Ministerio de Econom\u00eda y Competitividad (MINECO)", "grant_number": "SEV 2013-0319" }, { "agency": "Ministerio de Econom\u00eda y Competitividad (MINECO)", "grant_number": "ENE2016-82025-REDT" }, { "agency": "Ministerio de Econom\u00eda y Competitividad (MINECO)", "grant_number": "CTQ2016-81923-REDC" }, { "agency": "Ag\u00e8ncia de Gesti\u00f3 d'Ajuts Universitaris i de Recerca", "grant_number": "2014-SGR-915" }, { "agency": "La Caixa Foundation" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/jacs.7b06800", "primary_object": { "basename": "ja7b06800_si_001.pdf", "url": "https://authors.library.caltech.edu/records/cd461-wvq31/files/ja7b06800_si_001.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Matheu, Roc; Moreno-Hernandez, Ivan A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sfcde-25n38", "eprint_id": 80366, "eprint_status": "archive", "datestamp": "2023-08-19 04:43:44", "lastmod": "2023-10-17 15:57:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dasog-M", "name": { "family": "Dasog", "given": "Mita" }, "orcid": "0000-0002-7846-3414" }, { "id": "Thompson-J-R", "name": { "family": "Thompson", "given": "Jonathan R." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Oxidant-Activated Reactions of Nucleophiles with Silicon Nanocrystals", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 American Chemical Society. \n\nReceived: June 22, 2017; Revised: June 30, 2017; Published: July 11, 2017.\n\nThe authors acknowledge the National Science Foundation (Grant CHE-1214152) and Dalhousie University for providing financial support. Instrumentation support was provided by the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology and by the Institute for Research in Materials at Dalhousie University. M.D. acknowledges a postdoctoral fellowship from the National Sciences and Engineering Research Council of Canada. J.R.T. acknowledges support from the U.S. Department of Energy \"Light-Material Interactions in Energy Conversion\" Energy Frontier Research Center under Grant DE-SC0001293. We thank Dr. A. C. Nielander and Azhar Carim for insightful discussions during the preparation of this work. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - cm7b02572_si_001.pdf
", "abstract": "The oxidant-activated reactivity of Si toward nucleophiles was evaluated for Si nanocrystals (Si-NCs) of differing diameters, d. In the presence of ferrocenium as a one-electron, outer-sphere oxidant, d \u2265 8 nm Si-NCs readily reacted with nucleophiles, including methanol, butanol, butylamine, butanoic acid, butylthiol, and diethylphosphine. However, d < 8 nm Si-NCs did not undergo such reactions, and stronger oxidants such as acetylferrocenium or 1,1\u2032-diacetylferrocenium were required. Butylamine-, butylthiol-, and butanol-functionalized d \u2265 8 nm Si-NCs were partially oxidized and exhibited photoluminescence originating from defect states. In contrast, butanoic acid-functionalized Si-NCs were minimally oxidized and displayed core emission resulting from the excitation and relaxation of electrons across the Si-NC bandgap. Diethylphosphine-functionalized Si-NCs were stable only under inert conditions and showed core emission, with the Si\u2013P bonds being highly susceptible to oxidation and rapidly decomposing upon exposure to ambient conditions. The general reactivity is consistent with the redox potential of the one-electron oxidant and the valence band edge position of the Si-NCs. The trends in reactivity thus provide an example of differential chemical reactions of nanoparticles relative to bulk materials, reflecting the differences in electronic structure and the continuum of electronic properties between variously sized Si nanoparticles and bulk Si samples.", "date": "2017-08-22", "date_type": "published", "publication": "Chemistry of Materials", "volume": "29", "number": "16", "publisher": "American Chemical Society", "pagerange": "7002-7013", "id_number": "CaltechAUTHORS:20170814-133810210", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170814-133810210", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Dalhousie University" }, { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" } ] }, "doi": "10.1021/acs.chemmater.7b02572", "primary_object": { "basename": "cm7b02572_si_001.pdf", "url": "https://authors.library.caltech.edu/records/sfcde-25n38/files/cm7b02572_si_001.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Dasog, Mita; Thompson, Jonathan R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jk4at-0n759", "eprint_id": 78907, "eprint_status": "archive", "datestamp": "2023-08-19 04:38:22", "lastmod": "2023-10-26 14:27:19", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dhar-P", "name": { "family": "Dhar", "given": "Purnim" } }, { "id": "Plymale-N-T", "name": { "family": "Plymale", "given": "Noah T." }, "orcid": "0000-0003-2564-8009" }, { "id": "Malyk-S-S", "name": { "family": "Malyk", "given": "Sergey" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Benderskii-A-V", "name": { "family": "Benderskii", "given": "Alexander V." }, "orcid": "0000-0001-7031-2630" } ] }, "title": "Vibrational Sum-Frequency Spectroscopic Investigation of the Structure and Azimuthal Anisotropy of Propynyl-Terminated Si(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 American Chemical Society. \n\nReceived: May 30, 2017; Revised: July 6, 2017; Published: July 10, 2017.\n\nA.V.B. acknowledges the Air Force Office of Scientific Research under grant No. FA9550-15-1-0184. N.S.L. acknowledges the National Science Foundation under grant No. CHE-1214152. N.T.P. acknowledges support from a National Science Foundation Graduate Research Fellowship. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - jp7b05256_si_001.pdf
", "abstract": "Vibrational sum-frequency generation (VSFG) spectroscopy was used to investigate the orientation and azimuthal anisotropy of the C\u2013H stretching modes for propynyl-terminated Si(111) surfaces, Si\u2014C\u2261C\u2014CH_3. VSFG spectra revealed symmetric and asymmetric C\u2013H stretching modes in addition to a Fermi resonance mode resulting from the interaction of the asymmetric C\u2013H bending overtone with the symmetric C\u2013H stretching vibration. The polarization dependence of the C\u2013H stretching modes was consistent with the propynyl groups oriented such that the Si\u2014C\u2261C\u2013 bond is normal to the Si(111) surface. The azimuthal angle dependence of the resonant C\u2013H stretching amplitude revealed no rotational anisotropy for the symmetric C\u2013H stretching mode and a 3-fold rotational anisotropy for the asymmetric C\u2013H stretching mode in registry with the 3-fold symmetric Si(111) substrate. The results are consistent with the expectation that the C\u2013H stretching modes of a \u2013CH_3 group are decoupled from the Si substrate due to a \u2212C\u2261C\u2013 spacer. In contrast, the methyl-terminated Si(111) surface, Si\u2013CH_3, was previously reported to have pronounced vibronic coupling of the methyl stretch modes to the electronic bath of bulk Si. Vacuum-annealing of propynyl-terminated Si(111) resulted in increased 3-fold azimuthal anisotropy for the symmetric stretch, suggesting that removal of propynyl groups from the surface upon annealing allowed the remaining propynyl groups to tilt away from the surface normal into one of three preferred directions toward the vacated neighbor sites.", "date": "2017-08-10", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "121", "number": "31", "publisher": "American Chemical Society", "pagerange": "16872-16878", "id_number": "CaltechAUTHORS:20170710-143624667", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170710-143624667", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-15-1-0184" }, { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1021/acs.jpcc.7b05256", "primary_object": { "basename": "jp7b05256_si_001.pdf", "url": "https://authors.library.caltech.edu/records/jk4at-0n759/files/jp7b05256_si_001.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Dhar, Purnim; Plymale, Noah T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nxvs5-43s92", "eprint_id": 81321, "eprint_status": "archive", "datestamp": "2023-08-19 04:23:46", "lastmod": "2023-10-17 19:45:11", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Plymale-N-T", "name": { "family": "Plymale", "given": "Noah T." }, "orcid": "0000-0003-2564-8009" }, { "id": "Dasog-M", "name": { "family": "Dasog", "given": "Mita" }, "orcid": "0000-0002-7846-3414" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Mechanistic insights into the oxidative reaction of hydrogen-terminated Si(111) surfaces with liquid methanol", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "The reactivity of nucleophiles at H-terminated Si surfaces has been widely exploited to tailor the electronic\nand mech. properties of Si interfaces for targeted applications. In select cases, the addn. of nucleophiles to Si surfaces has no analogous reaction in mol. silane chem. To investigate this phenomenon, H-Si(111) surfaces\nwere reacted with liq. methanol (CH_3OH) in the absence or presence of a series of one-electron oxidants and\n/or illumination. Oxidant-activated methoxylation of H-Si(111) surfaces was obsd. in the dark after exposure to\nCH_3OH solns. contg. the oxidants acetylferrocenium, ferrocenium, or 1,1'-dimethylferrocenium. The oxidantactivated reactivity of intrinsic and n-type H-Si(111) surfaces toward CH_3OH increased upon exposure to\nambient light. The results suggest that oxidant-activated methoxylation requires that two conditions be met:\n(1) the position of the quasi-Fermi levels must energetically favor oxidn. of the H-Si(111) surface and (2) the position of the quasi-Fermi levels must energetically favor redn. of an oxidant in soln. The results are\ndescribed by a mechanistic framework that analyzes the positions of the quasi-Fermi levels relative to the\napplicable energy levels for each system. Thus, the reactions of nucleophiles at H-terminated Si surfaces\nimplicates the bulk charge carriers, allowing for reactions to occur at Si surfaces that are not accessible to mol.\nsilanes.", "date": "2017-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170911-151732957", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170911-151732957", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2017", "author_list": "Plymale, Noah T.; Dasog, Mita; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cvqwr-h3q05", "eprint_id": 81302, "eprint_status": "archive", "datestamp": "2023-08-19 04:23:08", "lastmod": "2023-10-17 19:44:23", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Richter-M-H", "name": { "family": "Richter", "given": "Matthias" }, "orcid": "0000-0003-0091-2045" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Crumlin-E-J", "name": { "family": "Crumlin", "given": "Ethan" }, "orcid": "0000-0003-3132-190X" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewerenz-A", "name": { "family": "Lewerenz", "given": "Achim" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Operando AP-XPS evaluation of semicondutor/liquid and associated systems", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "Through the use of tender X-rays from a synchrotron source, we evaluate the energetic relations of semiconductor/liq. junctions. A potentiostat maintains the working electrode, in a three electrode configuration, at an isopotential which can be varied throughout the potential range allowed by the electrolyte. We have evaluated the effects of metal deposition on the band energetics in the TiO_2/water system as well as providing a means to measure the defect state d. in a semiconductor in contact with a soln. Other expts. to investigate related systems will be discussed.", "date": "2017-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170911-135442962", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170911-135442962", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2017", "author_list": "Lichterman, Michael F.; Richter, Matthias; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jxd1g-k4521", "eprint_id": 81327, "eprint_status": "archive", "datestamp": "2023-08-19 04:24:18", "lastmod": "2023-10-17 19:45:35", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Batara-Nicolas-A", "name": { "family": "Batara", "given": "Nicolas A." } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Rapid, template-free synthesis of macroscale semiconductor nanopatterns via tailored photoexcitation", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "Template-free photoelectrodeposition of semiconducting chalcogen alloys resulted in the spontaneous generation of highly periodic nanostructured films over macroscopic length scales. The exact nature of the optical excitation was encoded in the deposit morphol. in terms of the feature sizes, periodicities, anisotropies, and orientations of the nanoscale pattern. The use of unpolarized light generated isotropic morphologies consisting of ordered arrays of nanopores whereas linearly polarized light resulted in a highly-anisotropic lamellar morphologies with the long axes of the patterns aligned along the E-field vector. Utilization of two same-wavelength, non-orthogonally polarized sources simultaneously generated patterns oriented along the av. E-field vector and with degrees of anisotropy related to the difference in orientation between the two input Efield vectors and the phase correlation between the sources. The illumination spectral profile encoded the pattern periodicity and feature width. A single periodicity in a single in-plane direction was consistently obsd. even with the use of broadband and multimodal spectral profiles and this periodicity was found to be sensitive to all investigated tuning of such profiles. The incidence of the illumination set the direction the material grew from the substrate, mimicking natural phototropism: grazing illumination resulted in growth at significant angle to the surface normal. Modeling of the growth using a combination of full-wave electromagnetic simulations of light absorption and scattering coupled with Monte Carlo simulations of mass addn. accurately reproduced the exptl. obsd. morphologies and indicated that the encoding process was a consequence of the fundamental light-matter interactions during growth. This photoelectrochem. deposition process is unique from other methods of\ngenerating ordered mesostructures with electrochem. means as no photomask, no photoactive substrate, no\nlithog. processing, nor any chem. templating agents (ligands, surfactants) were utilized. Illumination was simply conformal over the entire substrate surface (no far-field spatial modulation was used nor required). Complete\nnanoscale patterning over cm areas required only several minutes. Moreover, films were deposited from aq.\nsoln. using oxide precursors at room temp. with low-intensity illumination (\u223c10 mW cm^(-2)).", "date": "2017-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170911-154035863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170911-154035863", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2017", "author_list": "Carim, Azhar I.; Batara, Nicolas A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ck0am-62580", "eprint_id": 78686, "eprint_status": "archive", "datestamp": "2023-08-19 03:33:42", "lastmod": "2023-10-26 00:17:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chabi-Sakineh", "name": { "family": "Chabi", "given": "Sakineh" }, "orcid": "0000-0002-5578-3984" }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Freund-M-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" } ] }, "title": "Membranes for artificial photosynthesis", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2017 The Royal Society of Chemistry. \n\nReceived 30th January 2017, Accepted 5th May 2017, First published on 17 May 2017. \n\nThis work was supported by NSF under the NSF CCI Solar Fuels Program under Grant No. CHE-1305124. KMP and NSL acknowledge support for this work from the Gordon and Betty Moore Foundation, under grant GBMF1225.", "abstract": "Membrane-based architectures enable optimization of charge transport and electrochemical potential gradients in artificial photosynthesis. Spatial integration of the membrane-bound components reduces the impact of charge recombination and can reduce electrical resistances associated with ionic and electronic transport processes. In addition to eliminating the need for external electrical circuits, a membrane-based architecture also ensures separation of energetic products, thereby preventing the formation of potentially dangerous fuel/oxidant mixtures. Membrane-based structures may also be coupled with other devices, such as perovskite-based solar cells, to further benefit solar fuel production. This review discusses the key roles that various different types of membranes play in artificial photosynthetic systems.", "date": "2017-06-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "10", "number": "6", "publisher": "Royal Society of Chemistry", "pagerange": "1320-1338", "id_number": "CaltechAUTHORS:20170629-083151598", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170629-083151598", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1039/c7ee00294g", "resource_type": "article", "pub_year": "2017", "author_list": "Chabi, Sakineh; Papadantonakis, Kimberly M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/d1ejc-z1762", "eprint_id": 86738, "eprint_status": "archive", "datestamp": "2023-08-19 03:29:20", "lastmod": "2023-10-18 19:57:11", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Omelchenko-S-T", "name": { "family": "Omelchenko", "given": "Stefan T." }, "orcid": "0000-0003-1104-9291" }, { "id": "Tolstova-Y", "name": { "family": "Tolstova", "given": "Yulia" } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Excitonic effects in photovoltaic materials with large exciton binding energies", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 IEEE.", "abstract": "We investigate the effect of excitons on charge transport in photovoltaic materials with large exciton binding energies using Cu_2O as a model system. We develop a thermodynamic model to estimate the fraction of excitons in Cu_2O at quasi-equilibrium and find that over 20% of the generated population of carriers during photovoltaic operation could be excitons. Experiments show the presence of excitons at room temperature under visible light excitation and current collection due to excitons during device operation. This work demonstrates that excitons can play a fundamental role in photovoltaic materials with large exciton binding energies and lays the foundation for further studies.", "date": "2017-06", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "1-4", "id_number": "CaltechAUTHORS:20180601-090256322", "isbn": "978-1-5090-5605-7", "book_title": "2017 IEEE 44th Photovoltaic Specialist Conference (PVSC)", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180601-090256322", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1109/PVSC.2017.8366860", "resource_type": "book_section", "pub_year": "2017", "author_list": "Omelchenko, Stefan T.; Tolstova, Yulia; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5cbwp-qfh40", "eprint_id": 86750, "eprint_status": "archive", "datestamp": "2023-08-19 03:29:50", "lastmod": "2023-10-18 20:06:09", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yalamanchili-S", "name": { "family": "Yalamanchili", "given": "Sisir" } }, { "id": "Emmer-H-S", "name": { "family": "Emmer", "given": "Hal S." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Highly absorbing and high lifetime tapered silicon microwire arrays as an alternative for thin film crystalline silicon solar cells", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "silicon, microwires, reflection, absortion, surface passivation, carrier lifetime", "note": "\u00a9 2017 IEEE.", "abstract": "We report cryogenic inductively coupled plasma reactive ion etching (ICPRIE) etched tapered silicon microwires are ideal light trapping structures with extremely low (1.08% between 400 nm\u20131100 nm under normal incidence) reflectivity. We show that these tapered microwire arrays absorb 90.12% of incident light under normal incidence in an effectively 20 \u03bcm thick silicon when embedded in a polymer and peeled off the substrate, making them an attractive alternative for achieving high efficiency in thin film crystalline silicon solar cells. We show that microwave photoconductivity decay measurements as a simple quick way to measure carrier lifetimes in etched microwires under various liquid surface passivation techniques to estimate surface recombination velocities. The etched structures demonstrate >1 \u03bcs lifetimes.", "date": "2017-06", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "1-5", "id_number": "CaltechAUTHORS:20180601-141005255", "isbn": "978-1-5090-5605-7", "book_title": "2017 IEEE 44th Photovoltaic Specialist Conference (PVSC)", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180601-141005255", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1109/PVSC.2017.8366710", "resource_type": "book_section", "pub_year": "2017", "author_list": "Yalamanchili, Sisir; Emmer, Hal S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/n5fa1-84d93", "eprint_id": 89638, "eprint_status": "archive", "datestamp": "2023-08-19 03:12:28", "lastmod": "2023-10-18 22:53:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhou-Xinghao", "name": { "family": "Zhou", "given": "Xinghao" }, "orcid": "0000-0001-9229-7670" }, { "id": "Liu-Rui", "name": { "family": "Liu", "given": "Rui" } }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" } }, { "id": "Verlage-E", "name": { "family": "Verlage", "given": "Erik" } }, { "id": "Francis-S-A", "name": { "family": "Francis", "given": "Sonja A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" } ] }, "title": "Solar-Driven Reduction of 1 atm CO_2 to Formate at 10% Energy-Conversion Efficiency by Use of a TiO_2-Protected III-V Tandem Photoanode in Conjunction with a Bipolar Membrane and a Pd/C Cathode Electrocatalyst", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2017 ECS - The Electrochemical Society. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. S.A.F. acknowledges the Resnick Sustainability Institute at Caltech for a Postdoctoral Fellowship. The authors also thank N. Dalleska (Caltech) for his assistance with measurements and analysis of the ICPMS and TIC data.", "abstract": "A solar-driven CO_2-reduction (CO2R) cell, consisting of a tandem GaAs/InGaP/TiO_2/Ni photoanode in 1.0 M KOH(aq) (pH=13.7) to facilitate the oxygen-evolution reaction (OER), a Pd/C nanoparticle-coated Ti mesh cathode in 2.8 M KHCO_3(aq) (pH=8.0) to perform the CO_2R reaction, and a bipolar membrane to allow for steady-state operation of the catholyte and anolyte at different bulk pH values, was constructed. At the operational current density of 8.5 mA cm^(-2), in 2.8 M KHCO_3(aq), the cathode exhibited <100 mV overpotential and >94% Faradaic efficiency for the reduction of 1 atm of CO_2(g)to formate. The anode exhibited 320 \u00b1 7 mV overpotential for the OER in 1.0 M KOH(aq), and the bipolar membrane exhibited ~480 mV voltage loss with minimal product crossover as well as >90% and >95% selectivity for protons and hydroxide ions, respectively. The solar-driven CO_2R cell converted sunlight to fuels at an energy-conversion efficiency of ~10%.", "date": "2017-05-20", "date_type": "published", "publication": "ECS Transactions", "volume": "77", "number": "4", "publisher": "Electrochemical Society", "pagerange": "31-41", "id_number": "CaltechAUTHORS:20180914-100811320", "issn": "1938-6737", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180914-100811320", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1149/07704.0031ecst", "resource_type": "article", "pub_year": "2017", "author_list": "Zhou, Xinghao; Liu, Rui; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cejcq-j3821", "eprint_id": 75204, "eprint_status": "archive", "datestamp": "2023-08-19 03:01:37", "lastmod": "2023-10-25 14:50:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Singh-M-R", "name": { "family": "Singh", "given": "Meenesh R." }, "orcid": "0000-0002-3638-8866" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Evaluation of flow schemes for near-neutral pH electrolytes in solar-fuel generators", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 Royal Society of Chemistry. \n\nReceived 01 Feb 2017, Accepted 23 Feb 2017. First published online 23 Feb 2017. \n\nThis material is based on the work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award number DE-SC0004993.\n\nSupplemental Material - c7se00062f1.pdf
", "abstract": "The electrochemical performance of three different types of membrane-containing electrolyte-flow schemes for solar-driven water splitting has been studied quantitatively using 1-dimensional and 2-dimensional multi-physics models. The three schemes include a recirculation scheme with a well-mixed bulk electrolyte, a recirculation scheme with laminar flow fields, and a fresh-feed scheme with laminar flow fields. The Nernstian potential loss associated with pH gradients at the electrode surfaces, the resistive loss between the cathode and anode, the product-gas crossovers, and the required pumping energy in all three schemes have been evaluated as a function of the operational current density, the flow rates for the electrolyte, and the physical dimensions of the devices. The trade-offs in the voltage loss, safety considerations, and energy inputs from the balance-of-systems required to produce a practical device have been evaluated and compared to membrane-free devices as well as to devices that operate at extreme pH values.", "date": "2017-05-01", "date_type": "published", "publication": "Sustainable Energy and Fuels", "volume": "1", "number": "3", "publisher": "Royal Society of Chemistry", "pagerange": "458-466", "id_number": "CaltechAUTHORS:20170317-120009870", "issn": "2398-4902", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170317-120009870", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/C7SE00062F", "primary_object": { "basename": "c7se00062f1.pdf", "url": "https://authors.library.caltech.edu/records/cejcq-j3821/files/c7se00062f1.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Singh, Meenesh R.; Xiang, Chengxiang; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/k7z3d-ng196", "eprint_id": 76465, "eprint_status": "archive", "datestamp": "2023-08-19 02:32:46", "lastmod": "2023-10-25 16:01:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yao-Yuan", "name": { "family": "Yao", "given": "Yuan" } }, { "id": "Lee-Kyu-Tae", "name": { "family": "Lee", "given": "Kyu-Tae" } }, { "id": "Sheng-Xing", "name": { "family": "Sheng", "given": "Xing" } }, { "id": "Batara-N-A", "name": { "family": "Batara", "given": "Nicolas A." } }, { "id": "Hong-Nina", "name": { "family": "Hong", "given": "Nina" } }, { "id": "He-Junwen", "name": { "family": "He", "given": "Junwen" } }, { "id": "Xu-Lu", "name": { "family": "Xu", "given": "Lu" }, "orcid": "0000-0002-0021-9876" }, { "id": "Hussain-M-M", "name": { "family": "Hussain", "given": "Muhammad M." } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Nuzzo-R-G", "name": { "family": "Nuzzo", "given": "Ralph G." }, "orcid": "0000-0003-2310-2045" }, { "id": "Rogers-J-A", "name": { "family": "Rogers", "given": "John A." }, "orcid": "0000-0002-3830-5980" } ] }, "title": "Porous Nanomaterials for Ultrabroadband Omnidirectional Anti-Reflection Surfaces with Applications in High Concentration Photovoltaics", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 WILEY-VCH Verlag GmbH & Co. \n\nIssue online: 5 April 2017. Version of record online: 6 December 2016. Manuscript Revised: 14 October 2016. Manuscript Received: 7 September 2016. \n\nY.Y. and K.-T.L. contributed equally to this work. This work was supported by the \"Light-Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001293. X.S. acknowledges the support from National Natural Science Foundation of China (Project 51602172). M.M.H. acknowledges the support from King Abdullah University of Science and Technology (KAUST) Technology Transfer Office under Award No. GEN-01-4014. The authors thank B. Henderson (Sensofar), K. Walsh (UIUC), and J. C. Mabon (UIUC) for their assistance with materials characterization.\n\nSupplemental Material - aenm201601992-sup-0001-S1.pdf
", "abstract": "Materials for nanoporous coatings that exploit optimized chemistries and self-assembly processes offer capabilities to reach \u224898% transmission efficiency and negligible scattering losses over the broad wavelength range of the solar spectrum from 350 nm to 1.5 \u00b5m, on both flat and curved glass substrates. These nanomaterial anti-reflection coatings also offer wide acceptance angles, up to \u00b140\u00b0, for both s- and p-polarization states of incident light. Carefully controlled bilayer films have allowed for the fabrication of dual-sided, gradient index profiles on plano-convex lens elements. In concentration photovoltaics platforms, the resultant enhancements in the photovoltaics efficiencies are \u22488%, as defined by experimental measurements on systems that use microscale triple-junction solar cells. These materials and their applications in technologies that require control over interface reflections have the potential for broad utility in imaging systems, photolithography, light-emitting diodes, and display technologies.", "date": "2017-04-05", "date_type": "published", "publication": "Advanced Energy Materials", "volume": "7", "number": "7", "publisher": "Wiley", "pagerange": "Art. No. 1601992", "id_number": "CaltechAUTHORS:20170410-080135691", "issn": "1614-6832", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170410-080135691", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "National Natural Science Foundation of China", "grant_number": "51602172" }, { "agency": "King Abdullah University of Science and Technology (KAUST)", "grant_number": "GEN-01-4014" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1002/aenm.201601992", "primary_object": { "basename": "aenm201601992-sup-0001-S1.pdf", "url": "https://authors.library.caltech.edu/records/k7z3d-ng196/files/aenm201601992-sup-0001-S1.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Yao, Yuan; Lee, Kyu-Tae; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5jbv8-rzx78", "eprint_id": 75584, "eprint_status": "archive", "datestamp": "2023-08-19 02:16:38", "lastmod": "2023-10-25 15:09:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Moreno-Hernandez-Ivan-A", "name": { "family": "Moreno-Hernandez", "given": "Ivan A." }, "orcid": "0000-0001-6461-9214" }, { "id": "Schmidt-William-C", "name": { "family": "Schmidt", "given": "William C." } }, { "id": "Zhou-Xinghao", "name": { "family": "Zhou", "given": "Xinghao" }, "orcid": "0000-0001-9229-7670" }, { "id": "Crompton-J-Chance", "name": { "family": "Crompton", "given": "J. Chance" } }, { "id": "Liu-Rui", "name": { "family": "Liu", "given": "Rui" } }, { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" } }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A comparison of the chemical, optical and electrocatalytic properties of water-oxidation catalysts for use in integrated solar-fuel generators", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 Royal Society of Chemistry. \n\nReceived 7th December 2016 , Accepted 9th March 2017. First published on the web 9th March 2017. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. This work was also supported by the Gordon and Betty Moore Foundation under Award No. GBMF1225. This material is also based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469 (IAM).\n\nSupplemental Material - c6ee03563a1_si.pdf
", "abstract": "The in situ optical properties and electrocatalytic performance of representative catalysts for the oxygen-evolution reaction (OER) have been considered together to evaluate system-level effects that accompany the integration of OER catalysts into a solar-fuel device driven by a tandem-junction light absorber with a photoanode top cell, i.e., a design that requires incident light to be transmitted through the OER catalyst before reaching a semiconducting light absorber. The relationship between the overpotential and optical transmission of the catalysts determined the attainable efficiencies for integrated solar-fuel devices as well as the optimal band gaps for the photoanode in such devices. The systems investigated generally showed: (1) the OER catalysts dissolved in acid, and were less stable in buffered near-neutral pH electrolytes than in strongly alkaline electrolytes; (2) higher overpotentials were required to drive the OER at a specified current density when the catalysts were operated in contact with near-neutral pH electrolytes than strong alkaline electrolytes; (3) for some of the OER catalysts, the electrocatalytic activity and in situ absorption spectra depended strongly on the preparation method; (4) increasing the loading of the electrocatalyst reduced the overpotential and the optical transmission; (5) for the catalysts studied, the optical transmission and overpotential were generally correlated, and the trend lines did not cross, indicating that based on these factors alone, the optimal approach is to use lower loadings of highly active catalysts, rather than to use a less active but more transparent catalysts; (6) for a solar-fuel device driven by semiconductors operating at the Shockley\u2013Queisser limit and using a continuous film of a given OER catalyst in the path of incident light, the efficiency decrease due to the reduced optical transmittance that accompanies increased OER catalyst loading can be substantially greater than any efficiency increase that might be gained through the reduction in catalytic overpotential by increasing the catalyst loading; and (7) HER catalysts possessed the same performance trade-off when the light is incident through the HER catalysts as is observed for OER catalysts when the light is incident from the OER side.", "date": "2017-04", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "10", "number": "4", "publisher": "Royal Society of Chemistry", "pagerange": "987-1002", "id_number": "CaltechAUTHORS:20170331-105139021", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170331-105139021", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1144469" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/C6EE03563A", "primary_object": { "basename": "c6ee03563a1_si.pdf", "url": "https://authors.library.caltech.edu/records/5jbv8-rzx78/files/c6ee03563a1_si.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Sun, Ke; Moreno-Hernandez, Ivan A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/c7ft1-atj60", "eprint_id": 77236, "eprint_status": "archive", "datestamp": "2023-08-19 02:25:19", "lastmod": "2023-10-25 22:00:16", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Sunlight-driven hydrogen formation by membrane-supported photoelectrochemical water splitting", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "We are developing an artificial photosynthetic system that utilizes sunlight and water as the inputs and produce hydrogen and oxygen as the outputs. We are taking a modular, parallel development approach in which three distinct primary components-the photoanode, the photocathode, and the product-sepg. but ion-conducting membrane-are fabricated and optimized sep. before assembly into a complete water-splitting system. The design principles incorporate two sep., photosensitive semiconductor/liq. junctions that will collectively generate the 1.7-1.9 Vat open circuit necessary to support both the oxldn. of H_2O (or OH\u203e) and the redn. of H+ (or H_2O). The photoanode and photocathode will consist of rod-like semiconductor components, with attached heterogeneous multi-electron transfer catalysts, which are needed to drive the oxidn. or redn. reactions at low overpotentials. The high aspect-ratio semiconductor rod electrode architecture allows for the use of low cost, earth abundant materials without sacrificing energy conversion efficiency due to the orthogonalization of light absorption and charge-carrier collection. Addnl., the high surface-area design of the rod-based semiconductor array electrode inherently lowers the flux of charge carriers over the rod array surface relative to the projected geometric surface of the photoelectrode, thus lowering the photocurrent d. at the solid/liq. Junction and thereby relaxing the demands on the activity (and cost) of any electrocatalysts. A flexible composite polymer film will allow for electron and ion conduction between the photocanode and photocathode while simultaneously preventing mixing of the gaseous products. Sep. polymeric materials will be used to make elec. contact between the anode and cathode, and also to provide structural support Interspersed patches of an ion conducting polymer will maintain charge balance between the two half-cells.", "date": "2017-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170505-143903259", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170505-143903259", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2017", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rwdte-hvx35", "eprint_id": 73721, "eprint_status": "archive", "datestamp": "2023-08-19 01:56:48", "lastmod": "2023-10-24 16:23:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Plymale-N-T", "name": { "family": "Plymale", "given": "Noah T." }, "orcid": "0000-0003-2564-8009" }, { "id": "Dasog-M", "name": { "family": "Dasog", "given": "Mita" }, "orcid": "0000-0002-7846-3414" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A Mechanistic Study of the Oxidative Reaction of Hydrogen-Terminated Si(111) Surfaces with Liquid Methanol", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 American Chemical Society. \n\nReceived: November 16, 2016; Revised: January 14, 2017; Published: January 18, 2017. \n\nWe acknowledge the National Science Foundation grant No. CHE-1214152 for providing support for the materials used in this work. Instrumentation support was provided by the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology. N.T.P. acknowledges support from a National Science Foundation Graduate Research Fellowship. M.D. acknowledges support from a postdoctoral fellowship from the National Sciences and Engineering Research Council of Canada. N.T.P. and B.S.B acknowledge support from the National Science Foundation CCI Solar Fuels Program under Grant No. CHE-1305124. We thank Dr. Adam C. Nielander for insightful discussions during the preparation of this work.\n\nAccepted Version - acs_2Ejpcc_2E6b11555.pdf
Supplemental Material - jp6b11555_si_001.pdf
", "abstract": "H\u2013Si(111) surfaces have been reacted with liquid methanol (CH_3OH) in the absence or presence of a series of oxidants and/or illumination. Oxidant-activated methoxylation of H\u2013Si(111) surfaces was observed in the dark after exposure to CH_3OH solutions that contained the one-electron oxidants acetylferrocenium, ferrocenium, or 1,1'-dimethylferrocenium. The oxidant-activated reactivity toward CH_3OH of intrinsic and n-type H\u2013Si(111) surfaces increased upon exposure to ambient light. The results suggest that oxidant-activated methoxylation requires that two conditions be met: (1) the position of the quasi-Fermi levels must energetically favor oxidation of the H\u2013Si(111) surface and (2) the position of the quasi-Fermi levels must energetically favor reduction of an oxidant in solution. Consistently, illuminated n-type H\u2013Si(111) surfaces underwent methoxylation under applied external bias more rapidly and at more negative potentials than p-type H\u2013Si(111) surfaces. The results under potentiostatic control indicate that only conditions that favor oxidation of the H\u2013Si(111) surface need be met, with charge balance at the surface maintained by current flow at the back of the electrode. The results are described by a mechanistic framework that analyzes the positions of the quasi-Fermi levels relative to the energy levels relevant for each system.", "date": "2017-03-02", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "121", "number": "8", "publisher": "American Chemical Society", "pagerange": "4270-4282", "id_number": "CaltechAUTHORS:20170125-124627127", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170125-124627127", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "National Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "NSF", "grant_number": "CHE-1305124" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/acs.jpcc.6b11555", "primary_object": { "basename": "acs_2Ejpcc_2E6b11555.pdf", "url": "https://authors.library.caltech.edu/records/rwdte-hvx35/files/acs_2Ejpcc_2E6b11555.pdf" }, "related_objects": [ { "basename": "jp6b11555_si_001.pdf", "url": "https://authors.library.caltech.edu/records/rwdte-hvx35/files/jp6b11555_si_001.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Plymale, Noah T.; Dasog, Mita; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/48z17-4dz32", "eprint_id": 73753, "eprint_status": "archive", "datestamp": "2023-08-19 01:28:21", "lastmod": "2023-10-24 16:25:08", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Omelchenko-S-T", "name": { "family": "Omelchenko", "given": "Stefan T." }, "orcid": "0000-0003-1104-9291" }, { "id": "Tolstova-Y", "name": { "family": "Tolstova", "given": "Yulia" } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Excitonic Effects in Emerging Photovoltaic Materials: A Case Study in Cu_2O", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 American Chemical Society. \n\nReceived: December 19, 2016; Accepted: January 19, 2017; Published: January 19, 2017. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. Y.T. and H.A.A. are supported by the Dow Chemical Company under the earth-abundant semiconductor project. S.T.O. thanks S. Yalamanchili, K. Sun, and A. Carim for helpful discussions. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nz6b00704_si_001.pdf
", "abstract": "Excitonic effects account for a fundamental photoconversion and charge transport mechanism in Cu_2O; hence, the universally adopted \"free carrier\" model substantially underestimates the photovoltaic efficiency for such devices. The quasi-equilibrium branching ratio between excitons and free carriers in Cu_2O indicates that up to 28% of photogenerated carriers during photovoltaic operation are excitons. These large exciton densities were directly observed in photoluminescence and spectral response measurements. The results of a device physics simulation using a model that includes excitonic effects agree well with experimentally measured current\u2013voltage characteristics of Cu_2O-based photovoltaics. In the case of Cu_2O, the free carrier model underestimates the efficiency of a Cu_2O solar cell by as much as 1.9 absolute percent at room temperature.", "date": "2017-02-10", "date_type": "published", "publication": "ACS Energy Letters", "volume": "2", "number": "2", "publisher": "American Chemical Society", "pagerange": "431-437", "id_number": "CaltechAUTHORS:20170126-105722527", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170126-105722527", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Dow Chemical Company" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acsenergylett.6b00704", "primary_object": { "basename": "nz6b00704_si_001.pdf", "url": "https://authors.library.caltech.edu/records/48z17-4dz32/files/nz6b00704_si_001.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Omelchenko, Stefan T.; Tolstova, Yulia; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/catv3-xad41", "eprint_id": 69470, "eprint_status": "archive", "datestamp": "2023-08-19 00:12:16", "lastmod": "2023-10-20 19:05:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Developing a scalable artificial photosynthesis technology through nanomaterials by design", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2016 Macmillan Publishers Limited. \n\nReceived 31 July 2015; accepted 1 September 2016; published online 6 December 2016. \n\nThe work described herein was enabled by support from the National Science Foundation Center for Chemical Innovation, the Department of Energy Office of Basic Energy Sciences, the Air Force Office of Scientific Research, the Department of Energy through the Joint Center for Artificial Photosynthesis, and the Gordon and Betty Moore Foundation, as acknowledged in the individual publications referenced herein, as well as for partial salary support for N.S.L. that enabled the preparation of this manuscript. M. McDowell and K. Papadantonakis are acknowledged for assistance in preparation of this manuscript. A special acknowledgment is extended to the enthusiastic, talented and dedicated cohort of graduate students, post-doctoral fellows, collaborators and colleagues for their extraordinary, enabling contributions to this research effort, as acknowledged in the publications described and referenced herein. \n\nThe author declares no competing financial interests.", "abstract": "An artificial photosynthetic system that directly produces fuels from sunlight could provide an approach to scalable energy storage and a technology for the carbon-neutral production of high-energy-density transportation fuels. A variety of designs are currently being explored to create a viable artificial photosynthetic system, and the most technologically advanced systems are based on semiconducting photoelectrodes. Here, I discuss the development of an approach that is based on an architecture, first conceived around a decade ago, that combines arrays of semiconducting microwires with flexible polymeric membranes. I highlight the key steps that have been taken towards delivering a fully functional solar fuels generator, which have exploited advances in nanotechnology at all hierarchical levels of device construction, and include the discovery of earth-abundant electrocatalysts for fuel formation and materials for the stabilization of light absorbers. Finally, I consider the remaining scientific and engineering challenges facing the fulfilment of an artificial photosynthetic system that is simultaneously safe, robust, efficient and scalable.", "date": "2016-12", "date_type": "published", "publication": "Nature Nanotechnology", "volume": "11", "number": "12", "publisher": "Nature Publishing Group", "pagerange": "1010-1019", "id_number": "CaltechAUTHORS:20160805-102228624", "issn": "1748-3387", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160805-102228624", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "Department of Energy (DOE)" }, { "agency": "Air Force Office of Scientific Research (AFOSR)" }, { "agency": "Gordon and Betty Moore Foundation" } ] }, "collection": "CaltechAUTHORS", "local_group": { "items": [ { "id": "JCAP", "value": "JCAP" } ] }, "doi": "10.1038/nnano.2016.194", "resource_type": "article", "pub_year": "2016", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ya3p4-n2x38", "eprint_id": 71976, "eprint_status": "archive", "datestamp": "2023-08-20 14:20:30", "lastmod": "2023-10-23 17:44:17", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photon, electron, and ion management in artificial photosynthesis: Realizing efficient and stable renewable energy to fuel conversion", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society.", "abstract": "Direct prodn. of fuels from sunlight, air (N_2 or CO_2), and water that can be stored, transported, and later converted into hydrogen or electricity to provide power for transportation and distributed energy generation, have received recent attentions worldwide. This technol. could also in principle provide chems. as synthetic precursors or realize grid-level storage of intermittent solar energy. In artificial photosynthesis based on semiconductor photoelectrochem., the prodn. of chem. fuels generally requires the coupling of semiconductors with electrocatalysts where elec. charges are generated, sepd. and transferred for multi-electron chem. reactions, as well as the pairing of light-absorbing materials with optimum bandgap combinations. The development of such systems has been hindered in part by the lack of semiconducting materials that can provide efficiency and stability simultaneously in a corrosive environment, typically either strong acid or base. In this talk, I will present our efforts to fill this knowledge gap in the development of efficient and stable renewable energy to fuel conversion through the rational management of photons, electrons and ions in the coupled optoelec. and electrochem. process. First, I will summarize recent developments of photon management in PEC devices and modules from modeling to expt. Then, I will discuss methods for heterogeneous interfacial energetic modification on covalence-bond semiconductors for the efficient sepn. of free carriers (electrons/holes). Finally, I will present a novel concept for ion management in integrated PEC devices, which creates a defect-tolerant condition for unstable materials and leads to the demonstration of a record-setting solar water-splitting prototype.", "date": "2016-11", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20161114-084900934", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161114-084900934", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2016", "author_list": "Sun, Ke and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/vmvvn-f6e69", "eprint_id": 70747, "eprint_status": "archive", "datestamp": "2023-08-22 18:55:08", "lastmod": "2023-10-20 23:27:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yalamanchili-S", "name": { "family": "Yalamanchili", "given": "Sisir" } }, { "id": "Emmer-H-S", "name": { "family": "Emmer", "given": "Hal S." } }, { "id": "Fountaine-K-T", "name": { "family": "Fountaine", "given": "Katherine T." }, "orcid": "0000-0002-0414-8227" }, { "id": "Chen-Christopher-T", "name": { "family": "Chen", "given": "Christopher T." }, "orcid": "0000-0001-5848-961X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Enhanced Absorption and <1% Spectrum-and-Angle-Averaged Reflection in Tapered Microwire Arrays", "ispublished": "pub", "full_text_status": "public", "keywords": "absorption; carrier lifetime; ICPRIE; microwires; reflection; silicon; surface passivation; waveguide", "note": "\u00a9 2016 American Chemical Society. \n\nReceived: May 30, 2016; Publication Date (Web): September 19, 2016. \n\nThis work was supported in part by the National Science Foundation (NSF) and the Department of Energy (DOE) under NSF CA No. EEC-1041895 (H.S.E. and C.T.C.) and Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. Some of us (C.T.C., H.A.A.) are also supported in part by the U.S. Department of Energy through the Bay Area Photovoltaic Consortium under Award Number DE-EE0004946. We thank Dennis Friedrich for his collaborations for microwave-detected photoconductive decay measurements, Prof. Shu Hu for stimulating discussions, and Carol Garland for her assistance with TEM. This work benefited from use of the Applied Physics and Materials Science Department's Transmission Electron Microscopy Facility. Fabrication was performed in Kavli Nanoscience Institute (KNI) at Caltech, and we thank KNI staff for their assistance during fabrication. Lumerical FDTD simulations for this research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. \n\nS. Yalamanchili and H. S. Emmer contributed equally. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - ph6b00370_si_001.pdf
", "abstract": "We report ordered, high aspect ratio, tapered Si microwire arrays that exhibit an extremely low angular (0\u00b0 to 50\u00b0) and spectrally averaged reflectivity of <1% of the incident 400\u20131100 nm illumination. After isolating the microwires from the substrate with a polymer infill and peel off process, the arrays were found to absorb 89.1% of angular averaged incident illumination (0\u00b0 to 50\u00b0) in the equivalent volume of a 20 \u03bcm thick Si planar slab, reaching 99.5% of the classical light trapping limit between 400 and 1100 nm. We explain the broadband absorption by enhancement in coupling to waveguide modes due to the tapered microstructure of the arrays. Time-resolved microwave photoconductivity decay measurements yielded charge-carrier lifetimes of 0.75 \u03bcs (more than an order of magnitude higher than vapor\u2013liquid\u2013solid-grown Si microwires) in the tapered microwires, resulting in an implied V_(oc) of 0.655 V. The high absorption and high aspect ratio in these ordered microwire arrays make them an attractive platform for high-efficiency thin-film crystalline Si solar cells and as well as for the photoelectrochemical production of fuels from sunlight.", "date": "2016-10-19", "date_type": "published", "publication": "ACS Photonics", "volume": "3", "number": "10", "publisher": "American Chemical Society", "pagerange": "1854-1861", "id_number": "CaltechAUTHORS:20161003-084500313", "issn": "2330-4022", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161003-084500313", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "EEC-1041895" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-EE0004946" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acsphotonics.6b00370", "primary_object": { "basename": "ph6b00370_si_001.pdf", "url": "https://authors.library.caltech.edu/records/vmvvn-f6e69/files/ph6b00370_si_001.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Yalamanchili, Sisir; Emmer, Hal S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kdyj6-gva30", "eprint_id": 70765, "eprint_status": "archive", "datestamp": "2023-08-20 14:12:59", "lastmod": "2023-10-20 23:29:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhou-Xinghao", "name": { "family": "Zhou", "given": "Xinghao" }, "orcid": "0000-0001-9229-7670" }, { "id": "Liu-Rui", "name": { "family": "Liu", "given": "Rui" } }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" } }, { "id": "Verlage-E", "name": { "family": "Verlage", "given": "Erik" } }, { "id": "Francis-S-A", "name": { "family": "Francis", "given": "Sonja A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" } ] }, "title": "Solar-Driven Reduction of 1 atm of CO_2 to Formate at 10% Energy-Conversion Efficiency by Use of a TiO_2-Protected III\u2013V Tandem Photoanode in Conjunction with a Bipolar Membrane and a Pd/C Cathode", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 American Chemical Society. \n\nReceived: August 2, 2016; Accepted: September 9, 2016; Publication Date (Web): September 9, 2016. \n\nThis material is based on work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. S.A.F. acknowledges the Resnick Sustainability Institute at Caltech for a Postdoctoral Fellowship. The authors also thank N. Dalleska (Caltech) for his assistance with measurements and analysis of the ICPMS and TIC data. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nz6b00317_si_001.pdf
", "abstract": "A solar-driven CO_2 reduction (CO_2R) cell was constructed, consisting of a tandem GaAs/InGaP/TiO_2/Ni photoanode in 1.0 M KOH(aq) (pH = 13.7) to facilitate the oxygen-evolution reaction (OER), a Pd/C nanoparticle-coated Ti mesh cathode in 2.8 M KHCO_3(aq) (pH = 8.0) to perform the CO_2R reaction, and a bipolar membrane to allow for steady-state operation of the catholyte and anolyte at different bulk pH values. At the operational current density of 8.5 mA cm^(\u20132), in 2.8 M KHCO_3(aq), the cathode exhibited <100 mV overpotential and >94% Faradaic efficiency for the reduction of 1 atm of CO_2(g) to formate. The anode exhibited a 320 \u00b1 7 mV overpotential for the OER in 1.0 M KOH(aq), and the bipolar membrane exhibited \u223c480 mV voltage loss with minimal product crossovers and >90 and >95% selectivity for protons and hydroxide ions, respectively. The bipolar membrane facilitated coupling between two electrodes and electrolytes, one for the CO_2R reaction and one for the OER, that typically operate at mutually different pH values and produced a lower total cell overvoltage than known single-electrolyte CO_2R systems while exhibiting \u223c10% solar-to-fuels energy-conversion efficiency.", "date": "2016-10-14", "date_type": "published", "publication": "ACS Energy Letters", "volume": "1", "number": "4", "publisher": "American Chemical Society", "pagerange": "764-770", "id_number": "CaltechAUTHORS:20161003-141800305", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161003-141800305", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1021/acsenergylett.6b00317", "primary_object": { "basename": "nz6b00317_si_001.pdf", "url": "https://authors.library.caltech.edu/records/kdyj6-gva30/files/nz6b00317_si_001.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Zhou, Xinghao; Liu, Rui; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rjc7h-j7y77", "eprint_id": 69299, "eprint_status": "archive", "datestamp": "2023-08-22 18:52:02", "lastmod": "2023-10-20 16:46:49", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Weber-A-Z", "name": { "family": "Weber", "given": "Adam Z." }, "orcid": "0000-0002-7749-1624" }, { "id": "Ardo-S", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Berger-A-D", "name": { "family": "Berger", "given": "Alan" } }, { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" } }, { "id": "Coridan-R-H", "name": { "family": "Coridan", "given": "Robert" }, "orcid": "0000-0003-1916-4446" }, { "id": "Fountaine-K-T", "name": { "family": "Fountaine", "given": "Katherine T." }, "orcid": "0000-0002-0414-8227" }, { "id": "Haussener-S", "name": { "family": "Haussener", "given": "Sophia" }, "orcid": "0000-0002-3044-1662" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Liu-Rui", "name": { "family": "Liu", "given": "Rui" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Modestino-M-A", "name": { "family": "Modestino", "given": "Miguel A." }, "orcid": "0000-0003-2100-7335" }, { "id": "Shaner-M-R", "name": { "family": "Shaner", "given": "Matthew M." }, "orcid": "0000-0003-4682-9757" }, { "id": "Singh-M-R", "name": { "family": "Singh", "given": "Meenesh R." }, "orcid": "0000-0002-3638-8866" }, { "id": "Stevens-J-C", "name": { "family": "Stevens", "given": "John C." } }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Walczak-K-A", "name": { "family": "Walczak", "given": "Karl" } } ] }, "title": "Modeling, Simulation, and Implementation of Solar-Driven Water-Splitting Devices", "ispublished": "pub", "full_text_status": "restricted", "keywords": "device architecture; hydrogen; modeling; photoelectrochemistry; solar-driven water splitting", "note": "\u00a9 2016 Wiley-VCH Verlag GmbH & Co. \n\nReceived: November 11, 2015. Revised: January 31, 2016. Version of Record online: 27 Jul 2016. \n\nWe would like to thank the community of researchers whose work is reflected in this Review, especially those past and present at JCAP. This material is based upon work performed at the Joint Center for Artificial Photosynthesis (JCAP), a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. S.A. acknowledges support from the U.S. Department of Energy under Award No. DEEE0006963.", "abstract": "An integrated cell for the solar-driven splitting of water consists of multiple functional components and couples various photoelectrochemical (PEC) processes at different length and time scales. The overall solar-to-hydrogen (STH) conversion efficiency of such a system depends on the performance and materials properties of the individual components as well as on the component integration, overall device architecture, and system operating conditions. This Review focuses on the modeling- and simulation-guided development and implementation of solar-driven water-splitting prototypes from a holistic viewpoint that explores the various interplays between the components. The underlying physics and interactions at the cell level is are reviewed and discussed, followed by an overview of the use of the cell model to provide target properties of materials and guide the design of a range of traditional and unique device architectures.", "date": "2016-10-10", "date_type": "published", "publication": "Angewandte Chemie International Edition", "volume": "55", "number": "42", "publisher": "Wiley", "pagerange": "12974-12988", "id_number": "CaltechAUTHORS:20160729-070531307", "issn": "1433-7851", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160729-070531307", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-EE0006963" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1002/anie.201510463", "resource_type": "article", "pub_year": "2016", "author_list": "Xiang, Chengxiang; Weber, Adam Z.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/w57fw-crt07", "eprint_id": 71107, "eprint_status": "archive", "datestamp": "2023-08-20 13:48:34", "lastmod": "2023-10-23 15:20:25", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Callejas-J-F", "name": { "family": "Callejas", "given": "Juan F." } }, { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Roske-C-W", "name": { "family": "Roske", "given": "Christopher W." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Schaak-R-E", "name": { "family": "Schaak", "given": "Raymond E." } } ] }, "title": "Synthesis, Characterization, and Properties of Metal Phosphide Catalysts for the Hydrogen-Evolution Reaction", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society. \n\nReceived: May 27, 2016. Revised: July 28, 2016. Published: August 7, 2016. \n\nThis work was supported by the National Science Foundation (NSF) Center for Chemical Innovation in Solar Fuels (CHE-1305124). C.W.R. thanks the Link Energy Foundation for a graduate research fellowship. \n\nAuthor Contributions: (J.F.C. and C.G.R.) These authors contributed equally. \n\nThe authors declare no competing financial interest.", "abstract": "Hydrogen gas obtained by the electrolysis of water has long been proposed as a clean and sustainable alternative to fossil fuels. Noble metals such as Pt are capable of splitting water at low overpotentials, but the implementation of inexpensive solar-driven water-splitting systems and electrolyzers could benefit from the development of robust, efficient, and abundant alternatives to noble metal catalysts. Transition metal phosphides (M_xP_y) have recently been identified as a promising family of Earth abundant electrocatalysts for the hydrogen-evolution reaction (HER) and are capable of operating with low overpotentials at operationally relevant current densities while exhibiting stability under strongly acidic conditions. In this review, we highlight the progress that has been made in this field and provide insights into the synthesis, characterization, and electrochemical behavior of transition metal phosphides as HER electrocatalysts. We also discuss strategies for the incorporation of metal phosphides into integrated solar-driven water-splitting systems and highlight key considerations involved in the testing and benchmarking of such devices.", "date": "2016-09-13", "date_type": "published", "publication": "Chemistry of Materials", "volume": "28", "number": "17", "publisher": "American Chemical Society", "pagerange": "6017-6044", "id_number": "CaltechAUTHORS:20161014-131500162", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161014-131500162", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Link Energy Foundation" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/acs.chemmater.6b02148", "resource_type": "article", "pub_year": "2016", "author_list": "Callejas, Juan F.; Read, Carlos G.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/57b63-0a961", "eprint_id": 68756, "eprint_status": "archive", "datestamp": "2023-08-22 18:39:14", "lastmod": "2023-10-20 15:41:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewerenz-H-J", "name": { "family": "Lewerenz", "given": "Hans-Joachim" }, "orcid": "0000-0001-8433-9471" }, { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Richter-M-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Crumlin-E-J", "name": { "family": "Crumlin", "given": "Ethan J." }, "orcid": "0000-0003-3132-190X" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Axnanda-S", "name": { "family": "Axnanda", "given": "Stephanus" } }, { "id": "Favaro-M", "name": { "family": "Favaro", "given": "Marco" } }, { "id": "Drisdell-W-S", "name": { "family": "Drisdell", "given": "Walter" }, "orcid": "0000-0002-8693-4562" }, { "id": "Hussain-Z", "name": { "family": "Hussain", "given": "Zahid" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Liu-Zhi", "name": { "family": "Liu", "given": "Zhi" } }, { "id": "Nilsson-A", "name": { "family": "Nilsson", "given": "Anders" } }, { "id": "Bell-A-T", "name": { "family": "Bell", "given": "Alexis T." }, "orcid": "0000-0002-5738-4645" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Friebel-D", "name": { "family": "Friebel", "given": "Daniel" } } ] }, "title": "Operando Analyses of Solar Fuels Light Absorbers and Catalysts", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Catalysis; Semiconductors; Protection; operando spectroscopy; artificial photosynthesis", "note": "\u00a9 2016 Elsevier Ltd. \n\nReceived 11 December 2015, Revised 31 May 2016, Accepted 1 June 2016, Available online 6 June 2016. \n\nThis work was supported by the Office of Science of the U.S. Department of Energy (DOE) through award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis. The Advanced Light Source acknowledges support by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract no. DE-AC02-05CH11231. XAS data collection was carried out at Stanford Synchrotron Radiation Lightsource, a National User Facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. Computational work was carried out through NERSC computational resources under DOE Contract No. DE-AC02-05CH11231.", "abstract": "Operando synchrotron radiation photoelectron spectroscopy (SRPES) in the tender X-ray energy range has been used to obtain information on the energy-band relations of semiconductor and metal-covered semiconductor surfaces while in direct contact with aqueous electrolytes under potentiostatic control. The system that was investigated consists of highly doped Si substrates that were conformally coated with \u223c70 nm titania films produced by atomic-layer deposition. The TiO2/electrolyte and the Si/TiO2/Ni electrolyte interfaces were then analyzed by synchrotron radiation photoelectron spectroscopy. The PES data provided a determination of the flat-band position and identified regions of applied potential in which Fermi level pinning, depletion, or accumulation conditions occurred. Operando X-ray absorption spectroscopy (XAS) techniques were additionally used to investigate the properties of heterogeneous electrocatalysts for the oxygen-evolution reaction. Operando XAS including the pre-edge, edge and EXAFS regions allowed the development of a detailed picture of the catalysts under operating conditions, and elucidated the changes that in the physical and electronic structure of the catalyst that accompanied increases in the applied potential. Specifically, XAS data, combined with DFT studies, indicated that the activity of the electrocatalyst correlated with the formation of Fe dopant sites in \u03b3-NiOOH.", "date": "2016-09-01", "date_type": "published", "publication": "Electrochimica Acta", "volume": "211", "publisher": "Elsevier", "pagerange": "711-719", "id_number": "CaltechAUTHORS:20160629-130400375", "issn": "0013-4686", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160629-130400375", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1016/j.electacta.2016.06.006", "resource_type": "article", "pub_year": "2016", "author_list": "Lewerenz, Hans-Joachim; Lichterman, Michael F.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/n334z-epn96", "eprint_id": 71514, "eprint_status": "archive", "datestamp": "2023-08-20 13:31:51", "lastmod": "2024-01-13 18:34:16", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Progress Towards a Synergistically Integrated, Scalable Solar Fuels Generator", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society. \n\nPublication Date (Web): August 29, 2016. \n\nWe gratefully acknowledge support from the National Science Foundation, the Department of Energy Basic Energy Sciences, the Air Force Office of Scientific Research, the Department of Energy through the Joint Center for Artificial Photosynthesis, and the Gordon and Betty Moore Foundation, as acknowledged in the individual publications referenced herein, as well as for partial salary support for NSL that enabled the preparation of this manuscript. We also gratefully acknowledge the talented students and postdoctoral fellows who have made significant contributions to this work, especially including those listed as authors on the publications from our research group and referenced herein. Dr. Kimberly Papadantonakis is also acknowledged for assistance in preparation of this manuscript.", "abstract": "The development of an artificial photosynthetic system involves obtaining desired functionalities on the nanoscale. A viable blueprint for an artificial photosynthetic system involves two complementary, current-matched and voltage-adding photosystems, in conjunction with two different catalysts: one to oxidize water, and the other to reduce either water and/or carbon dioxide to solar fuels. Recent progress towards a robust, efficient, inexpensive and safe solar-fuels generator provides an example of nanoscale materials-by-design. The light-absorbing semiconductors have been designed and grown as high-aspect-ratio microwires which simultaneously allow minimization of ionic transport pathways, sufficient depth for light absorption in the semiconductor, efficient collection of charge carriers, and high surface areas for catalyst loading. Non-noble-metal catalysts for the redox reactions have been discovered, and methods for protecting the semiconductors against corrosion have been developed.", "date": "2016-08-29", "date_type": "published", "publisher": "American Chemical Society", "place_of_pub": "Washington, DC", "pagerange": "3-22", "id_number": "CaltechAUTHORS:20161026-151926632", "isbn": "9780841231467", "book_title": "Nanotechnology: Delivering on the Promise", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161026-151926632", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "Department of Energy (DOE)" }, { "agency": "Air Force Office of Scientific Research (AFOSR)" }, { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Gordon and Betty Moore Foundation" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "contributors": { "items": [ { "id": "Cheng-H-N", "name": { "family": "Cheng", "given": "H. N." } } ] }, "doi": "10.1021/bk-2016-1224.ch001", "resource_type": "book_section", "pub_year": "2016", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/338et-4de35", "eprint_id": 70263, "eprint_status": "archive", "datestamp": "2023-08-20 13:31:33", "lastmod": "2023-10-20 22:04:25", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nihill-K-J", "name": { "family": "Nihill", "given": "Kevin J." } }, { "id": "Hund-Z-M", "name": { "family": "Hund", "given": "Zachary M." } }, { "id": "Muzas-A", "name": { "family": "Muzas", "given": "Alberto" } }, { "id": "D\u00edaz-C", "name": { "family": "D\u00edaz", "given": "Cristina" } }, { "id": "del-Cueto-M", "name": { "family": "del Cueto", "given": "Marcos" } }, { "id": "Frankcombe-T", "name": { "family": "Frankcombe", "given": "Terry" } }, { "id": "Plymale-N-T", "name": { "family": "Plymale", "given": "Noah T." }, "orcid": "0000-0003-2564-8009" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Mart\u00edn-F", "name": { "family": "Mart\u00edn", "given": "Fernando" } }, { "id": "Sibener-S-J", "name": { "family": "Sibener", "given": "S. J." } } ] }, "title": "Experimental and theoretical study of rotationally inelastic diffraction of H_2(D_2) from methyl-terminated Si(111)", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 AIP Publishing LLC.\n\nReceived 17 June 2016; accepted 2 August 2016; published online 31 August 2016.\n\nS.J.S. acknowledges support from the Air Force Office of Scientific Research Grant No. FA9550-15-1-0428, and the Material Research Science and Engineering Center at the University of Chicago, No. NSF-DMR-14-20709. F.M., C.D., A.S.M., and M.d.C. acknowledge the MICINN Project No. FIS2013-42002-R, CAM Project No. S2014/MIT-2850, NANOFRONTMAG, and the CCC-UAM and the University of Chicago Research Computing Center for allocation of computer time. C.D. acknowledges the MICINN Project No. CTQ2013-50150-EXP and the Ram\u00f3n y Cajal program. A.S.M. and M.d.C. acknowledge the FPI program of the MICINN, co-financed by the E.S.F. N.T.P. acknowledges a National Science Foundation Graduate Research Fellowship. N.S.L. acknowledges support from the National Science Foundation (Grant No. CHE-1214152), and research was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. \n\nK. J. Nihill and Z. M. Hund contributed equally to this work.\n\nPublished - 1.4961257.pdf
", "abstract": "Fundamental details concerning the interaction between H_2 and CH_3\u2013Si(111) have been elucidated by the combination of diffractive scattering experiments and electronic structure and scattering calculations. Rotationally inelastic diffraction (RID) of H_2 and D_2 from this model hydrocarbon-decorated semiconductor interface has been confirmed for the first time via both time-of-flight and diffraction measurements, with modest j = 0 \u2192 2 RID intensities for H_2 compared to the strong RID features observed for D_2 over a large range of kinematic scattering conditions along two high-symmetry azimuthal directions. The Debye-Waller model was applied to the thermal attenuation of diffraction peaks, allowing for precise determination of the RID probabilities by accounting for incoherent motion of the CH_3\u2013Si(111) surface atoms. The probabilities of rotationally inelastic diffraction of H_2 and D_2 have been quantitatively evaluated as a function of beam energy and scattering angle, and have been compared with complementary electronic structure and scattering calculations to provide insight into the interaction potential between H_2 (D_2) and hence the surface charge density distribution. Specifically, a six-dimensional potential energy surface (PES), describing the electronic structure of the H_2(D_2)/CH_3\u2212Si(111) system, has been computed based on interpolation of density functional theory energies. Quantum and classical dynamics simulations have allowed for an assessment of the accuracy of the PES, and subsequently for identification of the features of the PES that serve as classical turning points. A close scrutiny of the PES reveals the highly anisotropic character of the interaction potential at these turning points. This combination of experiment and theory provides new and important details about the interaction of H_2 with a hybrid organic-semiconductor interface, which can be used to further investigate energy flow in technologically relevant systems.", "date": "2016-08-28", "date_type": "published", "publication": "Journal of Chemical Physics", "volume": "145", "number": "8", "publisher": "American Institute of Physics", "pagerange": "Art. No. 084705", "id_number": "CaltechAUTHORS:20160912-080646286", "issn": "0021-9606", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160912-080646286", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-15-1-0428" }, { "agency": "NSF", "grant_number": "DMR-14-20709" }, { "agency": "Ministerio de Econom\u00eda y Competitividad (MCINN)", "grant_number": "FIS2013-42002-R" }, { "agency": "CAM Project", "grant_number": "S2014/MIT-2850" }, { "agency": "Ministerio de Econom\u00eda y Competitividad (MCINN)", "grant_number": "CTQ2013-50150-EXP" }, { "agency": "Ram\u00f3n y Cajal Program" }, { "agency": "European Social Fund" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "NSF", "grant_number": "CHE-1214152" } ] }, "doi": "10.1063/1.4961257", "primary_object": { "basename": "1.4961257.pdf", "url": "https://authors.library.caltech.edu/records/338et-4de35/files/1.4961257.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Nihill, Kevin J.; Hund, Zachary M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kb4g0-98y63", "eprint_id": 69032, "eprint_status": "archive", "datestamp": "2023-08-20 13:21:54", "lastmod": "2023-10-20 16:27:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dasog-Mita", "name": { "family": "Dasog", "given": "Mita" }, "orcid": "0000-0002-7846-3414" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Yalamanchili-Sisir", "name": { "family": "Yalamanchili", "given": "Sisir" } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Profiling Photoinduced Carrier Generation in Semiconductor Microwire Arrays via Photoelectrochemical Metal Deposition", "ispublished": "pub", "full_text_status": "public", "keywords": "Semiconductor, silicon, microwires, electrodeposition, photoelectrochemistry, carrier generation", "note": "\u00a9 2016 American Chemical Society. \n\nReceived: May 2, 2016; Revised: June 7, 2016. Publication Date (Web): June 20, 2016. \n\nThis work was supported by the \"Light\u2212Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DESC0001293. The computational methods in this work used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This work was also supported in part by the National Science Foundation under Grant No. CHE-1214152 (support for N.S.L.). M.D. acknowledges a Postdoctoral Fellowship from the National Sciences and Engineering Research Council of Canada. A.I.C. acknowledges a Graduate Research Fellowship from the National Science Foundation. The authors gratefully acknowledge R. Jones and Dr. K. Walczak for assistance with photo electrochemical cell fabrication. \n\nAuthor Contributions: M.D. and A.I.C. contributed equally to this work. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nl6b01782_si_001.pdf
", "abstract": "Au was photoelectrochemically deposited onto cylindrical or tapered p-Si microwires on Si substrates to profile the photoinduced charge-carrier generation in individual wires in a photoactive semiconductor wire array. Similar experiments were repeated for otherwise identical Si microwires doped to be n-type. The metal plating profile was conformal for n-type wires, but for p-type wires was a function of distance from the substrate and was dependent on the illumination wavelength. Spatially resolved charge-carrier generation profiles were computed using full-wave electromagnetic simulations, and the localization of the deposition at the p-type wire surfaces observed experimentally correlated well with the regions of enhanced calculated carrier generation in the volumes of the microwires. This technique could potentially be extended to determine the spatially resolved carrier generation profiles in a variety of mesostructured, photoactive semiconductors.", "date": "2016-08-10", "date_type": "published", "publication": "Nano Letters", "volume": "16", "number": "8", "publisher": "American Chemical Society", "pagerange": "5015-5021", "id_number": "CaltechAUTHORS:20160714-133019238", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160714-133019238", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" }, { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acs.nanolett.6b01782", "primary_object": { "basename": "nl6b01782_si_001.pdf", "url": "https://authors.library.caltech.edu/records/kb4g0-98y63/files/nl6b01782_si_001.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Dasog, Mita; Carim, Azhar I.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3tjrg-5f472", "eprint_id": 68696, "eprint_status": "archive", "datestamp": "2023-08-20 12:50:31", "lastmod": "2023-10-19 23:16:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nielander-A-C", "name": { "family": "Nielander", "given": "Adam C." }, "orcid": "0000-0002-3639-2427" }, { "id": "Thompson-A-C", "name": { "family": "Thompson", "given": "Annelise C." }, "orcid": "0000-0003-2414-7050" }, { "id": "Roske-C-W", "name": { "family": "Roske", "given": "Christopher W." } }, { "id": "Masly-J-A", "name": { "family": "Maslyn", "given": "Jacqueline A." } }, { "id": "Hao-Yufeng", "name": { "family": "Hao", "given": "Yufeng" } }, { "id": "Plymale-N-T", "name": { "family": "Plymale", "given": "Noah T." }, "orcid": "0000-0003-2564-8009" }, { "id": "Hone-J", "name": { "family": "Hone", "given": "James" }, "orcid": "0000-0002-8084-3301" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Lightly Fluorinated Graphene as a Protective Layer for n-Type Si(111) Photoanodes in Aqueous Electrolytes", "ispublished": "pub", "full_text_status": "public", "keywords": "Photoelectrochemistry, graphene, 2D materials, solar energy conversion, anticorrosion", "note": "\u00a9 2016 American Chemical Society. \n\nReceived: February 22, 2016;\nRevised: May 19, 2016;\nPublished: June 20, 2016.\n\nN.S.L., A.C.N., and A.C.T. acknowledge NSF Grant CHE-\n1214152 for support, and the Beckman Institute Molecular\nMaterials Resource Center and Dr. Bruce S. Brunschwig for\nfacilities and valuable advice. A.C.N. and A.C.T. acknowledge Tom Lee and the UCLA Nanoelectronics Research Facility for valuable advice and access to instrumentation. A.C.N. and N.T.P. acknowledge support from NSF graduate research fellowships. C.W.R. thanks the Link Energy Foundation for a graduate research fellowship. J.A.M. thanks the Amgen Scholars program for a fellowship. This graphene material is based upon work supported by the NSF MRSEC program through Columbia in the Center for Precision Assembly of Superstratic and Superatomic Solids (DMR-1420634) and the Nanoelectronics Research Initiative (NRI) through the Institute for Nanoelectronics Discovery and Exploration (INDEX).\n\nSupplemental Material - nl6b00773_si_001.pdf
", "abstract": "The behavior of n-Si(111) photoanodes covered by monolayer sheets of fluorinated graphene (F\u2013Gr) was investigated under a range of chemical and electrochemical conditions. The electrochemical behavior of n-Si/F\u2013Gr and np^+-Si/F\u2013Gr photoanodes was compared to hydride-terminated n-Si (n-Si\u2212H) and np+-Si\u2212H electrodes in contact with aqueous Fe(CN)_6^(3-/4-) and Br_2/HBr electrolytes as well as in contact with a series of outer-sphere, one-electron redox couples in nonaqueous electrolytes. Illuminated n-Si/F\u2013Gr and np^+-Si/F\u2013Gr electrodes in contact with an aqueous K_3(Fe(CN)_6/K4(Fe(CN)_6 solutions exhibited stable short-circuit photocurrent densities of \u223c10 mA cm^(\u20132) for 100,000 s (>24 h), in comparison to bare Si electrodes, which yielded nearly a complete photocurrent decay over \u223c100 s. X-ray photoelectron spectra collected before and after exposure to aqueous anodic conditions showed that oxide formation at the Si surface was significantly inhibited for Si electrodes coated with F\u2013Gr relative to bare Si electrodes exposed to the same conditions. The variation of the open-circuit potential for n-Si/F\u2013Gr in contact with a series of nonaqueous electrolytes of varying reduction potential indicated that the n-Si/F\u2013Gr did not form a buried junction with respect to the solution contact. Further, illuminated n-Si/F\u2212Gr electrodes in contact with Br_2/HBr(aq) were significantly more electrochemically stable than n-Si\u2212H electrodes, and n-Si/F\u2212Gr electrodes coupled to a Pt catalyst exhibited ideal regenerative cell efficiencies of up to 5% for the oxidation of Br^\u2013 to Br_2.", "date": "2016-07-13", "date_type": "published", "publication": "Nano Letters", "volume": "16", "number": "7", "publisher": "American Chemical Society", "pagerange": "4082-4086", "id_number": "CaltechAUTHORS:20160627-153227823", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160627-153227823", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Caltech Beckman Institute" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Link Energy Foundation" }, { "agency": "Amgen Scholars Program" }, { "agency": "NSF", "grant_number": "DMR-1420634" }, { "agency": "Nanoelectronics Research Initiative (NRI)" }, { "agency": "Institute for Nanoelectronics Discovery and Exploration (INDEX)" } ] }, "doi": "10.1021/acs.nanolett.6b00773", "primary_object": { "basename": "nl6b00773_si_001.pdf", "url": "https://authors.library.caltech.edu/records/3tjrg-5f472/files/nl6b00773_si_001.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Nielander, Adam C.; Thompson, Annelise C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/j2adn-hqg33", "eprint_id": 67805, "eprint_status": "archive", "datestamp": "2023-08-20 12:47:49", "lastmod": "2023-10-18 21:46:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Plymale-N-T", "name": { "family": "Plymale", "given": "Noah T." }, "orcid": "0000-0003-2564-8009" }, { "id": "Ramachandran-A-A", "name": { "family": "Ramachandran", "given": "Anshul A." } }, { "id": "Lim-Alison-N", "name": { "family": "Lim", "given": "Allison" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Control of the Band-Edge Positions of Crystalline Si(111) by Surface Functionalization with 3,4,5-Trifluorophenylacetylenyl Moieties", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 American Chemical Society. \n\nReceived: April 14, 2016; Revised: June 1, 2016; Published: June 3, 2016. \n\nWe acknowledge the National Science Foundation Grant No. CHE-1214152 for support of supplies and equipment for this work. Instrumentation support was provided by the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology. N.T.P. acknowledges support from a National Science Foundation Graduate Research Fellowship. B.S.B. and N.T.P. acknowledge support from the National Science Foundation CCI Solar Fuels Program under Grant No. CHE-1305124. N.S.L. acknowledges support from a National Science Foundation Grant No. CHE-1214152. We thank Dr. Adam C. Nielander, Mr. Christopher W. Roske, and Dr. Kimberly M. Papadantonakis for helpful discussions.\n\nSupplemental Material - jp6b03824_si_001.pdf
", "abstract": "Functionalization of semiconductor surfaces with organic moieties can change the charge distribution, surface dipole, and electric field at the interface. The modified electric field will shift the semiconductor band-edge positions relative to those of a contacting phase. Achieving chemical control over the energetics at semiconductor surfaces promises to provide a means of tuning the band-edge energetics to form optimized junctions with a desired material. Si(111) surfaces functionalized with 3,4,5-trifluorophenylacetylenyl (TFPA) groups were characterized by transmission infrared spectroscopy (TIRS), X-ray photoelectron spectroscopy (XPS), and surface recombination velocity (S) measurements. Mixed methyl/TFPA-terminated (MMTFPA) n- and p-type Si(111) surfaces were synthesized and characterized by electrochemical methods. Current density versus voltage and Mott-Schottky measurements of Si(111)\u2013MMTFPA electrodes in contact with Hg indicated that the barrier height, \u03a6b, was a function of the fractional monolayer coverage of TFPA (\u03b8TFPA) in the alkyl monolayer. Relative to Si(111)\u2013CH3 surfaces, Si(111)\u2013MMTFPA samples with high \u03b8TFPA produced shifts in \u03a6b of \u22650.6 V for n-Si/Hg contacts and \u22650.5 V for p-Si/Hg contacts. Consistently, the open-circuit potential (Eoc) of Si(111)\u2013MMTFPA samples in contact with CH3CN solutions that contained the 1-electron redox couples decamethylferrocenium/decamethylferrocene (Cp*2Fe+/0) or methyl viologen (MV2+/+\u25cf) shifted relative to Si(111)\u2013CH3 samples by +0.27 V for n-Si and by up to +0.10 V for p-Si. Residual surface recombination limited the Eoc of p-Si samples at high \u03b8TFPA despite the favorable shift in the band-edge positions induced by the surface modification process.", "date": "2016-07-07", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "120", "number": "26", "publisher": "American Chemical Society", "pagerange": "14157-14169", "id_number": "CaltechAUTHORS:20160609-154706514", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160609-154706514", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "NSF", "grant_number": "CHE-1305124" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/acs.jpcc.6b03824", "primary_object": { "basename": "jp6b03824_si_001.pdf", "url": "https://authors.library.caltech.edu/records/j2adn-hqg33/files/jp6b03824_si_001.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Plymale, Noah T.; Ramachandran, Anshul A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6p4gf-1f651", "eprint_id": 66588, "eprint_status": "archive", "datestamp": "2023-08-20 12:46:55", "lastmod": "2023-10-18 18:36:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Liu-Rui", "name": { "family": "Liu", "given": "Rui" } }, { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" } }, { "id": "Verlage-E", "name": { "family": "Verlage", "given": "Erik" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" } ] }, "title": "A Stabilized, Intrinsically Safe, 10% Efficient, Solar-Driven Water-Splitting Cell Incorporating Earth-Abundant Electrocatalysts with Steady-State pH Gradients and Product Separation Enabled by a Bipolar Membrane", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. \n\nReceived: February 21, 2016; Revised: March 19, 2016; Published online: First published: 29 April 2016. \n\nThe authors declare no competing financial interests. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the US Department of Energy under Award Number DE-SC0004993, as well as grant number 1225 from the Gordon and Betty Moore Foundation. The authors also thank N. Dalleska (Caltech) for his assistance with measurements and analysis of the ICPMS data. The authors also thank S. Lu, K. Walczak for gas-crossover measurements, R.J.R. Jones for designing the flow-cell reactor, X. Zhou for preparation of the ALD TiO_2 coatings, and J. C. Crompton for preparation of the CoP-coated metal meshes.\n\nSupplemental Material - aenm201600379-sup-0001-S1.pdf
", "abstract": "An efficient, stable, and intrinsically safe solar water-splitting device is demonstrated using a III\u2013V tandem junction photoanode, an acid-stable, earth-abundant hydrogen evolution catalyst, and a bipolar membrane. The integrated photoelectrochemical cell operates under a steady-state pH gradient and achieves \u224810% solar-to-hydrogen conversion efficiency, >100 h of stability in a large (>1 cm^2) photoactive area in relation to most previous reports.", "date": "2016-07-06", "date_type": "published", "publication": "Advanced Energy Materials", "volume": "6", "number": "13", "publisher": "Wiley", "pagerange": "Art. No. 1600379", "id_number": "CaltechAUTHORS:20160502-135457387", "issn": "1614-6832", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160502-135457387", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "1225" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1002/aenm.201600379", "primary_object": { "basename": "aenm201600379-sup-0001-S1.pdf", "url": "https://authors.library.caltech.edu/records/6p4gf-1f651/files/aenm201600379-sup-0001-S1.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Sun, Ke; Liu, Rui; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/vx6tx-dsv97", "eprint_id": 67844, "eprint_status": "archive", "datestamp": "2023-08-20 12:45:22", "lastmod": "2023-10-18 21:48:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shaner-M-R", "name": { "family": "Shaner", "given": "Matthew R." }, "orcid": "0000-0003-4682-9757" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "McFarland-E-W", "name": { "family": "McFarland", "given": "Eric W." } } ] }, "title": "A comparative technoeconomic analysis of renewable hydrogen production using solar energy", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 Royal Society of Chemistry. \n\nReceived 19 Aug 2015, Accepted 05 May 2016, First published online 26 May 2016. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. Support for this technoeconomic analysis was provided jointly by the Dow Centre for Sustainable Engineering Innovation at the University of Queensland, and the Resnick Institute for Sustainability at Caltech.\n\nPublished - c5ee02573g.pdf
Supplemental Material - c5ee02573g1.pdf
", "abstract": "A technoeconomic analysis of photoelectrochemical (PEC) and photovoltaic-electrolytic (PV-E) solar-hydrogen production of 10 000 kg H_2 day^(\u22121) (3.65 kilotons per year) was performed to assess the economics of each technology, and to provide a basis for comparison between these technologies as well as within the broader energy landscape. Two PEC systems, differentiated primarily by the extent of solar concentration (unconcentrated and 10\u00d7 concentrated) and two PV-E systems, differentiated by the degree of grid connectivity (unconnected and grid supplemented), were analyzed. In each case, a base-case system that used established designs and materials was compared to prospective systems that might be envisioned and developed in the future with the goal of achieving substantially lower overall system costs. With identical overall plant efficiencies of 9.8%, the unconcentrated PEC and non-grid connected PV-E system base-case capital expenses for the rated capacity of 3.65 kilotons H_2 per year were $205 MM ($293 per m^2 of solar collection area (m_S^(\u22122)), $14.7 W_(H2,P)^(\u22121)) and $260 MM ($371 m_S^(\u22122), $18.8 W_(H2,P)^(\u22121)), respectively. The untaxed, plant-gate levelized costs for the hydrogen product (LCH) were $11.4 kg^(\u22121) and $12.1 kg^(\u22121) for the base-case PEC and PV-E systems, respectively. The 10\u00d7 concentrated PEC base-case system capital cost was $160 MM ($428 m_S^(\u22122), $11.5 W_(H2,P)^(\u22121)) and for an efficiency of 20% the LCH was $9.2 kg^(\u22121). Likewise, the grid supplemented base-case PV-E system capital cost was $66 MM ($441 m_S^(\u22122), $11.5 W_(H2,P)^(\u22121)), and with solar-to-hydrogen and grid electrolysis system efficiencies of 9.8% and 61%, respectively, the LCH was $6.1 kg^(\u22121). As a benchmark, a proton-exchange membrane (PEM) based grid-connected electrolysis system was analyzed. Assuming a system efficiency of 61% and a grid electricity cost of $0.07 kWh^(\u22121), the LCH was $5.5 kg^(\u22121). A sensitivity analysis indicated that, relative to the base-case, increases in the system efficiency could effect the greatest cost reductions for all systems, due to the areal dependencies of many of the components. The balance-of-systems (BoS) costs were the largest factor in differentiating the PEC and PV-E systems. No single or combination of technical advancements based on currently demonstrated technology can provide sufficient cost reductions to allow solar hydrogen to directly compete on a levelized cost basis with hydrogen produced from fossil energy. Specifically, a cost of CO_2 greater than \u223c$800 (ton CO_2)^(\u22121) was estimated to be necessary for base-case PEC hydrogen to reach price parity with hydrogen derived from steam reforming of methane priced at $12 GJ^(\u22121) ($1.39 (kg H_2)^(\u22121)). A comparison with low CO_2 and CO_2-neutral energy sources indicated that base-case PEC hydrogen is not currently cost-competitive with electrolysis using electricity supplied by nuclear power or from fossil-fuels in conjunction with carbon capture and storage. Solar electricity production and storage using either batteries or PEC hydrogen technologies are currently an order of magnitude greater in cost than electricity prices with no clear advantage to either battery or hydrogen storage as of yet. Significant advances in PEC technology performance and system cost reductions are necessary to enable cost-effective PEC-derived solar hydrogen for use in scalable grid-storage applications as well as for use as a chemical feedstock precursor to CO_2-neutral high energy-density transportation fuels. Hence such applications are an opportunity for foundational research to contribute to the development of disruptive approaches to solar fuels generation systems that can offer higher performance at much lower cost than is provided by current embodiments of solar fuels generators. Efforts to directly reduce CO_2 photoelectrochemically or electrochemically could potentially produce products with higher value than hydrogen, but many, as yet unmet, challenges include catalytic efficiency and selectivity, and CO_2 mass transport rates and feedstock cost. Major breakthroughs are required to obtain viable economic costs for solar hydrogen production, but the barriers to achieve cost-competitiveness with existing large-scale thermochemical processes for CO_2 reduction are even greater.", "date": "2016-07-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "9", "number": "7", "publisher": "Royal Society of Chemistry", "pagerange": "2354-2371", "id_number": "CaltechAUTHORS:20160610-132918453", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160610-132918453", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "University of Queensland" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1039/c5ee02573g", "primary_object": { "basename": "c5ee02573g.pdf", "url": "https://authors.library.caltech.edu/records/vx6tx-dsv97/files/c5ee02573g.pdf" }, "related_objects": [ { "basename": "c5ee02573g1.pdf", "url": "https://authors.library.caltech.edu/records/vx6tx-dsv97/files/c5ee02573g1.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Shaner, Matthew R.; Atwater, Harry A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5kpb8-3fp54", "eprint_id": 68687, "eprint_status": "archive", "datestamp": "2023-08-21 17:42:08", "lastmod": "2023-10-19 23:16:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Aspects of science and technology in support of legal and policy frameworks associated with a global carbon emissions-control regime", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 Royal Society of Chemistry. \n\nReceived 27th January 2016, Accepted 2nd June 2016, First published online 02 Jun 2016. \n\nI acknowledge the Department of Energy and the National Science Foundation for sustained support that made the preparation of this piece possible.\n\nPublished - c6ee00272b.pdf
", "abstract": "The delegates to COP21 in Paris, in conjunction with nationally formulated commitments and pledges, resolved that countries should take actions to \"hold the increase in global temperature to well below 2 \u00b0C above pre-industrial levels\" and to achieve \"a balance between anthropogenic emissions by sources and removal by sinks of greenhouse gases in the second half of this century\". This resolution for action suggests a step towards a global carbon emissions-control regime which, due to regional variabilities and remaining uncertainties as to the exact effects of atmospheric CO_2 concentrations, must be considered within the purview of risk management. In this Opinion, four topics are discussed that intertwine science, technology, legal, and policy issues critical to the implementation of any global carbon emissions-control regime: (i) What to regulate and at what levels; (ii) Regulating short-term versus long-term emissions; (iii) Validation of compliance in a regulated global emissions regime; and, (iv) Legal aspects of geoengineering.", "date": "2016-07-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "9", "number": "7", "publisher": "Royal Society of Chemistry", "pagerange": "2172-2176", "id_number": "CaltechAUTHORS:20160627-113518244", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160627-113518244", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "NSF" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c6ee00272b", "primary_object": { "basename": "c6ee00272b.pdf", "url": "https://authors.library.caltech.edu/records/5kpb8-3fp54/files/c6ee00272b.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/s88pb-v4372", "eprint_id": 68693, "eprint_status": "archive", "datestamp": "2023-09-15 05:28:26", "lastmod": "2023-10-23 21:17:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" } ] }, "title": "Modeling and Simulation of the Spatial and Light-Intensity Dependence of Product Distributions in an Integrated Photoelectrochemical CO_2 Reduction System", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2016 American Chemical Society. \n\nReceived: May 10, 2016\nAccepted: June 8, 2016. \n\nThis material is based upon work performed by the Joint\nCenter for Artificial Photosynthesis, a DOE Energy Innovation\nHub, supported through the Office of Science of the U.S.\nDepartment of Energy under Award Number DE-SC0004993.", "abstract": "A multiphysics model that accounts for the performance of electrocatalysts and triple-junction light absorbers, as well as for the transport properties of the electrolyte and dissolved CO_2, was used to evaluate the spatial and light-intensity dependence of product distributions in an integrated photoelectrochemical CO2 reduction (CO_2R) cell. Different sets of band gap combinations of triple-junction light absorbers were required to accommodate the optimal total operating current density relative to the optimal partial current density for CO_2R. The simulated product distribution was highly nonuniform along the width of the electrode and depended on the electrode dimensions as well as the illumination intensity. To achieve the same product selectivity as in a potentiostatic, \"half-cell\" configuration, the electrocatalyst must retain its selectivity over a range of cathode potentials, and this range is dependent on the transport losses and current\u2013voltage relationship of the light absorbers, the geometric parameters of the cell, and the illumination intensity.", "date": "2016-06-08", "date_type": "published", "publication": "ACS Energy Letters", "volume": "2016", "number": "1", "publisher": "American Chemical Society", "pagerange": "273-280", "id_number": "CaltechAUTHORS:20160627-135527397", "issn": "2380-8195", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160627-135527397", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acsenergylett.6b00134", "resource_type": "article", "pub_year": "2016", "author_list": "Chen, Yikai; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/tpz9v-q1t46", "eprint_id": 72342, "eprint_status": "archive", "datestamp": "2023-08-20 11:55:01", "lastmod": "2023-10-23 21:39:13", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Omelchenko-S-T", "name": { "family": "Omelchenko", "given": "Stefan T." }, "orcid": "0000-0003-1104-9291" }, { "id": "Tolstova-Y", "name": { "family": "Tolstova", "given": "Yulia" } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Excitonic effects in photovoltaic materials with large exciton binding energies", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "Excitons, Photovoltaic systems, Photoluminescence, Photonic band gap, Photovoltaic cells", "note": "\u00a9 2016 IEEE.", "abstract": "We investigate the effect of excitons on charge transport in photovoltaic materials with large exciton binding energies using Cu_2O as a model system. We develop a thermodynamic model to estimate the fraction of excitons in Cu_2O at quasi-equilibrium and find that over 20% of the generated population of carriers during photovoltaic operation could be excitons. Experiments show the presence of excitons at room temperature under visible light excitation and current collection due to excitons during device operation. This work demonstrates that excitons can play a fundamental role in photovoltaic materials with large exciton binding energies and lays the foundation for further studies.", "date": "2016-06", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "3616-3619", "id_number": "CaltechAUTHORS:20161128-152532394", "isbn": "978-1-5090-2724-8", "book_title": "IEEE 43rd Photovoltaic Specialists Conference", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161128-152532394", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1109/PVSC.2016.7750347", "resource_type": "book_section", "pub_year": "2016", "author_list": "Omelchenko, Stefan T.; Tolstova, Yulia; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mp97h-9yt54", "eprint_id": 72337, "eprint_status": "archive", "datestamp": "2023-08-20 11:54:55", "lastmod": "2023-10-23 21:38:57", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yalamanchili-S", "name": { "family": "Yalamanchili", "given": "Sisir" } }, { "id": "Emmer-H-S", "name": { "family": "Emmer", "given": "Hal S." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Highly absorbing and high lifetime tapered silicon microwire arrays as an alternative for thin film crystalline silicon solar cells", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "silicon, microwires, reflection, absortion, surface passivation, carrier lifetime", "note": "\u00a9 2016 IEEE.", "abstract": "We report cryogenic inductively coupled plasma reactive ion etching (ICPRIE) etched tapered silicon microwires are ideal light trapping structures with extremely low (1.08% between 400 nm\u20131100 nm under normal incidence) reflectivity. We show that these tapered microwire arrays absorb 90.12% of incident light under normal incidence in an effectively 20 \u03bcm thick silicon when embedded in a polymer and peeled off the substrate, making them an attractive alternative for achieving high efficiency in thin film crystalline silicon solar cells. We show that microwave photoconductivity decay measurements as a simple quick way to measure carrier lifetimes in etched microwires under various liquid surface passivation techniques to estimate surface recombination velocities. The etched structures demonstrate >1 \u03bcs lifetimes.", "date": "2016-06", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "2999-3003", "id_number": "CaltechAUTHORS:20161128-150914341", "isbn": "978-1-5090-2724-8", "book_title": "IEEE 43rd Photovoltaic Specialists Conference", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161128-150914341", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1109/PVSC.2016.7750213", "resource_type": "book_section", "pub_year": "2016", "author_list": "Yalamanchili, Sisir; Emmer, Hal S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/t3xb1-74d05", "eprint_id": 66254, "eprint_status": "archive", "datestamp": "2023-08-22 17:58:27", "lastmod": "2023-10-18 17:18:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Batara-Nicolas-A", "name": { "family": "Batara", "given": "Nicolas A." } }, { "id": "Premkumar-Anjali", "name": { "family": "Premkumar", "given": "Anjali" } }, { "id": "May-Richard", "name": { "family": "May", "given": "Richard" } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Morphological Expression of the Coherence and Relative Phase of Optical Inputs to the Photoelectrodeposition of Nanopatterned Se-Te Films", "ispublished": "pub", "full_text_status": "public", "keywords": "Electrodeposition; photoelectrochemistry; photodeposition; template-free; maskless; chalcogenide", "note": "\u00a9 2016 American Chemical Society. \n\nReceived: December 8, 2015; Revised: March 8, 2016; Publication Date (Web): March 16, 2016. \n\nThis work was supported by the \"Light\u2013Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0001293. The authors gratefully acknowledge Dr. B. Brunschwig and D. Ding for insightful discussions and R. Gerhart for assistance with photoelectrochemical cell fabrication. A.I.C. acknowledges a Graduate Research Fellowship from the National Science Foundation. A.P. acknowledges an Edward W. Hughes Research Fellowship from the California Institute of Technology. R.M. acknowledges a Summer Undergraduate Research Fellowship from the California Institute of Technology. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nl5b04999_si_001.pdf
", "abstract": "Highly anisotropic and ordered nanoscale lamellar morphologies can be spontaneously generated over macroscopic areas, without the use of a photomask or any templating agents, via the photoelectrodeposition of Se\u2013Te alloy films. To form such structures, the light source can be a single, linearly polarized light source that need not necessarily be highly coherent. In this work, the variation in the morphologies produced by this deposition process was evaluated in response to differences in the coherence and relative phase between multiple simultaneous linearly polarized illumination inputs. Specifically, the morphologies of photoelectrodeposits were evaluated when two tandem same-wavelength sources with discrete linear polarizations, both either mutually incoherent or mutually coherent (with defined phase differences), were used. Additionally, morphologies were simulated via computer modeling of the interfacial light scattering and absorption during the photoelectrochemical growth process. The morphologies that were generated using two coherent, in-phase sources were equivalent to those generated using only a single source. In contrast, the use of two coherent, out-of-phase sources produced a range of morphological patterns. For small out-of-phase addition of orthogonal polarization components, lamellar-type patterns were observed. When fully out-of-phase orthogonal sources (circular polarization) were used, an isotropic, mesh-type pattern was instead generated, similar to that observed when unpolarized illumination was utilized. In intermediate cases, anisotropic lamellar-type patterns were superimposed on the isotropic mesh-type patterns, and the relative height between the two structures scaled with the amount of out-of-phase addition of the orthogonal polarization components. Similar results were obtained when two incoherent sources were utilized. In every case, the long axis of the lamellar-type morphology component aligned parallel to the intensity-weighted average polarization orientation. The observations consistently agreed with computer simulations, indicating that the observed morphologies were fully determined by the nature of the illumination utilized during the growth process. The collective data thus indicated that the photoelectrodeposition process exhibits sensitivity toward the coherency, relative phase, and polarization orientations of all optical inputs and that this sensitivity is physically expressed in the morphology of the deposit.", "date": "2016-05-11", "date_type": "published", "publication": "Nano Letters", "volume": "16", "number": "5", "publisher": "American Chemical Society", "pagerange": "2963-2968", "id_number": "CaltechAUTHORS:20160418-145804523", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160418-145804523", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Caltech Summer Undergraduate Research Fellowship (SURF)" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acs.nanolett.5b04999", "primary_object": { "basename": "nl5b04999_si_001.pdf", "url": "https://authors.library.caltech.edu/records/t3xb1-74d05/files/nl5b04999_si_001.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Carim, Azhar I.; Batara, Nicolas A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/31ctk-1hg50", "eprint_id": 65099, "eprint_status": "archive", "datestamp": "2023-08-20 11:35:05", "lastmod": "2023-10-17 23:11:32", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Principles and implementations of electrolysis systems for water splitting", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 The Royal Society of Chemistry. \n\nReceived 18 Jan 2016, Accepted 05 Feb 2016; First published online 12 Feb 2016. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.\n\nPublished - c6mh00016a.pdf
", "abstract": "Efforts to develop renewable sources of carbon-neutral fuels have brought a renewed focus to research and development of sunlight-driven water-splitting systems. Electrolysis of water to produce H_2 and O_2 gases is the foundation of such systems, is conceptually and practically simple, and has been practiced both in the laboratory and industrially for many decades. In this Focus article, we present the fundamentals of water splitting and describe practices which distinguish commercial water-electrolysis systems from simple laboratory-scale demonstrations.", "date": "2016-05-01", "date_type": "published", "publication": "Materials Horizons", "volume": "2016", "number": "3", "publisher": "Royal Society of Chemistry", "pagerange": "169-173", "id_number": "CaltechAUTHORS:20160307-084720706", "issn": "2051-6347", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160307-084720706", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c6mh00016a", "primary_object": { "basename": "c6mh00016a.pdf", "url": "https://authors.library.caltech.edu/records/31ctk-1hg50/files/c6mh00016a.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Xiang, Chengxiang; Papadantonakis, Kimberly M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6jwpq-vsv45", "eprint_id": 64154, "eprint_status": "archive", "datestamp": "2023-08-20 11:14:30", "lastmod": "2023-10-17 19:33:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhou-Xinghao", "name": { "family": "Zhou", "given": "Xinghao" }, "orcid": "0000-0001-9229-7670" }, { "id": "Liu-Rui", "name": { "family": "Liu", "given": "Rui" } }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "570 mV photovoltage, stabilized n-Si/CoO_x heterojunction photoanodes fabricated using atomic layer deposition", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 The Royal Society of Chemistry. \n\nReceived 4th December 2015, Accepted 8th January 2016. First published online 08 Jan 2016. \n\nThis work was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. Atomic-force microscopy and UV-Vis spectroscopy were performed at the Molecular Materials Resource Center (MMRC) of the Beckman Institute at the California Institute of Technology. This work was additionally supported by the Gordon and Betty Moore Foundation under Award No. GBMF1225.\n\nPublished - c5ee03655k.pdf
Supplemental Material - c5ee03655k1.pdf
", "abstract": "Heterojunction photoanodes, consisting of n-type crystalline Si(100) substrates coated with a thin \u223c50 nm film of cobalt oxide fabricated using atomic-layer deposition (ALD), exhibited photocurrent-onset potentials of \u2212205 \u00b1 20 mV relative to the formal potential for the oxygen-evolution reaction (OER), ideal regenerative solar-to-O_2(g) conversion efficiencies of 1.42 \u00b1 0.20%, and operated continuously for over 100 days (\u223c2500 h) in 1.0 M KOH(aq) under simulated solar illumination. The ALD CoO_x thin film: (i) formed a heterojunction with the n-Si(100) that provided a photovoltage of 575 mV under 1 Sun of simulated solar illumination; (ii) stabilized Si photoanodes that are otherwise unstable when operated in aqueous alkaline electrolytes; and, (iii) catalyzed the oxidation of water, thereby reducing the kinetic overpotential required for the reaction and increasing the overall efficiency relative to electrodes that do not have an inherently electrocatalytic coating. The process provides a simple, effective method for enabling the use of planar n-Si(100) substrates as efficient and durable photoanodes in fully integrated, photovoltaic-biased solar fuels generators.", "date": "2016-04-08", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "9", "number": "3", "publisher": "Royal Society of Chemistry", "pagerange": "892-897", "id_number": "CaltechAUTHORS:20160202-092151363", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160202-092151363", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Joint Center for Artificial Photosynthesis" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/C5EE03655K", "primary_object": { "basename": "c5ee03655k.pdf", "url": "https://authors.library.caltech.edu/records/6jwpq-vsv45/files/c5ee03655k.pdf" }, "related_objects": [ { "basename": "c5ee03655k1.pdf", "url": "https://authors.library.caltech.edu/records/6jwpq-vsv45/files/c5ee03655k1.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Zhou, Xinghao; Liu, Rui; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ajt41-s0360", "eprint_id": 65891, "eprint_status": "archive", "datestamp": "2023-08-20 11:14:09", "lastmod": "2023-10-18 16:53:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yang-Fan", "name": { "family": "Yang", "given": "Fan" } }, { "id": "Nielander-A-C", "name": { "family": "Nielander", "given": "Adam C." }, "orcid": "0000-0002-3639-2427" }, { "id": "Grimm-R-L", "name": { "family": "Grimm", "given": "Ronald L." }, "orcid": "0000-0003-0407-937X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemical Behavior of n-Type GaAs(100) Electrodes Coated by a Single Layer of Graphene", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 American Chemical Society. \n\nReceived: January 8, 2016. Revised: March 8, 2016. Publication Date (Web): March 10, 2016. \n\nN.S.L. and F.Y. acknowledge support from the U.S. Department of Energy Office of Basic Energy Sciences, Grant DE-FG02-03ER15483, the Defense Advanced Research Projects Agency (DARPA) Grant W911NF-09-2-0011, and the Gordon and Betty Moore Foundation, grant 1225, for support, and the Beckman Institute Molecular Materials Resource Center for facilities. A.C.N. acknowledges support from NSF graduate research fellowship. The authors thank Dr. Nicholas Petrone and Professor James Hone of Columbia University for providing the graphene samples and K. Papadantonakis for assistance with editing this manuscript. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - jp6b00232_si_001.pdf
", "abstract": "Methods for cell-selective analysis of proteome dynamics will facilitate studies of biological processes in multicellular organisms. Here we describe a mutant murine methionyl-tRNA synthetase (designated L274GMmMetRS) that charges the noncanonical amino acid azidonorleucine (Anl) to elongator tRNA^(Met) in hamster (CHO), monkey (COS7), and human (HeLa) cell lines. Proteins made in cells that express the synthetase can be labeled with Anl, tagged with dyes or affinity reagents, and enriched on affinity resin to facilitate identification by mass spectrometry. The method does not require expression of orthogonal tRNAs or depletion of canonical amino acids. Successful labeling of proteins with Anl in several mammalian cell lines demonstrates the utility of L274GMmMetRS as a tool for cell-selective analysis of mammalian protein synthesis.", "date": "2016-04-07", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "120", "number": "13", "publisher": "American Chemical Society", "pagerange": "6989-6995", "id_number": "CaltechAUTHORS:20160404-104103120", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160404-104103120", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DEFG02-03ER15483" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "W911NF-09-2-0011" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "1225" }, { "agency": "Caltech Beckman Institute" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1021/acs.jpcc.6b00232", "primary_object": { "basename": "jp6b00232_si_001.pdf", "url": "https://authors.library.caltech.edu/records/ajt41-s0360/files/jp6b00232_si_001.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Yang, Fan; Nielander, Adam C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/g7vcr-qbe37", "eprint_id": 61970, "eprint_status": "archive", "datestamp": "2023-08-22 17:35:26", "lastmod": "2023-10-25 16:06:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Zhou-Xinghao", "name": { "family": "Zhou", "given": "Xinghao" }, "orcid": "0000-0001-9229-7670" }, { "id": "McDowell-Matthew-T", "name": { "family": "McDowell", "given": "Matthew T." }, "orcid": "0000-0001-5552-3456" }, { "id": "Shaner-Matthew-R", "name": { "family": "Shaner", "given": "Matthew R." }, "orcid": "0000-0003-4682-9757" }, { "id": "Richter-Matthias-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Crumlin-Ethan-J", "name": { "family": "Crumlin", "given": "Ethan J." }, "orcid": "0000-0003-3132-190X" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Protection of inorganic semiconductors for sustained, efficient photoelectrochemical water oxidation", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Artificial photosynthesis; Photoelectrochemistry; Corrosion; Catalysis", "note": "\u00a9 2015 Elsevier B.V. \n\nReceived 3 July 2015; Received in revised form 18 August 2015; Accepted 20 August 2015; Available online 25 October 2015. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, as well as by the Moore Foundation. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract no. DE-AC02-05CH11231. The authors thank Van Seebass for assistance in the preparation of this manuscript.", "abstract": "Small-band-gap (E_g < 2 eV) semiconductors must be stabilized for use in integrated devices that convert solar energy into the bonding energy of a reduced fuel, specifically H_2(g) or a reduced-carbon species such as CH_3OH or CH_4. To sustainably and scalably complete the fuel cycle, electrons must be liberated through the oxidation of water to O_2(g). Strongly acidic or strongly alkaline electrolytes are needed to enable efficient and intrinsically safe operation of a full solar-driven water-splitting system. However, under water-oxidation conditions, the small-band-gap semiconductors required for efficient cell operation are unstable, either dissolving or forming insulating surface oxides. We describe herein recent progress in the protection of semiconductor photoanodes under such operational conditions. We specifically describe the properties of two protective overlayers, TiO_2/Ni and NiO_x, both of which have demonstrated the ability to protect otherwise unstable semiconductors for >100 h of continuous solar-driven water oxidation when in contact with a highly alkaline aqueous electrolyte (1.0 M KOH(aq)). The stabilization of various semiconductor photoanodes is reviewed in the context of the electronic characteristics and a mechanistic analysis of the TiO_2 films, along with a discussion of the optical, catalytic, and electronic nature of NiO_x films for stabilization of semiconductor photoanodes for water oxidation.", "date": "2016-03-15", "date_type": "published", "publication": "Catalysis Today", "volume": "262", "publisher": "Elsevier", "pagerange": "11-23", "id_number": "CaltechAUTHORS:20151106-151700406", "issn": "0920-5861", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151106-151700406", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Gordon and Betty Moore Foundation" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1016/j.cattod.2015.08.017", "resource_type": "article", "pub_year": "2016", "author_list": "Lichterman, Michael F.; Sun, Ke; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4jd58-64z38", "eprint_id": 64740, "eprint_status": "archive", "datestamp": "2023-08-22 17:33:26", "lastmod": "2023-10-17 21:50:08", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Torelli-D-A", "name": { "family": "Torelli", "given": "Daniel A." }, "orcid": "0000-0002-6222-817X" }, { "id": "Francis-S-A", "name": { "family": "Francis", "given": "Sonja A." } }, { "id": "Crompton-J-C", "name": { "family": "Crompton", "given": "J. Chance" } }, { "id": "Javier-A", "name": { "family": "Javier", "given": "Alnald" }, "orcid": "0000-0002-0306-5462" }, { "id": "Thompson-J-R", "name": { "family": "Thompson", "given": "Joanthan R." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Soriaga-M-P", "name": { "family": "Soriaga", "given": "Manuel P." }, "orcid": "0000-0002-0077-6226" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Nickel\u2212Gallium-Catalyzed Electrochemical Reduction of CO_2 to Highly Reduced Products at Low Overpotentials", "ispublished": "pub", "full_text_status": "public", "keywords": "CO_2 reduction; electrocatalysis; nickel gallium; NiGa; ethane; methane; low overpotential; C_2 production", "note": "\u00a9 2016 American Chemical Society. \n\nReceived: December 17, 2015. Publication Date (Web): February 17, 2016. \n\nThe authors would like to thank Prof. Matthew McDowell for his help with TEM and insightful discussions, Dr. Ivonne Ferrer for her help with GC setup and calibration, and Dr. Kimberly Papadantonakis for help with editing. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. D.A.T. recognizes a Graduate Research Fellowship from the National Science Foundation for support. S.A.F. acknowledges the Resnick Sustainability Institute at Caltech for a Postdoctoral Fellowship. J.C.C. acknowledges support from the Department of Defense through the National Defense Science & Engineering Graduate Fellowship Program. N.S.L. acknowledges support through the Multidisciplinary University Research Initiative (MURI) under AFOSR Award No. FA9550-10-1-0572. \n\nThese authors contributed equally (D.A.T. and S.A.F.). \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - cs5b02888_si_001.pdf
", "abstract": "We report the electrocatalytic reduction of CO_2 to the highly reduced C_2 products, ethylene and ethane, as well as to the fully reduced C_1 product, methane, on three different phases of nickel\u2013gallium (NiGa, Ni_3Ga, and Ni_5Ga_3) films prepared by drop-casting. In aqueous bicarbonate electrolytes at neutral pH, the onset potential for methane, ethylene, and ethane production on all three phases was found to be \u22120.48 V versus the reversible hydrogen electrode (RHE), among the lowest onset potentials reported to date for the production of C_2 products from CO_2. Similar product distributions and onset potentials were observed for all three nickel\u2013gallium stoichiometries tested. The onset potential for the reduction of CO_2 to C_2 products at low current densities catalyzed by nickel\u2013gallium was >250 mV more positive than that of polycrystalline copper, and approximately equal to that of single crystals of copper, which have some of the lowest overpotentials to date for the reduction of CO_2 to C_2 products and methane. The nickel\u2013gallium films also reduced CO to ethylene, ethane, and methane, consistent with a CO_2 reduction mechanism that first involves the reduction of CO2 to CO. Isotopic labeling experiments with ^(13)CO_2 confirmed that the detected products were produced exclusively by the reduction of CO_2.", "date": "2016-03-04", "date_type": "published", "publication": "ACS Catalysis", "volume": "6", "number": "3", "publisher": "American Chemical Society", "pagerange": "2100-2104", "id_number": "CaltechAUTHORS:20160224-132719916", "issn": "2155-5435", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160224-132719916", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-10-1-0572" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1021/acscatal.5b02888", "primary_object": { "basename": "cs5b02888_si_001.pdf", "url": "https://authors.library.caltech.edu/records/4jd58-64z38/files/cs5b02888_si_001.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Torelli, Daniel A.; Francis, Sonja A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nm5he-pfh56", "eprint_id": 65483, "eprint_status": "archive", "datestamp": "2023-08-20 10:28:07", "lastmod": "2023-10-18 16:03:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jiang-S", "name": { "family": "Jiang", "given": "S." } }, { "id": "Ji-L-L", "name": { "family": "Ji", "given": "L. L." } }, { "id": "Audesirk-H", "name": { "family": "Audesirk", "given": "H." } }, { "id": "George-K-M", "name": { "family": "George", "given": "K. M." } }, { "id": "Snyder-J", "name": { "family": "Snyder", "given": "J." } }, { "id": "Krygier-A", "name": { "family": "Krygier", "given": "A." } }, { "id": "Poole-P", "name": { "family": "Poole", "given": "P." } }, { "id": "Willis-C", "name": { "family": "Willis", "given": "C." } }, { "id": "Daskalova-R", "name": { "family": "Daskalova", "given": "R." } }, { "id": "Chowdhury-E", "name": { "family": "Chowdhury", "given": "E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Schumacher-D-W", "name": { "family": "Schumacher", "given": "D. W." } }, { "id": "Pukhov-A", "name": { "family": "Pukhov", "given": "A." } }, { "id": "Freeman-R-R", "name": { "family": "Freeman", "given": "R. R." } }, { "id": "Akli-K-U", "name": { "family": "Akli", "given": "K. U." } } ] }, "title": "Microengineering Laser Plasma Interactions at Relativistic Intensities", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 American Physical Society. \n\nReceived 14 September 2015; published 25 February 2016. \n\nThis work is supported by the AFOSR under Contracts No. FA9550-14-1-0085 and No. FA9550-12-1-0341 and allocations of computing time from the Ohio Supercomputing Center. A.\u2009P. is supported by DFG Transregio TR18 (Germany). N.\u2009S.\u2009L. and H.\u2009A. acknowledge the National Science Foundation, Grant No. CHE-1214152, for support. D.\u2009W.\u2009S. is supported by the DARPA PULSE program through a grant from AMRDEC.\n\nPublished - PhysRevLett.116.085002.pdf
Submitted - 1509.04951v1.pdf
", "abstract": "We report on the first successful proof-of-principle experiment to manipulate laser-matter interactions on microscales using highly ordered Si microwire arrays. The interaction of a high-contrast short-pulse laser with a flat target via periodic Si microwires yields a substantial enhancement in both the total and cutoff energies of the produced electron beam. The self-generated electric and magnetic fields behave as an electromagnetic lens that confines and guides electrons between the microwires as they acquire relativistic energies via direct laser acceleration.", "date": "2016-02-26", "date_type": "published", "publication": "Physical Review Letters", "volume": "116", "number": "8", "publisher": "American Physical Society", "pagerange": "Art. No. 085002", "id_number": "CaltechAUTHORS:20160318-111253668", "issn": "0031-9007", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160318-111253668", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-14-1-0085" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-12-1-0341" }, { "agency": "Deutsche Forschungsgemeinschaft (DFG)" }, { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" } ] }, "doi": "10.1103/PhysRevLett.116.085002", "primary_object": { "basename": "1509.04951v1.pdf", "url": "https://authors.library.caltech.edu/records/nm5he-pfh56/files/1509.04951v1.pdf" }, "related_objects": [ { "basename": "PhysRevLett.116.085002.pdf", "url": "https://authors.library.caltech.edu/records/nm5he-pfh56/files/PhysRevLett.116.085002.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Jiang, S.; Ji, L. L.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1b7d4-0q641", "eprint_id": 64156, "eprint_status": "archive", "datestamp": "2023-08-20 10:24:37", "lastmod": "2023-10-17 19:33:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Richter-Matthias-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Beardslee-Joseph-A", "name": { "family": "Beardslee", "given": "Joseph" } }, { "id": "Mayer-Thomas", "name": { "family": "Mayer", "given": "Thomas" } }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electrical, Photoelectrochemical, and Photoelectron Spectroscopic Investigation of the Interfacial Transport and Energetics of Amorphous TiO\u2082/Si Heterojunctions", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 American Chemical Society. \n\nReceived: September 18, 2015. Revised: December 7, 2015. Publication Date (Web): December 15, 2015. \n\nThis work was supported through the Office of Science of the\nU.S. Department of Energy under Award DE-SC0004993 to\nthe Joint Center for Artificial Photosynthesis, a DOE Energy\nInnovation Hub. The authors thank Dr. Gang Liu and Prof.\nChongwu Zhou at the University of Southern California for\ntheir support of variable-temperature solid-state transport\nmeasurements. The authors also acknowledge Dr. Slobodan\nMitrovic and Natalie Becerra for assistance in the collection of XPS data, as well as Dr. Kimberley Papadantonakis for assistance with editing this manuscript. \n\nS.H. and M.H.R. contributed equally to this work. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - jp5b09121_si_001.pdf
", "abstract": "Solid-state electrical, photoelectrochemical, and photoelectron spectroscopic techniques have been used to characterize the behavior and electronic structure of interfaces between n-Si, n\u207a-Si, or p\u207a-Si surfaces and amorphous coatings of TiO\u2082 formed using atomic-layer deposition. Photoelectrochemical measurements of n-Si/TiO\u2082/Ni interfaces in contact with a series of one-electron, electrochemically reversible redox systems indicated that the n-Si/TiO\u2082/Ni structure acted as a buried junction whose photovoltage was independent of the formal potential of the contacting electrolyte. Solid-state current\u2013voltage analysis indicated that the built-in voltage of the n-Si/TiO\u2082 heterojunction was \u223c0.7 V, with an effective Richardson constant \u223c1/100th of the value of typical Si/metal Schottky barriers. X-ray photoelectron spectroscopic data allowed formulation of energy band-diagrams for the n-Si/TiO\u2082, n\u207a-Si/TiO\u2082, and p\u207a-Si/TiO\u2082 interfaces. The XPS data were consistent with the rectifying behavior observed for amorphous TiO\u2082 interfaces with n-Si and n\u207a-Si surfaces and with an ohmic contact at the interface between amorphous TiO\u2082 and p\u207a-Si.", "date": "2016-02-18", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "120", "number": "6", "publisher": "American Chemical Society", "pagerange": "3117-3129", "id_number": "CaltechAUTHORS:20160202-092151875", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160202-092151875", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acs.jpcc.5b09121", "primary_object": { "basename": "jp5b09121_si_001.pdf", "url": "https://authors.library.caltech.edu/records/1b7d4-0q641/files/jp5b09121_si_001.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Hu, Shu; Richter, Matthias H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/akpy1-bjn52", "eprint_id": 63881, "eprint_status": "archive", "datestamp": "2023-08-20 09:59:13", "lastmod": "2023-10-17 17:15:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Research opportunities to advance solar energy utilization", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2016 American Association for the Advancement of Science. \n\nWe acknowledge the NSF, CHE-1214152; the DOE Office of Science through the Joint Center for Artificial Photosynthesis, grant DE-SC0004993; and the DOE Office of Science, grant DE-FG02-03ER15483; and the Gordon and Betty Moore Foundation, grant 1225; for support that enabled the preparation of this Review, and M. Shaner for assistance in the preparation of this manuscript.", "abstract": "Major developments, as well as remaining challenges and the associated research opportunities, are evaluated for three technologically distinct approaches to solar energy utilization: solar electricity, solar thermal, and solar fuels technologies. Much progress has been made, but research opportunities are still present for all approaches. Both evolutionary and revolutionary technology development, involving foundational research, applied research, learning by doing, demonstration projects, and deployment at scale will be needed to continue this technology-innovation ecosystem. Most of the approaches still offer the potential to provide much higher efficiencies, much lower costs, improved scalability, and new functionality, relative to the embodiments of solar energy-conversion systems that have been developed to date.", "date": "2016-01-22", "date_type": "published", "publication": "Science", "volume": "351", "number": "6271", "publisher": "American Association for the Advancement of Science", "pagerange": "Art. No. aad1920", "id_number": "CaltechAUTHORS:20160122-095830294", "issn": "0036-8075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160122-095830294", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "1225" } ] }, "collection": "CaltechAUTHORS", "local_group": { "items": [ { "id": "JCAP", "value": "JCAP" } ] }, "doi": "10.1126/science.aad1920", "resource_type": "article", "pub_year": "2016", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5dsft-c8h19", "eprint_id": 120633, "eprint_status": "archive", "datestamp": "2023-08-22 17:13:03", "lastmod": "2023-10-18 17:55:52", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Armstrong-Robert-C", "name": { "family": "Armstrong", "given": "Robert C." } }, { "id": "Wolfram-Catherine", "name": { "family": "Wolfram", "given": "Catherine" } }, { "id": "de-Jong-Krijn-P", "name": { "family": "de Jong", "given": "Krijn P." }, "orcid": "0000-0002-9773-8110" }, { "id": "Gross-Robert", "name": { "family": "Gross", "given": "Robert" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Boardman-Brenda", "name": { "family": "Boardman", "given": "Brenda" } }, { "id": "Ragauskas-Arthur-J", "name": { "family": "Ragauskas", "given": "Arthur J." }, "orcid": "0000-0002-3536-554X" }, { "id": "Ehrhardt-Martinez-Karen", "name": { "family": "Ehrhardt-Martinez", "given": "Karen" } }, { "id": "Crabtree-George-W", "name": { "family": "Crabtree", "given": "George" }, "orcid": "0000-0002-8494-4468" }, { "id": "Ramana-M-V", "name": { "family": "Ramana", "given": "M. V." } } ] }, "title": "The frontiers of energy", "ispublished": "pub", "full_text_status": "public", "keywords": "Energy Engineering and Power Technology; Fuel Technology; Renewable Energy, Sustainability and the Environment; Electronic, Optical and Magnetic Materials", "abstract": "Great strides have been made over the past century in our ability to harness energy sources, leading to profound transformations \u2014 both good and bad \u2014 in society. Looking at the energy system of today, it is clear that meeting the energy needs of the world now and in the years to come requires the concerted efforts of many different actors across a range of technologies and approaches. In this Feature, ten leading experts in energy research share their vision of what challenges their respective fields need to address in the coming decades. The issues being faced are diverse and multifaceted, from the search for better materials for fuels, to the design of energy policy and markets for the developing world. However, a common theme emerges: changes to adapt and improve our energy system are greatly needed. By improving our mutual understanding of the issues faced by each area of energy research, these changes can happen more smoothly, efficiently and rapidly.", "date": "2016-01-11", "date_type": "published", "publication": "Nature Energy", "volume": "1", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 15020", "id_number": "CaltechAUTHORS:20230330-266464000.1", "issn": "2058-7546", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230330-266464000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1038/nenergy.2015.20", "resource_type": "article", "pub_year": "2016", "author_list": "Armstrong, Robert C.; Wolfram, Catherine; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/szdnf-xv968", "eprint_id": 61987, "eprint_status": "archive", "datestamp": "2023-08-20 09:49:42", "lastmod": "2023-10-25 16:07:31", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Velazquez-J-M", "name": { "family": "Velazquez", "given": "Jesus M." } }, { "id": "John-Jimmy", "name": { "family": "John", "given": "Jimmy" }, "orcid": "0000-0002-8772-8939" }, { "id": "Esposito-D-V", "name": { "family": "Esposito", "given": "Daniel V." }, "orcid": "0000-0002-0550-801X" }, { "id": "Pieterick-A-P", "name": { "family": "Pieterick", "given": "Adam" } }, { "id": "Pala-R-A", "name": { "family": "Pala", "given": "Ragip" } }, { "id": "Sun-Guofeng", "name": { "family": "Sun", "given": "Guofeng" } }, { "id": "Zhou-Xinghao", "name": { "family": "Zhou", "given": "Xinghao" }, "orcid": "0000-0001-9229-7670" }, { "id": "Huang-Zhuangqun", "name": { "family": "Huang", "given": "Zhuangqun" } }, { "id": "Ardo-S", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Soriaga-M-P", "name": { "family": "Soriaga", "given": "Manuel P." }, "orcid": "0000-0002-0077-6226" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A scanning probe investigation of the role of surface motifs in the behavior of p-WSe_2 photocathodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 Royal Society of Chemistry. \n\nReceived 17 Aug 2015, Accepted 08 Oct 2015. First published online 08 Oct 2015. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. Additional support for this work was provided by BP. JMV acknowledges support through an NRC Ford Foundation Postdoctoral Fellowship and the U.S. Department of Energy under Award No. DE-SC0004993. JJ thanks the Camille and Henry Dreyfus Foundation for financial support through its postdoctoral fellowship program in environmental chemistry and the U.S. Department of Energy, Office of Basic Energy Sciences under Award No. DE-FG02-03ER15483. DVE acknowledges support from the NIST NRC Fellowship program. JMV, JJ, and DVE also acknowledge the NIST Center for Nanoscale Science and Technology for use of its facilities for some SPCM measurements. SA acknowledges support from a United States Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under the EERE Fuel Cell Technologies Program. Certain commercial equipment, instruments, and materials are identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are the best available for the purpose.\n\nPublished - A_scanning_probe_investigation_of_the_role_of_surface_motifs_in_the_behavior_of_p-WSe2_photocathodes.pdf
Supplemental Material - c5ee02530c1.pdf
", "abstract": "The spatial variation in the photoelectrochemical performance for the reduction of an aqueous one-electron redox couple, Ru(NH_3)_6^(3+/2+), and for the evolution of H_2(g) from 0.5 M H_2SO_4(aq) at the surface of bare or Pt-decorated p-type WSe_2 photocathodes has been investigated in situ using scanning photocurrent microscopy (SPCM). The measurements revealed significant differences in the charge-collection performance (quantified by the values of external quantum yields, \u03a6_(ext)) on various macroscopic terraces. Local spectral response measurements indicated a variation in the local electronic structure among the terraces, which was consistent with a non-uniform spatial distribution of sub-band-gap states within the crystals. The photoconversion efficiencies of Pt-decorated p-WSe_2 photocathodes were greater for the evolution of H_2(g) from 0.5 M H_2SO_4 than for the reduction of Ru(NH_3)_6^(3+/2+), and terraces that exhibited relatively low values of \u03a6_(ext) for the reduction of Ru(NH_3)_6^(3+/2+) could in some cases yield values of \u03a6_(ext) for the evolution of H_2(g) comparable to the values of \u03a6_(ext) yielded by the highest-performing terraces. Although the spatial resolution of the techniques used in this work frequently did not result in observation of the effect of edge sites on photocurrent efficiency, some edge effects were observed in the measurements; however the observed edge effects differed among edges, and did not appear to determine the performance of the electrodes.", "date": "2016-01-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "9", "number": "1", "publisher": "Royal Society of Chemistry", "pagerange": "164-175", "id_number": "CaltechAUTHORS:20151109-102020642", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151109-102020642", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Ford Foundation" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "National Research Council" }, { "agency": "BP" }, { "agency": "EERE Fuel Cell Technologies Program" }, { "agency": "National Institute of Standards and Technology (NIST)" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/C5EE02530C", "primary_object": { "basename": "A_scanning_probe_investigation_of_the_role_of_surface_motifs_in_the_behavior_of_p-WSe2_photocathodes.pdf", "url": "https://authors.library.caltech.edu/records/szdnf-xv968/files/A_scanning_probe_investigation_of_the_role_of_surface_motifs_in_the_behavior_of_p-WSe2_photocathodes.pdf" }, "related_objects": [ { "basename": "c5ee02530c1.pdf", "url": "https://authors.library.caltech.edu/records/szdnf-xv968/files/c5ee02530c1.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Velazquez, Jesus M.; John, Jimmy; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/71psh-mhk72", "eprint_id": 63345, "eprint_status": "archive", "datestamp": "2023-08-20 09:41:20", "lastmod": "2023-10-25 23:44:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Batara-Nicolas-A", "name": { "family": "Batara", "given": "Nicolas A." } }, { "id": "Premkumar-Anjali", "name": { "family": "Premkumar", "given": "Anjali" } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Polarization Control of Morphological Pattern Orientation During Light-Mediated Synthesis of Nanostructured Se\u2013Te Films", "ispublished": "pub", "full_text_status": "restricted", "keywords": "electrodeposition, photoelectrochemistry, photodeposition, template-free, maskless, chalcogenide", "note": "\u00a9 2015 American Chemical Society. \n\nReceived: August 17, 2015; Accepted: November 22, 2015; Publication Date (Web): November 23, 2015. \n\nThis work was supported by the \"Light-Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001293. The authors gratefully acknowledge R. Gerhart for assistance with photoelectrochemical cell fabrication. A.I.C. recognizes a Graduate Research Fellowship from the National Science Foundation for support. A.P. recognizes an Edward W. Hughes Research Fellowship from the California Institute of Technology for support. \n\nThe authors declare no competing financial interest.", "abstract": "The template-free growth of well ordered, highly anisotropic lamellar structures has been demonstrated during the photoelectrodeposition of Se\u2013Te films, wherein the orientation of the pattern can be directed by orienting the linear polarization of the incident light. This control mechanism was investigated further herein by examining the morphologies of films grown photoelectrochemically using light from two simultaneous sources that had mutually different linear polarizations. Photoelectrochemical growth with light from two nonorthogonally polarized same-wavelength sources generated lamellar morphologies in which the long axes of the lamellae were oriented parallel to the intensity-weighted average polarization orientation. Simulations of light scattering at the solution\u2013film interface were consistent with this observation. Computer modeling of these growths using combined full-wave electromagnetic and Monte Carlo growth simulations successfully reproduced the experimental morphologies and quantitatively agreed with the pattern orientations observed experimentally by considering only the fundamental light-material interactions during growth. Deposition with light from two orthogonally polarized same-wavelength as well as different-wavelength sources produced structures that consisted of two intersecting sets of orthogonally oriented lamellae in which the relative heights of the two sets could be varied by adjusting the relative source intensities. Simulations of light absorption were performed in analogous, idealized intersecting lamellar structures and revealed that the lamellae preferentially absorbed light polarized with the electric field vector along their long axes. These data sets cumulatively indicate that anisotropic light scattering and light absorption generated by the light polarization produces the anisotropic morphology and that the resultant morphology is a function of all illumination inputs despite differing polarizations.", "date": "2016-01", "date_type": "published", "publication": "ACS Nano", "volume": "10", "number": "1", "publisher": "American Chemical Society", "pagerange": "102-111", "id_number": "CaltechAUTHORS:20160104-145744577", "issn": "1936-0851", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160104-145744577", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Caltech" } ] }, "doi": "10.1021/acsnano.5b05119", "resource_type": "article", "pub_year": "2016", "author_list": "Carim, Azhar I.; Batara, Nicolas A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kbrw5-0dq72", "eprint_id": 62955, "eprint_status": "archive", "datestamp": "2023-08-20 09:33:56", "lastmod": "2023-10-25 22:58:07", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Richter-M-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Crumlin-E-J", "name": { "family": "Crumlin", "given": "Ethan J." }, "orcid": "0000-0003-3132-190X" }, { "id": "Axnanda-S", "name": { "family": "Axnanda", "given": "Stephanus" } }, { "id": "Favaro-M", "name": { "family": "Favaro", "given": "Marco" } }, { "id": "Drisdell-W-S", "name": { "family": "Drisdell", "given": "Walter" }, "orcid": "0000-0002-8693-4562" }, { "id": "Hussain-Z", "name": { "family": "Hussain", "given": "Zahid" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Liu-Zhi", "name": { "family": "Liu", "given": "Zhi" } }, { "id": "Lewerenz-H-J", "name": { "family": "Lewerenz", "given": "Hans-Joachim" }, "orcid": "0000-0001-8433-9471" } ] }, "title": "An Electrochemical, Microtopographical and Ambient Pressure X-Ray Photoelectron Spectroscopic Investigation of Si/TiO_2/Ni/Electrolyte Interfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 The Author(s). Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. \n\nManuscript submitted September 9, 2015; revised manuscript received November 16, 2015. Published December 5, 2015. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE AC02 05CH11231. We thank Dr. Philip Ross for contributions to the conceptual development of the AP-XPS end station and experimental design.\n\nPublished - J._Electrochem._Soc.-2016-Lichterman-H139-46.pdf
", "abstract": "The electrical and spectroscopic properties of the TiO_2/Ni protection layer system, which enables stabilization of otherwise corroding photoanodes, have been investigated in contact with electrolyte solutions by scanning-probe microscopy, electrochemistry and in-situ ambient pressure X-ray photoelectron spectroscopy (AP-XPS). Specifically, the energy-band relations of the p+-Si/ALD-TiO_2/Ni interface have been determined for a selected range of Ni thicknesses. AP-XPS measurements using tender X-rays were performed in a three-electrode electrochemical arrangement under potentiostatic control to obtain information from the semiconductor near-surface region, the electrochemical double layer (ECDL) and the electrolyte beyond the ECDL. The degree of conductivity depended on the chemical state of the Ni on the TiO2surface. At low loadings of Ni, the Ni was present primarily as an oxide layer and the samples were not conductive, although the TiO_2 XPS core levels nonetheless displayed behavior indicative of a metal-electrolyte junction. In contrast, as the Ni thickness increased, the Ni phase was primarily metallic and the electrochemical behavior became highly conductive, with the AP-XPS data indicative of a metal-electrolyte junction. Electrochemical and microtopographical methods have been employed to better define the nature of the TiO_2/Ni electrodes and to contextualize the AP-XPS results.", "date": "2016", "date_type": "published", "publication": "Journal of the Electrochemical Society", "volume": "163", "number": "2", "publisher": "Electrochemical Society", "pagerange": "H139-H146", "id_number": "CaltechAUTHORS:20151215-152721755", "issn": "0013-4651", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151215-152721755", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1149/2.0861602jes", "primary_object": { "basename": "J._Electrochem._Soc.-2016-Lichterman-H139-46.pdf", "url": "https://authors.library.caltech.edu/records/kbrw5-0dq72/files/J._Electrochem._Soc.-2016-Lichterman-H139-46.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Lichterman, Michael F.; Richter, Matthias H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/k3tyh-n2h33", "eprint_id": 64889, "eprint_status": "archive", "datestamp": "2023-08-20 09:34:25", "lastmod": "2023-10-17 21:57:24", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shaner-M-R", "name": { "family": "Shaner", "given": "Matthew R." }, "orcid": "0000-0003-4682-9757" }, { "id": "McDowell-M-T", "name": { "family": "McDowell", "given": "Matthew T." }, "orcid": "0000-0001-5552-3456" }, { "id": "Pien-Alex", "name": { "family": "Pien", "given": "Alex" } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Si/TiO_2 Tandem-Junction Microwire Arrays for Unassisted Solar-Driven Water Splitting", "ispublished": "pub", "full_text_status": "public", "keywords": "Photoelectrochemistry Silicon Tandem Junction Water splitting", "note": "\u00a9 2016 The Electrochemical Society. \n\nManuscript submitted October 23, 2015; revised manuscript received December 17, 2015. Published January 15, 2016. \n\nThe authors acknowledge Stefan Omelchenko for assistance with the XRD measurements, John Lloyd for discussions about the cTLM measurements and Dr. Shawn Chatman for providing the Xe arc lamp spectral irradiance data. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S.\nDepartment of Energy under Award Number DE-SC0004993. M.R.S.\nacknowledges the Resnick Sustainability Institute for a graduate fellowship.\n\nPublished - J._Electrochem._Soc.-2016-Shaner-H261-4.pdf
Supplemental Material - README.txt
", "abstract": "Tandem-junction microwire array photoelectrodes have been fabricated by coating np^+-Si radial homojunction microwire arrays sequentially with fluorine-doped tin oxide (FTO) and titanium dioxide (TiO_2). These photoelectrodes effected unassisted water splitting under simulated 1 Sun conditions with an open-circuit potential (E_(oc)) of \u22121.5 V vs the formal potential for oxygen evolution, E^(0\u2032)(OH^\u2212/O_2), a current density at E = E^(0\u2032)(OH^\u2212/O_2) of 0.78 mA cm^(\u22122), a fill factor (\u2009ff\u2009) = 0.51, and a photovoltaic-biased photoelectrochemical ideal regenerative cell efficiency of 0.6%.", "date": "2016", "date_type": "published", "publication": "Journal of the Electrochemical Society", "volume": "163", "number": "5", "publisher": "Electrochemical Society", "pagerange": "H261-H264", "id_number": "CaltechAUTHORS:20160301-075443518", "issn": "0013-4651", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160301-075443518", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1149/2.0141605jes", "primary_object": { "basename": "J._Electrochem._Soc.-2016-Shaner-H261-4.pdf", "url": "https://authors.library.caltech.edu/records/k3tyh-n2h33/files/J._Electrochem._Soc.-2016-Shaner-H261-4.pdf" }, "related_objects": [ { "basename": "README.txt", "url": "https://authors.library.caltech.edu/records/k3tyh-n2h33/files/README.txt" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Shaner, Matthew R.; McDowell, Matthew T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/xr56n-xth56", "eprint_id": 63396, "eprint_status": "archive", "datestamp": "2023-08-20 09:30:05", "lastmod": "2023-10-25 23:47:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bruce-J-P", "name": { "family": "Bruce", "given": "Jared P." } }, { "id": "Oliver-D-R", "name": { "family": "Oliver", "given": "Derek R." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Freund-M-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" } ] }, "title": "Electrical Characteristics of the Junction between PEDOT:PSS and Thiophene-Functionalized Silicon Microwires", "ispublished": "pub", "full_text_status": "public", "keywords": "artificial photosynthesis, microwires, silicon, electrical characteristics, PEDOT:PSS, surface functionalization", "note": "\u00a9 2015 American Chemical Society. \n\nReceived: August 19, 2015; Accepted: November 17, 2015; Published: November 17, 2015. \n \nFinancial support from the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Canada Foundation for Innovation (CFI), the Manitoba Research and Innovation Fund, and the University of Manitoba is gratefully acknowledged. The work reported made use of surface characterization infrastructure in the Manitoba Institute for Materials. This work was supported by the NSF grant No. CHE-1214152 and made use of the Molecular Materials Research Center of the Beckman Institute at Caltech and the Kavli Nanoscience Institute at Caltech. This research was undertaken, in part, thanks to funding from the Canada Research Chairs Program. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - am5b07725_si_001.pdf
", "abstract": "Thiophene moieties have been attached to Si microwires (Si MWs) by a two-step chlorination/alkylation reaction method. X-ray photoelectron spectroscopy indicated that saturation of the surface occurred after 30 min of reaction time. Electrical measurements using a standard probe station indicated that the junction between individual thiophene-functionalized Si MWs and the conducting polymer poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) became more ohmic as more thiophene was added to the MW surface. Under a light-limited current of 20 nA, representative of operation of Si MWs under 1 Sun illumination conditions, the iR loss of thiophene-n-Si MW/PEDOT-PSS contacts was 20 mV, representing an order of magnitude reduction compared with PEDOT-PSS junctions formed with methyl terminated n-Si MWs. Such iR losses are much less than typical catalytic overpotentials for fuel formation, and hence the thiophene-functionalized Si MW contacts will not limit the performance of a Si MW array-based solar fuels device under 1 Sun illumination.", "date": "2015-12-16", "date_type": "published", "publication": "ACS Applied Materials & Interfaces", "volume": "7", "number": "49", "publisher": "American Chemical Society", "pagerange": "27160-27166", "id_number": "CaltechAUTHORS:20160105-150655557", "issn": "1944-8244", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160105-150655557", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "Canada Foundation for Innovation" }, { "agency": "Manitoba Research and Innovation Fund" }, { "agency": "University of Manitoba" }, { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Canada Research Chairs Program" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acsami.5b07725", "primary_object": { "basename": "am5b07725_si_001.pdf", "url": "https://authors.library.caltech.edu/records/xr56n-xth56/files/am5b07725_si_001.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Bruce, Jared P.; Oliver, Derek R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4kb9r-6gp79", "eprint_id": 62919, "eprint_status": "archive", "datestamp": "2023-08-20 09:27:36", "lastmod": "2023-10-25 21:59:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Introduction: Solar Energy Conversion", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.\n\nPublished: December 9, 2015.", "abstract": "This thematic issue contains reviews of various aspects of Solar Energy Conversion. The sun provides the largest energy source known to man, with more energy from sunlight striking the earth in 1 h than all of the energy consumed on the planet in an entire year. Solar panels provide a known, scalable technology to capture and convert sunlight into electricity. Moreover, the costs of Si-based photovoltaic panels have declined continuously in the past decade, to the point where solar electricity is now cost-competitive in certain regions and niche markets. Nevertheless, solar energy conversion continues to attract fervent efforts devoted to the discovery and development of new materials, concepts, devices, and systems that can provide new and/or dramatically improved functionality and scalability.", "date": "2015-12-09", "date_type": "published", "publication": "Chemical Reviews", "volume": "115", "number": "23", "publisher": "American Chemical Society", "pagerange": "12631-12632", "id_number": "CaltechAUTHORS:20151215-082636905", "issn": "0009-2665", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151215-082636905", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "collection": "CaltechAUTHORS", "doi": "10.1021/acs.chemrev.5b00654", "resource_type": "article", "pub_year": "2015", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9kdtn-8n505", "eprint_id": 61771, "eprint_status": "archive", "datestamp": "2023-08-20 09:13:34", "lastmod": "2023-10-25 15:43:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" } ] }, "title": "Operational constraints and strategies for systems to effect the sustainable, solar-driven reduction of atmospheric CO_2", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 The Royal Society of Chemistry. \n\nReceived 21st September 2015, Accepted 6th October 2015, First published online 08 Oct 2015. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993 as well as by the Gordon and Betty Moore Foundation, grant 1225. We also thank Dr Ken Caldeira and Dr Joe Berry of the Carnegie Institution for Science, Department of Global Ecology, for numerous stimulating and valuable discussions regarding the ocean/air CO_2 flux and the ABL/troposphere CO_2 transport properties.\n\nPublished - c5ee02908b.pdf
", "abstract": "The operational constraints for a 6-electron/6-proton CO_2 reduction system that operates at the concentration of CO_2 in the current atmosphere (p_(CO_2) = 400 ppm) have been evaluated on a variety of scale lengths that span from laboratory scale to global scale. Due to the low concentration of CO_2 in the atmosphere, limitations due to mass transport of CO_2 from the tropopause have been evaluated through five different regions, each with different characteristic length scales: the troposphere; the atmospheric boundary layer (ABL); the canopy layer; a membrane layer; and an aqueous electrolyte layer. The resulting CO_2 conductances, and associated physical transport limitations, will set the ultimate limit on the efficiency and areal requirements of a sustainable solar-driven CO_2 reduction system regardless of the activity or selectivity of catalysts for reduction of CO_2 at the molecular level. At the electrolyte/electrode interface, the steady-state limiting current density and the concomitant voltage loss associated with the CO_2 concentration overpotential in a one-dimensional solar-driven CO_2 reduction cell have been assessed quantitatively using a mathematical model that accounts for diffusion, migration and convective transport, as well as for bulk electrochemical reactions in the electrolyte. At p_(CO_2) = 400 ppm, the low diffusion coefficient combined with the low solubility of CO_2 in aqueous solutions constrains the steady-state limiting current density to <0.1 mA cm\u22122 in a typical electrochemical cell with natural convection and employing electrolytes with a range of pH values. Hence, in such a system, the CO_2 capture area must be 100- to 1000-fold larger than the solar photon collection area to enable a >10% efficient solar-driven CO_2 reduction system (based on the solar collection area). This flux limitation is consistent with estimates of oceanic CO_2 uptake fluxes that have been developed in conjunction with carbon-cycle analyses for use in coupled atmosphere/ocean general circulation models. Two strategies to improve the feasibility of obtaining efficient and sustainable CO_2 transport to a cathode surface at p_(CO_2) = 400 ppm are described and modeled quantitatively. The first strategy employs yet unknown catalysts, analogous to carbonic anhydrases, that dramatically accelerate the chemically enhanced CO_2 transport in the aqueous electrolyte layer by enhancing the acid\u2013base reactions in a bicarbonate buffer system. The rapid interconversion from bicarbonate to CO_2 in the presence of such catalysts near the cathode surface would in principle yield significant increases in the steady-state limiting current density and allow for >10% solar-fuel operation at the cell level. The second strategy employs a thin-layer cell architecture to improve the diffusive transport of CO_2 by use of an ultrathin polymeric membrane electrolyte. Rapid equilibration of CO_2 at the gas/electrolyte interface, and significantly enhanced diffusive fluxes of CO_2 in electrolytes, are required to increase the steady-state limiting current density of such a system. This latter approach however only is feasible for gaseous products, because liquid products would coat the electrode and therefore thicken the hydrodynamic boundary layer and accordingly reduce the diffusive CO_2 flux to the electrode surface. Regardless of whether the limitations due to mass transport to the electrode surface are overcome on the laboratory scale, at global scales the ultimate CO_2 flux limitations will be dictated by mass transport considerations related to transport of atmospheric CO_2 to the boundary plane of the solar-driven reactor system. The transport of CO_2 across the troposphere/ABL interface, the ABL/canopy layer interface, and the canopy layer/electrolyte interface have therefore been assessed in this work, to provide upper bounds on the ultimate limits for the solar-to-fuel (STF) conversion efficiency for systems that are intended to effect the reduction of atmospheric CO_2 in a sustainable fashion at global scale.", "date": "2015-12", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "12", "publisher": "Royal Society of Chemistry", "pagerange": "3663-3674", "id_number": "CaltechAUTHORS:20151102-111406745", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151102-111406745", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "1225" } ] }, "doi": "10.1039/c5ee02908b", "primary_object": { "basename": "c5ee02908b.pdf", "url": "https://authors.library.caltech.edu/records/9kdtn-8n505/files/c5ee02908b.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Chen, Yikai; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rc1cc-r8722", "eprint_id": 59897, "eprint_status": "archive", "datestamp": "2023-08-20 08:58:46", "lastmod": "2023-10-23 22:48:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Verlage-E", "name": { "family": "Verlage", "given": "Erik" } }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Liu-Rui", "name": { "family": "Liu", "given": "Rui" } }, { "id": "Jones-R-J-R", "name": { "family": "Jones", "given": "Ryan J. R." }, "orcid": "0000-0002-4629-3115" }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan" }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A., Jr." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "A Monolithically Integrated, Intrinsically Safe, 10% Efficient, Solar-Driven Water-Splitting System Based on Active, Stable Earth-Abundant Electrocatalysts in Conjunction with Tandem III-V Light Absorbers Protected by Amorphous TiO_2 Films", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 Royal Society of Chemistry. \n\nReceived 09 Jun 2015, Accepted 17 Aug 2015, First published online 18 Aug 2015. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. This work was additionally supported by the Gordon and Betty Moore Foundation under Award No. GBMF1225.\n\nPublished - c5ee01786f.pdf
Supplemental Material - c5ee01786f1.pdf
Supplemental Material - c5ee01786f2.mp4
", "abstract": "A monolithically integrated device consisting of a tandem-junction GaAs/InGaP photoanode coated by an amorphous TiO_2 stabilization layer, in conjunction with Ni-based, earth-abundant active electrocatalysts for the hydrogen-evolution and oxygen-evolution reactions, was used to effect unassisted, solar-driven water splitting in 1.0 M KOH(aq). When connected to a Ni-Mo-coated counterelectrode in a two-electrode cell configuration, the TiO_2-protected III-V tandem device exhibited a solar-to-hydrogen conversion efficiency, \u03b7_(STH), of 10.5% under 1 sun illumination, with stable performance for > 40 h of continuous operation at an efficiency of \u03b7_(STH) >10%. The protected tandem device also formed the basis for a monolithically integrated, intrinsically safe solar-hydrogen prototype system (1 cm^2) driven by a NiMo/GaAs/InGaP/TiO_2/Ni structure. The intrinsically safe system exhibited a hydrogen production rate of 0.81 \u03bcL s^(-1) and a solar-to-hydrogen conversion efficiency of 8.6% under 1 sun illumination in 1.0 M KOH(aq), with minimal product gas crossover while allowing for beneficial collection of separate streams of H_2(g) and O_2(g).", "date": "2015-11-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "11", "publisher": "Royal Society of Chemistry", "pagerange": "3166-3172", "id_number": "CaltechAUTHORS:20150825-164619530", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150825-164619530", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/C5EE01786F", "primary_object": { "basename": "c5ee01786f.pdf", "url": "https://authors.library.caltech.edu/records/rc1cc-r8722/files/c5ee01786f.pdf" }, "related_objects": [ { "basename": "c5ee01786f1.pdf", "url": "https://authors.library.caltech.edu/records/rc1cc-r8722/files/c5ee01786f1.pdf" }, { "basename": "c5ee01786f2.mp4", "url": "https://authors.library.caltech.edu/records/rc1cc-r8722/files/c5ee01786f2.mp4" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Verlage, Erik; Hu, Shu; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/g9c0k-d0w98", "eprint_id": 61557, "eprint_status": "archive", "datestamp": "2023-08-20 08:47:52", "lastmod": "2023-10-25 15:00:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Ager-J-W", "name": { "family": "Ager", "given": "Joel W." }, "orcid": "0000-0001-9334-9751" }, { "id": "Yang-Jinhui", "name": { "family": "Yang", "given": "Jinhui" } }, { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Strandwitz-N-C", "name": { "family": "Strandwitz", "given": "Nicholas C." } } ] }, "title": "Thin-Film Materials for the Protection of Semiconducting Photoelectrodes in Solar-Fuel Generators", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society. \n\nReceived: June 22, 2015. Revised: September 25, 2015. Publication Date (Web): September 28, 2015. \n\nNCS acknowledges start-up funds from Lehigh University. JRM acknowledges a postdoctoral research award from the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy through the SunShot Initiative. SH, NSL, JWA, and JY were supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993, and NSL was also supported by the National Science Foundation under Award Number CHE-1214152, the Department of Energy, Office of Basic Energy Sciences under Award Number DE-FG02-03ER15483, and the Gordon and Betty Moore Foundation under Award Number GBMF1225. \n\nThe authors declare no competing financial interest.", "abstract": "The electrochemical instability of semiconductors in aqueous electrolytes has impeded the development of robust sunlight-driven water-splitting systems. We review the use of protective thin films to improve the electrochemical stability of otherwise unstable semiconductor photoelectrodes (e.g., Si and GaAs). We first discuss the origins of instability and various strategies for achieving stable and functional photoelectrosynthetic interfaces. We then focus specifically on the use of thin protective films on photoanodes and photocathodes for photosynthetic reactions that include oxygen evolution, halide oxidation, and hydrogen evolution. Finally, we provide an outlook for the future development of thin-layer protection strategies to enable semiconductor-based solar-driven fuel production.", "date": "2015-10-29", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "119", "number": "43", "publisher": "American Chemical Society", "pagerange": "24201-24228", "id_number": "CaltechAUTHORS:20151027-111752059", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151027-111752059", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Lehigh University" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1021/acs.jpcc.5b05976", "resource_type": "article", "pub_year": "2015", "author_list": "Hu, Shu; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/arha0-sqn92", "eprint_id": 60761, "eprint_status": "archive", "datestamp": "2023-08-22 16:40:16", "lastmod": "2023-10-24 21:09:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Batara-Nicolas-A", "name": { "family": "Batara", "given": "Nicolas A." } }, { "id": "Premkumar-Anjali", "name": { "family": "Premkumar", "given": "Anjali" } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Self-Optimizing Photoelectrochemical Growth of Nanopatterned Se\u2013Te Films in Response to the Spectral Distribution of Incident Illumination", "ispublished": "pub", "full_text_status": "public", "keywords": "Electrodeposition; photoelectrochemistry; photodeposition; template-free; maskless; chalcogenide", "note": "\u00a9 2015 American Chemical Society. \n\nReceived: August 7, 2015. Revised: September 16, 2015. Publication Date (Web): September 21, 2015. \n\nThis work was supported by the \"Light-Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001293. The authors gratefully acknowledge R. Gerhart for assistance with photoelectrochemical cell fabrication. A.I.C. acknowledges a Graduate Research Fellowship from the National Science Foundation. A.P. acknowledges an Edward W. Hughes Research Fellowship from the California Institute of Technology. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nl5b03137_si_001.pdf
", "abstract": "Photoelectrochemical growth of Se\u2013Te films spontaneously produces highly ordered, nanoscale lamellar morphologies with periodicities that can be tuned by varying the illumination wavelength during deposition. This phenomenon has been characterized further herein by determining the morphologies of photoelectrodeposited Se\u2013Te films in response to tailored spectral illumination profiles. Se\u2013Te films grown under illumination from four different sources, having similar average wavelengths but having spectral bandwidths that spanned several orders of magnitude, all nevertheless produced similar structures which had a single, common periodicity as quantitatively identified via Fourier analysis. Film deposition using simultaneous illumination from two narrowband sources, which differed in average wavelength by several hundred nanometers, resulted in a structure with only a single periodicity intermediate between the periods observed when either source alone was used. This single periodicity could be varied by manipulating the relative intensity of the two sources. An iterative model that combined full-wave electromagnetic effects with Monte Carlo growth simulations, and that considered only the fundamental light-material interactions during deposition, was in accord with the morphologies observed experimentally. Simulations of light absorption and concentration in idealized lamellar arrays, in conjunction with all of the available data, additionally indicated that a self-optimization of the periodicity of the nanoscale pattern, resulting in the maximization of the anisotropy of interfacial light absorption in the three-dimensional structure, is consistent with the observed growth process of such films.", "date": "2015-10-14", "date_type": "published", "publication": "Nano Letters", "volume": "15", "number": "10", "publisher": "American Chemical Society", "pagerange": "7071-7076", "id_number": "CaltechAUTHORS:20151005-115233487", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151005-115233487", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Edward W. Hughes Research Fellowship" } ] }, "doi": "10.1021/acs.nanolett.5b03137", "primary_object": { "basename": "nl5b03137_si_001.pdf", "url": "https://authors.library.caltech.edu/records/arha0-sqn92/files/nl5b03137_si_001.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Carim, Azhar I.; Batara, Nicolas A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pkfn9-nvp65", "eprint_id": 60741, "eprint_status": "archive", "datestamp": "2023-08-20 08:30:49", "lastmod": "2023-10-24 21:08:57", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Coridan-R-H", "name": { "family": "Coridan", "given": "Robert H." }, "orcid": "0000-0003-1916-4446" }, { "id": "Nielander-A-C", "name": { "family": "Nielander", "given": "Adam C." }, "orcid": "0000-0002-3639-2427" }, { "id": "Francis-S-A", "name": { "family": "Francis", "given": "Sonja A." } }, { "id": "McDowell-M-T", "name": { "family": "McDowell", "given": "Matthew T." }, "orcid": "0000-0001-5552-3456" }, { "id": "Dix-Victoria", "name": { "family": "Dix", "given": "Victoria" } }, { "id": "Chatman-S-M", "name": { "family": "Chatman", "given": "Shawn M." }, "orcid": "0000-0002-7951-5968" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Methods for comparing the performance of energy-conversion systems for use in solar fuels and solar electricity generation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 The Royal Society of Chemistry. \n\nReceived 9th March 2015, Accepted 13th April 2015, First published online 13 Apr 2015.\n\nThe authors thank Dr Eric Miller for the motivation to participate in this review, and the members of the U.S. Department of Energy's Photoelectrochemical Working Group and Task 35 (Renewable Hydrogen) of the International Energy Agency's Hydrogen Implementing Agreement for providing helpful comments and suggestions. This work was supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. This work was also supported by the Gordon and Betty Moore Foundation under Award No. GBMF1225. R.H.C. and V.D. acknowledge support from the Air Force Office of Scientific Research (AFOSR) through the Multidisciplinary University Research Initiative (MURI) under AFOSR Award Number FA9550-10-1-0572, and A.C.N. acknowledges the National Science Foundation for a Graduate Research Fellowship.\n\nPublished - c5ee00777a.pdf
", "abstract": "The energy-conversion efficiency is a key metric that facilitates comparison of the performance of various approaches to solar energy conversion. However, a suite of disparate methodologies has been proposed and used historically to evaluate the efficiency of systems that produce fuels, either directly or indirectly, with sunlight and/or electrical power as the system inputs. A general expression for the system efficiency is given as the ratio of the total output power (electrical plus chemical) divided by the total input power (electrical plus solar). The solar-to-hydrogen (STH) efficiency follows from this globally applicable system efficiency but only is applicable in the special case for systems in which the only input power is sunlight and the only output power is in the form of hydrogen fuel derived from solar-driven water splitting. Herein, system-level efficiencies, beyond the STH efficiency, as well as component-level figures of merit are defined and discussed to describe the relative energy-conversion performance of key photoactive components of complete systems. These figures of merit facilitate the comparison of electrode materials and interfaces without conflating their fundamental properties with the engineering of the cell setup. The resulting information about the components can then be used in conjunction with a graphical circuit analysis formalism to obtain \"optimal\" system efficiencies that can be compared between various approaches. The approach provides a consistent method for comparison of the performance at the system and component levels of various technologies that produce fuels and/or electricity from sunlight.", "date": "2015-10-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "10", "publisher": "Royal Society of Chemistry", "pagerange": "2886-2901", "id_number": "CaltechAUTHORS:20151005-085140068", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151005-085140068", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-10-1-0572" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1039/c5ee00777a", "primary_object": { "basename": "c5ee00777a.pdf", "url": "https://authors.library.caltech.edu/records/pkfn9-nvp65/files/c5ee00777a.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Coridan, Robert H.; Nielander, Adam C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/aaz5a-sqf76", "eprint_id": 61716, "eprint_status": "archive", "datestamp": "2023-08-20 08:31:04", "lastmod": "2023-10-25 15:40:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Esposito-D-V", "name": { "family": "Esposito", "given": "Daniel V." }, "orcid": "0000-0002-0550-801X" }, { "id": "Baxter-J-B", "name": { "family": "Baxter", "given": "Jason B." } }, { "id": "John-J", "name": { "family": "John", "given": "Jimmy" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Moffat-T-P", "name": { "family": "Moffat", "given": "Thomas P." } }, { "id": "Ogitsu-Tadashi", "name": { "family": "Ogitsu", "given": "Tadashi" } }, { "id": "O'Neil-G-D", "name": { "family": "O'Neil", "given": "Glen D." } }, { "id": "Pham-Tuan-Anh", "name": { "family": "Pham", "given": "Tuan Anh" } }, { "id": "Talin-A-A", "name": { "family": "Talin", "given": "A. Alec" } }, { "id": "Velazquez-J-M", "name": { "family": "Velazquez", "given": "Jesus M." } }, { "id": "Wood-B-C", "name": { "family": "Wood", "given": "Brandon C." } } ] }, "title": "Methods of photoelectrode characterization with high spatial and temporal resolution", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 The Royal Society of Chemistry. \n\nReceived 13 Mar 2015, Accepted 18 Jun 2015; First published online 19 Jun 2015. \n\nThe authors thank Dr. Eric Miller for the inspiration to compile this review, and the members of the U.S. Department of Energy's Photoelectrochemical Working Group and Task 35 (Renewable Hydrogen) of the International Energy Agency's Hydrogen Implementing Agreement for helpful comments, suggestions, and discussions. DVE acknowledges support from the NIST National Research Council postdoctoral Fellowship Program. JMV and NSL would like to acknowledge the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993 and the National Science Foundation Grant CHE-1214152. JMV acknowledges support through a NRC Ford Foundation Postdoctoral Fellowship. JJ thanks the Camille and Henry Dreyfus Foundation for financial support through its postdoctoral fellowship program in environmental chemistry. JBB acknowledges support from NSF ECCS-1201957 and NSF CBET-1333649. BW and TO acknowledge support from the Fuel Cell Technologies Program within the DOE Office of Energy Efficiency and Renewable Energy. T.A.P acknowledges support from the Lawrence Fellowship. A portion of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the U.S. DOE National Nuclear Security Administration under Contract DE-AC04-94AL85000. AAT was supported by Science of Precision Multifunctional Nanostructures for Electrical Energy Storage (NEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences under award DESC0001160.\nA summary version of this review paper (DOI: 10.2172/1209497), and associated summary tables that will be updated as the field progresses, will be available on the working group website (http://energy.gov/eere/fuelcells/photoelectrochemical-working-group).\n\nPublished - c5ee00835b.pdf
", "abstract": "Materials and photoelectrode architectures that are highly efficient, extremely stable, and made from low cost materials are required for commercially viable photoelectrochemical (PEC) water-splitting technology. A key challenge is the heterogeneous nature of real-world materials, which often possess spatial variation in their crystal structure, morphology, and/or composition at the nano-, micro-, or macro-scale. Different structures and compositions can have vastly different properties and can therefore strongly influence the overall performance of the photoelectrode through complex structure\u2013property relationships. A complete understanding of photoelectrode materials would also involve elucidation of processes such as carrier collection and electrochemical charge transfer that occur at very fast time scales. We present herein an overview of a broad suite of experimental and computational tools that can be used to define the structure\u2013property relationships of photoelectrode materials at small dimensions and on fast time scales. A major focus is on in situ scanning-probe measurement (SPM) techniques that possess the ability to measure differences in optical, electronic, catalytic, and physical properties with nano- or micro-scale spatial resolution. In situ ultrafast spectroscopic techniques, used to probe carrier dynamics involved with processes such as carrier generation, recombination, and interfacial charge transport, are also discussed. Complementing all of these experimental techniques are computational atomistic modeling tools, which can be invaluable for interpreting experimental results, aiding in materials discovery, and interrogating PEC processes at length and time scales not currently accessible by experiment. In addition to reviewing the basic capabilities of these experimental and computational techniques, we highlight key opportunities and limitations of applying these tools for the development of PEC materials.", "date": "2015-10-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "10", "publisher": "Royal Society of Chemistry", "pagerange": "2863-2885", "id_number": "CaltechAUTHORS:20151029-140911122", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151029-140911122", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NIST National Research Council" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "NRC Ford Foundation Postdoctoral Fellowship" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "NSF", "grant_number": "ECCS-1201957" }, { "agency": "NSF", "grant_number": "CBET-1333649" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Lawrence Fellowship" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC52-07NA27344" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC04-94AL85000" }, { "agency": "Department of Energy (DOE)", "grant_number": "DESC0001160" } ] }, "doi": "10.1039/c5ee00835b", "primary_object": { "basename": "c5ee00835b.pdf", "url": "https://authors.library.caltech.edu/records/aaz5a-sqf76/files/c5ee00835b.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Esposito, Daniel V.; Baxter, Jason B.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/y51kf-4xb27", "eprint_id": 59572, "eprint_status": "archive", "datestamp": "2023-08-20 08:20:37", "lastmod": "2023-10-23 20:44:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shaner-M-R", "name": { "family": "Shaner", "given": "Matthew R." }, "orcid": "0000-0003-4682-9757" }, { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Functional integration of Ni\u2013Mo electrocatalysts with Si microwire array photocathodes to simultaneously achieve high fill factors and light-limited photocurrent densities for solar-driven hydrogen evolution", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 Royal Society of Chemistry 2015.\n\nReceived 05 Apr 2015, Accepted 13 Jul 2015; First published online 07 Aug 2015. \n\nThis article is part of themed collection: Fundamentals and Applications of Inorganic Chemistry.\n\nDevice modeling, fabrication and testing were supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub supported through the Office of Science of the U.S. Department of Energy under award number DE-SC004993. Development of the Ni\u2013Mo nanopowder catalyst was supported by the National Science Foundation (NSF) Powering the Planet Center for Chemical Innovation (CHE-1305124) and by the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology. The authors acknowledge additional support by the Gordon and Betty Moore Foundation (GBMF1225). MRS acknowledges the Resnick Sustainability Institute for a graduate fellowship. JRM acknowledges the Department of Energy, Office of Science, for a graduate research fellowship and the Department of Energy, Office of Energy Efficiency and Renewable Energy, for a SunShot postdoctoral research award.\n\nPublished - c5ee01076d.pdf
Supplemental Material - suppc5ee01076d1.pdf
", "abstract": "An n+p-Si microwire array coupled with a two-layer catalyst film consisting of Ni\u2013Mo nanopowder and TiO_2 light-scattering nanoparticles has been used to simultaneously achieve high fill factors and light-limited photocurrent densities from photocathodes that produce H_2(g) directly from sunlight and water. The TiO_2 layer scattered light back into the Si microwire array, while optically obscuring the underlying Ni\u2013Mo catalyst film. In turn, the Ni\u2013Mo film had a mass loading sufficient to produce high catalytic activity, on a geometric area basis, for the hydrogen-evolution reaction. The best-performing microwire array devices prepared in this work exhibited short-circuit photocurrent densities of \u221214.3 mA cm^(\u22122), photovoltages of 420 mV, and a fill factor of 0.48 under 1 Sun of simulated solar illumination, whereas the equivalent planar Ni\u2013Mo-coated Si device, without TiO_2 scatterers, exhibited negligible photocurrent due to complete light blocking by the Ni\u2013Mo catalyst layer.", "date": "2015-10", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "10", "publisher": "Royal Society of Chemistry", "pagerange": "2977-2984", "id_number": "CaltechAUTHORS:20150814-170845573", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150814-170845573", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC004993" }, { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "1225" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1039/C5EE01076D", "primary_object": { "basename": "c5ee01076d.pdf", "url": "https://authors.library.caltech.edu/records/y51kf-4xb27/files/c5ee01076d.pdf" }, "related_objects": [ { "basename": "suppc5ee01076d1.pdf", "url": "https://authors.library.caltech.edu/records/y51kf-4xb27/files/suppc5ee01076d1.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Shaner, Matthew R.; McKone, James R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qbvem-p2j52", "eprint_id": 60978, "eprint_status": "archive", "datestamp": "2023-08-20 08:19:05", "lastmod": "2023-10-24 22:33:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hund-Z-M", "name": { "family": "Hund", "given": "Zachary M." } }, { "id": "Nihill-K-J", "name": { "family": "Nihill", "given": "Kevin J." } }, { "id": "Campi-D", "name": { "family": "Campi", "given": "Davide" } }, { "id": "Wong-Keith-T", "name": { "family": "Wong", "given": "Keith T." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Bernasconi-M", "name": { "family": "Bernasconi", "given": "M." } }, { "id": "Benedek-G", "name": { "family": "Benedek", "given": "G." } }, { "id": "Sibener-S-J", "name": { "family": "Sibener", "given": "S. J." } } ] }, "title": "Vibrational dynamics and band structure of methyl-terminated Ge(111)", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 AIP Publishing LLC. \n\nReceived 17 July 2015; accepted 31 August 2015; published online 25 September 2015. \n\nS.J.S. acknowledges support from the Air Force Office of Scientific Research Grant Nos. FA9550-10-1-0219 and FA9550-15-1-0428, and the Material Research Science and Engineering Center at the University of Chicago, Grant No. NSF-DMR-14-20709. N.S.L. acknowledges support from the National Science Foundation (Grant No. CHE-1214152), and research was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology.\n\nPublished - 1.4931178.pdf
", "abstract": "A combined synthesis, experiment, and theory approach, using elastic and inelastic helium atom scattering along with ab initio density functional perturbation theory, has been used to investigate the vibrational dynamics and band structure of a recently synthesized organic-functionalized semiconductor interface. Specifically, the thermal properties and lattice dynamics of the underlying Ge(111) semiconductor crystal in the presence of a commensurate (1 \u00d7 1) methyl adlayer were defined for atomically flat methylated Ge(111) surfaces. The mean-square atomic displacements were evaluated by analysis of the thermal attenuation of the elastic He diffraction intensities using the Debye-Waller model, revealing an interface with hybrid characteristics. The methyl adlayer vibrational modes are coupled with the Ge(111) substrate, resulting in significantly softer in-plane motion relative to rigid motion in the surface normal. Inelastic helium time-of-flight measurements revealed the excitations of the Rayleigh wave across the surface Brillouin zone, and such measurements were in agreement with the dispersion curves that were produced using density functional perturbation theory. The dispersion relations for H-Ge(111) indicated that a deviation in energy and lineshape for the Rayleigh wave was present along the nearest-neighbor direction. The effects of mass loading, as determined by calculations for CD_3-Ge(111), as well as by force constants, were less significant than the hybridization between the Rayleigh wave and methyl adlayer librations. The presence of mutually similar hybridization effects for CH_3-Ge(111) and CH_3-Si(111) surfaces extends the understanding of the relationship between the vibrational dynamics and the band structure of various semiconductor surfaces that have been functionalized with organic overlayers.", "date": "2015-09-28", "date_type": "published", "publication": "Journal of Chemical Physics", "volume": "143", "number": "12", "publisher": "American Institute of Physics", "pagerange": "Art. No. 124705", "id_number": "CaltechAUTHORS:20151012-125128525", "issn": "0021-9606", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151012-125128525", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-10-1-0219" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-15-1-0428" }, { "agency": "NSF", "grant_number": "DMR-14-20709" }, { "agency": "NSF", "grant_number": "CHE-1214152" } ] }, "doi": "10.1063/1.4931178", "primary_object": { "basename": "1.4931178.pdf", "url": "https://authors.library.caltech.edu/records/qbvem-p2j52/files/1.4931178.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Hund, Zachary M.; Nihill, Kevin J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0w1et-cwv76", "eprint_id": 60354, "eprint_status": "archive", "datestamp": "2023-08-20 08:05:17", "lastmod": "2023-10-24 16:28:08", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Singh-M-R", "name": { "family": "Singh", "given": "Meenesh R." }, "orcid": "0000-0002-3638-8866" }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "An electrochemical engineering assessment of the operational conditions and constraints for solar-driven water-splitting systems at near-neutral pH", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 The Royal Society of Chemistry.\n\nReceived 3rd June 2015, Accepted 29th June 2015, First published online 30 Jun 2015.\n\nThis material is based on work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award number DE-SC0004993.\n\nPublished - Singh_2015p2760.pdf
Supplemental Material - c5ee01721a1_si.pdf
", "abstract": "The solution transport losses in a one-dimensional solar-driven water-splitting cell that operates in either concentrated acid, dilute acid, or buffered near-neutral pH electrolytes have been evaluated using a mathematical model that accounts for diffusion, migration and convective transport, as well as for bulk electrochemical reactions in the electrolyte. The Ohmic resistance loss, the Nernstian potential loss associated with pH gradients at the surface of the electrode, and electrodialysis in different electrolytes were assessed quantitatively in a stagnant cell as well as in a bubble-convected cell, in which convective mixing occurred due to product-gas evolution. In a stagnant cell that did not have convective mixing, small limiting current densities (<3 mA cm^(\u22122)) and significant polarization losses derived from pH gradients were present in dilute acid as well as in near-neutral pH buffered electrolytes. In contrast, bubble-convected cells exhibited a significant increase in the limiting current density, and a significant reduction of the concentration overpotentials. In a bubble-convected cell, minimal solution transport losses were present in membrane-free cells, in either buffered electrolytes or in unbuffered solutions with pH \u2264 1. However, membrane-free cells lack a mechanism for product-gas separation, presenting significant practical and engineering impediments to the deployment of such systems. To produce an intrinsically safe cell, an ion-exchange membrane was incorporated into the cell. The accompanying solution losses, especially the pH gradients at the electrode surfaces, were modeled and simulated for such a system. Hence this work describes the general conditions under which intrinsically safe, efficient solar-driven water-splitting cells can be operated.", "date": "2015-09-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "9", "publisher": "Royal Society of Chemistry", "pagerange": "2760-2767", "id_number": "CaltechAUTHORS:20150918-153945062", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150918-153945062", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c5ee01721a", "primary_object": { "basename": "Singh_2015p2760.pdf", "url": "https://authors.library.caltech.edu/records/0w1et-cwv76/files/Singh_2015p2760.pdf" }, "related_objects": [ { "basename": "c5ee01721a1_si.pdf", "url": "https://authors.library.caltech.edu/records/0w1et-cwv76/files/c5ee01721a1_si.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Singh, Meenesh R.; Papadantonakis, Kimberly M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/66hw7-jws13", "eprint_id": 59172, "eprint_status": "archive", "datestamp": "2023-08-20 08:04:50", "lastmod": "2023-10-23 20:08:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhou-Xinghao", "name": { "family": "Zhou", "given": "Xinghao" }, "orcid": "0000-0001-9229-7670" }, { "id": "Liu-Rui", "name": { "family": "Liu", "given": "Rui" } }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Friedrich-Dennis", "name": { "family": "Friedrich", "given": "Dennis" }, "orcid": "0000-0003-4844-368X" }, { "id": "McDowell-Matthew-T", "name": { "family": "McDowell", "given": "Matthew T." }, "orcid": "0000-0001-5552-3456" }, { "id": "Yang-Fan", "name": { "family": "Yang", "given": "Fan" } }, { "id": "Omelchenko-Stefan-T", "name": { "family": "Omelchenko", "given": "Stefan T." }, "orcid": "0000-0003-1104-9291" }, { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "Nielander-Adam-C", "name": { "family": "Nielander", "given": "Adam C." }, "orcid": "0000-0002-3639-2427" }, { "id": "Yalamanchili-Sisir", "name": { "family": "Yalamanchili", "given": "Sisir" } }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Interface engineering of the photoelectrochemical performance of Ni-oxide-coated n-Si photoanodes by atomic-layer deposition of ultrathin films of cobalt oxide", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 The Royal Society of Chemistry.\n\nReceived 30th May 2015, Accepted 15th July 2015, First published online 15 Jul 2015. \n\nThis work was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. UV-VIS spectroscopy, atomic-force microscopy, and Kelvin probe force microscopy were performed at the Molecular Materials Resource Center (MMRC) of the Beckman Institute at the California Institute of Technology. ACN was supported by a Graduate Research Fellowship from the National Science Foundation. This work was additionally supported by the Gordon and Betty Moore Foundation under Award No. GBMF1225. \n\nAuthor contribution: X.Z., R.L., K.S., K.M.P, B.S.B and N.S.L designed the experiments and wrote the manuscript. X.Z., R.L., K.S., D.F., M.T.M, F.Y., S.T.O., F.H.S., A.C.N., S.Y. performed the experiments.\n\nPublished - Zhou_2015p2644.pdf
Supplemental Material - c5ee01687h1_si.pdf
", "abstract": "Introduction of an ultrathin (2 nm) film of cobalt oxide (CoO_x) onto n-Si photoanodes prior to sputter-deposition of a thick multifunctional NiO_x coating yields stable photoelectrodes with photocurrent-onset potentials of ~\u2212240 mV relative to the equilibrium potential for O2(g) evolution and current densities of ~28 mA cm^(\u22122) at the equilibrium potential for water oxidation when in contact with 1.0 M KOH(aq) under 1 sun of simulated solar illumination. The photoelectrochemical performance of these electrodes was very close to the Shockley diode limit for moderately doped n-Si(100) photoelectrodes, and was comparable to that of typical protected Si photoanodes that contained np+ buried homojunctions.", "date": "2015-09-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "9", "publisher": "Royal Society of Chemistry", "pagerange": "2644-2649", "id_number": "CaltechAUTHORS:20150804-104946656", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150804-104946656", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c5ee01687h", "primary_object": { "basename": "Zhou_2015p2644.pdf", "url": "https://authors.library.caltech.edu/records/66hw7-jws13/files/Zhou_2015p2644.pdf" }, "related_objects": [ { "basename": "c5ee01687h1_si.pdf", "url": "https://authors.library.caltech.edu/records/66hw7-jws13/files/c5ee01687h1_si.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Zhou, Xinghao; Liu, Rui; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mjegz-jvf34", "eprint_id": 59887, "eprint_status": "archive", "datestamp": "2023-08-20 07:54:03", "lastmod": "2023-10-23 22:48:20", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Plymale-Noah-T", "name": { "family": "Plymale", "given": "Noah T." }, "orcid": "0000-0003-2564-8009" }, { "id": "Kim-Youn-Geun", "name": { "family": "Kim", "given": "Youn-Geun" }, "orcid": "0000-0002-5936-6520" }, { "id": "Soriaga-Manuel-P", "name": { "family": "Soriaga", "given": "Manuel P." }, "orcid": "0000-0002-0077-6226" }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Synthesis, Characterization, and Reactivity of Ethynyl- and Propynyl-Terminated Si(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 American Chemical Society. \n\nReceived: May 26, 2015, Revised: July 7, 2015, Publication Date (Web): July 10, 2015. \n\nWe acknowledge the National Science Foundation Grant No. CHE-1214152 and the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology for support. N.T.P. acknowledges support from the NSF for a Graduate Research Fellowship. Support for Y.-G.K. and M.P.S. to perform the EC-STM experiments was provided by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. We thank Dr. Leslie E. O'Leary, Dr. Ronald L. Grimm, and Mr. Christopher W. Roske for helpful discussions. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - jp5b05028_si_001.pdf
", "abstract": "Ethynyl- and propynyl-terminated Si(111) surfaces synthesized using a two-step halogenation/alkylation method have been characterized by transmission infrared spectroscopy (TIRS), high-resolution electron energy-loss spectroscopy (HREELS), X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), atomic-force microscopy (AFM), electrochemical scanning\u2013tunneling microscopy (EC-STM) and measurements of surface recombination velocities (S). For the ethynyl-terminated Si(111) surface, TIRS revealed signals corresponding to ethynyl \u2261C\u2013H and C\u2261C stretching oriented perpendicular to the surface, HREELS revealed a Si\u2013C stretching signal, and XPS data showed the presence of C bound to Si with a fractional monolayer (ML) coverage (\u03a6) of \u03a6_(Si\u2013CCH) = 0.63 \u00b1 0.08 ML. The ethynyl-terminated surfaces were also partially terminated by Si\u2013OH groups (\u03a6_(Si\u2013OH) = 0.35 \u00b1 0.03 ML) with limited formation of Si^(3+) and Si^(4+) oxides. For the propynyl-terminated Si(111) surface, TIRS revealed the presence of a (C\u2013H)CH_3 symmetric bending, or \"umbrella,\" peak oriented perpendicular to the surface, while HREELS revealed signals corresponding to Si\u2013C and C\u2261C stretching, and XPS showed C bound to Si with \u03a6_(Si\u2013CCCH_3) = 1.05 \u00b1 0.06 ML. The LEED patterns were consistent with a (1 \u00d7 1) surface unit cell for both surfaces, but room-temperature EC-STM indicated that the surfaces did not exhibit long-range ordering. HCC\u2013Si(111) and CH_3CC\u2013Si(111) surfaces yielded S values of (3.5 \u00b1 0.1) \u00d7 10^3 and (5 \u00b1 1) \u00d7 10^2 cm s^(\u20131), respectively, after 581 h exposure to air. These observations are consistent with the covalent binding of ethynyl and propynyl groups, respectively, to the Si(111) surface.", "date": "2015-08-27", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "119", "number": "34", "publisher": "American Chemical Society", "pagerange": "19847-19862", "id_number": "CaltechAUTHORS:20150825-113614153", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150825-113614153", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Caltech Beckman Institute" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1021/acs.jpcc.5b05028", "primary_object": { "basename": "jp5b05028_si_001.pdf", "url": "https://authors.library.caltech.edu/records/mjegz-jvf34/files/jp5b05028_si_001.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Plymale, Noah T.; Kim, Youn-Geun; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9tcqq-28e12", "eprint_id": 60123, "eprint_status": "archive", "datestamp": "2023-08-20 07:45:31", "lastmod": "2023-10-24 14:54:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hund-Z-M", "name": { "family": "Hund", "given": "Zachary M." } }, { "id": "Nihill-K-J", "name": { "family": "Nihill", "given": "Kevin J." } }, { "id": "Campi-D", "name": { "family": "Campi", "given": "Davide" } }, { "id": "Wong-K-T", "name": { "family": "Wong", "given": "Keith T." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Bernasconi-M", "name": { "family": "Bernasconi", "given": "M." } }, { "id": "Benedek-G", "name": { "family": "Benedek", "given": "G." } }, { "id": "Sibener-S-J", "name": { "family": "Sibener", "given": "S. J." } } ] }, "title": "Atomic Surface Structure of CH_3-Ge(111) Characterized by Helium Atom Diffraction and Density Functional Theory", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.\n\nReceived: June 14, 2015; Revised: July 6, 2015; Published: July 31, 2015. \n\nS.J.S. acknowledges support from the Air Force Office of Scientific Research Grant No. FA9550-10-1-0219, and the Material Research Science and Engineering Center at the University of Chicago, NSF-DMR-14-20709. N.S.L. acknowledges support from the National Science Foundation (CHE-1214152), and the research was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. \n\nThe authors declare no competing financial interest.", "abstract": "The atomic-scale surface structure of methyl-terminated germanium (111) has been characterized by using a combination of helium atom scattering and density functional theory. High-resolution helium diffraction patterns taken along both the \u27e81\u030521\u0305\u27e9 and the \u27e8011\u0305\u27e9 azimuthal directions reveal a hexagonal packing arrangement with a 4.00 \u00b1 0.02 \u00c5 lattice constant, indicating a commensurate (1 \u00d7 1) methyl termination of the primitive Ge(111) surface. Taking advantage of Bragg and anti-Bragg diffraction conditions, a step height of 3.28 \u00b1 0.02 \u00c5 at the surface has been extracted using variable de Broglie wavelength specular scattering; this measurement agrees well with bulk values from CH_3-Ge(111) electronic structure calculations reported herein. Density functional theory showed that methyl termination of the Ge(111) surface induces a mild inward relaxation of 1.66% and 0.60% from bulk values for the first and second Ge\u2013Ge bilayer spacings, respectively. The DFT-calculated rotational activation barrier of a single methyl group about the Ge\u2013C axis on a fixed methyl-terminated Ge(111) surface was found to be approximately 55 meV, as compared to 32 meV for a methyl group on the H-Ge(111) surface, sufficient to hinder the free rotation of the methyl groups on the Ge(111) surface at room temperature. However, accurate MD simulations demonstrate that cooperative motion of neighboring methyl groups allows a fraction of the methyl groups to fully rotate on the picosecond time scale. These experimental data in conjunction with theory provide a quantitative evaluation of the atomic-scale surface structure for this largely unexplored, yet technologically interesting, hybrid organic\u2013semiconductor interface.", "date": "2015-08-13", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "119", "number": "32", "publisher": "American Chemical Society", "pagerange": "18458-18466", "id_number": "CaltechAUTHORS:20150909-104325636", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150909-104325636", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-10-1-0219" }, { "agency": "NSF", "grant_number": "DMR-14-20709" }, { "agency": "NSF", "grant_number": "CHE-1214152" } ] }, "doi": "10.1021/acs.jpcc.5b05678", "resource_type": "article", "pub_year": "2015", "author_list": "Hund, Zachary M.; Nihill, Kevin J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/f2x75-4wx06", "eprint_id": 58774, "eprint_status": "archive", "datestamp": "2023-08-20 07:40:44", "lastmod": "2023-10-23 19:42:24", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Richter-M-H", "name": { "family": "Richter", "given": "Matthias H." }, "orcid": "0000-0003-0091-2045" }, { "id": "Crumlin-E-J", "name": { "family": "Crumlin", "given": "Ethan J." }, "orcid": "0000-0003-3132-190X" }, { "id": "Axnanda-S", "name": { "family": "Axnanda", "given": "Stephanus" } }, { "id": "Favaro-M", "name": { "family": "Favaro", "given": "Marco" } }, { "id": "Drisdell-W-S", "name": { "family": "Drisdell", "given": "Walter" }, "orcid": "0000-0002-8693-4562" }, { "id": "Hussain-Z", "name": { "family": "Hussain", "given": "Zahid" } }, { "id": "Mayer-T", "name": { "family": "Mayer", "given": "Thomas" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Liu-Zhi", "name": { "family": "Liu", "given": "Zhi" } }, { "id": "Lewerenz-H-J", "name": { "family": "Lewerenz", "given": "Hans-Joachim" }, "orcid": "0000-0001-8433-9471" } ] }, "title": "Direct observation of the energetics at a semiconductor/liquid junction by operando X-ray photoelectron spectroscopy", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 Royal Society of Chemistry. \n\nReceived 30th March 2015; accepted 29th May 2015. First published online 29 May 2015. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract no. DE-AC02-05CH11231. We acknowledge Dr. Philip Ross for his contributions to the conceptual development of the AP-XPS endstation and experimental design, and Junko Yano for fruitful discussions. We acknowledge Fadl Saadi, Beomgyun Jeong, and Sana Rani for assistance during data collection at the beamline.\n\nPublished - c5ee01014d.pdf
Supplemental Material - c5ee01014d1.pdf
", "abstract": "Photoelectrochemical (PEC) cells based on semiconductor/liquid interfaces provide a method of converting solar energy to electricity or fuels. Currently, the understanding of semiconductor/liquid interfaces is inferred from experiments and models. Operando ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) has been used herein to directly characterize the semiconductor/liquid junction at room temperature under real-time electrochemical control. X-ray synchrotron radiation in conjunction with AP-XPS has enabled simultaneous monitoring of the solid surface, the solid/electrolyte interface, and the bulk electrolyte of a PEC cell as a function of the applied potential, U. The observed shifts in binding energy with respect to the applied potential have directly revealed ohmic and rectifying junction behavior on metallized and semiconducting samples, respectively. Additionally, the non-linear response of the core level binding energies to changes in the applied electrode potential has revealed the influence of defect-derived electronic states on the Galvani potential across the complete cell.", "date": "2015-08-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "8", "publisher": "Royal Society of Chemistry", "pagerange": "2409-2416", "id_number": "CaltechAUTHORS:20150706-104957791", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150706-104957791", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/C5EE01014D", "primary_object": { "basename": "c5ee01014d.pdf", "url": "https://authors.library.caltech.edu/records/f2x75-4wx06/files/c5ee01014d.pdf" }, "related_objects": [ { "basename": "c5ee01014d1.pdf", "url": "https://authors.library.caltech.edu/records/f2x75-4wx06/files/c5ee01014d1.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Lichterman, Michael F.; Hu, Shu; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/he732-m3594", "eprint_id": 60435, "eprint_status": "archive", "datestamp": "2023-08-20 07:34:32", "lastmod": "2023-10-24 16:33:18", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Plymale-N-T", "name": { "family": "Plymale", "given": "Noah T." }, "orcid": "0000-0003-2564-8009" }, { "id": "Ramachandran-A-A", "name": { "family": "Ramachandran", "given": "Anshul A." } }, { "id": "Lim-Allison-N", "name": { "family": "Lim", "given": "Allison N." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Band edge control of crystalline silicon by chemical functionalization of the surface", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "Methyl-termination of the silicon (111) crystal plane has been shown to yield nearly complete termination of\nthe silicon atop sites with Me groups to yield exceptional stability to oxidn. and low elec. defect densities at the\nsurface. However, Me groups impart a -0.4 eV surface dipole that shifts the semiconductor band-edge\npositions of p-type silicon unfavorably for the prodn. of fuels, namely hydrogen, from sunlight. Incorporation\nof electroneg. elements, such as fluorine, into alkyl monolayers can effectively reverse the unfavorable shift on\nthe band-edge positions and maximize the efficiency of solar-fuels devices. Thus, a mixed methyl/4-\nfluorobenzyl monolayer has been developed herein to shift the band-edge positions on a sliding scale while\nmaintaining low elec. defect densities at the surface. The band-edge positions were detd. using electrochem.\nmeasurements and photoelectron spectroscopy to develop a relationship between the band-edge positions and\nthe monolayer compn. Samples with favorable band-edge positions for the prodn. of hydrogen were tested\nelectrochem. to demonstrate the improved efficiency of devices fabricated using mixed methyl/4-fluorobenzyl\nmonolayers compared with homogeneous Me monolayers. This work holds promise to motivate the\ndevelopment of a new class of solar-fuels devices based on chem. functionalization of semiconductor\nsurfaces.", "date": "2015-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20150923-082551116", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-082551116", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2015", "author_list": "Plymale, Noah T.; Ramachandran, Anshul A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kx8yc-9eq86", "eprint_id": 60028, "eprint_status": "archive", "datestamp": "2023-08-20 07:30:21", "lastmod": "2023-10-24 14:49:28", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Schaak-R-E", "name": { "family": "Schaak", "given": "Raymond E." } } ] }, "title": "Discovery and characterization of transition metal phosphides as electrocatalysts and photocatalysts for the hydrogen evolution reaction", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "Platinum is a highly active and acid stable electrocatalyst for the hydrogen evolution reaction (HER).\nNonetheless, its high cost and scarcity limits its utility in clean energy systems on a large scale. Nanostructured\ntransition metal phosphides have recently emerged as Earth-abundant alternatives for the catalytic prodn.\nof mol. hydrogen from acidic aq. solns. Phosphides of nickel, cobalt, iron, molybdenum, and tungsten have\nbeen evaluated for the HER and found to require low overpotentials to produce H2 at operationally relevant\ncurrent densities for photoelectrochem. cells, while at the same time exhibiting high stability under strongly\nacidic conditions. Furthermore, the microwire geometry allows the fabrication of photocathodes entirely\ncomprised of Earth-abundant materials that exhibit performance comparable to that of devices that contain Pt.", "date": "2015-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20150902-104609737", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150902-104609737", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2015", "author_list": "Lewis, Nathan S. and Schaak, Raymond E." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/vfp5w-egw80", "eprint_id": 60437, "eprint_status": "archive", "datestamp": "2023-08-20 07:34:46", "lastmod": "2023-10-24 16:33:35", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "Kuang-Yanjin", "name": { "family": "Kuang", "given": "Yanjin" }, "orcid": "0000-0002-2191-6654" }, { "id": "McDowell-Matthew-T", "name": { "family": "McDowell", "given": "Matthew T." }, "orcid": "0000-0001-5552-3456" }, { "id": "Zhou-Xinghao", "name": { "family": "Zhou", "given": "Xinghao" }, "orcid": "0000-0001-9229-7670" }, { "id": "Verlage-Erik", "name": { "family": "Verlage", "given": "Erik" } }, { "id": "Friedrich-Dennis", "name": { "family": "Friedrich", "given": "Dennis" }, "orcid": "0000-0003-4844-368X" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Tu-Charles-W", "name": { "family": "Tu", "given": "Charles W." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Enabling small band-gap semiconductors for solar water oxidation using multifunctional NiOx coating", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "Technol. important small band gap (< 2 eV) semiconductors must be stabilized against corrosion or\npassivation in aq. electrolytes before they can be used as photoelectrodes that directly produce fuels from\nsunlight. In addn., incorporation of electrocatalysts on the surface of the photoelectrodes is required for\nefficient oxidn. of H_2O to O_2(g) and redn. of H_2O or H_2O and CO_2 to fuels. Stabilization of technol. important\nsemiconductors against photocorrosion and photopassivation would have a significant impact on\nphotoelectrochem. energy conversion, and could enable the development of a new generation of robust\nintegrated devices for efficient solar-driven water splitting and solar-driven CO_2 redn. Previous efforts have\nbeen extensively dedicated on elongating the lifetime of semiconductors under harsh fuel forming reaction\nconditions esp. during the water oxidn. half reaction. To date, the energy conversion performances and\nstability were limited on these systems, obscuring the realization of integrated solar fuel devices. In this work,\nwe presented our recent effort on prepn. of a multifunctional coating using Ni oxide, which provides multiple\nimportant functions on semiconductor photoelectrodes surfaces, including chem./corrosion protection, elec.\nconducting, optical transparent/antireflective, and inherent electrocatalytic activity.", "date": "2015-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20150923-083052914", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-083052914", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2015", "author_list": "Sun, Ke; Saadi, Fadl H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jpy2p-k3w82", "eprint_id": 60325, "eprint_status": "archive", "datestamp": "2023-08-20 07:33:12", "lastmod": "2023-10-24 16:26:03", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nielander-A-C", "name": { "family": "Nielander", "given": "Adam C." }, "orcid": "0000-0002-3639-2427" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Graphene as a protective layer for silicon in an aqueous PEC cell", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "Graphene may be an almost ideal protection layer for semiconductor photoelectrodes. It can be grown in\nnearly pinhole-free large area layers and has been shown to inhibit the oxidn. of metals in air as well as in aq.\nelectrochem. environments. In this study, the chem., electrochem., and photoelectrochem. behavior of\ngraphene-coated n-type Si(111) photoanodes was compared to that of H-terminated and Me terminated n-type\nSi(111) photoanodes in contact with aq. K_3[Fe(CN)_6]/K_4[Fe(CN)_6] as well as in contact with a series of oneelectron\nredox couples in non-aq. electrolytes. The n-Si/Graphene electrodes exhibited stable short-circuit\nphotocurrent densities of over 10 mA cm^(-2) for over 1000 s of operation in aq. electrolyte, whereas n-Si-H and n-\nSi-Me electrodes yielded nearly complete decay of the c.d. within approx. 30 s and 120 s, resp. The values of\nthe open-circuit photovoltages and the flat-band potentials of the Si were a function of both the Fermi level of\nthe graphene and the electrochem. potential of the electrolyte soln., indicating that the n-Si/Graphene\ninterface did not form a buried junction with the soln. contact. The use of addnl. layers of graphene further\nimproved stability while leading to a junction that was increasingly pinned by the Si/graphene interface.\nFinally, the chem. stability of graphene in acidic and basic environments relevant to solar water splitting was\ndemonstrated and the possibility for non-covalent hydrogen evolution catalyst attachment via pi-pi interactions\nbetween graphene and pyrene moieties appended to known mol. hydrogen evolution catalysts was explored.", "date": "2015-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20150918-123657541", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150918-123657541", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2015", "author_list": "Nielander, Adam C. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/98m4g-ehs32", "eprint_id": 61388, "eprint_status": "archive", "datestamp": "2023-08-20 07:36:28", "lastmod": "2023-10-25 14:49:40", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Francis-S-A", "name": { "family": "Francis", "given": "Sonja A." } }, { "id": "Crompton-J-C", "name": { "family": "Crompton", "given": "J. C." } }, { "id": "Torelli-D-A", "name": { "family": "Torelli", "given": "Daniel" }, "orcid": "0000-0002-6222-817X" }, { "id": "Ferrer-I-M", "name": { "family": "Ferrer", "given": "Ivonne M." } }, { "id": "Schaak-R-E", "name": { "family": "Schaak", "given": "Raymond E." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Survey of nanostructured transition metal phosphide catalysts for carbon dioxide reduction", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "Previous reports show a no. of nanostructured transition metal phosphides (e.g. Ni_2P, MoP, FeP, WP and\nCoP) as effective Earth-abundant alternatives to Pt for the hydrogen evolution reaction (HER) via electrochem.\nand/or photochem. redn. of water. We now present a comprehensive study of these and other new phosphides\nfor the electrocatalytic carbon dioxide redn. (CO2R). We examine the effect of surface chem. compn. and\nelectronic structure on the selectivity and activity of the catalysts towards CO2R, det. the HER behavior under\nCO2R conditions, and investigate the trends in product distribution and faradaic efficiencies as a function of\ncompn., potential and supporting electrolyte.", "date": "2015-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20151021-132937758", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151021-132937758", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2015", "author_list": "Francis, Sonja A.; Crompton, J. C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/n964t-6zc97", "eprint_id": 58885, "eprint_status": "archive", "datestamp": "2023-08-20 07:22:28", "lastmod": "2023-10-23 19:50:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Wong-Keith-T", "name": { "family": "Wong", "given": "Keith T." } }, { "id": "Kim-Youn-Geun", "name": { "family": "Kim", "given": "Youn-Geun" }, "orcid": "0000-0002-5936-6520" }, { "id": "Soriaga-Manuel-P", "name": { "family": "Soriaga", "given": "Manuel P." }, "orcid": "0000-0002-0077-6226" }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Synthesis and Characterization of Atomically Flat Methyl-Terminated Ge(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 American Chemical Society. \n\nReceived: March 31, 2015; publication Date (Web): July 8, 2015. \n\nThis work was supported by the National Science Foundation grant CHE-1214152 and by the Gordon and Betty Moore Foundation (GBMF1225). The research was in part carried out in the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology and in part through the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993, which provided support for Y.-G.K. and M.P.S. to perform the EC-STM experiments. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - ja5b03339_si_001.pdf
", "abstract": "Atomically flat, terraced H\u2013Ge(111) was prepared by annealing in H_2(g) at 850 \u00b0C. The formation of monohydride Ge\u2013H bonds oriented normal to the surface was indicated by angle-dependent Fourier-transform infrared (FTIR) spectroscopy. Subsequent reaction in CCl_3Br(l) formed Br-terminated Ge(111), as shown by the disappearance of the Ge\u2013H absorption in the FTIR spectra concomitant with the appearance of Br photoelectron peaks in X-ray photoelectron (XP) spectra. The Br\u2013Ge(111) surface was methylated by reaction with (CH_3)_2Mg. These surfaces exhibited a peak at 568 cm^\u20131 in the high-resolution electron energy loss spectrum, consistent with the formation of a Ge\u2013C bond. The absorption peaks in the FTIR spectra assigned to methyl \"umbrella\" and rocking modes were dependent on the angle of the incident light, indicating that the methyl groups were bonded directly atop surface Ge atoms. Atomic-force micrographs of CH_3\u2013Ge(111) surfaces indicated that the surface remained atomically flat after methylation. Electrochemical scanning\u2013tunneling microscopy showed well-ordered methyl groups that covered nearly all of the surface. Low-energy electron diffraction images showed sharp, bright diffraction spots with a 3-fold symmetry, indicating a high degree of order with no evidence of surface reconstruction. A C 1s peak at 284.1 eV was observed in the XP spectra, consistent with the formation of a C\u2013Ge bond. Annealing in ultrahigh vacuum revealed a thermal stability limit of \u223c400 \u00b0C of the surficial CH_3\u2013Ge(111) groups. CH_3\u2013Ge(111) surfaces showed significantly greater resistance to oxidation in air than H\u2013Ge(111) surfaces.", "date": "2015-07-22", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "137", "number": "28", "publisher": "American Chemical Society", "pagerange": "9006-9014", "id_number": "CaltechAUTHORS:20150714-134139272", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150714-134139272", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/jacs.5b03339", "primary_object": { "basename": "ja5b03339_si_001.pdf", "url": "https://authors.library.caltech.edu/records/n964t-6zc97/files/ja5b03339_si_001.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Wong, Keith T.; Kim, Youn-Geun; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hzr78-4ft45", "eprint_id": 58896, "eprint_status": "archive", "datestamp": "2023-08-20 07:22:38", "lastmod": "2023-10-23 19:51:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "McDowell-Matthew-T", "name": { "family": "McDowell", "given": "Matthew T." }, "orcid": "0000-0001-5552-3456" }, { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Liu-Rui", "name": { "family": "Liu", "given": "Rui" } }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "The Influence of Structure and Processing on the Behavior of TiO_2 Protective Layers for Stabilization of n-Si/TiO_2/Ni Photoanodes for Water Oxidation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 American Chemical Society. \n\nReceived: January 13, 2015, Accepted: June 17, 2015, Publication Date (Web): June 17, 2015. \n\nThis material is based upon work performed at the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. XPS data were collected at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. TEM data were collected at the Caltech Transmission Electron Microscopy Facility. A.I.C. recognizes a Graduate Research Fellowship from the National Science Foundation for support. The authors gratefully acknowledge the assistance of Dr. Yunbin Guan during collection of SIMS data. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - am5b00379_si_001.pdf
", "abstract": "Light absorbers with moderate band gaps (1\u20132 eV) are required for high-efficiency solar fuels devices, but most semiconducting photoanodes undergo photocorrosion or passivation in aqueous solution. Amorphous TiO_2 deposited by atomic-layer deposition (ALD) onto various n-type semiconductors (Si, GaAs, GaP, and CdTe) and coated with thin films or islands of Ni produces efficient, stable photoanodes for water oxidation, with the TiO_2 films protecting the underlying semiconductor from photocorrosion in pH = 14 KOH(aq). The links between the electronic properties of the TiO_2 in these electrodes and the structure and energetic defect states of the material are not yet well-elucidated. We show herein that TiO_2 films with a variety of crystal structures and midgap defect state distributions, deposited using both ALD and sputtering, form rectifying junctions with n-Si and are highly conductive toward photogenerated carriers in n-Si/TiO_2/Ni photoanodes. Moreover, the photovoltage of these electrodes can be modified by annealing the TiO_2 in reducing or oxidizing environments. All of the polycrystalline TiO_2 films with compact grain boundaries investigated herein protected the n-Si photoanodes against photocorrosion in pH = 14 KOH(aq). Hence, in these devices, conduction through the TiO_2 layer is neither specific to a particular amorphous or crystalline structure nor determined wholly by a particular extrinsic dopant impurity. The coupled structural and energetic properties of TiO_2, and potentially other protective oxides, can therefore be controlled to yield optimized photoelectrode performance.", "date": "2015-07-22", "date_type": "published", "publication": "ACS Applied Materials & Interfaces", "volume": "7", "number": "28", "publisher": "American Chemical Society", "pagerange": "15189-15199", "id_number": "CaltechAUTHORS:20150715-142850363", "issn": "1944-8244", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150715-142850363", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/acsami.5b00379", "primary_object": { "basename": "am5b00379_si_001.pdf", "url": "https://authors.library.caltech.edu/records/hzr78-4ft45/files/am5b00379_si_001.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "McDowell, Matthew T.; Lichterman, Michael F.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3n6th-06065", "eprint_id": 68223, "eprint_status": "archive", "datestamp": "2023-08-20 07:16:07", "lastmod": "2023-10-19 22:10:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Nocera-Daniel-G", "name": { "family": "Nocera", "given": "Daniel G." }, "orcid": "0000-0001-5055-320X" } ] }, "title": "The solar opportunity", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 by the National Academy of Sciences. \n\nNSL acknowledges support from the National Science Foundation (CHE-1214152), the Department of Energy Office of Science through the Joint Center for Artificial Photosynthesis (grant DE-SC0004993), and the DOE Office of Science (grant DE-FG02-03ER15483). DGN acknowledges support from the US DOE Office of Science (grant DE-SC0009565), Air Force Office of Scientific Research (grant FA9550-09-1-0689), and the TomKat Trust.", "abstract": "Solar energy utilization poses a vexing conundrum: at present, we cannot afford to use it, but eventually we probably cannot afford not to use it. The promise rests in the unmatched size of the solar resource: more energy from the sun strikes the Earth in one hour than all of the energy consumed on the planet in an entire year (DOE 2005; Lewis and Nocera 2006). \n\nAs with all energy sources, challenges for solar energy use reside in the \"cost of extraction.\" The diffuseness of solar energy, typically providing a yearly averaged power density of about 200 W/m2 at representative midlatitudes, requires the coverage of relatively large areas with a sunlight capture system, in turn requiring very inexpensive but high-performance materials and balance of systems to be viable. Additionally, to contribute to a large fraction of a global energy system, use of solar energy requires concomitant development of an accompanying technological approach to provide tera-watt (TW)-days of reliable, robust, persistent, scalable, and cost-effective energy storage.", "date": "2015-07-03", "date_type": "published", "publication": "The Bridge", "volume": "45", "number": "2", "publisher": "National Academy of Engineering", "pagerange": "41-47", "id_number": "CaltechAUTHORS:20160616-173850450", "issn": "0737-6278", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160616-173850450", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0009565" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-09-1-0689" }, { "agency": "TomKat Charitable Trust" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "resource_type": "article", "pub_year": "2015", "author_list": "Lewis, Nathan S. and Nocera, Daniel G." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rcy10-7av17", "eprint_id": 57205, "eprint_status": "archive", "datestamp": "2023-08-22 15:52:23", "lastmod": "2023-10-23 17:09:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Liu-Rui", "name": { "family": "Liu", "given": "Rui" } }, { "id": "Han-Lihao", "name": { "family": "Han", "given": "Lihao" }, "orcid": "0000-0002-0452-3381" }, { "id": "Huang-Zhuangqun", "name": { "family": "Huang", "given": "Zhuangqun" } }, { "id": "Ferrer-I-M", "name": { "family": "Ferrer", "given": "Ivonne M." } }, { "id": "Smets-A-H-M", "name": { "family": "Smets", "given": "Arno H. M." } }, { "id": "Zeman-M", "name": { "family": "Zeman", "given": "Miro" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A low-temperature synthesis of electrochemical active Pt nanoparticles and thin films by atomic layer deposition on Si(111) and glassy carbon surfaces", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Atomic layer deposition; Platinum; Nanoparticles; Thin films; Water splitting; Hydrogen evolution", "note": "\u00a9 2015 Elsevier B.V.\n\nReceived 29 August 2014; Received in revised form 6 April 2015; Accepted 9 April 2015; Available online 18 April 2015.\n\nThis work was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. BSB was supported by the Beckmann Institute of California Institute of Technology. Research was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. LH would like to thank the VIDI project granted to Dr. Arno H.M. Smets by NWO-STW to financially support his stay in California Institute of Technology.", "abstract": "Atomic layer deposition (ALD) was used to deposit nanoparticles and thin films of Pt onto etched p-type Si(111) wafers and glassy carbon discs. Using precursors of MeCpPtMe_3 and ozone and a temperature window of 200\u2013300 \u00b0C, the growth rate was 80\u2013110 pm/cycle. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were used to analyze the composition, structure, morphology, and thickness of the ALD-grown Pt nanoparticle films. The catalytic activity of the ALD-grown Pt for the hydrogen evolution reaction was shown to be equivalent to that of e-beam evaporated Pt on glassy carbon electrode.", "date": "2015-07-01", "date_type": "published", "publication": "Thin Solid Films", "volume": "586", "publisher": "Elsevier", "pagerange": "28-34", "id_number": "CaltechAUTHORS:20150504-140234191", "issn": "0040-6090", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150504-140234191", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1016/j.tsf.2015.04.018", "resource_type": "article", "pub_year": "2015", "author_list": "Liu, Rui; Han, Lihao; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nbzks-p3g03", "eprint_id": 62602, "eprint_status": "archive", "datestamp": "2023-08-22 15:51:14", "lastmod": "2023-10-25 17:16:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kuang-Yanjin", "name": { "family": "Kuang", "given": "Yanjin" }, "orcid": "0000-0002-2191-6654" }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Sukrittanon-S", "name": { "family": "Sukrittanon", "given": "Supanee" } }, { "id": "Takabayashi-Ko", "name": { "family": "Takabayashi", "given": "Ko" } }, { "id": "Kamiya-Itaru", "name": { "family": "Kamiya", "given": "Itaru" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Tu-Charles-W", "name": { "family": "Tu", "given": "Charles W." } } ] }, "title": "Enhancement of the performance of GaP solar cells by embedded In(N)P quantum dots", "ispublished": "pub", "full_text_status": "public", "keywords": "Quantum dots; InNP; Solar cells; Indirect bandgap engineering; MBE", "note": "\u00a9 2015 Elsevier. \n\nReceived 3 February 2015, Revised 18 May 2015, Accepted 8 June 2015, Available online 17 June 2015.", "abstract": "Improving the utilization of solar spectra of wide bandgap semiconductors that can potentially provide enough free energy is one of the promising strategies for realizing efficient and spontaneous integrated conversion of solar energy to chemical fuels. We demonstrate herein that nitrogen doped InP quantum dots (QDs) embedded in wide bandgap GaP could improve the solar energy conversion performance. Photoelectrochemical experiments in contact with a nonaqueous, reversible redox couple indicated that the QD-embedded devices exhibited improved performance relative to devices without QDs, with short-circuit current densities increasing from 0.16 mA cm^(\u22122) for GaP-only devices to 0.23 and 0.29 mA cm^(\u22122) for InP and InNP QD-embedded devices, respectively. Additionally, the open-circuit voltages increased from 0.95 V for GaP-only devices to 1.11 and 1.14 V for InP and InNP QD-embedded devices, respectively, and the external quantum yield of the devices was also enhanced by the embedded QDs. The improvement is attributed to the absorption of sub-bandgap photons by the In(N)P QDs.", "date": "2015-07", "date_type": "published", "publication": "Nano Energy", "volume": "15", "publisher": "Elsevier", "pagerange": "782-788", "id_number": "CaltechAUTHORS:20151204-091530978", "issn": "2211-2855", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151204-091530978", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1016/j.nanoen.2015.06.003", "resource_type": "article", "pub_year": "2015", "author_list": "Kuang, Yanjin; Sun, Ke; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fyrbk-1ev15", "eprint_id": 59021, "eprint_status": "archive", "datestamp": "2023-08-20 07:04:34", "lastmod": "2023-10-23 19:58:33", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shing-A-M", "name": { "family": "Shing", "given": "Amanda M." } }, { "id": "Coronel-N-C", "name": { "family": "Coronel", "given": "Naomi C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Semiconducting ZnSn_xGe_(1\u2212x)N_2 alloys prepared by reactive radio-frequency sputtering", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.\n\nReceived 1 June 2015; accepted 7 July 2015; published online 17 July 2015.\n\nThe authors gratefully acknowledge support from the Dow Chemical Company under the earth-abundant semiconductor project. We also acknowledge the Joint Center for Artificial Photosynthesis and the Molecular Materials Research Center of the Beckman Institute at Caltech for instrument access.\n\nPublished - 1.4927009.pdf
", "abstract": "We report on the fabrication and structural and optoelectronic characterization of II-IV-nitride ZnSn_x Ge(1\u2212x)N_2 thin-films. Three-target reactive radio-frequency sputtering was used to synthesize non-degenerately doped semiconducting alloys having <10% atomic composition (x = 0.025) of tin. These low-Sn alloys followed the structural and optoelectronic trends of the alloy series. Samples exhibited semiconducting properties, including optical band gaps and increasing in resistivities with temperature. Resistivity vs. temperature measurements indicated that low-Sn alloys were non-degenerately doped, whereas alloys with higher Sn content were degenerately doped. These films show potential for ZnSn_x Ge_(1\u2212x)N_2 as tunable semiconductor absorbers for possible use in photovoltaics, light-emitting diodes, or optical sensors.", "date": "2015-07", "date_type": "published", "publication": "APL Materials", "volume": "3", "number": "7", "publisher": "American Institute of Physics", "pagerange": "Art. No. 076104", "id_number": "CaltechAUTHORS:20150728-080847685", "issn": "2166-532X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150728-080847685", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Dow Chemical Company" } ] }, "doi": "10.1063/1.4927009", "primary_object": { "basename": "1.4927009.pdf", "url": "https://authors.library.caltech.edu/records/fyrbk-1ev15/files/1.4927009.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Shing, Amanda M.; Coronel, Naomi C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cy499-hvg44", "eprint_id": 58090, "eprint_status": "archive", "datestamp": "2023-08-20 06:49:07", "lastmod": "2023-10-23 19:01:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Kuang-Yanjin", "name": { "family": "Kuang", "given": "Yanjin" }, "orcid": "0000-0002-2191-6654" }, { "id": "Verlage-E", "name": { "family": "Verlage", "given": "Erik" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Tu-Charles-W", "name": { "family": "Tu", "given": "Charles W." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Sputtered NiO_x Films for Stabilization of p^+n-lnP Photoanodes for Solar-Driven Water Oxidation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 Wiley\u00b7VCH Verlag GmbH & Co. \n\nArticle first Received: December 17, 2014. Revised : February 6, 2015. Published online: March 18, 2015. \n\nThis work was supported th rough the Office of Science of the U.S. Department of Energy (DOE) under Award No. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. Material growth by GSMBE was supported by the National Science Foundation (NSF) under Grant Nos. DMR-0907652 and DMR-1106369. UV-vis spectroscopy was performed at the Molecular Materials Research Center (MMRC) in the Beckman Institute at the California Institute of Technology. This work was also supported by the Gordon and Betty Moore Foundation under Award No. GBMF1225. N.S.L., as well as the work at near-neutral pH, was supported by the Air Force Office of Scientific Research (AFOSR) through the Multidisciplinary University Research Initiative (MURI) under AFOSR Award No. FA9550-10-1-0572. The authors thank M. Lichterman, I. Moreno-Hernandez, and S. Hu for stimulating discussions and K. Papadantonakis for editing this paper. The authors declare no competing financial interests.\n\nSupplemental Material - aenm201402276-sup-0001-S1.pdf
", "abstract": "A photoanode protection strategy using a multifunctional NiO_x coating is presented. The ransparency/antireflectivity, low electrochromism, conduction of holes, corrosion protection, and active electrocatalysis for water-oxidation half-reaction are described.", "date": "2015-06-03", "date_type": "published", "publication": "Advanced Energy Materials", "volume": "5", "number": "11", "publisher": "Wiley", "pagerange": "Art. No. 1402276", "id_number": "CaltechAUTHORS:20150608-142332412", "issn": "1614-6832", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150608-142332412", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "DMR-0907652" }, { "agency": "NSF", "grant_number": "DMR-1106369" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-10-1-0572" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1002/aenm.201402276", "primary_object": { "basename": "aenm201402276-sup-0001-S1.pdf", "url": "https://authors.library.caltech.edu/records/cy499-hvg44/files/aenm201402276-sup-0001-S1.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Sun, Ke; Kuang, Yanjin; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/c5k1s-m1z53", "eprint_id": 57019, "eprint_status": "archive", "datestamp": "2023-09-22 22:28:56", "lastmod": "2023-10-23 23:23:04", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" } }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Audesirk-H-A", "name": { "family": "Audesirk", "given": "Heather A." } }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A quantitative analysis of the efficiency of solar-driven water-splitting device designs based on tandem photoabsorbers patterned with islands of metallic electrocatalysts", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 The Royal Society of Chemistry.\n\n\nReceived 29th January 2015, Accepted 23rd March 2015, First published online 23 Mar 2015.\n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. UV-VIS spectroscopy and AFM were performed at the Beckman Institute Molecular Materials Resource Center (MMRC) at the California Institute of Technology. We also thank E. Warren for stimulating discussions, Z. Huang for assistance with the AFM measurement and K. Papadantonakis for assistance on the editing of this manuscript.\n\nSupplemental Material - c5ee00311c1_si.pdf
", "abstract": "The trade-off between the optical obscuration and kinetic overpotentials of electrocatalyst films patterned onto the surface of tandem light-absorber structures in model photoelectrosynthetic water-splitting systems was investigated using a 0-dimensional load-line analysis and experimental measurements. The electrocatalytic performance of the catalyst at high current densities, normalized to the electrocatalyst surface area, is an important factor in the dependence of the optimal solar-to-hydrogen (STH) conversion efficiency, \u03b7_(STH,opt), on the filling fraction (f_c) of the patterned catalysts, because even under conditions that produce minority-carrier current densities of ~10 mA cm^(\u22122) at the solid/liquid interface, the current density at catalyst-bearing sites can be >1\u20132 A cm^(\u22122) in low filling-fraction films. A universal current-density versus potential relationship, up to current densities of 10 A cm^(\u22122), was obtained experimentally for the hydrogen-evolution reaction (HER) using patterned Pt ultramicroelectrode (UME) arrays with a range of filling fractions and disc diameters. The \u03b7_(STH,opt) of system designs that utilize patterned electrocatalysts located on the illuminated side of tandem photoabsorbers was then evaluated systematically. The maximum STH conversion efficiency, \u03b7_(STH,max), using a hypothetical electrocatalyst that was optically transparent but which nevertheless exhibited a current-density versus potential behavior that is characteristic of the most active Pt films measured experimentally regardless of their optical obscuration, was 26.7%. By comparison, the maximum \u03b7_(STH,opt) of 24.9% for real patterned Pt electrocatalyst films closely approached this ideal-case limit. The performance and materials utilization of the patterned electrocatalysts and of the uniformly coated electrocatalysts on tandem photoabsorbers were also compared in this study. Hence, patterned electrocatalysts with very low filling fractions can provide a potentially promising path to the realization of efficient large-scale photoelectrolysis systems while minimizing the use of scarce noble metals.", "date": "2015-06-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "6", "publisher": "Royal Society of Chemistry", "pagerange": "1736-1747", "id_number": "CaltechAUTHORS:20150427-134904440", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150427-134904440", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c5ee00311c", "primary_object": { "basename": "c5ee00311c1_si.pdf", "url": "https://authors.library.caltech.edu/records/c5k1s-m1z53/files/c5ee00311c1_si.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Chen, Yikai; Sun, Ke; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/bgc8w-9pt64", "eprint_id": 63187, "eprint_status": "archive", "datestamp": "2023-09-15 05:14:24", "lastmod": "2023-10-23 21:15:17", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shing-A-M", "name": { "family": "Shing", "given": "Amanda M." } }, { "id": "Coronel-N-C", "name": { "family": "Coronel", "given": "Naomi C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Fabrication and Characterization of ZnSn_xGe_(1-x)N_2 Alloys for Light\n Absorbers", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "absorber material, nitrides, reactive RF sputtering, thin-films, tunable band gap materials", "note": "\u00a9 2015 IEEE. \n\nThe authors gratefully acknowledge support from the Dow Chemical Company under the earth abundant semiconductor project. We also thank the Joint Center for Artificial Photosynthesis and the Molecular Materials Research Center at Caltech for instrument access.", "abstract": "The II-IV-nitrides are an alloy series\nanalogous to the well-characterized III-nitrides, where a Group\nII and Group IV element replace the Group III element. We\nreport on the fabrication and structural and optoelectronic\ncharacterization of earth-abundant II-IV-nitrides: ZnSn_xGe_(1-x)N_2.\nThe sputtered thin-films show potential for ZnSn_xGe_(1-x)N_2 to be\ntunable semiconductor photovoltaic absorber materials.", "date": "2015-06", "date_type": "published", "publisher": "IEEE", "id_number": "CaltechAUTHORS:20151223-115056420", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151223-115056420", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Dow Chemical Company" } ] }, "doi": "10.1109/PVSC.2015.7355918", "resource_type": "book_section", "pub_year": "2015", "author_list": "Shing, Amanda M.; Coronel, Naomi C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/08vym-exy07", "eprint_id": 63186, "eprint_status": "archive", "datestamp": "2023-09-15 05:14:15", "lastmod": "2023-10-23 21:15:14", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tolstova-Y", "name": { "family": "Tolstova", "given": "Yulia" } }, { "id": "Wilson-S-S", "name": { "family": "Wilson", "given": "Samantha S." } }, { "id": "Omelchenko-S-T", "name": { "family": "Omelchenko", "given": "Stefan T." }, "orcid": "0000-0003-1104-9291" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Molecular Beam Epitaxy of Cu_2O Heterostructures for Photovoltaics", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "Cuprous oxide, molecular beam epitaxy, heteroepitaxy, photovoltaic", "note": "\u00a9 2015 IEEE. \n\nThe authors gratefully acknowledge support from the Dow Chemical Company under the earth abundant semiconductor project.", "abstract": "Cu_2O is a p-type semiconductor that has demonstrated attractive photovoltaic properties, but its efficiencies have been limited by surface instability and lack of high quality thin films. In this work, plasma-assisted molecular beam epitaxy is used to precisely control film orientation and interface chemistry of Cu_2O heterostructures. Thin films of Cu_2O are deposited by MBE onto thin films of Pt and Au sputtered on MgO single crystal substrates. This heterostructure configuration provides a path for an all-epitaxial thin film Cu_2O solar cell, which can serve as a top cell in a tandem structure with a crystalline Si bottom cell.", "date": "2015-06", "date_type": "published", "publisher": "IEEE", "id_number": "CaltechAUTHORS:20151223-114554576", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151223-114554576", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Dow Chemical Company" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1109/PVSC.2015.7355913", "resource_type": "book_section", "pub_year": "2015", "author_list": "Tolstova, Yulia; Wilson, Samantha S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/w2gsq-3yq23", "eprint_id": 63207, "eprint_status": "archive", "datestamp": "2023-09-15 05:14:33", "lastmod": "2023-10-23 21:15:19", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Omelchenko-S-T", "name": { "family": "Omelchenko", "given": "Stefan T." }, "orcid": "0000-0003-1104-9291" }, { "id": "Tolstova-Y", "name": { "family": "Tolstova", "given": "Yulia" } }, { "id": "Wilson-S-S", "name": { "family": "Wilson", "given": "Samantha S." } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Single crystal Cu_2O photovoltaics by the floating zone method", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "Cuprous oxide, floating zone, single crystal, earth abundant photovoltaic", "note": "\u00a9 2015 IEEE. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DESC0004993.", "abstract": "Cu_2O is a p-type semiconductor with desirable bulk properties for photovoltaics. However, the lack of an n-type dopant and surface instability have hindered the development of a high efficiency Cu_2O device. In this work, the floating zone method is used to grow high quality single crystals of Cu_2O in order to controllably study the interfacial reactions between Cu_2O and its heterojunction partners. While inclusions of CuO are inherent to the floating zone growth process we show that they can be removed by post-annealing with phase purity and crystallinity shown by x-ray diffraction. We discuss the role of CuO inclusions on the electronic properties of single crystal Cu_2O wafers using Hall measurements. Changes in the resistivity and mobility due to post-annealing are correlated to changing defect densities obtained from steady-state photoluminescence. The optimization of the Cu_2O wafers provides a pathway towards the first float zone single crystal Cu_2O photovoltaic device.", "date": "2015-06", "date_type": "published", "publisher": "IEEE", "id_number": "CaltechAUTHORS:20151224-073038812", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151224-073038812", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1109/PVSC.2015.7355920", "resource_type": "book_section", "pub_year": "2015", "author_list": "Omelchenko, Stefan T.; Tolstova, Yulia; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sgp5c-41g13", "eprint_id": 72185, "eprint_status": "archive", "datestamp": "2023-08-20 06:19:03", "lastmod": "2023-10-23 18:01:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael Frankston" }, "orcid": "0000-0002-0710-7068" }, { "id": "Richter-M-H", "name": { "family": "Richter", "given": "Matthias Hermann" }, "orcid": "0000-0003-0091-2045" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Crumlin-E-J", "name": { "family": "Crumlin", "given": "Ethan J." }, "orcid": "0000-0003-3132-190X" }, { "id": "Axnanda-S", "name": { "family": "Axnanda", "given": "S." } }, { "id": "Favaro-M", "name": { "family": "Favaro", "given": "Marco" } }, { "id": "Drisdell-W-S", "name": { "family": "Drisdell", "given": "Walter" }, "orcid": "0000-0002-8693-4562" }, { "id": "Hussain-Z", "name": { "family": "Hussain", "given": "Z." } }, { "id": "Mayer-T", "name": { "family": "Mayer", "given": "Thomas" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce" }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Liu-Zhu", "name": { "family": "Liu", "given": "Z." }, "orcid": "0000-0002-8968-7050" }, { "id": "Lewerenz-H-J", "name": { "family": "Lewerenz", "given": "Hans Joachim" }, "orcid": "0000-0001-8433-9471" } ] }, "title": "Investigation of the Si/TiO_2/Electrolyte Interface Using Operando Tender X-ray Photoelectron Spectroscopy", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 ECS - The Electrochemical Society. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. We thank Dr. Philip Ross for contributions to the conceptual development of the AP-XPS end-station and experimental design.\n\nPublished - ECS_Trans.-2015-Lichterman-97-103.pdf
", "abstract": "Semiconductor-electrolyte interfaces allow for the creation of photoactive semiconductor systems that have band bending and other characteristics analogous to semiconductor-metal junctions (Schottky junctions). We demonstrate herein that XPS measurements can be obtained on a full three-electrode electrochemical system under potentiostatic control by use of tender X-rays to provide photoelectrons with sufficient kinetic energy to penetrate through a thin electrolyte overlayer on a portion of the working electrode. The response of the photoelectron binding energies to variations in applied voltage demonstrates that the XPS investigation works in an operando manner to elucidate the energetics of such interfaces.", "date": "2015-05-15", "date_type": "published", "publication": "ECS Transactions", "volume": "66", "number": "6", "publisher": "Electrochemical Society", "pagerange": "97-103", "id_number": "CaltechAUTHORS:20161121-082816017", "issn": "1938-6737", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161121-082816017", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1149/06606.0097ecst", "primary_object": { "basename": "ECS_Trans.-2015-Lichterman-97-103.pdf", "url": "https://authors.library.caltech.edu/records/sgp5c-41g13/files/ECS_Trans.-2015-Lichterman-97-103.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Lichterman, Michael Frankston; Richter, Matthias Hermann; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qen0s-4t131", "eprint_id": 72186, "eprint_status": "archive", "datestamp": "2023-08-20 06:19:07", "lastmod": "2023-10-23 18:01:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Richter-M-H", "name": { "family": "Richter", "given": "Matthias Hermann" }, "orcid": "0000-0003-0091-2045" }, { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael Frankston" }, "orcid": "0000-0002-0710-7068" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Crumlin-E-J", "name": { "family": "Crumlin", "given": "Ethan J." }, "orcid": "0000-0003-3132-190X" }, { "id": "Mayer-T", "name": { "family": "Mayer", "given": "Thomas" } }, { "id": "Axnanda-S", "name": { "family": "Axnanda", "given": "S." } }, { "id": "Favaro-M", "name": { "family": "Favaro", "given": "Marco" } }, { "id": "Drisdell-W-S", "name": { "family": "Drisdell", "given": "Walter" }, "orcid": "0000-0002-8693-4562" }, { "id": "Hussain-Z", "name": { "family": "Hussain", "given": "Z." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce" }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Liu-Zhu", "name": { "family": "Liu", "given": "Z." }, "orcid": "0000-0002-8968-7050" }, { "id": "Lewerenz-H-J", "name": { "family": "Lewerenz", "given": "Hans Joachim" }, "orcid": "0000-0001-8433-9471" } ] }, "title": "Measurement of the Energy-Band Relations of Stabilized Si Photoanodes Using Operando Ambient Pressure X-ray Photoelectron Spectroscopy", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 ECS - The Electrochemical Society. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE AC02 05CH11231. We acknowledge Dr. Philip Ross for contributions to the conceptual development of the AP-PES end station and experimental design. We acknowledge Fadl Saadi, Beomgyun Jeong, and Sana Rani for assistance during data collection at the beamline, Ravishankar Sundararaman for helpful discussions and assistance with theory, and Joseph A. Beardslee for assistance in XPS data collection.\n\nPublished - ECS_Trans.-2015-Richter-105-13.pdf
", "abstract": "The energy-band relations and electronic properties for the light absorber/protection-layer stack of TiO_2-stabilized Si photoanodes have been determined by ambient pressure x-ray synchrotron radiation photoelectron spectroscopy under an applied potential (operando), from single core-level emission lines. The experiments have also been complemented with laboratory-based monochromatic XPS data. Electrochemical parameters are additionally derived directly from x-ray photoemission data, and a method is presented to derive interface-state densities from such operando data.", "date": "2015-05-15", "date_type": "published", "publication": "ECS Transactions", "volume": "66", "number": "6", "publisher": "Electrochemical Society", "pagerange": "105-113", "id_number": "CaltechAUTHORS:20161121-083409878", "issn": "1938-6737", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161121-083409878", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1149/06606.0105ecst", "primary_object": { "basename": "ECS_Trans.-2015-Richter-105-13.pdf", "url": "https://authors.library.caltech.edu/records/qen0s-4t131/files/ECS_Trans.-2015-Richter-105-13.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Richter, Matthias Hermann; Lichterman, Michael Frankston; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7723a-zqd43", "eprint_id": 57042, "eprint_status": "archive", "datestamp": "2023-09-28 00:55:36", "lastmod": "2023-10-24 14:56:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Roske-C-W", "name": { "family": "Roske", "given": "Christopher W." } }, { "id": "Popczun-E-J", "name": { "family": "Popczun", "given": "Eric J." } }, { "id": "Seger-B", "name": { "family": "Seger", "given": "Brian" } }, { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Pedersen-T", "name": { "family": "Pedersen", "given": "Thomas" } }, { "id": "Hansen-O", "name": { "family": "Hansen", "given": "Ole" } }, { "id": "Vesborg-P-C-K", "name": { "family": "Vesborg", "given": "Peter C. K." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Schaak-R-E", "name": { "family": "Schaak", "given": "Raymond E." } }, { "id": "Chorkendorff-Ib", "name": { "family": "Chorkendorff", "given": "Ib" } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparison of the Performance of CoP-Coated and Pt-Coated Radial Junction n\u207ap-Silicon Microwire-Array Photocathodes for the Sunlight-Driven Reduction of Water to H\u2082(g)", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 American Chemical Society.\n\nReceived: March 9, 2015; Accepted: April 7, 2015; Publication Date (Web): April 20, 2015.\n\nThis work was supported by the NSF CCI Solar Fuels Program (CHE-1305124) and the Center for Individual Nanoparticle Functionality (CINF) (DNRF54). C.W.R. thanks the National Science Foundation and Link Energy Foundation for graduate research fellowships. Research was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. N.S.L. acknowledges support from the Energy from Sunlight Project funded by the Gordon and Betty Moore Foundation (GBMF1225).\n\nSupplemental Material - jz5b00495_si_001.pdf
", "abstract": "The electrocatalytic performance for hydrogen evolution has been evaluated for radial-junction n^+p-Si microwire (MW) arrays with Pt or cobalt phosphide, CoP, nanoparticulate catalysts in contact with 0.50 M H_2SO_4(aq). The CoP-coated (2.0 mg cm^(\u20132)) n^+p-Si MW photocathodes were stable for over 12 h of continuous operation and produced an open-circuit photovoltage (V_(oc)) of 0.48 V, a light-limited photocurrent density (J_(ph)) of 17 mA cm^(\u20132), a fill factor (ff) of 0.24, and an ideal regenerative cell efficiency (\u03b7_(IRC)) of 1.9% under simulated 1 Sun illumination. Pt-coated (0.5 mg cm^(\u20132)) n^+p-Si MW-array photocathodes produced V_(oc) = 0.44 V, J_(ph) = 14 mA cm^(\u20132), ff = 0.46, and \u03b7 = 2.9% under identical conditions. Thus, the MW geometry allows the fabrication of photocathodes entirely comprised of earth-abundant materials that exhibit performance comparable to that of devices that contain Pt.", "date": "2015-05-07", "date_type": "published", "publication": "Journal of Physical Chemistry Letters", "volume": "6", "number": "9", "publisher": "American Chemical Society", "pagerange": "1679-1683", "id_number": "CaltechAUTHORS:20150428-095042468", "issn": "1948-7185", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150428-095042468", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Danish National Research Foundation", "grant_number": "DNRF54" }, { "agency": "Link Energy Foundation" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/acs.jpclett.5b00495", "primary_object": { "basename": "jz5b00495_si_001.pdf", "url": "https://authors.library.caltech.edu/records/7723a-zqd43/files/jz5b00495_si_001.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Roske, Christopher W.; Popczun, Eric J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2jg0n-9c688", "eprint_id": 56993, "eprint_status": "archive", "datestamp": "2023-08-20 06:10:09", "lastmod": "2023-10-23 16:13:00", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ardo-S", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Park-Sang-Hee", "name": { "family": "Park", "given": "Sang Hee" } }, { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Unassisted solar-driven photoelectrosynthetic HI splitting using membrane-embedded Si microwire arrays", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 Royal Society of Chemistry.\n\nReceived 22 Jan 2015, Accepted 01 Apr 2015, First published online 01 Apr 2015.\n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. S.A. acknowledges support from a U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under the EERE Fuel Cell Technologies Program. The authors would like to thank Dan Turner\u2013Evans, Morgan Putnam, and Mike Kelzenberg for their generous assistance and donation of Si microwire array samples for some of the preliminary studies; Jacob Good for his assistance with the mass spectrometer; Rick P. Gerhart from the Caltech Glassblowing Shop for fabricating custom borosilicate electrochemical cells; Steve Olson and Mike Roy from the Caltech Machine Shop for fabricating custom free-standing\ndevice holders and a sample holder for the absorption spectrometer; and Harry Gray, Harry Atwater, and Bruce Brunschwig for useful discussions and guidance.\n\nPublished - c5ee00227c.pdf
Supplemental Material - c5ee00227c1_si.pdf
", "abstract": "Free-standing, membrane-embedded, Si microwire arrays have been used to affect the solar-driven, unassisted splitting of HI into H_2 and I_3\u2212. The Si microwire arrays were grown by a chemical-vapor-deposition vapor\u2013liquid\u2013solid growth process using Cu growth catalysts, with a radial n+p junction then formed on each microwire. A Nafion proton-exchange membrane was introduced between the microwires and Pt electrocatalysts were then photoelectrochemically deposited on the microwires. The composite Si/Pt\u2013Nafion membrane was mechanically removed from the growth substrate, and Pt electrocatalysts were then also deposited on the back side of the structure. The resulting membrane-bound Si microwire arrays spontaneously split concentrated HI into H_2(g) and I_3\u2212 under 1 Sun of simulated solar illumination. The reaction products (i.e. H_2 and I_3\u2212) were confirmed by mass spectrometry and ultraviolet\u2013visible electronic absorption spectroscopy.", "date": "2015-05-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "5", "publisher": "Royal Society of Chemistry", "pagerange": "1484-1492", "id_number": "CaltechAUTHORS:20150427-090213779", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150427-090213779", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c5ee00227c", "primary_object": { "basename": "c5ee00227c.pdf", "url": "https://authors.library.caltech.edu/records/2jg0n-9c688/files/c5ee00227c.pdf" }, "related_objects": [ { "basename": "c5ee00227c1_si.pdf", "url": "https://authors.library.caltech.edu/records/2jg0n-9c688/files/c5ee00227c1_si.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Ardo, Shane; Park, Sang Hee; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ajwss-5sa63", "eprint_id": 60374, "eprint_status": "archive", "datestamp": "2023-08-20 06:06:09", "lastmod": "2023-10-24 16:29:41", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Stable Solar-Driven Water Oxidation to O_2(g) By Multifunctional Electrocatalysts Coated Small Band Gap Semiconductors", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 ECS - The Electrochemical Society.\n\nPublished - Sun_2015p254.pdf
", "abstract": "Technologically important small band gap (<2 eV) semiconductors must be stabilized against corrosion or passivation in aqueous electrolytes before they can be used as photoelectrodes that directly produce fuels from sunlight. In addition, incorporation of electrocatalysts on the surface of the photoelectrodes is required for efficient oxidation of H_2O to O_2(g) and reduction of H_2O or H_2O and CO_2 to fuels. Stabilization of technologically important semiconductors against photocorrosion and photopassivation would have a significant impact on photoelectrochemical energy conversion, and could enable the development of a new generation of robust integrated devices for efficient solar-driven water splitting and solar-driven CO_2 reduction. Previous efforts have been extensively dedicated on elongating the lifetime of semiconductors under harsh fuel forming reaction conditions especially during the water oxidation half reaction. To date, the energy conversion performances and stability were limited on these systems, obscuring the realization of integrated solar fuel devices. In this work, we presented our recent effort on preparation of a multifunctional coating using Ni oxide, which provides multiple important functions on semiconductor photoelectrodes surfaces, including chemical/corrosion protection, electrically conducting, optical transparent/antireflective, and inherent electrocatalytic activity. The combination of the extraordinary film properties has resulted benchmark performances and stability on Si photoanodes, as well as other group II-VI and group III-V semiconductors that have never been able to be protected in relevant water oxidation conditions before. Results presented here indicated a viable strategy that is a promising approach to achieve the long-term stability of semiconducting photoanodes for use in solar fuel applications.", "date": "2015-05", "date_type": "published", "publication": "ECS Meeting Abstracts", "publisher": "Electrochemical Society", "pagerange": "Art. No. 2019", "id_number": "CaltechAUTHORS:20150921-110949836", "issn": "1091-8213", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150921-110949836", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "primary_object": { "basename": "Sun_2015p254.pdf", "url": "https://authors.library.caltech.edu/records/ajwss-5sa63/files/Sun_2015p254.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Sun, Ke and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3en75-zmq24", "eprint_id": 57086, "eprint_status": "archive", "datestamp": "2023-08-22 15:26:18", "lastmod": "2023-10-23 17:02:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gallant-B-M", "name": { "family": "Gallant", "given": "Betar M." } }, { "id": "Gu-X-W", "name": { "family": "Gu", "given": "X. Wendy" } }, { "id": "Chen-D-Z", "name": { "family": "Chen", "given": "David Z." } }, { "id": "Greer-J-R", "name": { "family": "Greer", "given": "Julia R." }, "orcid": "0000-0002-9675-1508" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Tailoring of Interfacial Mechanical Shear Strength by Surface Chemical Modification of Silicon Microwires Embedded in Nafion Membranes", "ispublished": "pub", "full_text_status": "public", "keywords": "Si microwires; in situ tension; nanomechanical; surface functionalization; Nafion", "note": "\u00a9 2015 American Chemical Society.\n\nReceived for review January 21, 2015 and accepted April 14, 2015. Publication Date (Web): April 14, 2015.\n\nThis research made use of the Shared Experimental Facilities supported by the Molecular Materials Research Center at the California Institute of Technology and of funds provided by the National Science Foundation (NSF) Center for Chemical Innovation: Solar Fuels (Grant CHE-1305124). B.M.G. acknowledges financial support from a Caltech Kavli Nanoscience Institute Prize Postdoctoral Fellowship.\n\nSupplemental Material - nn5b00468_si_001.pdf
", "abstract": "The interfacial shear strength between Si microwires and a Nafion membrane has been tailored through surface functionalization of the Si. Acidic (\u2212COOH-terminated) or basic (\u2212NH_2-terminated) surface-bound functionality was introduced by hydrosilylation reactions to probe the interactions between the functionalized Si microwires and hydrophilic ionically charged sites in the Nafion polymeric side chains. Surfaces functionalized with SiO_x, Si\u2013H, or Si\u2013CH_3 were also synthesized and investigated. The interfacial shear strength between the functionalized Si microwire surfaces and the Nafion matrix was quantified by uniaxial wire pull-out experiments in an in situ nanomechanical instrument that allowed simultaneous collection of mechanical data and visualization of the deformation process. In this process, an axial load was applied to the custom-shaped top portions of individual wires until debonding occurred from the Nafion matrix. The shear strength obtained from the nanomechanical measurements correlated with the chemical bond strength and the functionalization density of the molecular layer, with values ranging from 7 MPa for Si\u2013CH3 surfaces to \u223c16\u201320 MPa for oxygen-containing surface functionalities. Hence surface chemical control can be used to influence the mechanical adhesion forces at a Si\u2013Nafion interface.", "date": "2015-05", "date_type": "published", "publication": "ACS Nano", "volume": "9", "number": "5", "publisher": "American Chemical Society", "pagerange": "5143-5153", "id_number": "CaltechAUTHORS:20150429-103132238", "issn": "1936-0851", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150429-103132238", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Kavli Nanoscience Institute" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/acsnano.5b00468", "primary_object": { "basename": "nn5b00468_si_001.pdf", "url": "https://authors.library.caltech.edu/records/3en75-zmq24/files/nn5b00468_si_001.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Gallant, Betar M.; Gu, X. Wendy; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0xnhm-6wk36", "eprint_id": 55703, "eprint_status": "archive", "datestamp": "2023-08-22 15:12:53", "lastmod": "2023-10-20 22:59:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Hale-William-G", "name": { "family": "Hale", "given": "William G." } }, { "id": "Wang-Hsin-Ping", "name": { "family": "Wang", "given": "Hsin-Ping" } }, { "id": "Zhou-Xinghao", "name": { "family": "Zhou", "given": "Xinghao" }, "orcid": "0000-0001-9229-7670" }, { "id": "Plymale-Noah-T", "name": { "family": "Plymale", "given": "Noah T." }, "orcid": "0000-0003-2564-8009" }, { "id": "Omelchenko-Stefan-T", "name": { "family": "Omelchenko", "given": "Stefan T." }, "orcid": "0000-0003-1104-9291" }, { "id": "He-Jr-Hau", "name": { "family": "He", "given": "Jr-Hau" } }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films", "ispublished": "pub", "full_text_status": "public", "keywords": "electrocatalysis; solar-driven water oxidation; photoanode stabilization; nickel oxide", "note": "\u00a9 2015 National Academy of Sciences. \n\nEdited by Michael L. Klein, Temple University, Philadelphia, PA, and approved February 10, 2015 (received for review December 3, 2014). Published online before print March 11, 2015, doi: 10.1073/pnas.1423034112 \n\nThis material is based on work performed by the Joint Center for Artificial Photosynthesis, a Department of Energy (DOE) Energy Innovation Hub, supported through the Office of Science of the US DOE under Award DE-SC0004993. N.T.P. acknowledges support from the Graduate Research Fellowship Program of the US National Science Foundation. B.S.B. was supported by the Beckman Institute of the California Institute of Technology. This work was also supported by the Gordon and Betty Moore Foundation under Award GBMF1225.\n\nAuthor contributions: K.S. and N.S.L. designed research; K.S., F.H.S., M.F.L., W.G.H., H.-P.W., X.Z., N.T.P., and S.T.O. performed research; K.S., B.S.B., and N.S.L. analyzed data; and K.S., J.-H.H., K.M.P., B.S.B., and N.S.L. wrote the paper. \n\nThe authors declare no conflict of interest. \n\nThis article is a PNAS Direct Submission. \n\nThis article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1423034112/-/DCSupplemental.\n\nPublished - 3612.full.pdf
Supplemental Material - pnas.1423034112.sapp.pdf
", "abstract": "Reactively sputtered nickel oxide (NiO_x) films provide transparent, antireflective, electrically conductive, chemically stable coatings that also are highly active electrocatalysts for the oxidation of water to O_2(g). These NiO_x coatings provide protective layers on a variety of technologically important semiconducting photoanodes, including textured crystalline Si passivated by amorphous silicon, crystalline n-type cadmium telluride, and hydrogenated amorphous silicon. Under anodic operation in 1.0 M aqueous potassium hydroxide (pH 14) in the presence of simulated sunlight, the NiO_x films stabilized all of these self-passivating, high-efficiency semiconducting photoelectrodes for >100 h of sustained, quantitative solar-driven oxidation of water to O_2(g).", "date": "2015-03-24", "date_type": "published", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "volume": "112", "number": "12", "publisher": "National Academy of Sciences", "pagerange": "3612-3617", "id_number": "CaltechAUTHORS:20150311-121532251", "issn": "0027-8424", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150311-121532251", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1073/pnas.1423034112", "pmcid": "PMC4378389", "primary_object": { "basename": "pnas.1423034112.sapp.pdf", "url": "https://authors.library.caltech.edu/records/0xnhm-6wk36/files/pnas.1423034112.sapp.pdf" }, "related_objects": [ { "basename": "3612.full.pdf", "url": "https://authors.library.caltech.edu/records/0xnhm-6wk36/files/3612.full.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Sun, Ke; Saadi, Fadl H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/f2s8d-8np53", "eprint_id": 56590, "eprint_status": "archive", "datestamp": "2023-08-20 05:25:29", "lastmod": "2023-10-23 15:35:46", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Popczun-E-J", "name": { "family": "Popczun", "given": "Eric J." } }, { "id": "Roske-C-W", "name": { "family": "Roske", "given": "Christopher W." } }, { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Crompton-J-C", "name": { "family": "Crompton", "given": "J. Chance" } }, { "id": "McEnaney-J-M", "name": { "family": "McEnaney", "given": "Joshua M." } }, { "id": "Callejas-J-F", "name": { "family": "Callejas", "given": "Juan F." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Schaak-R-E", "name": { "family": "Schaak", "given": "Raymond E." } } ] }, "title": "Highly branched cobalt phosphide nanostructures for hydrogen-evolution electrocatalysis", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 The Royal Society of Chemistry.\n\nReceived 3rd December 2014; Accepted 15th January 2015; First published online 16 Jan 2015.\n\nThe work at PSU was supported by the National Science Foundation (NSF) Center for Chemical Innovation on Solar Fuels (CHE-1305124) and at Caltech by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993, as well as the Gordon and Betty Moore Foundation. TEM was performed in the Penn State Microscopy and Cytometry Facility (University Park, PA) and HRTEM, EDS, SEM, and BET data were acquired at the Materials Characterization Laboratory of the Penn State Materials Research Institute. C.W.R. thanks the NSF for a graduate research fellowship.\n\nPublished - c4ta06642a.pdf
Supplemental Material - c4ta06642a1_si.pdf
", "abstract": "CoP nanostructures that exposed predominantly (111) crystal facets were synthesized and evaluated for performance as electrocatalysts for the hydrogen-evolution reaction (HER). The branched CoP nanostructures were synthesized by reacting cobalt(II) acetylacetonate with trioctylphosphine in the presence of trioctylphosphine oxide. Electrodes comprised of the branched CoP nanostructures deposited at a loading density of ~1 mg cm^(\u22122) on Ti electrodes required an overpotential of \u2212117 mV to produce a current density of \u221220 mA cm^(\u22122) in 0.50 M H_2SO_4. Hence the branched CoP nanostructures belong to the growing family of highly active non-noble-metal HER electrocatalysts. Comparisons with related CoP systems have provided insights into the impact that shape-controlled nanoparticles and nanoparticle\u2013electrode interactions have on the activity and stability of nanostructured HER electrocatalysts.", "date": "2015-03-14", "date_type": "published", "publication": "Journal of Materials Chemistry A", "volume": "3", "number": "10", "publisher": "Royal Society of Chemistry", "pagerange": "5420-5425", "id_number": "CaltechAUTHORS:20150413-094253407", "issn": "2050-7488", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150413-094253407", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Gordon and Betty Moore Foundation" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1039/c4ta06642a", "primary_object": { "basename": "c4ta06642a.pdf", "url": "https://authors.library.caltech.edu/records/f2s8d-8np53/files/c4ta06642a.pdf" }, "related_objects": [ { "basename": "c4ta06642a1_si.pdf", "url": "https://authors.library.caltech.edu/records/f2s8d-8np53/files/c4ta06642a1_si.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Popczun, Eric J.; Roske, Christopher W.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cp2rh-mc727", "eprint_id": 57103, "eprint_status": "archive", "datestamp": "2023-08-20 05:18:39", "lastmod": "2023-10-23 17:04:19", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" } }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A sensitivity analysis to assess the relative importance of improvements in electrocatalysts, light absorbers, and system geometry on the efficiency of solar-fuels generators", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 The Royal Society of Chemistry.\n\nReceived 23 Jul 2014, Accepted 23 Dec 2014, First published online 24 Dec 2014.\n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award number DE-SC0004993.\n\nPublished - c4ee02314e.pdf
", "abstract": "A sensitivity analysis has been performed for a variety of generic designs for solar-fuels generators. The analysis has revealed the relative importance of reductions in the overpotentials of electrocatalysts, of improvements in the materials properties of light absorbers, and of optimization in the system geometry for various different types of solar-fuels generators, while considering operation at a range of temperatures as well as under a variety of illumination intensities including up to 10-fold optical concentration.", "date": "2015-03-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "3", "publisher": "Royal Society of Chemistry", "pagerange": "876-886", "id_number": "CaltechAUTHORS:20150430-084157336", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150430-084157336", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1039/c4ee02314e", "primary_object": { "basename": "c4ee02314e.pdf", "url": "https://authors.library.caltech.edu/records/cp2rh-mc727/files/c4ee02314e.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Chen, Yikai; Hu, Shu; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9gt1g-qqh36", "eprint_id": 56861, "eprint_status": "archive", "datestamp": "2023-08-20 05:11:00", "lastmod": "2023-10-23 16:03:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Sunlight-driven hydrogen formation by membrane- supported photoelectrochemical water splitting", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "We are developing an artificial photosynthetic system that will utilize sunlight and water as the inputs and produce\nhydrogen and oxygen as the outputs. We are taking a modular, parallel development approach in which three distinct primary\ncomponents- the photoanode, the photocathode, and the product- sepg. but ion- conducting membrane- are fabricated and\noptimized sep. before assembly into a complete water- splitting system. The design principles incorporate two sep.,\nphotosensitive semiconductor /liq. junctions that will collectively generate the 1.7- 1.9 V at open circuit necessary to support both\nthe oxidn. of H_2O (or OH-) and the redn. of H+ (or H_2O). The photoanode and photocathode will consist of rod- like\nsemiconductor components, with attached heterogeneous multi- electron transfer catalysts, which are needed to drive the oxidn.\nor redn. reactions at low overpotentials. The high aspect- ratio semiconductor rod electrode architecture allows for the use of\nlow cost, earth abundant materials without sacrificing energy conversion efficiency due to the orthogonalization of light\nabsorption and charge- carrier collection. Addnl., the high surface- area design of the rod- based semiconductor array electrode\ninherently lowers the flux of charge carriers over the rod array surface relative to the projected geometric surface of the\nphotoelectrode, thus lowering the photocurrent d. at the solid /liq. junction and thereby relaxing the demands on the activity\n(and cost) of any electrocatalysts. A flexible composite polymer film will allow for electron and ion conduction between the\nphotoanode and photocathode while simultaneously preventing mixing of the gaseous products. Sep. polymeric materials will\nbe used to make elec. contact between the anode and cathode, and also to provide structural support. Interspersed patches of\nan ion conducting polymer will maintain charge balance between the two half- cells.", "date": "2015-03", "date_type": "published", "publication": "Abstracts of Papers of the American Chemical Society", "volume": "249", "publisher": "American Chemical Society", "pagerange": "INOR-43", "id_number": "CaltechAUTHORS:20150422-095608699", "issn": "0065-7727", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150422-095608699", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "article", "pub_year": "2015", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/e217y-rhf80", "eprint_id": 56871, "eprint_status": "archive", "datestamp": "2023-08-20 05:11:27", "lastmod": "2023-10-23 16:04:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Technical and operational perspective on the DOE Energy Innovation Hub and Fuels from Sunlight, the Joint Center for Artificial Photosynthesis", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2015 American Chemical Society.", "abstract": "The design of highly efficient, non- biol., mol.- level energy conversion 'machines' that generate fuels directly from sunlight,\nwater, and carbon dioxide is both a formidable challenge and an opportunity that, if realized, could have a revolutionary impact\non our energy system. Basic research has already provided enormous advances in our understanding of the subtle and\ncomplex photochem. behind the natural photosynthetic system, and in the use of inorg. photo- catalytic methods to split water\nor reduce carbon dioxide- key steps in photosynthesis. Yet we still lack sufficient knowledge to design solar fuel generation\nsystems with the required efficiency, scalability, and sustainability to be economically viable. In the DOE Energy Innovation\nHub, the Joint Center for Artificial Photosynthesis, we are developing an artificial photosynthetic system that will only utilize\nsunlight and water as the inputs and will produce hydrogen and oxygen as the outputs. We are taking a modular, parallel\ndevelopment approach in which the three distinct primary components- the photoanode, the photocathode, and the productsepg.\nbut ion- conducting membrane- are fabricated and optimized sep. before assembly into a complete water- splitting system.\nThe design principles incorporate two sep., photosensitive semiconductor /liq. junctions that will collectively generate the 1.7-\n1.9 V at open circuit necessary to support both the oxidn. of H_2O (or OH-) and the redn. of H+ (or H_2O). The photoanode and\nphotocathode will consist of rod- like semiconductor components, with attached heterogeneous multi- electron transfer catalysts,\nwhich are needed to drive the oxidn. or redn. reactions at low overpotentials. This talk will discuss a feasible and functional\nprototype and blueprint for an artificial photosynthetic system, composed of only inexpensive, earth- abundant materials, that is\nsimultaneously efficient, durable, manufacturably scalable, and readily upgradeable, including both the operational and tech.\nscope of the JCAP Hub, as well as tech. results towards this goal that has recently been developed at Caltech.", "date": "2015-03", "date_type": "published", "publication": "Abstracts of Papers of the American Chemical Society", "volume": "249", "publisher": "American Chemical Society", "pagerange": "ENFL-169", "id_number": "CaltechAUTHORS:20150422-104843870", "issn": "0065-7727", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150422-104843870", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001298" }, { "agency": "Chevron USA Inc." }, { "agency": "NSF", "grant_number": "CHE-1214158" } ] }, "resource_type": "article", "pub_year": "2015", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ft6sa-gk325", "eprint_id": 54285, "eprint_status": "archive", "datestamp": "2023-08-22 14:58:29", "lastmod": "2023-10-20 15:46:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "McDowell-M-T", "name": { "family": "McDowell", "given": "Matthew T." }, "orcid": "0000-0001-5552-3456" }, { "id": "Nielander-A-C", "name": { "family": "Nielander", "given": "Adam C." }, "orcid": "0000-0002-3639-2427" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Shaner-M-R", "name": { "family": "Shaner", "given": "Matthew R." }, "orcid": "0000-0003-4682-9757" }, { "id": "Yang-Fan", "name": { "family": "Yang", "given": "Fan" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Stable Solar-Driven Water Oxidation to O_2(g) by Ni-Oxide-Coated Silicon Photoanodes", "ispublished": "pub", "full_text_status": "public", "keywords": "semiconductors; photoanodes; solar-fuels; water-splitting", "note": "\u00a9 2015 American Chemical Society.\n\nReceived: December 11, 2014; accepted: January 19.\n\nThis work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DESC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. UV\u2212vis spectroscopy and atomic-force microscopy were performed at the Molecular Materials Research Center (MMRC) in the Beckman Institute at the California Institute of Technology. B.S.B. was supported by the Beckman Institute of the California Institute of Technology. A.C.N. was supported by a Graduate Research Fellowship from the National Science Foundation. M.R.S. was supported by a graduate fellowship from the Resnick Sustainability Institute. This work was additionally supported by the Gordon and Betty Moore Foundation under Award No. GBMF1225. We thank K. Walczak for providing the FTO coated np+-Si(100) samples, C. Koval, R. Liu, and M. Lichterman for stimulating discussions, N. Becerra and L. Zhou for their assistance with XRD measurements, and K. Papadantonakis for assistance with editing this manuscript.\n\nSupplemental Material - jz5026195_si_001.pdf
", "abstract": "Semiconductors with small band gaps (<2 eV) must be stabilized against corrosion or passivation in aqueous electrolytes before such materials can be used as photoelectrodes to directly produce fuels from sunlight. In addition, incorporation of electrocatalysts on the surface of photoelectrodes is required for efficient oxidation of H_2O to O_2(g) and reduction of H_2O or H_2O and CO_2 to fuels. We report herein the stabilization of np^+-Si(100) and n-Si(111) photoanodes for over 1200 h of continuous light-driven evolution of O_2(g) in 1.0 M KOH(aq) by an earth-abundant, optically transparent, electrocatalytic, stable, conducting nickel oxide layer. Under simulated solar illumination and with optimized index-matching for proper antireflection, NiO_x-coated np+-Si(100) photoanodes produced photocurrent-onset potentials of \u2212180 \u00b1 20 mV referenced to the equilibrium potential for evolution of O_2(g), photocurrent densities of 29 \u00b1 1.8 mA cm^(\u20132) at the equilibrium potential for evolution of O_2(g), and a solar-to-O_2(g) conversion figure-of-merit of 2.1%.", "date": "2015-02-19", "date_type": "published", "publication": "Journal of Physical Chemistry Letters", "volume": "6", "number": "4", "publisher": "American Chemical Society", "pagerange": "592-598", "id_number": "CaltechAUTHORS:20150202-095259720", "issn": "1948-7185", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150202-095259720", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Caltech Beckman Institute" }, { "agency": "NSF" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1225" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1021/jz5026195", "primary_object": { "basename": "jz5026195_si_001.pdf", "url": "https://authors.library.caltech.edu/records/ft6sa-gk325/files/jz5026195_si_001.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Sun, Ke; McDowell, Matthew T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/vev5s-vhw76", "eprint_id": 56173, "eprint_status": "archive", "datestamp": "2023-08-22 14:58:38", "lastmod": "2023-10-20 23:44:31", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "O'Leary-L-E", "name": { "family": "O'Leary", "given": "Leslie E." } }, { "id": "Strandwitz-N-C", "name": { "family": "Strandwitz", "given": "Nicholas C." } }, { "id": "Roske-C-W", "name": { "family": "Roske", "given": "Christopher W." } }, { "id": "Pyo-Suyeon", "name": { "family": "Pyo", "given": "Suyeon" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Use of Mixed CH_3\u2212/HC(O)CH_2CH_2\u2212Si(111) Functionality to Control Interfacial Chemical and Electronic Properties During the Atomic-Layer Deposition of Ultrathin Oxides on Si(111)", "ispublished": "pub", "full_text_status": "public", "keywords": "two-step halogenation/alkylation; mixed monolayer; surface recombination velocity; interfacial oxidation; surface passivation; gate oxide", "note": "\u00a9 2015 American Chemical Society. Received: December 2, 2014.\nAccepted: January 25, 2015. Published: January 26, 2015. Publication Date (Web): January 26, 2015.\n\nThis work was supported by the National Science Foundation (CHE-1214152) and the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology. This work was additionally supported by BP and the Gordon and Betty Moore Foundation. The Link Foundation Energy fellowship (L.E.O.), the NSF ACC-F (CHE-1042006, N.C.S.), and the NSF-GRFP (C.W.R.) are gratefully acknowledged for graduate and postdoctoral fellowship support. The authors thank Judith Lattimer for assistance with XPS data, and Ron Grimm for H-terminated silicon data.\n\nSupplemental Material - jz502542a_si_001.pdf
", "abstract": "Silicon surfaces terminated with a mixed monolayer containing both a propyl aldehyde functionality and methyl groups were prepared and used to control the interfacial chemical and electronic properties of Si(111) surfaces during atomiclayer deposition (ALD) of Al_2O_3 or MnO. Si(111) surfaces functionalized only with the aldehyde moiety exhibited surface recombination velocities, S, of 2500 \u00b1 600 cm s^(\u22121) whereas the mixed CH_3\u2212/HC(O)CH_2CH_2\u2212Si(111) surfaces displayed S = 25 \u00b1\n7 cm s^(\u22121). During the ALD growth of either Al_2O_3 or MnO, both the HC(O)CH_2CH_2\u2212Si(111) and CH_3\u2212/HC(O)CH_2CH_2\u2212Si(111) surfaces produced increased metal oxide deposition at low cycle number, relative to H\u2212Si(111) or CH_3\u2212Si(111) surfaces. As detected by X-ray photoelectron spectroscopy after the ALD process, the CH_3\u2212 and mixed CH_3\u2212/HC(O)CH_2CH_2\u2212 functionalized Si(111)\nsurfaces exhibited less interfacial SiO_x than was observed for ALD of metal oxides on H\u2212Si(111) substrates.", "date": "2015-02-19", "date_type": "published", "publication": "Journal of Physical Chemistry Letters", "volume": "6", "number": "4", "publisher": "American Chemical Society", "pagerange": "722-726", "id_number": "CaltechAUTHORS:20150327-095906689", "issn": "1948-7185", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150327-095906689", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Gordon and Betty Moore Foundation" }, { "agency": "Link Foundation" }, { "agency": "NSF", "grant_number": "CHE-1042006" }, { "agency": "BP" } ] }, "doi": "10.1021/jz502542a", "primary_object": { "basename": "jz502542a_si_001.pdf", "url": "https://authors.library.caltech.edu/records/vev5s-vhw76/files/jz502542a_si_001.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "O'Leary, Leslie E.; Strandwitz, Nicholas C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3j3em-rcz45", "eprint_id": 56006, "eprint_status": "archive", "datestamp": "2023-08-22 14:51:26", "lastmod": "2023-10-20 23:32:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Berweger-S", "name": { "family": "Berweger", "given": "Samuel" } }, { "id": "Weber-J-C", "name": { "family": "Weber", "given": "Joel C." } }, { "id": "John-Jimmy", "name": { "family": "John", "given": "Jimmy" }, "orcid": "0000-0002-8772-8939" }, { "id": "Velazquez-J-M", "name": { "family": "Velazquez", "given": "Jesus M." } }, { "id": "Pieterick-A-P", "name": { "family": "Pieterick", "given": "Adam" } }, { "id": "Sanford-N-A", "name": { "family": "Sanford", "given": "Norman A." } }, { "id": "Davydov-A-V", "name": { "family": "Davydov", "given": "Albert V." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce" }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Wallis-T-M", "name": { "family": "Wallis", "given": "Thomas M." } }, { "id": "Kabos-P", "name": { "family": "Kabos", "given": "Pavel" } } ] }, "title": "Microwave Near-Field Imaging of Two-Dimensional Semiconductors", "ispublished": "pub", "full_text_status": "public", "keywords": "Transition metal dichalcogenide; MoS_2; microwave; near-field; quantum capacitance; atomic force microscope", "note": "\u00a9 2015 American Chemical Society.\n\nReceived: October 24, 2014; Revised: January 20, 2015; Published: January 27, 2015.\n\nWe would like to thank Will Gannett, Mark Keller, and Alexandra Curtin for helpful advice on sample preparation. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. Mention of commercial products is for informational purposes only, it does not imply NIST's recommendation or endorsement.\n\nSupplemental Material - nl504960u_si_001.pdf
", "abstract": "Optimizing new generations of two-dimensional devices based on van der Waals materials will require techniques capable of measuring variations in electronic properties in situ and with nanometer spatial resolution. We perform scanning microwave microscopy (SMM) imaging of single layers of MoS_2 and n- and p-doped WSe_2. By controlling the sample charge carrier concentration through the applied tip bias, we are able to reversibly control and optimize the SMM contrast to image variations in electronic structure and the localized effects of surface contaminants. By further performing tip bias-dependent point spectroscopy together with finite element simulations, we distinguish the effects of the quantum capacitance and determine the local dominant charge carrier species and dopant concentration. These results underscore the capability of SMM for the study of 2D materials to image, identify, and study electronic defects.", "date": "2015-02", "date_type": "published", "publication": "Nano Letters", "volume": "15", "number": "2", "publisher": "American Chemical Society", "pagerange": "1122-1127", "id_number": "CaltechAUTHORS:20150324-085931498", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150324-085931498", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/nl504960u", "primary_object": { "basename": "nl504960u_si_001.pdf", "url": "https://authors.library.caltech.edu/records/3j3em-rcz45/files/nl504960u_si_001.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Berweger, Samuel; Weber, Joel C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zx5dk-ap869", "eprint_id": 55671, "eprint_status": "archive", "datestamp": "2023-08-22 14:51:02", "lastmod": "2023-10-20 22:57:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Walczak-K-A", "name": { "family": "Walczak", "given": "Karl" } }, { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" } }, { "id": "Karp-C-L", "name": { "family": "Karp", "given": "Christoph" } }, { "id": "Beeman-J-W", "name": { "family": "Beeman", "given": "Jeffrey W." } }, { "id": "Shaner-M-R", "name": { "family": "Shaner", "given": "Matthew" }, "orcid": "0000-0003-4682-9757" }, { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Sharp-I-D", "name": { "family": "Sharp", "given": "Ian D." }, "orcid": "0000-0001-5238-7487" }, { "id": "Amashukeli-X", "name": { "family": "Amashukeli", "given": "Xenia" } }, { "id": "West-W-C", "name": { "family": "West", "given": "William" } }, { "id": "Jin-Jian", "name": { "family": "Jin", "given": "Jian" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" } ] }, "title": "Modeling, Simulation, and Fabrication of a Fully Integrated, Acid-stable, Scalable Solar-Driven Water-Splitting System", "ispublished": "pub", "full_text_status": "public", "keywords": "multi-physics modeling; prototype; solar fuels; tungsten oxide; water splitting", "note": "\u00a9 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.\n\nReceived: August 26, 2014; Published online on January 7, 2015.\n\nThis material is based upon work performed by the Joint Center\nfor Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.\n\nSupplemental Material - cssc_201402896_sm_miscellaneous_information.pdf
", "abstract": "A fully integrated solar-driven water-splitting system comprised of WO3/FTO/p^(+)n Si as the photoanode, Pt/TiO_2/Ti/n^(+)p Si as the photocathode, and Nafion as the membrane separator, was simulated, assembled, operated in 1.0\u2009M HClO_4, and evaluated for performance and safety characteristics under dual side illumination. A multi-physics model that accounted for the performance of the photoabsorbers and electrocatalysts, ion transport in the solution electrolyte, and gaseous product crossover was first used to define the optimal geometric design space for the system. The photoelectrodes and the membrane separators were then interconnected in a louvered design system configuration, for which the light-absorbing area and the solution-transport pathways were simultaneously optimized. The performance of the photocathode and the photoanode were separately evaluated in a traditional three-electrode photoelectrochemical cell configuration. The photocathode and photoanode were then assembled back-to-back in a tandem configuration to provide sufficient photovoltage to sustain solar-driven unassisted water-splitting. The current\u2013voltage characteristics of the photoelectrodes showed that the low photocurrent density of the photoanode limited the overall solar-to-hydrogen (STH) conversion efficiency due to the large band gap of WO_3. A hydrogen-production rate of 0.17\u2005mL\u2009hr^\u22121 and a STH conversion efficiency of 0.24\u2009% was observed in a full cell configuration for >20\u2005h with minimal product crossover in the fully operational, intrinsically safe, solar-driven water-splitting system. The solar-to-hydrogen conversion efficiency, \u03b7S_TH, calculated using the multiphysics numerical simulation was in excellent agreement with the experimental behavior of the system. The value of \u03b7STH was entirely limited by the performance of the photoelectrochemical assemblies employed in this study. The louvered design provides a robust platform for implementation of various types of photoelectrochemical assemblies, and can provide an approach to significantly higher solar conversion efficiencies as new and improved materials become available.", "date": "2015-02", "date_type": "published", "publication": "ChemSusChem", "volume": "8", "number": "3", "publisher": "Wiley", "pagerange": "544-551", "id_number": "CaltechAUTHORS:20150310-113150374", "issn": "1864-5631", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150310-113150374", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1002/cssc.201402896", "primary_object": { "basename": "cssc_201402896_sm_miscellaneous_information.pdf", "url": "https://authors.library.caltech.edu/records/zx5dk-ap869/files/cssc_201402896_sm_miscellaneous_information.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Walczak, Karl; Chen, Yikai; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hej8y-f2e36", "eprint_id": 53854, "eprint_status": "archive", "datestamp": "2023-08-20 04:41:06", "lastmod": "2023-10-19 22:18:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Audesirk-H-A", "name": { "family": "Audesirk", "given": "Heather A." } }, { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Ku-Jessie", "name": { "family": "Ku", "given": "Jessie" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Ordered Silicon Microwire Arrays Grown from Substrates Patterned Using Imprint Lithography and Electrodeposition", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 American Chemical Society.\n\nReceived: October 17, 2014; Accepted: January 6, 2015; Publication Date (Web): January 6, 2015.\n\nThis work was supported by the National Science Foundation (Grant NSF-1214152), BP, the Gordon and Betty Moore Foundation, and DARPA. H.A.A. also acknowledges partial support from Dow Chemical. This work was partially performed at the Kavli Nanoscience Institute at the California Institute of Technology.\n\nSupplemental Material - am507200j_si_001.pdf
", "abstract": "Silicon microwires grown by the vapor\u2013liquid\u2013solid process have attracted a great deal of interest as potential light absorbers for solar energy conversion. However, the research-scale techniques that have been demonstrated to produce ordered arrays of micro and nanowires may not be optimal for use as high-throughput processes needed for large-scale manufacturing. Herein we demonstrate the use of microimprint lithography to fabricate patterned templates for the confinement of an electrodeposited Cu catalyst for the vapor\u2013liquid\u2013solid (VLS) growth of Si microwires. A reusable polydimethylsiloxane stamp was used to pattern holes in silica sol\u2013gels on silicon substrates, and the Cu catalyst was electrodeposited into the holes. Ordered arrays of crystalline p-type Si microwires were grown across the sol\u2013gel-patterned substrates with materials quality and performance comparable to microwires fabricated with high-purity metal catalysts and cleanroom processing.", "date": "2015-01-28", "date_type": "published", "publication": "ACS Applied Materials & Interfaces", "volume": "7", "number": "3", "publisher": "American Chemical Society", "pagerange": "1396-1400", "id_number": "CaltechAUTHORS:20150120-082307878", "issn": "1944-8244", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150120-082307878", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "NSF-1214152" }, { "agency": "BP" }, { "agency": "Gordon and Betty Moore Foundation" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Dow Chemical" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/am507200j", "primary_object": { "basename": "am507200j_si_001.pdf", "url": "https://authors.library.caltech.edu/records/hej8y-f2e36/files/am507200j_si_001.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Audesirk, Heather A.; Warren, Emily L.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/c63sw-pdv64", "eprint_id": 50252, "eprint_status": "archive", "datestamp": "2023-08-20 04:29:31", "lastmod": "2023-10-17 22:52:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nielander-A-C", "name": { "family": "Nielander", "given": "Adam C." }, "orcid": "0000-0002-3639-2427" }, { "id": "Shaner-M-R", "name": { "family": "Shaner", "given": "Matthew R." }, "orcid": "0000-0003-4682-9757" }, { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Francis-S-A", "name": { "family": "Francis", "given": "Sonja A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A taxonomy for solar fuels generators", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 The Royal Society of Chemistry.\n\nReceived 18 Jul 2014, Accepted 19 Sep 2014,\nFirst published online 19 Sep 2014.\n\nACN acknowledges the NSF, Grant CHE-1214152, and the National Science Foundation Graduate Research Fellowship for support. KMP acknowledges support from the DOE, Grant DEFG02-03ER15483. MRS acknowledges the Resnick Sustainability\nInstitute for a graduate fellowship. This material is based upon\nwork performed by the Joint Center for Artificial Photosynthesis,\na DOE Energy Innovation Hub, supported through the\nOffice of Science of the U.S. Department of Energy under Award\nNumber DE-SC0004993.\n\nPublished - c4ee02251c.pdf
", "abstract": "A number of approaches to solar fuels generation are being developed, each of which has associated\nadvantages and challenges. Many of these solar fuels generators are identified as \"photoelectrochemical\ncells\" even though these systems collectively operate based on a suite of fundamentally different\nphysical principles. To facilitate appropriate comparisons between solar fuels generators, as well as to\nenable concise and consistent identification of the state-of-the-art for designs based on comparable\noperating principles, we have developed a taxonomy and nomenclature for solar fuels generators based\non the source of the asymmetry that separates photogenerated electrons and holes. Three basic device\ntypes have been identified: photovoltaic cells, photoelectrochemical cells, and particulate/molecular\nphotocatalysts. We outline the advantages and technological challenges associated with each type, and\nprovide illustrative examples for each approach as well as for hybrid approaches.", "date": "2015-01-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "1", "publisher": "Royal Society of Chemistry", "pagerange": "16-25", "id_number": "CaltechAUTHORS:20141008-080542214", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141008-080542214", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1039/c4ee02251c", "primary_object": { "basename": "c4ee02251c.pdf", "url": "https://authors.library.caltech.edu/records/c63sw-pdv64/files/c4ee02251c.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Nielander, Adam C.; Shaner, Matthew R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rc4xp-yqj60", "eprint_id": 51816, "eprint_status": "archive", "datestamp": "2023-08-20 04:29:37", "lastmod": "2023-10-18 17:57:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shaner-Matthew-R", "name": { "family": "Shaner", "given": "Matthew R." }, "orcid": "0000-0003-4682-9757" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Sun-Ke", "name": { "family": "Sun", "given": "Ke" }, "orcid": "0000-0001-8209-364X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Stabilization of Si microwire arrays for solar-driven H\u2082O oxidation to O\u2082(g) in 1.0 M KOH(aq) using conformal coatings of amorphous TiO\u2082", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 The Royal Society of Chemistry.\n\nReceived 22 Sep 2014, Accepted 29 Oct 2014,\nFirst published online 05 Nov 2014.\n\nThe authors would like to acknowledge Dr Ragip Pala for assistance with the spectral response measurement system. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. M. R. S. is supported by a graduate fellowship from the Resnick Institute for Sustainability. The authors also acknowledge support from the Gordon and Betty Moore Foundation.\n\nPublished - c4ee03012e.pdf
Supplemental Material - c4ee03012e1.pdf
", "abstract": "Conductive, amorphous TiO\u2082 coatings deposited by atomic-layer deposition, in combination with a sputter deposited NiCrO\u2093 oxygen-evolution catalyst, have been used to protect Si microwire arrays from passivation or corrosion in contact with aqueous electrolytes. Coated np\u207a-Si/TiO\u2082/NiCrO\u2093 as well as heterojunction n-Si/TiO\u2082/NiCrO\u2093 Si microwire-array photoanodes exhibited stable photoelectrochemical operation in aqueous ferri-/ferro-cyanide solutions. The coatings also allowed for photoanodic water oxidation in 1.0 M KOH(aq) solutions for >2200 h of continuous operation under simulated 1 Sun conditions with 100% Faradaic efficiency for the evolution of O\u2082(g).", "date": "2015-01-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "8", "number": "1", "publisher": "Royal Society of Chemistry", "pagerange": "203-207", "id_number": "CaltechAUTHORS:20141117-083607403", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141117-083607403", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "Gordon and Betty Moore Foundation" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "Kavli-Nanoscience-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1039/c4ee03012e", "primary_object": { "basename": "c4ee03012e.pdf", "url": "https://authors.library.caltech.edu/records/rc4xp-yqj60/files/c4ee03012e.pdf" }, "related_objects": [ { "basename": "c4ee03012e1.pdf", "url": "https://authors.library.caltech.edu/records/rc4xp-yqj60/files/c4ee03012e1.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Shaner, Matthew R.; Hu, Shu; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5dqs1-2a635", "eprint_id": 49770, "eprint_status": "archive", "datestamp": "2023-08-22 14:35:08", "lastmod": "2023-10-17 22:11:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Soriaga-Manuel-P", "name": { "family": "Soriaga", "given": "Manuel P." }, "orcid": "0000-0002-0077-6226" }, { "id": "Baricuatro-Jack-H", "name": { "family": "Baricuatro", "given": "Jack H." } }, { "id": "Cummins-Kyle-D", "name": { "family": "Cummins", "given": "Kyle D." } }, { "id": "Kim-Youn-Geun", "name": { "family": "Kim", "given": "Youn-Geun" }, "orcid": "0000-0002-5936-6520" }, { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "Sun-Guofeng", "name": { "family": "Sun", "given": "Guofeng" } }, { "id": "McCrory-Charles-C-L", "name": { "family": "McCrory", "given": "Charles C. L." }, "orcid": "0000-0001-9039-7192" }, { "id": "McKone-James-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Velazquez-Jesus-M", "name": { "family": "Velazquez", "given": "Jesus M." } }, { "id": "Ferrer-Ivonne-M", "name": { "family": "Ferrer", "given": "Ivonne M." } }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Javier-Alnald-C", "name": { "family": "Javier", "given": "Alnald" }, "orcid": "0000-0002-0306-5462" }, { "id": "Chmielowiec-Brian", "name": { "family": "Chmielowiec", "given": "Brian" }, "orcid": "0000-0002-3004-9345" }, { "id": "Lacy-David-C", "name": { "family": "Lacy", "given": "David C." } }, { "id": "Gregoire-J-M", "name": { "family": "Gregoire", "given": "John M." }, "orcid": "0000-0002-2863-5265" }, { "id": "Sanabria-Chinchilla-Jean", "name": { "family": "Sanabria-Chinchilla", "given": "Jean" } }, { "id": "Amashukeli-Xenia", "name": { "family": "Amashukeli", "given": "Xenia" } }, { "id": "Royea-William-J", "name": { "family": "Royea", "given": "William J." } }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Hemminger-John-C", "name": { "family": "Hemminger", "given": "John C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Stickney-John-L", "name": { "family": "Stickney", "given": "John L." } } ] }, "title": "Electrochemical surface science twenty years later: Expeditions into the electrocatalysis of reactions at the core of artificial photosynthesis", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Electroctrochemical surface science; Artificial photosynthesis; Water-splitting reaction; Carbon dioxide reduction reaction; Electrochemistry-surface science apparatus", "note": "\u00a9 2014 Elsevier B.V.\n\nAvailable online 22 July 2014.\n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. JRM was the recipient of a US DOE graduate research fellowship. BSB would like to acknowledge Beckman Institute of the California Institute of Technology for support. MPS and JLS thank Arthur T. Hubbard; friend, colleague and mentor.", "abstract": "Surface science research fixated on phenomena and processes that transpire at the electrode-electrolyte interface has been pursued in the past. A considerable proportion of the earlier work was on materials and reactions pertinent to the operation of small-molecule fuel cells. The experimental approach integrated a handful of surface-sensitive physical\u2013analytical methods with traditional electrochemical techniques, all harbored in a single environment-controlled electrochemistry-surface science apparatus (EC-SSA); the catalyst samples were typically precious noble metals constituted of well-defined single-crystal surfaces. More recently, attention has been diverted from fuel-to-energy generation to its converse, (solar) energy-to-fuel transformation; e.g., instead of water synthesis (from hydrogen and oxygen) in fuel cells, water decomposition (to hydrogen and oxygen) in artificial photosynthesis. The rigorous surface-science protocols remain unchanged but the experimental capabilities have been expanded by the addition of several characterization techniques, either as EC-SSA components or as stand-alone instruments. The present manuscript describes results selected from on-going studies of earth-abundant electrocatalysts for the reactions that underpin artificial photosynthesis: nickel-molybdenum alloys for the hydrogen evolution reaction, calcium birnessite as a heterogeneous analogue for the oxygen-evolving complex in natural photosynthesis, and single-crystalline copper in relation to the carbon dioxide reduction reaction.", "date": "2015-01", "date_type": "published", "publication": "Surface Science", "volume": "631", "publisher": "Elsevier", "pagerange": "285-294", "id_number": "CaltechAUTHORS:20140917-091954518", "issn": "0039-6028", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140917-091954518", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Caltech Beckman Institute" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1016/j.susc.2014.06.028", "resource_type": "article", "pub_year": "2015", "author_list": "Soriaga, Manuel P.; Baricuatro, Jack H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/re8ys-5y746", "eprint_id": 50531, "eprint_status": "archive", "datestamp": "2023-08-20 04:03:35", "lastmod": "2023-10-17 23:54:15", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Verlage-Erik", "name": { "family": "Verlage", "given": "Erik" } }, { "id": "Hemminger-John-C", "name": { "family": "Hemminger", "given": "John C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Soriaga-M-P", "name": { "family": "Soriaga", "given": "Manuel P." }, "orcid": "0000-0002-0077-6226" } ] }, "title": "CoP as an Acid-Stable Active Electrocatalyst for the Hydrogen-Evolution Reaction: Electrochemical Synthesis, Interfacial Characterization and Performance Evaluation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Chemical Society. \n\nReceived: June 2, 2014. Revised: September 27, 2014. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. A.I.C. acknowledges a National Science Foundation Graduate Research Fellowship for support.\n\nSupplemental Material - jp5054452_si_001.pdf
", "abstract": "Films of CoP have been electrochemically synthesized, characterized, and evaluated for performance as a catalyst for the hydrogen-evolution reaction (HER). The film was synthesized by cathodic deposition from a boric acid solution of Co^(2+) and H_2PO_2^\u2013 on copper substrates followed by operando remediation of exogenous contaminants. The films were characterized structurally and compositionally by scanning-electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman spectrophotometry. The catalytic activity was evaluated by cyclic voltammetry and chronopotentiometry. Surface characterization prior to electrocatalysis indicated that the film consisted of micrometer-sized spherical clusters located randomly and loosely on a slightly roughened surface. The composition of both the clusters and surface consisted of cobalt in the metallic, phosphide, and amorphous-oxide forms (CoO\u00b7Co_2O_3) and of phosphorus as phosphide and orthophosphate. The orthophosphate species, produced by air-oxidation, were eliminated upon HER electrocatalysis in sulfuric acid. The operando film purification yielded a functional electrocatalyst with a Co:P stoichiometric ratio of 1:1. After the HER, the surface was densely packed with micrometer-sized, mesa-like particles whose tops were flat and smooth. The CoP eletrodeposit exhibited an 85 mV overvoltage (\u03b7) for the HER at a current density of 10 mA cm^(\u20132) and was stable under operation in highly acidic solution, with an increase in \u03b7 of 18 mV after 24 h of continuous operation. The comparative HER catalytic performance of CoP, film or nanoparticles, is as follows: \u03b7_(Pt) < \u03b7_(CoP film) = \u03b7_(CoP NP), \u03b7_(Ni_2P) < \u03b7_(CoSe)_2 < \u03b7_(MoS)_2 < \u03b7_(MoSe)_2.", "date": "2014-12-18", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "118", "number": "50", "publisher": "American Chemical Society", "pagerange": "29294-29300", "id_number": "CaltechAUTHORS:20141020-091512216", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141020-091512216", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/jp5054452", "primary_object": { "basename": "jp5054452_si_001.pdf", "url": "https://authors.library.caltech.edu/records/re8ys-5y746/files/jp5054452_si_001.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Saadi, Fadl H.; Carim, Azhar I.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/03rh5-j1z05", "eprint_id": 53452, "eprint_status": "archive", "datestamp": "2023-08-20 03:58:01", "lastmod": "2023-10-19 21:45:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bruce-J-P", "name": { "family": "Bruce", "given": "Jared P." } }, { "id": "Asgari-S", "name": { "family": "Asgari", "given": "Sommayeh" } }, { "id": "Ardo-S", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Oliver-D-R", "name": { "family": "Oliver", "given": "Derek R." } }, { "id": "Freund-M-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" } ] }, "title": "Measurement of the Electrical Resistance of n-Type Si Microwire/p-Type Conducting Polymer Junctions for Use in Artificial Photosynthesis", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Chemical Society. \n\nReceived: September 11, 2014. Revised: October 29, 2014. Published: October 29, 2014. \n\nFinancial support from the Natural Sciences and Engineering\nResearch Council (NSERC) of Canada, the Canada Foundation\nfor Innovation (CFI), the Manitoba Research and Innovation Fund, and the University of Manitoba is gratefully acknowledged. The work reported made use of surface\ncharacterization infrastructure in the Manitoba Institute for Materials. This work was supported by a National Science\nFoundation (NSF) Center for Chemical Innovation (CCI)\nPowering the Planet (Grants CHE-0802907, CHE-0947829, and NSF-ACCF) and made use of the Molecular Materials Research Center of the Beckman Institute at Caltech and the Kavli Nanoscience Institute at Caltech. This research was undertaken, in part, thanks to funding from the Canada Research Chairs Program. S.A. acknowledges partial support from a U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award, under the EERE Fuel Cell Technologies Program. This material is based in part (support for NSL) upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award DE-SC0004993.\n\nSupplemental Material - jp509211k_si_001.pdf
", "abstract": "The junction between n-type silicon microwires and p-type conducting polymer PEDOT:PSS (poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)) was investigated using a soft contact method. Dopant levels within the microwires were varied during growth to give a highly-doped region for improved contact and a low-doped region for light absorption. The low-doped region of the microwires had a dopant density of 5 X 10(17) cm(-3) while the highly-doped region had an increased dopant density of 5 X 10(18) cm(-3) over similar to 20 mu m. Uniform, highly-doped microwires, with a dopant density of 4 X 10(19) cm(3), were used as a comparison. Regions of highly-doped n-type Si microwires (N-D = 5 X 10(18) cm(-3) and 4 X 10(19) cm(-3)) contacted by PEDOT:PSS showed a significantly lower junction resistance compared to the low-doped (3 X 10(17) cm(-3)) regions of the microwire. Junctions incorporating the metal catalyst used during growth were also investigated. Microwires with copper at the interface had similar currentvoltage characteristics to those observed for the highly-doped microwire/conducting polymer junction; however, junctions that incorporated gold exhibited significantly lower resistances, decreasing the iR contribution of the junction by an order of magnitude with respect to the total voltage drop in the entire structure.", "date": "2014-12-04", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "118", "number": "48", "publisher": "American Chemical Society", "pagerange": "27742-27748", "id_number": "CaltechAUTHORS:20150109-083207621", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150109-083207621", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "Canada Foundation for Innovation" }, { "agency": "Manitoba Research and Innovation Fund" }, { "agency": "University of Manitoba" }, { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "NSF", "grant_number": "CHE-0947829" }, { "agency": "Canada Research Chairs Program" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" }, { "id": "Kavli-Nanoscience-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1021/jp509211k", "primary_object": { "basename": "jp509211k_si_001.pdf", "url": "https://authors.library.caltech.edu/records/03rh5-j1z05/files/jp509211k_si_001.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Bruce, Jared P.; Asgari, Sommayeh; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/c64x9-wxs59", "eprint_id": 53260, "eprint_status": "archive", "datestamp": "2023-08-22 14:16:47", "lastmod": "2023-10-19 14:41:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Callejas-J-F", "name": { "family": "Callejas", "given": "Juan F." } }, { "id": "McEnaney-J-M", "name": { "family": "McEnaney", "given": "Joshua M." } }, { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Crompton-J-C", "name": { "family": "Crompton", "given": "J. Chance" } }, { "id": "Biacchi-A_J", "name": { "family": "Biacchi", "given": "Adam J." } }, { "id": "Popczun-E-J", "name": { "family": "Popczun", "given": "Eric J." } }, { "id": "Gordon-T-R", "name": { "family": "Gordon", "given": "Thomas R." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Schaak-R-E", "name": { "family": "Schaak", "given": "Raymond E." } } ] }, "title": "Electrocatalytic and Photocatalytic Hydrogen Production from Acidic and Neutral-pH Aqueous Solutions Using Iron Phosphide Nanoparticles", "ispublished": "pub", "full_text_status": "restricted", "keywords": "hydrogen evolution reaction; metal phosphides; nanoparticles; electrocatalysis; photocatalysis", "note": "\u00a9 2014 American Chemical Society.\n\nReceived for review August 28, 2014 and accepted September 24, 2014; published online September 24, 2014.\n\nThe work at PSU was supported by the National Science Foundation (NSF) Center for Chemical Innovation on Solar Fuels (CHE-1305124) and at Caltech by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. TEM was performed in the Penn State Microscopy and Cytometry Facility (University Park, PA), and HRTEM, EDS, XPS, and DRIFTS datawere acquired at theMaterials Characterization Laboratory of the Penn State Materials Research Institute. The authors thank Greg Barber, Jennifer Gray, Lymaris Ortiz Rivera, and Nella Vargas-Barbosa for technical support and helpful discussions.", "abstract": "Nanostructured transition-metal phosphides have recently emerged as Earth-abundant alternatives to platinum for catalyzing the hydrogen-evolution reaction (HER), which is central to several clean energy technologies because it produces molecular hydrogen through the electrochemical reduction of water. Iron-based catalysts are very attractive targets because iron is the most abundant and least expensive transition metal. We report herein that iron phosphide (FeP), synthesized as nanoparticles having a uniform, hollow morphology, exhibits among the highest HER activities reported to date in both acidic and neutral-pH aqueous solutions. As an electrocatalyst operating at a current density of \u221210 mA cm^\u20132, FeP nanoparticles deposited at a mass loading of \u223c1 mg cm^\u20132 on Ti substrates exhibited overpotentials of \u221250 mV in 0.50 M H_2SO_4 and \u2212102 mV in 1.0 M phosphate buffered saline. The FeP nanoparticles supported sustained hydrogen production with essentially quantitative faradaic yields for extended time periods under galvanostatic control. Under UV illumination in both acidic and neutral-pH solutions, FeP nanoparticles deposited on TiO_2 produced H_2 at rates and amounts that begin to approach those of Pt/TiO_2. FeP therefore is a highly Earth-abundant material for efficiently facilitating the HER both electrocatalytically and photocatalytically.", "date": "2014-11-25", "date_type": "published", "publication": "ACS Nano", "volume": "8", "number": "11", "publisher": "American Chemical Society", "pagerange": "11101-11107", "id_number": "CaltechAUTHORS:20150107-093231817", "issn": "1936-0851", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150107-093231817", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/nn5048553", "resource_type": "article", "pub_year": "2014", "author_list": "Callejas, Juan F.; McEnaney, Joshua M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/g13k8-em036", "eprint_id": 47541, "eprint_status": "archive", "datestamp": "2023-08-22 14:01:20", "lastmod": "2023-10-26 20:41:32", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Blumenfeld-C-M", "name": { "family": "Blumenfeld", "given": "Carl M." } }, { "id": "Sadtler-B-F", "name": { "family": "Sadtler", "given": "Bryce F." } }, { "id": "Fernandez-G-E", "name": { "family": "Fernandez", "given": "G. Esteban" } }, { "id": "Dara-L", "name": { "family": "Dara", "given": "Lily" } }, { "id": "Nugyen-Cathie", "name": { "family": "Nguyen", "given": "Cathie" } }, { "id": "Alonso-Valenteen-F", "name": { "family": "Alonso-Valenteen", "given": "Felix" } }, { "id": "Medina-Kauwe-L-K", "name": { "family": "Medina-Kauwe", "given": "Lali" } }, { "id": "Moats-R-A", "name": { "family": "Moats", "given": "Rex A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Sorasaenee-K", "name": { "family": "Sorasaenee", "given": "Karn" }, "orcid": "0000-0002-3364-1918" } ] }, "title": "Cellular uptake and cytotoxicity of a near-IR fluorescent corrole\u2013TiO_2 nanoconjugate", "ispublished": "pub", "full_text_status": "public", "keywords": "Nanoconjugate; TiO2 nanoparticle; Corrole; Fluorescence; Cytotoxic effect; Cellular uptake", "note": "\u00a9 2014 Elsevier Inc. \n\nReceived 13 March 2014, Revised 19 June 2014, Accepted 20 June 2014, Available online 28 June 2014. \n\nWe thank the CHLA Radiology Endowment Fund (K.S.), Sanofi (H.B.G.), Doheny Eye Institute (R.H.G.), and Beckman Institute Postdoctoral Fellowship (B.F.S.) for the support. We also thank Anahit Hovsepyan, Seda Mkhitaryan, Vazgen Khankaldyyan, and Gevorg Karapetyan for the help with the bioluminescence assays. Absorption measurements and profilometry were performed at the Molecular Materials Research Center, Beckman Institute, Caltech. We thank\nCarol M. Garland for the assistance in TEM imaging. B.F.S. and N.S.L. acknowledge the support from the \"Light\u2013Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences (DE-SC0001293).\n\nAccepted Version - nihms811177.pdf
Supplemental Material - mmc1.docx
Supplemental Material - mmc2.zip
", "abstract": "We are investigating the biological and biomedical imaging roles and impacts of fluorescent metallocorrole\u2013TiO_2 nanoconjugates as potential near-infrared optical contrast agents in vitro in cancer and normal cell lines. The TiO_2 nanoconjugate labeled with the small molecule 2,17-bis(chlorosulfonyl)-5,10,15-tris(pentafluorophenyl)corrolato aluminum(III) (1-Al\u2013TiO_2) was prepared. The nanoparticle 1-Al\u2013TiO_2 was characterized by transmission electron microscopy (TEM) and integrating-sphere electronic absorption spectroscopy. TEM images of three different samples of TiO_2 nanoparticles (bare, H_2O_2 etched, and 1-Al functionalized) showed similarity in shapes and sizes with an average diameter of 29 nm for 1-Al\u2013TiO_2. Loading of 1-Al on the TiO_2 surfaces was determined to be ca. 20\u201340 mg 1-Al/g TiO_2. Confocal fluorescence microscopy (CFM) studies of luciferase-transfected primary human glioblastoma U87-Luc cells treated with the nanoconjugate 1-Al\u2013TiO_2 as the contrast agent in various concentrations were performed. The CFM images revealed that 1-Al\u2013TiO_2 was found inside the cancer cells even at low doses (0.02\u20132 \u03bcg/mL) and localized in the cytosol. Bioluminescence studies of the U87-Luc cells exposed to various amounts of 1-Al\u2013TiO_2 showed minimal cytotoxic effects even at higher doses (2\u20132000 \u03bcg/mL) after 24 h. A similar observation was made using primary mouse hepatocytes (PMH) treated with 1-Al\u2013TiO_2 at low doses (0.0003\u20133 \u03bcg/mL). Longer incubation times (after 48 and 72 h for U87-Luc) and higher doses (> 20 \u03bcg/mL 1-Al\u2013TiO_2 for U87-Luc and > 3 \u03bcg/mL 1-Al\u2013TiO_2 for PMH) showed decreased cell viability.", "date": "2014-11", "date_type": "published", "publication": "Journal of Inorganic Biochemistry", "volume": "140", "publisher": "Elsevier", "pagerange": "39-44", "id_number": "CaltechAUTHORS:20140729-072109271", "issn": "0162-0134", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140729-072109271", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "CHLA Radiology Endowment Fund" }, { "agency": "Sanofi" }, { "agency": "Doheny Eye Institute" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" } ] }, "doi": "10.1016/j.jinorgbio.2014.06.015", "pmcid": "PMC4998051", "primary_object": { "basename": "mmc1.docx", "url": "https://authors.library.caltech.edu/records/g13k8-em036/files/mmc1.docx" }, "related_objects": [ { "basename": "mmc2.zip", "url": "https://authors.library.caltech.edu/records/g13k8-em036/files/mmc2.zip" }, { "basename": "nihms811177.pdf", "url": "https://authors.library.caltech.edu/records/g13k8-em036/files/nihms811177.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Blumenfeld, Carl M.; Sadtler, Bryce F.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/gf5cw-3yq39", "eprint_id": 120629, "eprint_status": "archive", "datestamp": "2023-08-22 14:07:38", "lastmod": "2023-10-23 17:52:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "McDonald-Michael-B", "name": { "family": "McDonald", "given": "Michael B." } }, { "id": "Ardo-Shane", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Freund-Michael-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" } ] }, "title": "Use of Bipolar Membranes for Maintaining Steady-State pH Gradients in Membrane-Supported, Solar-Driven Water Splitting", "ispublished": "pub", "full_text_status": "public", "keywords": "General Energy; General Materials Science; General Chemical Engineering; Environmental Chemistry", "note": "M.S.F. and M.B.M. acknowledge support by the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Canada Research Chair program, the Province of Manitoba's Science and Technology International Collaboration Fund, and the University of Manitoba. This research made use of the Manitoba Institute for Materials facility, which is supported by the Canada Foundation for Innovation (CFI), the Manitoba Research and Innovation Fund, and the University of Manitoba. N.S.L. and S.A. acknowledge support by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. S.A. also acknowledges partial support from the United States Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under the EERE Fuel Cell Technologies Program. We also acknowledge Nathan Craig, Adam Nielander, and Carl Koval for helpful discussions.\n\nMcDonald, M.B., Ardo, S., Lewis, N.S. and Freund, M.S. (2015), Corrigendum: Use of Bipolar Membranes for Maintaining Steady-State pH Gradients in Membrane-Supported, Solar-Driven Water Splitting. ChemSusChem, 8: 14-14. https://doi.org/10.1002/cssc.201403359", "abstract": "A bipolar membrane can maintain a steady-state pH difference between the sites of oxidation and reduction in membrane-supported, solar-driven water-splitting systems without changing the overall thermodynamics required to split water. A commercially available bipolar membrane that can serve this purpose has been identified, its performance has been evaluated quantitatively, and is demonstrated to meet the requirements for this application. For effective utilization in integrated solar-driven water-splitting systems, such bipolar membranes must, however, be modified to simultaneously optimize their physical properties such as optical transparency, electronic conductivity and kinetics of water dissociation.", "date": "2014-11", "date_type": "published", "publication": "ChemSusChem", "volume": "7", "number": "11", "publisher": "Wiley", "pagerange": "3021-3027", "id_number": "CaltechAUTHORS:20230330-372386000.2", "issn": "1864-5631", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230330-372386000.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "Canada Research Chairs Program" }, { "agency": "Manitoba Science and Technology International Collaboration Fund" }, { "agency": "University of Manitoba" }, { "agency": "Canada Foundation for Innovation" }, { "agency": "Manitoba Research and Innovation Fund" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1002/cssc.201402288", "resource_type": "article", "pub_year": "2014", "author_list": "McDonald, Michael B.; Ardo, Shane; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sjsxv-6v640", "eprint_id": 47359, "eprint_status": "archive", "datestamp": "2023-08-20 03:26:02", "lastmod": "2023-10-26 20:31:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lattimer-J-R-C", "name": { "family": "Lattimer", "given": "Judith R. C." } }, { "id": "Blakemore-J-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Sattler-W", "name": { "family": "Sattler", "given": "Wesley" }, "orcid": "0000-0001-5316-260X" }, { "id": "Gul-S", "name": { "family": "Gul", "given": "Sheraz" }, "orcid": "0000-0001-8920-8737" }, { "id": "Chatterjee-Ruchira", "name": { "family": "Chatterjee", "given": "Ruchira" }, "orcid": "0000-0002-0865-061X" }, { "id": "Yachandra-V-K", "name": { "family": "Yachandra", "given": "Vittal K." } }, { "id": "Yano-Junko", "name": { "family": "Yano", "given": "Junko" }, "orcid": "0000-0001-6308-9071" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Assembly, characterization, and electrochemical properties of immobilized metal bipyridyl complexes on silicon(111) surface", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 Royal Society of Chemistry. \n\nAdvance Article. Received 18th April 2014; Accepted 9th July 2014. First published online 17 Jul 2014. \n\nThe authors thank Aaron Sattler for helpful discussions. Research was carried out in part at the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology. This work was supported by the NSF CCI Solar Fuels Program (CHE-1305124) and CCI Postdoctoral Fellowships to JDB and WS. The synchrotron facility was provided by the Stanford Synchrotron Radiation Laboratory (SSRL) at beam line 7-3. The SSRL Biomedical Technology program is supported by the National Institute of Health (NIH), the National Center for Research Resources, and the DOE Office of Biological and Environmental Research. XAS work was funded by the Director, Office of Science, Office of Basic Energy Sciences (OBES), Division of Chemical Sciences, Geosciences, and Biosciences of the Department of Energy (DOE) under Contract DE-AC02-05CH11231.\n\nPublished - c4dt01149j.pdf
Supplemental Material - c4dt01149j1.pdf
", "abstract": "Silicon(111) surfaces have been functionalized with mixed monolayers consisting of submonolayer coverages of immobilized 4-vinyl-2,2\u2032-bipyridyl (1, vbpy) moieties, with the remaining atop sites of the silicon surface passivated by methyl groups. As the immobilized bipyridyl ligands bind transition metal ions, metal complexes can be assembled on the silicon surface. X-ray photoelectron spectroscopy (XPS) demonstrates that bipyridyl complexes of [Cp*Rh], [Cp*Ir], and [Ru(acac)2] were formed on the surface (Cp* is pentamethylcyclopentadienyl, acac is acetylacetonate). For the surface prepared with Ir, X-ray absorption spectroscopy at the Ir LIII edge showed an edge energy as well as post-edge features that were essentially identical with those observed on a powder sample of [Cp*Ir(bpy)Cl]Cl (bpy is 2,2\u2032-bipyridyl). Charge-carrier lifetime measurements confirmed that the silicon surfaces retain their highly favorable photoelectronic properties upon assembly of the metal complexes. Electrochemical data for surfaces prepared on highly doped, n-type Si(111) electrodes showed that the assembled molecular complexes were redox active. However the stability of the molecular complexes on the surfaces was limited to several cycles of voltammetry.", "date": "2014-10-28", "date_type": "published", "publication": "Dalton Transactions", "volume": "43", "number": "40", "publisher": "Royal Society of Chemistry", "pagerange": "15004-15012", "id_number": "CaltechAUTHORS:20140721-090909176", "issn": "1477-9226", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140721-090909176", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "NSF Postdoctoral Fellowship" }, { "agency": "NIH" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1039/c4dt01149j", "primary_object": { "basename": "c4dt01149j.pdf", "url": "https://authors.library.caltech.edu/records/sjsxv-6v640/files/c4dt01149j.pdf" }, "related_objects": [ { "basename": "c4dt01149j1.pdf", "url": "https://authors.library.caltech.edu/records/sjsxv-6v640/files/c4dt01149j1.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Lattimer, Judith R. C.; Blakemore, James D.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/d8a97-7fh05", "eprint_id": 120630, "eprint_status": "archive", "datestamp": "2023-08-22 14:00:13", "lastmod": "2023-10-23 19:09:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lattimer-Judith-R-C", "name": { "family": "Lattimer", "given": "Judith R. C." } }, { "id": "Blakemore-James-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Sattler-Wesley", "name": { "family": "Sattler", "given": "Wesley" }, "orcid": "0000-0001-5316-260X" }, { "id": "Gul-Sheraz", "name": { "family": "Gul", "given": "Sheraz" }, "orcid": "0000-0001-8920-8737" }, { "id": "Chatterjee-Ruchira", "name": { "family": "Chatterjee", "given": "Ruchira" }, "orcid": "0000-0002-0865-061X" }, { "id": "Yachandra-Vittal-K", "name": { "family": "Yachandra", "given": "Vittal K." }, "orcid": "0000-0002-3983-7858" }, { "id": "Yano-Junko", "name": { "family": "Yano", "given": "Junko" }, "orcid": "0000-0001-6308-9071" }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Assembly, characterization, and electrochemical properties of immobilized metal bipyridyl complexes on silicon(111) surfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "Inorganic Chemistry", "note": "This article is part of the themed collection: Inorganic Chemistry for Renewable Energy Conversion and Storage. \n\nThe authors thank Aaron Sattler for helpful discussions. Research was carried out in part at the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology. This work was supported by the NSF CCI Solar Fuels Program (CHE-1305124) and CCI Postdoctoral Fellowships to JDB and WS. The synchrotron facility was provided by the Stanford Synchrotron Radiation Laboratory (SSRL) at beam line 7-3. The SSRL Biomedical Technology program is supported by the National Institute of Health (NIH), the National Center for Research Resources, and the DOE Office of Biological and Environmental Research. XAS work was funded by the Director, Office of Science, Office of Basic Energy Sciences (OBES), Division of Chemical Sciences, Geosciences, and Biosciences of the Department of Energy (DOE) under Contract DE-AC02-05CH11231.", "abstract": "Silicon(111) surfaces have been functionalized with mixed monolayers consisting of submonolayer coverages of immobilized 4-vinyl-2,2\u2032-bipyridyl (1, vbpy) moieties, with the remaining atop sites of the silicon surface passivated by methyl groups. As the immobilized bipyridyl ligands bind transition metal ions, metal complexes can be assembled on the silicon surface. X-ray photoelectron spectroscopy (XPS) demonstrates that bipyridyl complexes of [Cp*Rh], [Cp*Ir], and [Ru(acac)2] were formed on the surface (Cp* is pentamethylcyclopentadienyl, acac is acetylacetonate). For the surface prepared with Ir, X-ray absorption spectroscopy at the Ir LIII edge showed an edge energy as well as post-edge features that were essentially identical with those observed on a powder sample of [Cp*Ir(bpy)Cl]Cl (bpy is 2,2\u2032-bipyridyl). Charge-carrier lifetime measurements confirmed that the silicon surfaces retain their highly favorable photoelectronic properties upon assembly of the metal complexes. Electrochemical data for surfaces prepared on highly doped, n-type Si(111) electrodes showed that the assembled molecular complexes were redox active. However the stability of the molecular complexes on the surfaces was limited to several cycles of voltammetry.", "date": "2014-10-28", "date_type": "published", "publication": "Dalton Transactions", "volume": "43", "number": "40", "publisher": "Royal Society of Chemistry", "pagerange": "15004-15012", "id_number": "CaltechAUTHORS:20230330-668861000.1", "issn": "1477-9226", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230330-668861000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech Beckman Institute" }, { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1039/c4dt01149j", "resource_type": "article", "pub_year": "2014", "author_list": "Lattimer, Judith R. C.; Blakemore, James D.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6hcdb-j9406", "eprint_id": 51710, "eprint_status": "archive", "datestamp": "2023-08-20 03:20:35", "lastmod": "2023-10-18 17:03:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Antunez-P-D", "name": { "family": "Antunez", "given": "Priscilla D." } }, { "id": "Torelli-D-A", "name": { "family": "Torelli", "given": "Daniel A." }, "orcid": "0000-0002-6222-817X" }, { "id": "Yang-Fan", "name": { "family": "Yang", "given": "Fan" } }, { "id": "Rabuffetti-F-A", "name": { "family": "Rabuffetti", "given": "Federico A." }, "orcid": "0000-0001-8500-3427" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Brutchey-R-L", "name": { "family": "Brutchey", "given": "Richard L." }, "orcid": "0000-0002-7781-5596" } ] }, "title": "Low Temperature Solution-Phase Deposition of SnS Thin Films", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Chemical Society.\n\nReceived: August 25, 2014;\nRevised: September 19, 2014;\nPublished: September 22, 2014.\n\nThis work was supported in part by the National Science\nFoundation under DMR-1205712. P.D.A. acknowledges the\nNational Science Foundation for a Graduate Research Fellowship.\nN.S.L., D.A.T., and F.Y. acknowledge support work\nthrough the Office of Science of the U.S. Department of Energy\n(DOE) under Award No. DE-SC0004993 to the Joint Center\nfor Artificial Photosynthesis, a DOE Energy Innovation Hub.\n\nSupplemental Material - cm503124u_si_001.pdf
", "abstract": "The solution-phase deposition of inorganic semiconductors\nis a promising, scalable method for the manufacture of\nthin film photovoltaics. Deposition of photovoltaic materials\nfrom molecular or colloidal inks offers the possibility of\ninexpensive, rapid, high-throughput thin film fabrication\nthrough processes such as spray coating. For example, CdTe,\nCu(In,Ga)(S,Se)_2 (CIGS), and CH_3NH_3Pb(Cl,I)_3 perovskite-based\nthin film solar cells have been previously deposited using\nsolution-based processes. Inks have also recently been\ndeveloped for the solution deposition of Cu_2ZnSn(S,Se)_4\n(CZTS) and FeS_2 (iron pyrite) absorber layers for thin film\nsolar applications, in order to provide sustainable alternatives to\nmaterials that contain environmentally harmful heavy metals\n(e.g., Cd, Pb) and/or scarce elements (e.g., Te, In).", "date": "2014-10-14", "date_type": "published", "publication": "Chemistry of Materials", "volume": "26", "number": "19", "publisher": "American Chemical Society", "pagerange": "5444-5446", "id_number": "CaltechAUTHORS:20141113-111008849", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141113-111008849", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1205712" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "doi": "10.1021/cm503124u", "primary_object": { "basename": "cm503124u_si_001.pdf", "url": "https://authors.library.caltech.edu/records/6hcdb-j9406/files/cm503124u_si_001.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Antunez, Priscilla D.; Torelli, Daniel A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4p0aq-va764", "eprint_id": 48727, "eprint_status": "archive", "datestamp": "2023-08-23 16:54:57", "lastmod": "2023-10-17 20:23:00", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jin-Jian", "name": { "family": "Jin", "given": "Jian" } }, { "id": "Walczak-K", "name": { "family": "Walczak", "given": "Karl" } }, { "id": "Singh-M-R", "name": { "family": "Singh", "given": "Meenesh R." }, "orcid": "0000-0002-3638-8866" }, { "id": "Karp-C", "name": { "family": "Karp", "given": "Chris" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" } ] }, "title": "An experimental and modeling/simulation-based evaluation of the efficiency and operational performance characteristics of an integrated, membrane-free, neutral pH solar-driven water-splitting system", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 The Royal Society of Chemistry.\n\nReceived 16th June 2014. Accepted 24th July 2014. First published online 25 Jul 2014. \n\nThis material is based upon work performed by the Joint Center\nfor Artificial Photosynthesis, a DOE Energy Innovation Hub,\nsupported through the Office of Science of the U.S. Department\nof Energy under Award Number DE-SC0004993.\n\nPublished - c4ee01824a.pdf
Supplemental Material - c4ee01824a1.pdf
", "abstract": "The efficiency limits, gas-crossover behavior, formation of local pH gradients near the electrode surfaces, and safety characteristics have been evaluated experimentally as well as by use of multi-physics modeling and simulation methods for an integrated solar-driven water-splitting system that operates with bulk electrolyte solutions buffered at near-neutral pH. The integrated membrane-free system utilized a triple-junction amorphous hydrogenated Si (a-Si:H) cell as the light absorber, Pt and cobalt phosphate (Co\u2013Pi) as electrocatalysts for the hydrogen-evolution reaction (HER) and oxygen-evolution reaction (OER), respectively, and a bulk aqueous solution buffered at pH = 9.2 by 1.0 M of boric acid/borate as an electrolyte. Although the solar-to-electrical efficiency of the stand-alone triple-junction a-Si:H photovoltaic cell was 7.7%, the solar-to-hydrogen (STH) conversion efficiency for the integrated membrane-free water-splitting system was limited under steady-state operation to 3.2%, and the formation of pH gradients near the electrode surfaces accounted for the largest voltage loss. The membrane-free system exhibited negligible product-recombination loss while operating at current densities near 3.0 mA cm^(\u22122), but exhibited significant crossover of products (up to 40% H_2 in the O_2 chamber), indicating that the system was not intrinsically safe. A system that contained a membrane to minimize the gas crossover, but which was otherwise identical to the membrane-free system, yielded very low energy-conversion efficiencies at steady state, due to low transference numbers for protons across the membranes resulting in electrodialysis of the solution and the consequent formation of large concentration gradients of both protons and buffer counterions near the electrode surfaces. The modeling and simulation results showed that despite the addition of 1.0 M of buffering agent to the bulk of the solution, during operation significant pH gradients developed near the surfaces of the electrodes. Hence, although the bulk electrolyte was buffered to near-neutral pH, the electrode surfaces and electrocatalysts experienced local environments under steady-state operation that were either highly acidic or highly alkaline in nature, changing the chemical form of the electrocatalysts and exposing the electrodes to potentially corrosive local pH conditions. In addition to significant pH gradients, the STH conversion efficiency of both types of systems was limited by the mass transport of ionic species to the electrode surfaces. Even at operating current densities of <3 mA cm^(\u22122), the voltage drops due to these pH gradients exceeded the combined electrocatalyst overpotentials for the hydrogen- and oxygen-evolution reactions at current densities of 10 mA cm^(\u22122). Hence, such near-neutral pH solar-driven water-splitting systems were both fundamentally limited in efficiency and/or co-evolved explosive mixtures of H_2(g) and O_2(g) in the presence of active catalysts for the recombination of H_2(g) and O_2(g).", "date": "2014-10", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "7", "number": "10", "publisher": "Royal Society of Chemistry", "pagerange": "3371-3380", "id_number": "CaltechAUTHORS:20140820-110452543", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140820-110452543", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c4ee01824a", "primary_object": { "basename": "c4ee01824a.pdf", "url": "https://authors.library.caltech.edu/records/4p0aq-va764/files/c4ee01824a.pdf" }, "related_objects": [ { "basename": "c4ee01824a1.pdf", "url": "https://authors.library.caltech.edu/records/4p0aq-va764/files/c4ee01824a1.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Jin, Jian; Walczak, Karl; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2nyxw-mwc81", "eprint_id": 48864, "eprint_status": "archive", "datestamp": "2023-08-20 03:04:02", "lastmod": "2023-10-17 20:29:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Pala-R-A", "name": { "family": "Pala", "given": "Ragip A." } }, { "id": "Leenheer-A-J", "name": { "family": "Leenheer", "given": "Andrew J." } }, { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael" }, "orcid": "0000-0002-0710-7068" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Measurement of minority-carrier diffusion lengths using wedge-shaped semiconductor photoelectrodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 Royal Society of Chemistry 2014. \n\nReceived 22 May 2014, Accepted 29 July 2014. First published online 29 July 2014. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. We thank C. Garland for advice on polishing techniques. \n\nElectronic supplementary information (ESI) available: Additional equations for photocurrent calculations, XRD for WO_3 deposited at various temperature, optical determination of thickness profile, cyclic voltammetry scan of WO_3 electrodes, and further details on the ALD processing and polishing. See DOI: 10.1039/c4ee01580k\n\nPublished - c4ee01580k.pdf
Supplemental Material - c4ee01580k1.pdf
", "abstract": "Measurement of the photocurrent as a function of the thickness of a light absorber has been shown herein both theoretically and experimentally to provide a method for determination of the minority-carrier diffusion length of a sample. To perform the measurement, an illuminated spot of photons with an energy well above the band gap of the material was scanned along the thickness gradient of a wedge-shaped, rear-illuminated semiconducting light absorber. Photogenerated majority carriers were collected through a back-side transparent ohmic contact, and a front-side liquid or Schottky junction collected the photogenerated minority carriers. Calculations showed that the diffusion length could be evaluated from the exponential variation in photocurrent as a function of the thickness of the sample. Good agreement was observed between experiment and theory for a solid-state silicon Schottky junction measured using this method. As an example for the application of the technique to semiconductor/liquid-junction photoelectrodes, the minority-carrier diffusion length was determined for graded thickness, sputtered tungsten trioxide and polished bismuth vanadate films under back-illumination in contact with an aqueous electrolyte. This wedge technique does not require knowledge of the spectral absorption coefficient, doping, or surface recombination velocity of the sample.", "date": "2014-10", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "7", "number": "10", "publisher": "Royal Society of Chemistry", "pagerange": "3424-3430", "id_number": "CaltechAUTHORS:20140825-152741705", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140825-152741705", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/C4EE01580K", "primary_object": { "basename": "c4ee01580k.pdf", "url": "https://authors.library.caltech.edu/records/2nyxw-mwc81/files/c4ee01580k.pdf" }, "related_objects": [ { "basename": "c4ee01580k1.pdf", "url": "https://authors.library.caltech.edu/records/2nyxw-mwc81/files/c4ee01580k1.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Pala, Ragip A.; Leenheer, Andrew J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hpj51-xa558", "eprint_id": 53625, "eprint_status": "archive", "datestamp": "2023-08-20 03:09:55", "lastmod": "2023-10-19 21:55:37", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Eisler-C-N", "name": { "family": "Eisler", "given": "Carissa" }, "orcid": "0000-0002-5755-5280" }, { "id": "Lloyd-J", "name": { "family": "Lloyd", "given": "John" } }, { "id": "Flowers-C-A", "name": { "family": "Flowers", "given": "Cris" }, "orcid": "0000-0001-7864-3629" }, { "id": "Darbe-S", "name": { "family": "Darbe", "given": "Sunita" }, "orcid": "0000-0002-8099-1814" }, { "id": "Warmann-E-C", "name": { "family": "Warmann", "given": "Emily" }, "orcid": "0000-0002-2810-4608" }, { "id": "Verlage-E", "name": { "family": "Verlage", "given": "Erik" } }, { "id": "Fountaine-K-T", "name": { "family": "Fountaine", "given": "Kate" }, "orcid": "0000-0002-0414-8227" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Routes to Ultrahigh Efficiency Photovoltaic and Photoelectrochemical Devices", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 IEEE.", "abstract": "We discuss 'full spectrum' photovoltaic modules that leverage low-cost III-V compound semiconductor cells, efficient optics and unconventional fabrication/assembly methods, and discuss advances in photoelectrochemical water-splitting with high efficiency.", "date": "2014-10", "date_type": "published", "publisher": "IEEE", "id_number": "CaltechAUTHORS:20150113-111351350", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150113-111351350", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1109/IPCon.2014.6995432", "resource_type": "book_section", "pub_year": "2014", "author_list": "Eisler, Carissa; Lloyd, John; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fr6k2-kgx11", "eprint_id": 49692, "eprint_status": "archive", "datestamp": "2023-08-20 03:04:45", "lastmod": "2023-10-17 22:05:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "McDowell-Matthew-T", "name": { "family": "McDowell", "given": "Matthew T." }, "orcid": "0000-0001-5552-3456" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Stabilization of n-cadmium telluride photoanodes for water oxidation to O_2(g) in aqueous alkaline electrolytes using amorphous TiO_2 films formed by atomic-layer deposition", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 Royal Society of Chemistry. \n\nReceived 20th June 2014; accepted 21st August 2014. First published online 22 Aug 2014. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U. S. Department of Energy under Award Number DE-SC0004993. The authors gratefully acknowledge Dr Ke Sun for insightful discussions and Dr Slobodan Mitrovic for assistance collecting XPS data. AIC is grateful to the National Science Foundation for support from an NSF Graduate Research Fellowship. BSB and HBG acknowledge\nthe Beckman Institute Materials and Laser Resource Centers\nand NSF CHE-1305124 for support.\n\nPublished - c4ee01914h.pdf
Supplemental Material - c4ee01914h1.pdf
", "abstract": "Although II\u2013VI semiconductors such as CdS, CdTe, CdSe, ZnTe, and alloys thereof can have nearly ideal band gaps and band-edge positions for the production of solar fuels, II\u2013VI photoanodes are well-known to be unstable towards photocorrosion or photopassivation when in contact with aqueous electrolytes. Atomic-layer deposition (ALD) of amorphous, \"leaky\" TiO_2 films coated with thin films or islands of Ni oxide has been shown to robustly protect Si, GaAs, and other III\u2013V materials from photocorrosion and therefore to facilitate the robust, solar-driven photoelectrochemical oxidation of H_2O to O_2(g). We demonstrate herein that ALD-deposited 140 nm thick amorphous TiO_2 films also effectively protect single crystalline n-CdTe photoanodes from corrosion or passivation. An n-CdTe/TiO_2 electrode with a thin overlayer of a Ni-oxide based oxygen-evolution electrocatalyst produced 435 \u00b1 15 mV of photovoltage with a light-limited current density of 21 \u00b1 1 mA cm^\u22122 under 100 mW cm^\u22122 of simulated Air Mass 1.5 illumination. The ALD-deposited TiO_2 films are highly optically transparent and electrically conductive. We show that an n-CdTe/TiO_2/Ni oxide electrode enables the stable solar-driven oxidation of H_2O to O_2(g) in strongly alkaline aqueous solutions, where passive, intrinsically safe, efficient systems for solar-driven water splitting can be operated.", "date": "2014-10", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "7", "number": "10", "publisher": "Royal Society of Chemistry", "pagerange": "3334-3337", "id_number": "CaltechAUTHORS:20140915-092918358", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140915-092918358", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Caltech Beckman Institute" }, { "agency": "NSF", "grant_number": "CHE-1305124" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/C4EE01914H", "primary_object": { "basename": "c4ee01914h1.pdf", "url": "https://authors.library.caltech.edu/records/fr6k2-kgx11/files/c4ee01914h1.pdf" }, "related_objects": [ { "basename": "c4ee01914h.pdf", "url": "https://authors.library.caltech.edu/records/fr6k2-kgx11/files/c4ee01914h.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Lichterman, Michael F.; Carim, Azhar I.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/xrm2y-w7r50", "eprint_id": 49306, "eprint_status": "archive", "datestamp": "2023-08-20 03:04:10", "lastmod": "2023-10-17 21:18:04", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Wong-K-T", "name": { "family": "Wong", "given": "Keith T." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "What a Difference a Bond Makes: The Structural, Chemical, and Physical Properties of Methyl-Terminated Si(111) Surfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.\n\nReceived: May 30, 2014.\nPublication Date (Web): September 5, 2014.\n\nThis work was supported by the National Science Foundation\n(CHE-1214152). The authors thank Noah T. Plymale for\nhelpful comments during preparation of this manuscript.", "abstract": "The chemical, electronic, and structural properties of surfaces are affected by the chemical termination of the surface. Two-step halogenation/alkylation of silicon provides a scalable, wet-chemical method for grafting molecules onto the silicon surface. Unlike other commonly studied wet-chemical methods of surface modification, such as self-assembly of monolayers on metals or hydrosilylation on silicon, the two-step method enables attachment of small alkyl chains, even methyl groups, to a silicon surface with high surface coverage and homogeneity. The methyl-terminated Si(111) surface, by comparison to hydrogen-terminated Si(111), offers a unique opportunity to study the effects of the first surface bond connecting the overlayer to the surface. This Account describes studies of methyl-terminated Si(111), which have shown that the H\u2013Si(111) and CH_3\u2013Si(111) surfaces are structurally nearly identical, yet impart significantly different chemical and electronic properties to the resulting Si surface.\nThe structure of methyl-terminated Si(111) formed by a two-step halogenation/methylation process has been studied by a variety of spectroscopic methods. A covalent Si\u2013C bond is oriented normal to the surface, with the methyl group situated directly atop a surface Si atom. Multiple spectroscopic methods have shown that methyl groups achieve essentially complete coverage of the surface atoms while maintaining the atomically flat, terraced structure of the original H\u2013Si(111) surface. Thus, the H\u2013Si(111) and CH_3\u2013Si(111) surface share essentially identical structures aside from the replacement of a Si\u2013H bond with a Si\u2013C bond.\nDespite their structural similarity, hydrogen and methyl termination exhibit markedly different chemical passivation. Specifically, CH_3\u2013Si(111) exhibits significantly greater oxidation resistance than H\u2013Si(111) in air and in aqueous electrolyte under photoanodic current flow. Both surfaces exhibit similar thermal stability in vacuum, and the Si\u2013H and Si\u2013C bond strengths are expected to be very similar, so the results suggest that methyl termination presents a greater kinetic barrier to oxidation of the underlying Si surface. Hydrogen termination of Si(111) provides nearly perfect electronic passivation of surface states (i.e., less than 1 electronic defect per 40 million surface atoms), but this electronic passivation is rapidly degraded by oxidation in air or under electrochemical conditions. In contrast, methyl termination provides excellent electronic passivation that resists degradation due to oxidation. Moreover, alkylation modifies the surface electronic structure by creating a surface dipole that effectively changes the electron affinity of the Si surface, facilitating modification of the charge-transfer kinetics across Si/metal or Si/electrolyte junctions.\nThis Account also briefly describes recent studies of mixed monolayers formed by the halogenation/alkylation of silicon. Mixed monolayers allow attachment of bulkier groups that enable secondary chemistry at the surface (e.g., attachment of molecular catalysts or seeding of atomic layer deposition) to be combined with methyl termination of remaining unreacted surface sites. Thus, secondary chemistry can be enabled while maintaining the chemical and electronic passivation provided by complete termination of surface atoms with Si\u2013C bonds. Such studies of mixed monolayers demonstrate the potential use of a wet-chemical surface modification scheme that combines both chemical and electronic passivation.", "date": "2014-10", "date_type": "published", "publication": "Accounts of Chemical Research", "volume": "47", "number": "10", "publisher": "American Chemical Society", "pagerange": "3037-3044", "id_number": "CaltechAUTHORS:20140908-081237661", "issn": "0001-4842", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140908-081237661", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" } ] }, "doi": "10.1021/ar500207y", "resource_type": "article", "pub_year": "2014", "author_list": "Wong, Keith T. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7hsq8-3g478", "eprint_id": 45110, "eprint_status": "archive", "datestamp": "2023-08-22 13:43:01", "lastmod": "2023-10-26 17:33:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Huang-Zhuangqun", "name": { "family": "Huang", "given": "Zhuangqun" } }, { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Grimm-R-L", "name": { "family": "Grimm", "given": "Ronald L." }, "orcid": "0000-0003-0407-937X" }, { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Lewerenz-H-J", "name": { "family": "Lewerenz", "given": "Hans-Joachim" }, "orcid": "0000-0001-8433-9471" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparison between the measured and modeled hydrogen-evolution activity of Ni- or Pt-coated silicon photocathodes", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Silicon; Photoelectrochemistry; Photocatalysis; HER; Interface; Solar fuels", "note": "\u00a9 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. \n\nReceived 10 October 2013; Received in revised form 19 December 2013; Accepted 24 December 2013; Available online 13 April 2014. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. JRM acknowledges graduate research fellowship support from the U.S. Department of Energy, Office of Science. Research was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. Z.H. thanks Prof. Steve Maldonado, Joseph Beardslee, Heather Audesirk and Craig Wiggenhorn for their assistance with the experiments and for helpful discussions.", "abstract": "The electrocatalytic behavior of Ni and Pt nanoparticles for the hydrogen-evolution reaction (HER) on p-type Si photocathodes was measured experimentally and the current density vs. potential (J\u2013E) characteristics of a general metal catalyst on p-Si was modeled as a combination of a Si photodiode in series electrically with metal electrocatalysts. Relative to the rest potential, the J\u2013E characteristics produced by the model showed an increase in total overpotential required to reach a specified current density for the metallized photoelectrodes relative to that of a metal electrode. This prediction was in accord with the experimentally observed behavior of Pt on p-Si, but was in contrast to the behavior observed for Ni on p-Si. Properly accounting for junction energetics and kinetics of the HER is critical to accurate predictions of the solar-to-hydrogen (STH) energy-conversion efficiency of metallized integrated photoelectrochemical systems. Further, models that accurately predict the performance of metal catalysts on semiconductor light absorbers are required to optimize the catalytic performance of metallized photoelectrodes.", "date": "2014-09-23", "date_type": "published", "publication": "International Journal of Hydrogen Energy", "volume": "39", "number": "28", "publisher": "Elsevier", "pagerange": "16220-16226", "id_number": "CaltechAUTHORS:20140422-103752009", "issn": "0360-3199", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140422-103752009", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1016/j.ijhydene.2013.12.162", "resource_type": "article", "pub_year": "2014", "author_list": "Huang, Zhuangqun; McKone, James R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hh58q-9ph72", "eprint_id": 47878, "eprint_status": "archive", "datestamp": "2023-08-20 02:56:16", "lastmod": "2023-10-26 21:19:31", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "Soriaga-M-P", "name": { "family": "Soriaga", "given": "Manuel P." }, "orcid": "0000-0002-0077-6226" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electrocatalysis of the hydrogen-evolution reaction by electrodeposited amorphous cobalt selenide films", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 The Royal Society of Chemistry. \n\nReceived 25th May 2014. Accepted 11th June 2014. First published online 24 Jul 2014. \n\nThis material is based in part upon work performed by the Joint Center for Artificial photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U. S. Department of Energy under Award Number DE-SC0004993. The authors gratefully acknowledge Dr S. Mitrovic for assistance with X-ray photoelectron spectra acquisition, R. Gerhart for\nassistance with cell fabrication and Dr J. H. Baricuatro for\ninsightful discussions. AIC recognizes a Graduate Research\nFellowship from the National Science Foundation for support.\n\nPublished - c4ta02611j.pdf
Supplemental Material - c4ta02611j1.pdf
", "abstract": "Using an electrochemical method under ambient conditions, crystallographically amorphous films of cobalt selenide have been deposited from aqueous solution onto planar Ti supports. These films have been evaluated as electrocatalysts for the hydrogen-evolution reaction. In 0.500 M H_2SO_4, the cobalt selenide films required an overpotential of ~135 mV to drive the hydrogen-evolution reaction at a benchmark current density of \u221210 mA cm^(\u22122). Galvanostatic measurements indicated stability of the electrocatalytic films for >16 h of continuous operation at \u221210 mA cm^(\u22122). The facile preparation method, and the activity of the cobalt selenide films, suggest that electrodeposited metal chalcogenides are potentially attractive earth-abundant electrocatalysts for the hydrogen-evolution reaction.", "date": "2014-09-14", "date_type": "published", "publication": "Journal of Materials Chemistry A", "volume": "2", "number": "34", "publisher": "Royal Society of Chemistry", "pagerange": "13835-13839", "id_number": "CaltechAUTHORS:20140804-095437360", "issn": "2050-7488", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140804-095437360", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1039/C4TA02611J", "primary_object": { "basename": "c4ta02611j.pdf", "url": "https://authors.library.caltech.edu/records/hh58q-9ph72/files/c4ta02611j.pdf" }, "related_objects": [ { "basename": "c4ta02611j1.pdf", "url": "https://authors.library.caltech.edu/records/hh58q-9ph72/files/c4ta02611j1.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Carim, Azhar I.; Saadi, Fadl H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rt9d5-8e422", "eprint_id": 47873, "eprint_status": "archive", "datestamp": "2023-08-20 02:42:08", "lastmod": "2023-10-26 21:19:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "Carim-Azhar-I", "name": { "family": "Carim", "given": "Azhar I." }, "orcid": "0000-0003-3630-6872" }, { "id": "Velazquez-Jesus-M", "name": { "family": "Velazquez", "given": "Jesus M." } }, { "id": "Baricuatro-Jack-H", "name": { "family": "Baricuatro", "given": "Jack H." }, "orcid": "0000-0002-9210-344X" }, { "id": "McCrory-Charles-C-L", "name": { "family": "McCrory", "given": "Charles C. L." }, "orcid": "0000-0001-9039-7192" }, { "id": "Soriaga-M-P", "name": { "family": "Soriaga", "given": "Manuel P." }, "orcid": "0000-0002-0077-6226" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Operando Synthesis of Macroporous Molybdenum Diselenide Films for Electrocatalysis of the Hydrogen-Evolution Reaction", "ispublished": "pub", "full_text_status": "public", "keywords": "hydrogen-evolution reaction, synthesis of molybdenum diselenide, wet-chemical synthesis of layered electrocatalysts,\nmesoporous catalysts, synthesis of group VI dichalcogenides", "note": "\u00a9 2014 American Chemical Society. \n\nReceived: December 16, 2013. Revised: July 17, 2014. Published: July 17, 2014. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a U.S. Department of Energy (DOE) Energy Innovation Hub, supported through the Office of Science of the DOE via Grant DE-SC0004993. A.I.C. acknowledges a National Science Foundation Graduate Research Fellowship for support.\n\nSupplemental Material - cs500412u_si_001.pdf
", "abstract": "The catalytically inactive components of a film have been converted, through an operando method of synthesis, to produce a catalyst for the reaction that the film is catalyzing. Specifically, thin films of molybdenum diselenide have been synthesized using a two-step wet-chemical method, in which excess sodium selenide was first added to a solution of ammonium heptamolydbate in aqueous sulfuric acid, resulting in the spontaneous formation of a black precipitate that contained molybdenum triselenide (MoSe_3), molybdenum trioxide (MoO_3), and elemental selenium. After purification and after the film had been drop cast onto a glassy carbon electrode, a reductive potential was applied to the precipitate-coated electrode. Hydrogen evolution occurred within the range of potentials applied to the electrode, but during the initial voltammetric cycle, an overpotential of ~400 mV was required to drive the hydrogen-evolution reaction at a benchmark current density of \u221210 mA cm^(\u20132). The overpotential required to evolve hydrogen at the benchmark rate progressively decreased with subsequent voltammetry cycles, until a steady state was reached at which only ~250 mV of overpotential was required to pass \u221210 mA cm^(\u20132) of current density. During the electrocatalysis, the catalytically inactive components in the as-prepared film were (reductively) converted to MoSe_2 through an operando method of synthesis of the hydrogen-evolution catalyst. The initial film prepared from the precipitate was smooth, but the converted film was completely covered with pores ~200 nm in diameter. The porous MoSe_2 film was stable while being assessed by cyclic voltammetry for 48 h, and the overpotential required to sustain 10 mA cm^(\u20132) of hydrogen evolution increased by <50 mV over this period of operation.", "date": "2014-09", "date_type": "published", "publication": "ACS Catalysis", "volume": "4", "number": "9", "publisher": "American Chemical Society", "pagerange": "2866-2873", "id_number": "CaltechAUTHORS:20140804-090046189", "issn": "2155-5435", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140804-090046189", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "primary_object": { "basename": "cs500412u_si_001.pdf", "url": "https://authors.library.caltech.edu/records/rt9d5-8e422/files/cs500412u_si_001.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Saadi, Fadl H.; Carim, Azhar I.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mhzgr-bbg02", "eprint_id": 48856, "eprint_status": "archive", "datestamp": "2023-08-20 02:38:54", "lastmod": "2023-10-17 20:29:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "McDowell-M-T", "name": { "family": "McDowell", "given": "Matthew T." }, "orcid": "0000-0001-5552-3456" }, { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Sharp-I-D", "name": { "family": "Sharp", "given": "Ian D." }, "orcid": "0000-0001-5238-7487" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Improved Stability of Polycrystalline Bismuth Vanadate Photoanodes by Use of Dual-Layer Thin TiO_2/Ni Coatings", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Chemical Society. \n\nReceived: June 20, 2014; Revised: August 6, 2014; Published: August 7, 2014. \n\nThis material is based upon work performed at the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award DE-SC0004993. XPS data were collected at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology.\n\nSupplemental Material - jp506133y_si_001.pdf
", "abstract": "Ultrathin dual layers of TiO_2 and Ni have been used to stabilize polycrystalline BiVO_4 photoanodes against photocorrosion in an aqueous alkaline (pH = 13) electrolyte. Conformal, amorphous TiO_2 layers were deposited on BiVO_4 thin films by atomic-layer deposition, with Ni deposited onto the TiO_2 by sputtering. Under simulated air mass 1.5 illumination, the dual-layer coating extended the lifetime of the BiVO4 photoanodes during photoelectrochemical water oxidation from minutes, for bare BiVO4, to hours, for the modified electrodes. X-ray photoelectron spectroscopy showed that these layers imparted chemical stability to the semiconductor/electrolyte interface. Transmission electron microscopy revealed the structure and morphology of the polycrystalline BiVO_4 film as well as of the thin coating layers. This work demonstrates that protection schemes based on ultrathin corrosion-resistant overlayers can be applied beneficially to polycrystalline photoanode materials under conditions relevant to efficient solar-driven water-splitting systems.", "date": "2014-08-28", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "118", "number": "34", "publisher": "American Chemical Society", "pagerange": "19618-19624", "id_number": "CaltechAUTHORS:20140825-134317366", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140825-134317366", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/jp506133y", "primary_object": { "basename": "jp506133y_si_001.pdf", "url": "https://authors.library.caltech.edu/records/mhzgr-bbg02/files/jp506133y_si_001.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "McDowell, Matthew T.; Lichterman, Michael F.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/vddy0-6wp73", "eprint_id": 50117, "eprint_status": "archive", "datestamp": "2023-08-20 02:37:31", "lastmod": "2023-10-17 22:31:44", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "McEnaney-J-M", "name": { "family": "McEnaney", "given": "Joshua M." } }, { "id": "Crompton-J-C", "name": { "family": "Crompton", "given": "J. Chance" } }, { "id": "Callejas-J-F", "name": { "family": "Callejas", "given": "Juan F." } }, { "id": "Popczun-E-J", "name": { "family": "Popczun", "given": "Eric J." } }, { "id": "Biacchi-A-J", "name": { "family": "Biacchi", "given": "Adam J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Schaak-R-E", "name": { "family": "Schaak", "given": "Raymond E." } } ] }, "title": "Amorphous Molybdenum Phosphide Nanoparticles for Electrocatalytic Hydrogen Evolution", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Chemical Society.\n\nReceived: June 4, 2014; revised: July 15, 2014; published: July 17, 2014.\n\nThis work was supported at PSU by the National Science\nFoundation (NSF) Center for Chemical Innovation on Solar\nFuels (CHE-1305124) and at Caltech by the Joint Center for\nArtificial Photosynthesis, a DOE Energy Innovation Hub,\nsupported through the Office of Science of the U.S.\nDepartment of Energy under Award DE-SC0004993. TEM\nimaging was performed in the Penn State Microscopy and\nCytometry Facility (University Park, PA) and HRTEM\nimaging, EDS spectra, XPS spectra, and DRIFTS spectra\nwere acquired at the Materials Characterization Laboratory of the Penn State Materials Research Institute. J.M.M. thanks Jennifer Gray for assistance with analyzing the XPS spectra and Dr. Thomas Gordon for assistance with quantitative yield experiments.\n\nSupplemental Material - cm502035s_si_001.pdf
", "abstract": "Amorphous molybdenum phosphide (MoP) nanoparticles have been synthesized and characterized as electrocatalysts for the hydrogen-evolution reaction (HER) in 0.50 M H_2SO_4 (pH 0.3). Amorphous MoP nanoparticles (having diameters of 4.2 \u00b1 0.5 nm) formed upon heating Mo(CO)6 and trioctylphosphine in squalane at 320 \u00b0C, and the nanoparticles remained amorphous after heating at 450 \u00b0C in H_2(5%)/Ar(95%) to remove the surface ligands. At mass loadings of 1 mg cm^\u20132, MoP/Ti electrodes exhibited overpotentials of \u221290 and \u2212105 mV (\u2212110 and \u2212140 mV without iR correction) at current densities of \u221210 and \u221220 mA cm^\u20132, respectively. These HER overpotentials remained nearly constant over 500 cyclic voltammetric sweeps and 18 h of galvanostatic testing, indicating stability in acidic media under operating conditions. Amorphous MoP nanoparticles are therefore among the most active known molybdenum-based HER systems and are part of a growing family of active, acid-stable, non-noble-metal HER catalysts.", "date": "2014-08-26", "date_type": "published", "publication": "Chemistry of Materials", "volume": "26", "number": "16", "publisher": "American Chemical Society", "pagerange": "4826-4831", "id_number": "CaltechAUTHORS:20140930-095609063", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140930-095609063", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/cm502035s", "primary_object": { "basename": "cm502035s_si_001.pdf", "url": "https://authors.library.caltech.edu/records/vddy0-6wp73/files/cm502035s_si_001.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "McEnaney, Joshua M.; Crompton, J. Chance; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/yny2z-2pb07", "eprint_id": 50146, "eprint_status": "archive", "datestamp": "2023-08-20 02:23:32", "lastmod": "2023-10-17 22:48:10", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" } }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Modeling the Performance of an Integrated Photoelectrolysis System with 10\u00d7 Solar Concentrators", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.\n\nManuscript submitted June 13, 2014; revised manuscript received July 10, 2014. Published August 1, 2014.\n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. The authors thank John C. Stevens for helpful discussion regarding the optics of solar concentrator designs. Authors Yikai Chen and Chengxiang Xiang contributed equally to this work.\n\nPublished - J._Electrochem._Soc.-2014-Chen-F1101-10.pdf
", "abstract": "Two designs for an integrated photoelectrolysis system that uses a 10\u00d7 concentrating solar collector have been investigated in detail. The system performance was evaluated using a multi-physics model that accounted for the properties of the tandem photoabsorbers, mass transport, and the electrocatalytic performance of the oxygen-evolution and hydrogen-evolution reactions (OER and HER, respectively). The solar-to-hydrogen (STH) conversion efficiencies and the ohmic losses associated with proton transport in the solution electrolyte and through the membrane of the photoelectrolysis system were evaluated systematically as a function of the cell dimensions, the operating temperatures, the bandgap combinations of the tandem cell, and the performance of both the photoabsorbers and electrocatalysts. Relative to designs of optimized systems that would operate without a solar concentrator, the optimized 10\u00d7 solar concentrator designs possessed larger ohmic losses and exhibited less uniformity in the distribution of the current density along the width of the photoelectrode. To minimize resistive losses while maximizing the solar-to-hydrogen conversion efficiency, \u03b7_(STH), both of the designs, a two-dimensional \"trough\" design and a three-dimensional \"bubble wrap\" design, required that the electrode width or diameter, respectively, was no larger than a few millimeters. As the size of the electrodes increased beyond this limiting dimension, the \u03b7_(STH) became more sensitive to the performance of the photoabsorbers and catalysts. At a fixed electrode dimension, increases in the operating temperature reduced the efficiency of cells with smaller electrodes, due to degradation in the performance of the photoabsorber with increasing temperature. In contrast, cells with larger electrode dimensions showed increases in efficiency as the temperature increased, due to increases in the rates of electrocatalysis and due to enhanced mass transport. The simulations indicted that cells that contained 10% photoabsorber area, and minimal amounts of Nafion or other permselective membranes (i.e. areal coverages and volumetric fractions of only a few percent of the cell), with the remaining area comprised of a suitable, low-cost inert, non porous material (flexible polymers, inert inorganic materials, etc.) should be able to produce high values of \u03b7_(STH), with \u03b7_(STH) = 29.8% for an optimized design with a bandgap combination of 1.6 eV/0.9 eV in a tandem photoabsorber system at 350 K.", "date": "2014-08-01", "date_type": "published", "publication": "Journal of the Electrochemical Society", "volume": "161", "number": "10", "publisher": "Electrochemical Society", "pagerange": "F1101-F1110", "id_number": "CaltechAUTHORS:20141001-112924015", "issn": "0013-4651", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141001-112924015", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1149/2.0751410jes", "primary_object": { "basename": "J._Electrochem._Soc.-2014-Chen-F1101-10.pdf", "url": "https://authors.library.caltech.edu/records/yny2z-2pb07/files/J._Electrochem._Soc.-2014-Chen-F1101-10.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Chen, Yikai; Xiang, Chengxiang; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/f4vwg-fyj11", "eprint_id": 48477, "eprint_status": "archive", "datestamp": "2023-08-20 02:11:33", "lastmod": "2023-10-20 23:21:04", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Blakemore-J-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Lattimer-J-R-C", "name": { "family": "Lattimer", "given": "Judith R." } }, { "id": "Sattler-W", "name": { "family": "Sattler", "given": "Wesley" }, "orcid": "0000-0001-5316-260X" }, { "id": "Gul-S", "name": { "family": "Gul", "given": "Sheraz" }, "orcid": "0000-0001-8920-8737" }, { "id": "Yano-Junko", "name": { "family": "Yano", "given": "Junko" }, "orcid": "0000-0001-6308-9071" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Assembly, characterization, and electrochemical properties of immobilized metal bipyridyl complexes on silicon(111) surfaces", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "A route to bipyridine-functionalized silicon(111) surfaces has been developed which gave submonolayer surface coverage of immobilized 4-vinyl-2,2'-bipyridyl (vbpy). The remaining atop sites of the silicon surface were passivated with Me groups. The immobilized bipyridyl ligands bound metal ions, thus enabling assembly of metal complexes on the silicon surface. XPS studies demonstrated that [Cp*Rh(vbpy)Cl]Cl, [Cp*Ir(vbpy)Cl]Cl, and Ru(acac)2vbpy were assembled on the surface (Cp* is pentamethylcyclopentadienyl, acac is acetylacetonate). For the surface prepd. with iridium, X-ray absorption spectroscopy at the Ir L_(III) edge showed an edge energy and post-edge features consistent with a powder sample of [Cp*Ir(bpy)Cl]Cl (bpy is 2,2'-bipyridyl). Cyclic voltammetry data for surfaces prepd. on highly doped, conducting silicon confirmed electroactivity of the assembled complexes.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140813-084518207", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140813-084518207", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Blakemore, James D.; Lattimer, Judith R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/as5ke-14470", "eprint_id": 48426, "eprint_status": "archive", "datestamp": "2023-08-20 02:10:15", "lastmod": "2023-10-17 19:20:42", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Chemical control over the electrical, electronic, and electrochemical properties of Si surfaces", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "We have developed mixed monolayer chem. that allows for incorporation of a versatile component and a 'filler' component to impart simultaneous stability and function at Si surfaces. Optoelectronic device efficiency depends on control over chem. and electronic properties. We were able to functionalize silicon surfaces with mixed thiophene/methyl monolayers. The mixed monolayer method allowed for functionalization with thiophene groups while maintaining a low surface recombination velocity, S, of 27\u00b19 cm s^(-1), while the single component thiophene-functionalized Si(111) surface displayed S=670\u00b1190 cm s^(-1). Pd-catalyzed Heck coupling was achieved at mixed thienylBr/CH_3-Si(111) surfaces. Coverage of \u03b8 = 0.11\u00b10.03 was achieved for Heck-coupled fluorostyrene. The Heck coupling reaction was versatile, vinylferrocene and protoporphyrin-IX were also successfully coupled to the surface, and low surface recombination velocity was maintained after the coupling chem. Thienybromide functionalization induced an interfacial dipole, which was studied via spectroscopic and electronic experimentation and was investigated by ab initio methods. The band-edge positions were favorably shifted 400 mV from those at the CH_3-Si(111) surfaces. The mixed monolayer technique can be similarly applied to attach protected aldehydes. Once deprotected, mixed propanal/methyl-Si(111) assisted at. layer deposition of Al_2O_3 and MnO_x. Increased deposition and decreased surface electronic defects were obsd. at propanal functionalized surfaces as compared to H-Si(111) surfaces. This has direct benefits for both surface protection and field effect transistors. The mixed monolayer method was shown to increase synthetic versatility, decrease electronic trap state d., and improve control of interfacial energetics.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140812-142326452", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140812-142326452", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/x5pkv-v8p92", "eprint_id": 48420, "eprint_status": "archive", "datestamp": "2023-08-20 02:10:01", "lastmod": "2023-10-17 18:48:05", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nielander-A-C", "name": { "family": "Nielander", "given": "Adam C." }, "orcid": "0000-0002-3639-2427" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Graphene as protective layer for silicon in an aqueous PEC cell", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "Graphene may be an almost ideal protection layer for semiconductor photoelectrodes. It can be grown in nearly pinhole-free large area layers and has been shown to inhibit the oxidn. of metals in air as well as in aq. electrochem. environments. In this study, the electrochem. behavior of graphene-coated n-type Si(111) photoanodes was compared to that of H-terminated n-type Si(111) photoanodes in contact with aq. K_3[Fe(CN)_6]/K_4[Fe(CN)_6] as well as in contact with a series of one-electron redox couples in non-aq. electrolytes. The n-Si/Graphene electrodes exhibited stable short-circuit photocurrent densities of over 10 mA cm^(-2) for over 1000 s of operation in aq. electrolytes, whereas n-Si-H electrodes yielded nearly complete decay of the c.d. within approx. 30 s. The values of the open-circuit photovoltages and the flat-band potentials of the Si were a function of both the Fermi level of the graphene and the electrochem. potential of the electrolyte soln., indicating that the n-Si/Graphene interface did not form a buried junction with the soln. contact. The use of addnl. layers of graphene further improved stability while leading to a junction that was increasingly pinned by the Si/graphene interface.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140812-135108732", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140812-135108732", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Nielander, Adam C. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/570jq-a6r63", "eprint_id": 48593, "eprint_status": "archive", "datestamp": "2023-08-20 02:14:36", "lastmod": "2023-10-17 19:28:23", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Sunlight-driven hydrogen formation by membrane-supported photoelectrochemical water splitting", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "We are developing an artificial photosynthetic system that will utilize sunlight and water as the inputs and produce hydrogen and oxygen as the outputs. We are taking a modular, parallel development approach in which three distinct primary components-the photoanode, the photocathode, and the product-sepg. but ion-conducting membrane-are fabricated and optimized sep. before assembly into a complete water-splitting system. The design principles incorporate two sep., photosensitive semiconductor/liq. junctions that will collectively generate the 1.7-1.9 V at open circuit necessary to support both the oxidn. of H_2O (or OH^-) and the redn. of H^+ (or H_2O). The photoanode and photocathode will consist of rod-like semiconductor components, with attached heterogeneous multi-electron transfer catalysts, which are needed to drive the oxidn. or redn. reactions at low overpotentials. The high aspect-ratio semiconductor rod electrode architecture allows for the use of low cost, earth abundant materials without sacrificing energy conversion efficiency due to the orthogonalization of light absorption and charge-carrier collection. Addnl., the high surface-area design of the rod-based semiconductor array electrode inherently lowers the flux of charge carriers over the rod array surface relative to the projected geometric surface of the photoelectrode, thus lowering the photocurrent d. at the solid/liq. junction and thereby relaxing the demands on the activity (and cost) of any electrocatalysts. A flexible composite polymer film will allow for electron and ion conduction between the photoanode and photocathode while simultaneously preventing mixing of the gaseous products. Sep. polymeric materials will be used to make elec. contact between the anode and cathode, and also to provide structural support. Interspersed patches of an ion conducting polymer will maintain charge balance between the two half-cells.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140815-091820889", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140815-091820889", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3f7fa-6ee61", "eprint_id": 48604, "eprint_status": "archive", "datestamp": "2023-08-20 02:15:05", "lastmod": "2023-10-17 19:28:53", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Plymale-N-T", "name": { "family": "Plymale", "given": "Noah T." }, "orcid": "0000-0003-2564-8009" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Synthesis and characterization of well-ordered methyl-, ethynyl-, and propynyl-terminated Si(111) surfaces", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "Alkyl-termination of Si(111) surfaces has been shown to effectively passivate the surface to oxidn. in air. Me groups are unique among satd. hydrocarbons in that they are capable of terminating nearly all of the Si(111) atop sites. However, secondary functionalization of methyl-terminated Si has proven challenging. Ethynyl and propynyl groups, which have Van der Waals radii similar to Me groups, contain functional groups capable of secondary reactivity. Thus, ethynyl- and propynyl-terminated Si(111) surfaces were prepd. by a two-step halogenation/alkylation procedure and characterized by transmission IR spectroscopy (TIRS), XPS, high-resoln. electron energy loss spectroscopy (HREELS), LEED (LEED), at. force microscopy (AFM), and surface recombination velocity (SRV) measurements. Vibrational spectra of ethynyl-terminated Si(111) surfaces exhibit acetylenic C-H and C\u2261C stretching modes that are oriented perpendicular to the surface, while spectra of propynyl-terminated Si(111) surfaces show a C-H sym. bending (umbrella) mode also oriented perpendicular to the surface. LEED patterns indicate the preservation of a 1 \u00d7 1 surface unit cell, and AFM images show the preservation of at. terraces. Ethynyl-terminated Si(111) surfaces were deprotonated with a strong base and soaked in CD_3OD to produce partially deutorated ethyne functionality on the surface, demonstrating the reactivity of the terminal alkyne moiety.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140815-094110145", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140815-094110145", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Plymale, Noah T.; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/n50tt-d7685", "eprint_id": 48584, "eprint_status": "archive", "datestamp": "2023-08-20 02:13:35", "lastmod": "2023-10-17 19:27:47", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Technical and operational perspective on the DOE Fuels from Sunlight Energy Innovation Hub, the Joint Center for Artificial Photosynthesis", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "The design of highly efficient, non biol., mol. level energy conversion \"machines\" that generate fuels directly from sunlight, water, and carbon dioxide is both a formidable challenge and an opportunity that, if realized, could have a revolutionary impact on our energy system. Basic research has already provided enormous advances in our understanding of the subtle and complex photochem. behind the natural photosynthetic system, and in the use of inorg. photocatalytic methods to split water or reduce carbon dioxide-key steps in photosynthesis. Yet we still lack sufficient knowledge to design solar fuel generation systems with the required efficiency, scalability, and sustainability to be economically viable. In the DOE Energy Innovation Hub, the Joint Center for Artificial Photosynthesis, we are developing an artificial photosynthetic system that will only utilize sunlight and water as the inputs and will produce hydrogen and oxygen as the outputs. We are taking a modular, parallel development approach in which the three distinct primary components-the photoanode, the photocathode, and the product-sepg. but ion-conducting membrane-are fabricated and optimized sep. before assembly into a complete water-splitting system. The design principles incorporate two sep., photosensitive semiconductor/liq. junctions that will collectively generate the 1.7-1.9 V at open circuit necessary to support both the oxidn. of H_2O (or OH^-) and the redn. of H^+ (or H_2O). The photoanode and photocathode will consist of rod-like semiconductor components, with attached heterogeneous multi-electron transfer catalysts, which are needed to drive the oxidn. or redn. reactions at low overpotentials. This talk will discuss a feasible and functional prototype and blueprint for an artificial photosynthetic system, composed of only inexpensive, earth-abundant materials, that is simultaneously efficient, durable, scalably manufacturable, and readily upgradeable, including both the operational and tech. scope of the JCAP Hub, as well as tech. results towards this goal that has recently been developed at Caltech.", "date": "2014-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140815-080427795", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140815-080427795", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/axgv5-4z409", "eprint_id": 49849, "eprint_status": "archive", "datestamp": "2023-08-20 02:02:37", "lastmod": "2023-10-17 22:15:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "McEnaney-J-M", "name": { "family": "McEnaney", "given": "Joshua M." } }, { "id": "Crompton-J-C", "name": { "family": "Crompton", "given": "J. Chance" } }, { "id": "Callejas-J-F", "name": { "family": "Callejas", "given": "Juan F." } }, { "id": "Popczun-E-J", "name": { "family": "Popczun", "given": "Eric J." } }, { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Schaak-R-E", "name": { "family": "Schaak", "given": "Raymond E." } } ] }, "title": "Electrocatalytic hydrogen evolution using amorphous tungsten phosphide nanoparticles", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 The Royal Society of Chemistry. Received 20th June 2014, Accepted 30th July 2014. First published online 30 Jul 2014.\n\nThis work was supported at PSU by the National Science\nFoundation (NSF) Center for Chemical Innovation on Solar\nFuels (CHE-1305124) and at Caltech by the Joint Center for\nArtificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. TEM imaging was performed in the Penn State Microscopy and Cytometry Facility (University Park, PA) and HRTEM imaging, EDS spectra, XPS spectra, and DRIFTS spectra were acquired at the Materials Characterization Laboratory of the Penn State Materials Research Institute. J.M.M. thanks Jennifer Gray for assistance with analyzing the XPS spectra and Dr Thomas Gordon for assistance with quantitative yield experiments.\n\nPublished - c4cc04709e.pdf
Supplemental Material - c4cc04709e1.pdf
", "abstract": "Amorphous tungsten phosphide (WP), which has been synthesized as colloidal nanoparticles with an average diameter of 3 nm, has been identified as a new electrocatalyst for the hydrogen-evolution reaction (HER) in acidic aqueous solutions. WP/Ti electrodes produced current densities of \u221210 mA cm^(\u22122) and \u221220 mA cm^(\u22122) at overpotentials of only \u2212120 mV and \u2212140 mV, respectively, in 0.50 M H_2SO_4(aq).", "date": "2014-07-30", "date_type": "published", "publication": "Chemical Communications", "volume": "50", "number": "75", "publisher": "Royal Society of Chemistry", "pagerange": "11026-11028", "id_number": "CaltechAUTHORS:20140919-100006692", "issn": "0009-241X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140919-100006692", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "doi": "10.1039/C4CC04709E", "primary_object": { "basename": "c4cc04709e.pdf", "url": "https://authors.library.caltech.edu/records/axgv5-4z409/files/c4cc04709e.pdf" }, "related_objects": [ { "basename": "c4cc04709e1.pdf", "url": "https://authors.library.caltech.edu/records/axgv5-4z409/files/c4cc04709e1.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "McEnaney, Joshua M.; Crompton, J. Chance; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/k828h-8ff72", "eprint_id": 48562, "eprint_status": "archive", "datestamp": "2023-08-20 01:49:05", "lastmod": "2023-10-17 19:26:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "McCaig-H-C", "name": { "family": "McCaig", "given": "Heather C." } }, { "id": "Myers-E", "name": { "family": "Myers", "given": "Ed" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Roukes-M-L", "name": { "family": "Roukes", "given": "Michael L." }, "orcid": "0000-0002-2916-6026" } ] }, "title": "Vapor Sensing Characteristics of Nanoelectromechanical Chemical Sensors Functionalized Using Surface-Initiated Polymerization", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Chemical Society.\n\nReceived: February 6, 2014; Revised: June 10, 2014; Published: June 12, 2014.\n\nWe gratefully acknowledge assistance from Derrick Chi in\nfabrication of the NEMS devices, from Xinchang Zhang for\ndevelopment of the NEMS control electronics, the Caltech\nGeology and Planetary Science Analytical Facility and the Kavli Nanoscience Institute for SEM imaging, and from Bruce S. Brunschwig and the Molecular Materials Research Center for the use of their ellipsometer. We acknowledge support for this work from DARPA/MTO-MGA through Grant NBCH1050001, and from the Department of Homeland Security, Centers of Excellence, Agreement 2008-ST-061-ED0002.\n\nAccepted Version - nihms844890.pdf
Supplemental Material - nl500475b_si_001.pdf
", "abstract": "Surface-initiated polymerization has been used to grow thick, uniform poly(methyl methacrylate) films on nanocantilever sensors. Cantilevers with these coatings yielded significantly greater sensitivity relative to bare devices as well as relative to devices that had been coated with drop-cast polymer films. The devices with surface-initiated polymer films also demonstrated high selectivity toward polar analytes. Surface-initiated polymerization can therefore provide a straightforward, reproducible method for large-scale functionalization of nanosensors.", "date": "2014-07-09", "date_type": "published", "publication": "Nano Letters", "volume": "14", "number": "7", "publisher": "American Chemical Society", "pagerange": "3728-3732", "id_number": "CaltechAUTHORS:20140814-112736743", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140814-112736743", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "NBCH1050001" }, { "agency": "Department of Homeland Security", "grant_number": "2008-ST-061- ED0002" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/nl500475b", "pmcid": "PMC5297368", "primary_object": { "basename": "nihms844890.pdf", "url": "https://authors.library.caltech.edu/records/k828h-8ff72/files/nihms844890.pdf" }, "related_objects": [ { "basename": "nl500475b_si_001.pdf", "url": "https://authors.library.caltech.edu/records/k828h-8ff72/files/nl500475b_si_001.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "McCaig, Heather C.; Myers, Ed; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/p5mr8-hkn76", "eprint_id": 47454, "eprint_status": "archive", "datestamp": "2023-08-20 01:36:41", "lastmod": "2023-10-26 20:36:52", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Santori-E-A", "name": { "family": "Santori", "given": "Elizabeth A." } }, { "id": "Strandwitz-N-C", "name": { "family": "Strandwitz", "given": "Nicholas C." } }, { "id": "Grimm-R-L", "name": { "family": "Grimm", "given": "Ronald L." }, "orcid": "0000-0003-0407-937X" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Operation of lightly doped Si microwires under high-level injection conditions", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 Royal Society of Chemistry. \n\nReceived 18th January 2014; Accepted 18th March 2014. \n\nWe acknowledge the Department of Energy Office of Basic Energy Sciences grant DOE DE-FG02-03ER15483, and BP for financial support. NCS acknowledges the NSF for an American\nCompetitiveness in Chemistry postdoctoral fellowship (CHE-1042006). Critical support and infrastructure for this work were provided by the Kavli Nanoscience Institute and the Molecular Materials Research Center at Caltech. The angle-resolved optical characterization work was supported by the US Department of Energy 'Light-Material Interactions in Energy Conversion' Energy Frontier Research Center Award (grant DESC0001293).\n\nPublished - c4ee00202d.pdf
Supplemental Material - c4ee00202d1.pdf
", "abstract": "The operation of lightly doped Si microwire arrays under high-level injection conditions was investigated by measurement of the current-potential behavior and carrier-collection efficiency of the wires in contact with non-aqueous electrolytes, and through complementary device physics simulations. The current-potential behavior of the lightly doped Si wire array photoelectrodes was dictated by both the radial contact and the carrier-selective back contact. For example, the Si microwire arrays exhibited n-type behavior when grown on a n^(+)-doped substrate and placed in contact with the 1,1\u2032-dimethylferrocene+/0\u2013CH_(3)OH redox system. The microwire arrays exhibited p-type behavior when grown on a p^(+)-doped substrate and measured in contact with a redox system with a sufficiently negative Nernstian potential. The wire array photoelectrodes exhibited internal quantum yields of ~0.8, deviating from unity for these radial devices. Device physics simulations of lightly doped n-Si wires in radial contact with the 1,1\u2032-dimethylferrocene^(+/0)\u2013CH_(3)OH redox system showed that the carrier-collection efficiency should be a strong function of the wire diameter and the carrier lifetime within the wire. Small diameter (d < 200 nm) wires exhibited low quantum yields for carrier collection, due to the strong inversion of the wires throughout the wire volume. In contrast, larger diameter wires (d > 400 nm) exhibited higher carrier collection efficiencies that were strongly dependent on the carrier lifetime in the wire, and wires with carrier lifetimes exceeding 5 \u03bcs were predicted to have near-unity quantum yields. The simulations and experimental measurements collectively indicated that the Si microwires possessed carrier lifetimes greater than 1 \u03bcs, and showed that radial structures with micron dimensions and high material quality can result in excellent device performance with lightly doped, structured semiconductors.", "date": "2014-07", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "7", "number": "7", "publisher": "Royal Society of Chemistry", "pagerange": "2329-2338", "id_number": "CaltechAUTHORS:20140724-082011157", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140724-082011157", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "NSF Postdoctoral Fellowship", "grant_number": "CHE-1042006" }, { "agency": "Kavli Nanoscience Institute" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "BP" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/C4EE00202D", "primary_object": { "basename": "c4ee00202d.pdf", "url": "https://authors.library.caltech.edu/records/p5mr8-hkn76/files/c4ee00202d.pdf" }, "related_objects": [ { "basename": "c4ee00202d1.pdf", "url": "https://authors.library.caltech.edu/records/p5mr8-hkn76/files/c4ee00202d1.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Santori, Elizabeth A.; Strandwitz, Nicholas C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ja1t6-nwh19", "eprint_id": 49585, "eprint_status": "archive", "datestamp": "2023-08-20 01:39:35", "lastmod": "2023-10-17 21:34:18", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Brown-R-D", "name": { "family": "Brown", "given": "Ryan D." } }, { "id": "Hund-Z-M", "name": { "family": "Hund", "given": "Zachary M." } }, { "id": "Campi-D", "name": { "family": "Campi", "given": "Davide" } }, { "id": "O'Leary-L-E", "name": { "family": "O'Leary", "given": "Leslie E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Bernasconi-M", "name": { "family": "Bernasconi", "given": "M." } }, { "id": "Benedek-G", "name": { "family": "Benedek", "given": "G." } }, { "id": "Sibener-S-J", "name": { "family": "Sibener", "given": "S. J." } } ] }, "title": "The interaction of organic adsorbate vibrations with substrate lattice waves in methyl-Si(111)-(1\u2009\u00d7\u20091)", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 AIP Publishing LLC. Received 1 May 2014; accepted 23 June 2014; published online 9 July 2014. S.J.S. acknowledges support from the Air Force Office of Scientific Research (AFOSR) Grant No. FA9550-10-1-0219, and the Material Research Science and Engineering Center at the University of Chicago for infrastructure support, and N.S.L. acknowledges support from the National Science Foundation (NSF) (CHE-1214152).\n\nPublished - 1.4886810.pdf
", "abstract": "A combined helium atom scattering and density functional perturbation theory study has been performed to elucidate the surface phonon dispersion relations for both the CH_3-Si(111)-(1\u2009\u00d7\u20091) and CD_3-Si(111)-(1\u2009\u00d7\u20091) surfaces. The combination of experimental and theoretical methods has allowed characterization of the interactions between the low energy vibrations of the adsorbate and the lattice waves of the underlying substrate, as well as characterization of the interactions between neighboring methyl groups, across the entire wavevector resolved vibrational energy spectrum of each system. The Rayleigh wave was found to hybridize with the surface rocking libration near the surface Brillouin zone edge at both the M-point and K-point. The calculations indicated that the range of possible energies for the potential barrier to the methyl rotation about the Si-C axis is sufficient to prevent the free rotation of the methyl groups at a room temperature interface. The density functional perturbation theory calculations revealed several other surface phonons that experienced mode-splitting arising from the mutual interaction of adjacent methyl groups. The theory identified a Lucas pair that exists just below the silicon optical bands. For both the CH_3- and CD_3-terminated Si(111) surfaces, the deformations of the methyl groups were examined and compared to previous experimental and theoretical work on the nature of the surface vibrations. The calculations indicated a splitting of the asymmetric deformation of the methyl group near the zone edges due to steric interactions of adjacent methyl groups. The observed shifts in vibrational energies of the -CD_3 groups were consistent with the expected effect of isotopic substitution in this system.", "date": "2014-07", "date_type": "published", "publication": "Journal of Chemical Physics", "volume": "141", "number": "2", "publisher": "American Institute of Physics", "pagerange": "Art. No. 024702", "id_number": "CaltechAUTHORS:20140911-100847244", "issn": "0021-9606", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140911-100847244", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-10-1-0219" }, { "agency": "University of Chicago Material Research Science and Engineering Center" }, { "agency": "NSF", "grant_number": "CHE-1214152" } ] }, "doi": "10.1063/1.4886810", "primary_object": { "basename": "1.4886810.pdf", "url": "https://authors.library.caltech.edu/records/ja1t6-nwh19/files/1.4886810.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Brown, Ryan D.; Hund, Zachary M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fqd0g-9fy53", "eprint_id": 45771, "eprint_status": "archive", "datestamp": "2023-08-20 01:03:35", "lastmod": "2023-10-26 18:27:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Shaner-M-R", "name": { "family": "Shaner", "given": "Matthew R." }, "orcid": "0000-0003-4682-9757" }, { "id": "Beardslee-J-A", "name": { "family": "Beardslee", "given": "Joseph A." } }, { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael" }, "orcid": "0000-0002-0710-7068" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Amorphous TiO_2 coatings stabilize Si, GaAs, and GaP photoanodes for efficient water oxidation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Association for the Advancement of Science. \n\nReceived for publication 28 January 2014. Accepted for publication 1 May 2014. \n\nThis work is supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. M.S. acknowledges the Resnick Sustainability Institute for a graduate fellowship, and B.S.B. acknowledges the Beckman Institute at the California Institute of Technology for support. XPS was performed at the Molecular Materials Research Center in the Beckman Institute at the California Institute of Technology. TEM imaging and spectroscopy were performed at the Center for Electron Microscopy and Microanalysis, University of Southern California. We thank H.- J. Lewerenz, C. Koval, and F. Houle for fruitful discussions; Y. Guan for secondary-ion mass spectrometry measurements; S. R. Nutt for use of the microscopy and microanalysis facility; P. D. Dapkus for the use of the metal-organic chemical vapor deposition facility; S. Ardo for help in boron-diffusion doping; and K. Papadantonakis for assistance with editing this manuscript. The authors' institution (California Institute of Technology) has filed a provisional U.S. patent application directly relating to the work described in the paper (patent application no. 61/889,430, filed on 10 October 2013).\n\nSupplemental Material - Hu.S.SM.pdf
", "abstract": "Although semiconductors such as silicon (Si), gallium arsenide (GaAs), and gallium phosphide (GaP) have band gaps that make them efficient photoanodes for solar fuel production, these materials are unstable in aqueous media. We show that TiO_2 coatings (4 to 143 nanometers thick) grown by atomic layer deposition prevent corrosion, have electronic defects that promote hole conduction, and are sufficiently transparent to reach the light-limited performance of protected semiconductors. In conjunction with a thin layer or islands of Ni oxide electrocatalysts, Si photoanodes exhibited continuous oxidation of 1.0 molar aqueous KOH to O_2 for more than 100 hours at photocurrent densities of >30 milliamperes per square centimeter and ~100% Faradaic efficiency. TiO_2-coated GaAs and GaP photoelectrodes exhibited photovoltages of 0.81 and 0.59 V and light-limiting photocurrent densities of 14.3 and 3.4 milliamperes per square centimeter, respectively, for water oxidation.", "date": "2014-05-30", "date_type": "published", "publication": "Science", "volume": "344", "number": "6187", "publisher": "American Association for the Advancement of Science", "pagerange": "1005-1009", "id_number": "CaltechAUTHORS:20140515-133039268", "issn": "0036-8075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140515-133039268", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "Caltech Beckman Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1126/science.1251428", "primary_object": { "basename": "Hu.S.SM.pdf", "url": "https://authors.library.caltech.edu/records/fqd0g-9fy53/files/Hu.S.SM.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Hu, Shu; Shaner, Matthew R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/71ry9-s6y66", "eprint_id": 46395, "eprint_status": "archive", "datestamp": "2023-08-22 12:43:06", "lastmod": "2023-10-26 19:42:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Popczun-E-J", "name": { "family": "Popczun", "given": "Eric J." } }, { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Roske-C-W", "name": { "family": "Roske", "given": "Christopher W." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Schaak-R-E", "name": { "family": "Schaak", "given": "Raymond E." } } ] }, "title": "Highly Active Electrocatalysis of the Hydrogen Evolution Reaction by Cobalt Phosphide Nanoparticles", "ispublished": "pub", "full_text_status": "restricted", "keywords": "electrocatalysis; hydrogen evolution; metal phosphide; nanomaterials; water splitting", "note": "\u00a9 2014 Wiley-VCH Verlag GmbH & Co. \n\nReceived: February 20, 2014;\nPublished online: April 11, 2014. \n\nThis work was supported by the National Science Foundation (NSF) Center for Chemical Innovation on Solar Fuels (CHE-1305124). C.W.R. thanks the NSF for a graduate research fellowship. Research was in part performed at the Beckman Institute Molecular Materials\nResearch Center. TEM and BET data were acquired using facilities in the Materials Characterization Lab of the Penn State Materials Research Institute. E.J.P. and C.G.R. thank Trevor Clark, Ke Wang, and Lymaris Ortiz Rivera for assistance.", "abstract": "Nanoparticles of cobalt phosphide, CoP, have been prepared and evaluated as electrocatalysts for the hydrogen evolution reaction (HER) under strongly acidic conditions (0.50\u2009M H_2SO_4, pH\u20050.3). Uniform, multi-faceted CoP nanoparticles were synthesized by reacting Co nanoparticles with trioctylphosphine. Electrodes comprised of CoP nanoparticles on a Ti support (2\u2005mg\u2009cm^(\u22122) mass loading) produced a cathodic current density of 20\u2005mA\u2009cm^(\u22122) at an overpotential of \u221285\u2005mV. The CoP/Ti electrodes were stable over 24\u2005h of sustained hydrogen production in 0.50\u2009M H_2SO_4. The activity was essentially unchanged after 400 cyclic voltammetric sweeps, suggesting long-term viability under operating conditions. CoP is therefore amongst the most active, acid-stable, earth-abundant HER electrocatalysts reported to date.", "date": "2014-05-19", "date_type": "published", "publication": "Angewandte Chemie International Edition", "volume": "53", "number": "21", "publisher": "Wiley", "pagerange": "5427-5430", "id_number": "CaltechAUTHORS:20140620-100535755", "issn": "1433-7851", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140620-100535755", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Center for Chemical Innovation on Solar Fuels", "grant_number": "CHE-1305124" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1002/anie.201402646", "resource_type": "article", "pub_year": "2014", "author_list": "Popczun, Eric J.; Read, Carlos G.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/c648m-ggt49", "eprint_id": 45238, "eprint_status": "archive", "datestamp": "2023-08-22 12:33:32", "lastmod": "2023-10-26 17:53:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Coridan-R-H", "name": { "family": "Coridan", "given": "Robert H." }, "orcid": "0000-0003-1916-4446" }, { "id": "Arpin-K-A", "name": { "family": "Arpin", "given": "Kevin A." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Braun-P-V", "name": { "family": "Braun", "given": "Paul V." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemical Behavior of Hierarchically Structured Si/WO_3 Core\u2013Shell Tandem Photoanodes", "ispublished": "pub", "full_text_status": "public", "keywords": "Photoelectrochemical energy conversion; hierarchical structuring; silicon; core\u2212shell semiconductor; tandem semiconductor devices", "note": "\u00a9 2014 American Chemical Society. \n\nReceived: December 13, 2013; Revised: March 10, 2014. Publication Date (Web): March 28, 2014. \n\nThis work is part of the \"Light\u2212Material Interactions in Energy\nConversion\" Energy Frontier Research Center funded by the\nU.S. Department of Energy, Office of Science, Office of Basic\nEnergy Sciences, under Award DE-SC0001293. This work used\nthe Extreme Science and Engineering Discovery Environment\n(XSEDE), which is supported by National Science Foundation\nGrant OCI-1053575, and the Molecular Materials Research\nCenter of the Beckman Institute at the California Institute of\nTechnology. \n\nA detailed description of the materials, synthetic methods, and\ncharacterization/simulation protocols of plain and porous\ncore\u2212shell microwires; SEM micrographs of the large-scale\ninfiltration of the microwire array by colloids and large-area\nporous core\u2212shell templating; fractional absorption-depth\nprofiles from FDTD simulations.\n\nSupplemental Material - nl404623t_si_001.pdf
", "abstract": "WO_3 thin films have been deposited in a hierarchically structured core\u2013shell morphology, with the cores consisting of an array of Si microwires and the shells consisting of a controlled morphology WO_3 layer. Porosity was introduced into the WO_3 outer shell by using a self-assembled microsphere colloidal crystal as a mask during the deposition of the WO_3 shell. Compared to conformal, unstructured WO_3 shells on Si microwires, the hierarchically structured core\u2013shell photoanodes exhibited enhanced near-visible spectral response behavior, due to increased light absorption and reduced distances over which photogenerated carriers were collected. The use of structured substrates also improved the growth rate of microsphere-based colloidal crystals and suggests strategies for the use of colloidal materials in large-scale applications.", "date": "2014-05", "date_type": "published", "publication": "Nano Letters", "volume": "14", "number": "5", "publisher": "American Chemical Society", "pagerange": "2310-2317", "id_number": "CaltechAUTHORS:20140428-091112366", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140428-091112366", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "NSF", "grant_number": "OCI-1053575" }, { "agency": "Caltech Beckman Institute" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/nl404623t", "primary_object": { "basename": "nl404623t_si_001.pdf", "url": "https://authors.library.caltech.edu/records/c648m-ggt49/files/nl404623t_si_001.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Coridan, Robert H.; Arpin, Kevin A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nrsag-pw466", "eprint_id": 44728, "eprint_status": "archive", "datestamp": "2023-08-20 00:21:05", "lastmod": "2023-10-26 14:54:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Leenheer-A-J", "name": { "family": "Leenheer", "given": "Andrew J." } }, { "id": "Narang-P", "name": { "family": "Narang", "given": "Prineha" }, "orcid": "0000-0003-3956-4594" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Solar energy conversion via hot electron internal photoemission in metallic nanostructure: Efficiency estimates", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Institute of Physics Publishing LLC. Received 31 October 2013; accepted 15 February 2014; published online 1 April 2014. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy\nInnovation Hub, supported through the Office of Science of\nthe U.S. Department of Energy under Award No. DESC0004993.\nP.N. is supported by a National Science\nFoundation Graduate Research Fellowship and by the\nResnick Sustainability Institute.\n\nPublished - 1.4870040.pdf
", "abstract": "Collection of hot electrons generated by the efficient absorption of light in metallic nanostructures, in contact with semiconductor substrates can provide a basis for the construction of solar energy-conversion devices. Herein, we evaluate theoretically the energy-conversion efficiency of systems that rely on internal photoemission processes at metal-semiconductor Schottky-barrier diodes. In this theory, the current-voltage characteristics are given by the internal photoemission yield as well as by the thermionic dark current over a varied-energy barrier height. The Fowler model, in all cases, predicts solar energy-conversion efficiencies of <1% for such systems. However, relaxation of the assumptions regarding constraints on the escape cone and momentum conservation at the interface yields solar energy-conversion efficiencies as high as 1%\u201310%, under some assumed (albeit optimistic) operating conditions. Under these conditions, the energy-conversion efficiency is mainly limited by the thermionic dark current, the distribution of hot electron energies, and hot-electron momentum considerations.", "date": "2014-04-07", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "115", "number": "13", "publisher": "American Institute of Physics", "pagerange": "Art. No. 134301", "id_number": "CaltechAUTHORS:20140408-084811849", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140408-084811849", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Resnick Sustainability Institute" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1063/1.4870040", "primary_object": { "basename": "1.4870040.pdf", "url": "https://authors.library.caltech.edu/records/nrsag-pw466/files/1.4870040.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Leenheer, Andrew J.; Narang, Prineha; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8t4ef-w2q72", "eprint_id": 45204, "eprint_status": "archive", "datestamp": "2023-08-20 00:07:43", "lastmod": "2023-10-26 17:51:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Huang-Zhuangqun", "name": { "family": "Huang", "given": "Zhuangqun" } }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Lewerenz-H-J", "name": { "family": "Lewerenz", "given": "Hans-Joachim" }, "orcid": "0000-0001-8433-9471" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Two stories from the ISACS 12 conference: solar-fuel devices and catalyst identification", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 The Royal Society of Chemistry.\n\nReceived 05 Nov 2013, Accepted 05 Nov 2013.\nFirst published online 16 Jan 2014. \n\nZ. Huang thanks an EES grant for\ntravel and conference expenses and the\nauthors all acknowledge DE-SC0004993\nfor support that allowed preparation of\nthis manuscript.\n\nPublished - c3ee90043f.pdf
", "abstract": "The International Symposia for\nadvancing the Chemical Sciences, a\npartner of the journal Chemical Science,\nheld its 12th meeting (ISACS 12) at the\nUniversity of Cambridge on September\n3\u20136 2013. ISACS 12 focused on \"Challenges\nin Chemical Renewable Energy\",\nwith oral presentations organized along\nfive themes: photovoltaics, solar fuels,\nmolecular and bio-inspired catalysts, new\nmaterials for batteries, and fuel cells.\nISACS 12 also included a presentation on\nthe sugar cane-based energy industry in\nBrazil, a recording by the BBC World\nService, and two poster sessions. This\nconference was an exciting, busy place to\nmeet people, exchange ideas, and foster\ncollaboration.", "date": "2014-04", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "7", "number": "4", "publisher": "Royal Society of Chemistry", "pagerange": "1207-1211", "id_number": "CaltechAUTHORS:20140425-070837177", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140425-070837177", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c3ee90043f", "primary_object": { "basename": "c3ee90043f.pdf", "url": "https://authors.library.caltech.edu/records/8t4ef-w2q72/files/c3ee90043f.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Huang, Zhuangqun; Xiang, Chengxiang; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/q9db1-cwp52", "eprint_id": 43454, "eprint_status": "archive", "datestamp": "2023-08-22 11:53:21", "lastmod": "2023-10-25 23:33:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Velazquez-Jesus-M", "name": { "family": "Velazquez", "given": "Jesus M." } }, { "id": "Saadi-Fadl-H", "name": { "family": "Saadi", "given": "Fadl H." }, "orcid": "0000-0003-3941-0464" }, { "id": "Pieterick-Adam-P", "name": { "family": "Pieterick", "given": "Adam P." } }, { "id": "Spurgeon-Joshua-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Soriaga-M-P", "name": { "family": "Soriaga", "given": "Manuel P." }, "orcid": "0000-0002-0077-6226" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Synthesis and hydrogen-evolution activity of tungsten selenide thin films deposited on tungsten foils", "ispublished": "pub", "full_text_status": "public", "keywords": "Hydrogen-evolution reaction; Tungsten selenide thin films; Chemical vapor transport; Thin-film electrocatalysts; Synthesis of Group VI dichalcogenides", "note": "\u00a9 2014 Elsevier B.V. \n \nAvailable online 11 December 2013; Special Issue in Honour of Kingo Itaya. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. XPS data were collected at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. We also acknowledge the MPR Institute for helpful discussions and assistance in the preparation of this manuscript.\n\nSupplemental Material - Figs._S1-S5.docx
", "abstract": "Thin films of WSe_2 have been deposited onto a conductive substrate (tungsten foil) using a relatively simple chemical-vapor-transport technique. X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy indicated that the films consisted of micron-sized single crystals of WSe_2 that were oriented perpendicular to the surface of the tungsten foil substrate. Linear sweep voltammetry was used to assess the ability of the WSe_2 films to catalyze the hydrogen-evolution reaction and chronopotentiometry was used to gauge the temporal stability of the catalytic performance of the films under cathodic conditions. A 350 mV overpotential (\u03b7) was required to drive the hydrogen-evolution reaction at a current density of \u221210 mA cm^(\u22122) in aqueous 0.5 M H_2SO_4, representing a significant improvement in catalytic performance relative to the behavior of macroscopic WSe_2 single crystals. The WSe_2 thin films were relatively stable under catalytic conditions, with the overpotential changing by only \u223c10 mV after one hour and exhibiting an additional change of \u223c5mV after another hour of operation.", "date": "2014-03-01", "date_type": "published", "publication": "Journal of Electroanalytical Chemistry", "volume": "716", "publisher": "Elsevier", "pagerange": "45-48", "id_number": "CaltechAUTHORS:20140121-113850320", "issn": "0022-0728", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140121-113850320", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1016/j.jelechem.2013.11.030", "primary_object": { "basename": "Figs._S1-S5.docx", "url": "https://authors.library.caltech.edu/records/q9db1-cwp52/files/Figs._S1-S5.docx" }, "resource_type": "article", "pub_year": "2014", "author_list": "Velazquez, Jesus M.; Saadi, Fadl H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kgqzt-a4p92", "eprint_id": 45100, "eprint_status": "archive", "datestamp": "2023-08-19 23:38:26", "lastmod": "2023-10-26 17:33:33", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nate" }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Powering the planet: The future of energy in the world", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "This presentation describes and evaluates the tech., political, and economic challenges involved with\nwidespread adoption of renewable energy technologies.First, the available fossil fuel resources and reserves\nare estd., based on data from the World Energy Assessment and World Energy Council. A comparison of\nthe price per unit of energy of these sources to those of renewable energy technologies is presented. Next,\nthe level and timescale of Research and Development investment that is needed to produce the required\nquantity of carbon-free power by the 2050 timeframe is evaluated, to support the expected global energy\ndemand for carbon-free power. Then the energy potential of various renewable energy resources will be\nassessed to ascertain which resources are adequately available globally to support the projected global carbonfree\nenergy demand requirements. This is followed by an evaluation of the challenge to the chem. sciences to\nenable the cost-effective prodn. of carbon-free power on the needed scale by the 2050 timeframe. Finally, the\neffects of a change in primary power technol. on the energy supply infrastructure will be discussed and the\nimpact of such a change on the modes of energy consumption by the energy consumer will be presented.", "date": "2014-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140422-085402717", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140422-085402717", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Lewis, Nate" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4dk61-7k313", "eprint_id": 45372, "eprint_status": "archive", "datestamp": "2023-08-19 23:41:55", "lastmod": "2023-10-26 17:57:38", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Technical and operational perspective on the DOE energy innovation hub and fuels from sunlight, the Joint Center for Artificial Photosynthesis", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 American Chemical Society.", "abstract": "The design of highly efficient, non-biol., mol.-level energy conversion \"machines\" that generate fuels directly from sunlight,\nwater, and carbon dioxide is both a formidable challenge and an opportunity that, if realized, could have a revolutionary impact\non our energy system. Basic research has already provided enormous advances in our understanding of the subtle and complex\nphotochem. behind the natural photosynthetic system, and in the use of inorg. photo-catalytic methods to split water or reduce\ncarbon dioxide-key steps in photosynthesis. Yet we still lack sufficient knowledge to design solar fuel generation systems with\nthe required efficiency, scalability, and sustainability to be economically viable. In the DOE Energy Innovation Hub, the Joint\nCenter for Artificial Photosynthesis, we are developing an artificial photosynthetic system that will only utilize sunlight and water\nas the inputs and will produce hydrogen and oxygen as the outputs. We are taking a modular, parallel development approach in\nwhich the three distinct primary components-the photoanode, the photocathode, and the product-sepg. but ion-conducting\nmembrane-are fabricated and optimized sep. before assembly into a complete water-splitting system. The design principles\nincorporate two sep., photosensitive semiconductor/liq. junctions that will collectively generate the 1.7-1.9 V at open circuit\nnecessary to support both the oxidn. of H_2O (or OH-) and the redn. of H+ (or H_2O). The photoanode and photocathode will\nconsist of rod-like semiconductor components, with attached heterogeneous multi-electron transfer catalysts, which are needed\nto drive the oxidn. or redn. reactions at low overpotentials. This talk will discuss a feasible and functional prototype and\nblueprint for an artificial photosynthetic system, composed of only inexpensive, earth-abundant materials, that is simultaneously\nefficient, durable, manufacturably scalable, and readily upgradeable, including both the operational and tech. scope of the\nJCAP Hub, as well as tech. results towards this goal that has recently been developed at Caltech.", "date": "2014-03", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20140430-145747003", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140430-145747003", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2014", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/a14fd-faw27", "eprint_id": 42895, "eprint_status": "archive", "datestamp": "2023-08-22 11:47:33", "lastmod": "2023-10-25 23:08:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Narang-P", "name": { "family": "Narang", "given": "Prineha" }, "orcid": "0000-0003-3956-4594" }, { "id": "Chen-Shiyou", "name": { "family": "Chen", "given": "Shiyou" } }, { "id": "Coronel-N-C", "name": { "family": "Coronel", "given": "Naomi C." } }, { "id": "Gul-S", "name": { "family": "Gul", "given": "Sheraz" }, "orcid": "0000-0001-8920-8737" }, { "id": "Yano-Junko", "name": { "family": "Yano", "given": "Junko" }, "orcid": "0000-0001-6308-9071" }, { "id": "Wang-Lin-Wang", "name": { "family": "Wang", "given": "Lin-Wang" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Bandgap Tunability in Zn(Sn,Ge)N_2 Semiconductor Alloys", "ispublished": "pub", "full_text_status": "public", "keywords": "Zn(Sn,Ge)N_2 semiconductor alloys; miscibility; bandgap", "note": "\u00a9 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.\n\nReceived: September 5, 2013.\n\nArticle first published online: 5 Dec. 2013.\n\nThis material is based upon work performed by the Joint Center for\nArtificial Photosynthesis, a DOE Energy Innovation Hub, supported\nthrough the Office of Science of the U.S. Department of Energy under\nAward Number DE-SC0004993, and was also supported by the Dow\nChemical Company. P.N. acknowledges support from a National\nScience Foundation Graduate Research Fellowship and from the Resnick\nSustainability Institute. X-ray spectroscopy work was performed at the\nAdvanced Light Source (ALS, BL 10.3.2 and 7.0.1), Berkeley, under\nContract DE-AC02\u201305CH11231. The authors thank Drs. Jinghua Guo\nand Per-Anders Glans-Suzuki for their support at BL 7.0.1.\n\nSupplemental Material - adma201304473-sup-0001-S1.pdf
", "abstract": "ZnSn_(1-x)Ge_xN_2 direct bandgap semiconductor alloys, with a crystal structure and electronic structure similar to InGaN, are earth-abundant alternatives for efficient, high-quality optoelectronic devices and solar energy conversion. The bandgap is tunable almost monotonically from 2 eV (ZnSnN_2) to 3.1 eV (ZnGeN_2) by control of the Sn/Ge ratio.", "date": "2014-02-26", "date_type": "published", "publication": "Advanced Materials", "volume": "26", "number": "8", "publisher": "Wiley", "pagerange": "1235-1241", "id_number": "CaltechAUTHORS:20131209-100236108", "issn": "0935-9648", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131209-100236108", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Dow Chemical Company" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1002/adma.201304473", "primary_object": { "basename": "adma201304473-sup-0001-S1.pdf", "url": "https://authors.library.caltech.edu/records/a14fd-faw27/files/adma201304473-sup-0001-S1.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Narang, Prineha; Chen, Shiyou; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/etehb-02v25", "eprint_id": 43320, "eprint_status": "archive", "datestamp": "2023-08-19 23:19:38", "lastmod": "2023-10-25 23:27:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shaner-M-R", "name": { "family": "Shaner", "given": "Matthew R." }, "orcid": "0000-0003-4682-9757" }, { "id": "Fountaine-K-T", "name": { "family": "Fountaine", "given": "Katherine T." }, "orcid": "0000-0002-0414-8227" }, { "id": "Ardo-S", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Coridan-R-H", "name": { "family": "Coridan", "given": "Robert H." }, "orcid": "0000-0003-1916-4446" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemistry of core\u2013shell tandem junction n\u2013p^+-Si/n-WO_3 microwire array photoelectrodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 The Royal Society of Chemistry.\nReceived 10 Sep 2013, Accepted 07 Nov 2013;\nFirst published online 16 Dec 2013.\nThis material is based upon work performed by the Joint Center\nfor Artificial Photosynthesis, a DOE Energy Innovation Hub,\nsupported through the Office of Science of the U.S. Department\nof Energy under Award Number DE-SC0004993. M.S. acknowledges\nthe Resnick Sustainability Institute for a graduate\nfellowship. K.F. is supported by the National Science Foundation\nGraduate Research Fellowship under Grant No. DGE-1144469. S.A. acknowledges support from a U.S. Department\nof Energy, Office of Energy Efficiency and Renewable Energy\n(EERE) Postdoctoral Research Award under the EERE Fuel Cell\nTechnologies Program. The authors would like to thank Dr Shu\nHu for assistance in boron doping, Rick Gerhart for fabrication\nof the electrochemical cells used and Dr Andrew Leenheer for\nthe WO3 refractive index data.\n\nPublished - c3ee43048k.pdf
Supplemental Material - c3ee43048k_si.pdf
", "abstract": "Tandem junction (n\u2013p^+-Si/ITO/WO_3/liquid) core\u2013shell microwire devices for solar-driven water splitting have been designed, fabricated and investigated photoelectrochemically. The tandem devices exhibited open-circuit potentials of E_(\u221d) = \u22121.21 V versus E^0\u2032(O_2/H_2O), demonstrating additive voltages across the individual junctions (n\u2013p^+-Si E_(\u221d) = \u22120.5 V versus solution; WO_3/liquid E_(\u221d) = \u22120.73 V versus E^0\u2032(O_2/H_2O)). Optical concentration (12\u00d7, AM1.5D) shifted the open-circuit potential to E_(\u221d) = \u22121.27 V versus E^0\u2032(O_2/H_2O) and resulted in unassisted H_2 production during two-electrode measurements (anode: tandem device, cathode: Pt disc). The solar energy-conversion efficiencies were very low, 0.0068% and 0.0019% when the cathode compartment was saturated with Ar or H_2, respectively, due to the non-optimal photovoltage and band-gap of the WO_3 that was used in the demonstration system to obtain stability of all of the system components under common operating conditions while also insuring product separation for safety purposes.", "date": "2014-02", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "7", "number": "2", "publisher": "Royal Society of Chemistry", "pagerange": "779-790", "id_number": "CaltechAUTHORS:20140110-150648310", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140110-150648310", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1144469" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "JCAP" } ] }, "doi": "10.1039/C3EE43048K", "primary_object": { "basename": "c3ee43048k.pdf", "url": "https://authors.library.caltech.edu/records/etehb-02v25/files/c3ee43048k.pdf" }, "related_objects": [ { "basename": "c3ee43048k_si.pdf", "url": "https://authors.library.caltech.edu/records/etehb-02v25/files/c3ee43048k_si.pdf" } ], "resource_type": "article", "pub_year": "2014", "author_list": "Shaner, Matthew R.; Fountaine, Katherine T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hmn8z-a2b42", "eprint_id": 44029, "eprint_status": "archive", "datestamp": "2023-08-19 23:09:14", "lastmod": "2023-10-26 00:07:08", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Silicon Microwire Arrays for Solar Energy-Conversion Applications", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society. \n\nReceived: June 25, 2013; Revised: November 1, 2013; Published: December 9, 2013. \n\nThe authors would like to thank many of the researchers who\nhave contributed to the development of Si MW-based energy conversion devices and the work discussed in this article: Brendan Kayes, Michael Filler, James Maiolo, Joshua Spurgeon, Michael Kelzenberg, Morgan Putnam, Kate Plass, Shannon Boettcher, Daniel Turner-Evans, Hal Emmer, Adele Tamboli, Chris Chen, Elizabeth Santori, Ronald Grimm, Matthew Bierman, Heather Audesirk, Joseph Beardslee, Michael Walter, Chengxiang Xiang, Andrew Meng, Shane Ardo, Robert Coridan, Anna Beck, Ryan Briggs, Clara Cho, Leslie O'Leary, and Matthew Shaner. We acknowledge BP (support for E.L.W.), DOE DE-FG02-03-ER15483, and the Joint Center for Artificial Photosynthesis, DOE DE-SC0004993 (support for N.S.L. and H.A.A.), for financial support that allowed the preparation of this manuscript.", "abstract": "Highly structured silicon microwire (Si MW) arrays have been synthesized and characterized as absorbers for solar energy-conversion systems. These materials are of great interest for applications in solar energy conversion, including solar electricity and solar fuels production, due to their unique materials properties, form factors, ease of fabrication, and device-processing attributes. The Si MW array geometry allows for efficient collection of photogenerated carriers from impure materials that have short minority-carrier diffusion lengths while simultaneously allowing for high optical absorption and high external quantum yields for charge-carrier collection. In addition, Si MW arrays exhibit unique mesoscale optical behavior and can be removed from the growth substrate to provide flexible, processable arrays of Si microwires ordered in a variety of organic polymers and ionomers. The unique photon-management properties of Si MW arrays, combined with their high internal surface area and controlled morphology for catalyst placement and support, allow for the use of earth-abundant electrocatalysts to produce an integrated, functional photoelectrode. These materials therefore also provide an opportunity to explore the 3-dimensional photoelectrochemical behavior of fuel-forming microstructured electrodes.", "date": "2014-01-16", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "118", "number": "2", "publisher": "American Chemical Society", "pagerange": "747-759", "id_number": "CaltechAUTHORS:20140227-090625946", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140227-090625946", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03-ER15483" }, { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/jp406280x", "resource_type": "article", "pub_year": "2014", "author_list": "Warren, Emily L.; Atwater, Harry A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/bdpep-gw588", "eprint_id": 44051, "eprint_status": "archive", "datestamp": "2023-08-22 11:27:17", "lastmod": "2023-10-26 00:08:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Will Solar-Driven Water-Splitting Devices See the Light of Day?", "ispublished": "pub", "full_text_status": "restricted", "keywords": "solar fuels; hydrogen evolution; HER; oxygen evolution; OER; photoelectrochemistry; electrocatalysis; semiconductor; ion-exchange membrane", "note": "\u00a9 2013 American Chemical Society.\n\nPublished In Issue January 14, 2014; Article ASAP October 14, 2013; Just Accepted Manuscript August 27, 2013; Received: July 01, 2013; Revised: August 22, 2013.\n\nThis article is part of the Celebrating Twenty-Five Years of Chemistry of Materials special issue.\n\nN.S.L. acknowledges support from the Joint Center for\nArtificial Photosynthesis, a DOE Energy Innovation Hub,\nsupported through the Office of Science of the U.S.\nDepartment of Energy under Award Number DE-SC0004993.\nJ.R.M. and H.B.G. acknowledge the National Science\nFoundation for support through the Powering the Planet\nCenter for Chemical Innovation, Grant CHE-1305124. J.R.M.\nacknowledges the DOE Office of Science for a graduate\nresearch fellowship. The authors thank Dr. Shane Ardo and\nAdam Nielander for helpful comments during the preparation\nof this manuscript.", "abstract": "Through decades of sustained effort, researchers have made substantial progress on developing technologies for solar-driven water splitting. Nevertheless, more basic research is needed before prototype devices with a chance for commercial success can be demonstrated. In this Perspective, we summarize the major design constraints that motivate continued research in the field of solar-driven water splitting. Additionally, we discuss key device components that are now available for use in demonstration systems and prototypes. Finally, we highlight research areas where breakthroughs will be critical for continued progress toward commercial viability for solar-driven water-splitting devices.", "date": "2014-01-14", "date_type": "published", "publication": "Chemistry of Materials", "volume": "26", "number": "1", "publisher": "American Chemical Society", "pagerange": "407-414", "id_number": "CaltechAUTHORS:20140228-085825144", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140228-085825144", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "CHE-1305124" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" }, { "id": "JCAP" } ] }, "doi": "10.1021/cm4021518", "resource_type": "article", "pub_year": "2014", "author_list": "McKone, James R.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/tnk2z-pz394", "eprint_id": 43700, "eprint_status": "archive", "datestamp": "2023-08-19 22:40:20", "lastmod": "2023-10-25 23:47:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lattimer-J-R-C", "name": { "family": "Lattimer", "given": "Judith R. C." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Redox Properties of Mixed Methyl/Vinylferrocenyl Monolayers on Si(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Chemical Society. \n\nReceived: October 7, 2013; revised: November 27, 2013; published: December 2, 2013. \n\nWe thank Dr. James Blakemore for helpful discussions, Dr.\nLeslie O'Leary for training in silicon surface modification and discussions, and Joseph Beardslee and Dr. Ron Grimm for\nassistance with the instrumentation. This work was supported\nby the NSF Powering the Planet Center for Chemical\nInnovation (CHE-1305124), the National Science Foundation\n(CHE-1214152), and the Molecular Materials Research Center\nof the Beckman Institute at the California Institute of\nTechnology.\n\nSupplemental Material - jp409958c_si_001.pdf
", "abstract": "We report the redox properties of Si(111) surfaces functionalized with a mixed monolayer of vinylferrocenyl and methyl moieties that have been characterized using spectroscopic, electrical, and electrochemical techniques. The silicon was functionalized using reaction conditions analogous to those of hydrosilylation, but instead of a H-terminated Si surface, a chlorine-terminated Si precursor surface was used to produce the linked vinyl-modified functional group. The functionalized surfaces were characterized by time-resolved photoconductivity decay, X-ray photoelectron spectroscopy, electrochemical measurements, and photoelectrochemical measurements. The functionalized Si surface was well passivated, exhibited high surface coverage and few remaining reactive Si atop sites, had a very low surface recombination velocity, and displayed little initial surface oxidation. The surface was stable toward atmospheric and electrochemical oxidation. The surface coverage of vinylferrocene (or fluorostyrene) was controllably varied from 0 up to 30% of a monolayer. Interfacial charge transfer to the attached ferrocene group was relatively rapid, and a photovoltage of 0.4 V was generated upon illumination of functionalized n-type silicon surfaces in CH_(3)CN.", "date": "2013-12-27", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "117", "number": "51", "publisher": "American Chemical Society", "pagerange": "27012-27022", "id_number": "CaltechAUTHORS:20140206-113901424", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140206-113901424", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1305124" }, { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Caltech Beckman Institute" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/jp409958c", "primary_object": { "basename": "jp409958c_si_001.pdf", "url": "https://authors.library.caltech.edu/records/tnk2z-pz394/files/jp409958c_si_001.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Lattimer, Judith R. C.; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hcg5e-jws83", "eprint_id": 43303, "eprint_status": "archive", "datestamp": "2023-08-19 22:30:50", "lastmod": "2023-10-25 23:26:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lichterman-Michael-Frankston-Yang", "name": { "family": "Lichterman", "given": "Michael F." }, "orcid": "0000-0002-0710-7068" }, { "id": "Shaner-M-R", "name": { "family": "Shaner", "given": "Matthew R." }, "orcid": "0000-0003-4682-9757" }, { "id": "Handler-S-G", "name": { "family": "Handler", "given": "Sheila G." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" } ] }, "title": "Enhanced Stability and Activity for Water Oxidation in Alkaline Media with Bismuth Vanadate Photoelectrodes Modified with a Cobalt Oxide Catalytic Layer Produced by Atomic Layer Deposition", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Chemical Society. \n\nReceived: October 16, 2013; Accepted: November 21, 2013; Published: November 21, 2013. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy under award DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. XPS and AFM data were collected at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. We thank Dr. Ragip Pala for helpful discussions.\n\nSupplemental Material - jz4022415_si_001.pdf
", "abstract": "Atomic-layer deposition (ALD) of thin layers of cobalt oxide on n-type BiVO_4 produced photoanodes capable of water oxidation with essentially 100% faradaic efficiency in alkaline, pH = 13 electrolytes. By contrast, under the same operating conditions, BiVO_4 photoanodes without the Co oxide catalytic layer exhibited lower faradaic yields, of ca. 70%, for O_2 evolution and were unstable, becoming rapidly photopassivated. High numbers (>25) of ALD cycles of Co oxide deposition gave electrodes that displayed poor photoelectrochemical behavior, but 15\u201320 ALD cycles produced Co oxide overlayers ~1 nm in thickness, with the resulting photoelectrodes exhibiting a stable photocurrent density of 1.49 mA cm^(\u20132) at the oxygen-evolution potential and an open-circuit potential of 0.404 V versus the reversible hydrogen electrode, under 100 mW cm^(\u20132) of simulated air mass 1.5 illumination.", "date": "2013-12-05", "date_type": "published", "publication": "Journal of Physical Chemistry Letters", "volume": "4", "number": "23", "publisher": "American Chemical Society", "pagerange": "4188-4191", "id_number": "CaltechAUTHORS:20140110-084420760", "issn": "1948-7185", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140110-084420760", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/jz4022415", "primary_object": { "basename": "jz4022415_si_001.pdf", "url": "https://authors.library.caltech.edu/records/hcg5e-jws83/files/jz4022415_si_001.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Lichterman, Michael F.; Shaner, Matthew R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3q4pb-yja60", "eprint_id": 42886, "eprint_status": "archive", "datestamp": "2023-08-19 22:29:30", "lastmod": "2023-10-25 23:07:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sadtler-B", "name": { "family": "Sadtler", "given": "Bryce" } }, { "id": "Burgos-S-P", "name": { "family": "Burgos", "given": "Stanley P." } }, { "id": "Batara-N-A", "name": { "family": "Batara", "given": "Nicolas A." } }, { "id": "Beardslee-J-A", "name": { "family": "Beardslee", "given": "Joseph A." } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Phototropic growth control of nanoscale pattern formation in photoelectrodeposited Se-Te films", "ispublished": "pub", "full_text_status": "public", "keywords": "spontaneous pattern formation, dynamic response, nanostructured material, light-directed growth", "note": "\u00a9 2013 National Academy of Sciences. \n\nEdited by Harry B. Gray, California Institute of Technology, Pasadena, CA, and approved October 8, 2013 (received for review August 16, 2013). Published online before print November 11, 2013. \n\nWe thank Chi Ma for advice on SEM imaging. XPS was performed at the Molecular Materials Research Center in the Beckman Institute at the California Institute of Technology. SEM and EDS were performed at the Analytical Facility in the Geological and Planetary Sciences Division at the California Institute of Technology. This work is part of the \"Light\u2013Material Interactions in Energy Conversion\" Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award DE-SC0001293. B.S. acknowledges the Beckman Institute of the California Institute of Technology for a postdoctoral fellowship. \n\nAuthor contributions: B.S., H.A.A., and N.S.L. designed research; B.S., S.P.B., N.A.B., and J.A.B. performed research; B.S., S.P.B., N.A.B., and J.A.B. analyzed data; and B.S., H.A.A., and N.S.L. wrote the paper. \n\nConflict of interest statement: N.S.L. and B.S. have published a manuscript with Editorial Board Member Harry B. Gray within the last 24 months.\n\nPublished - Sadtler_2013_PNAS.pdf
Supplemental Material - sapp.pdf
", "abstract": "Photoresponsive materials that adapt their morphologies, growth directions, and growth rates dynamically in response to the local incident electromagnetic field would provide a remarkable route to the synthesis of complex 3D mesostructures via feedback between illumination and the structure that develops under optical excitation. We report the spontaneous development of ordered, nanoscale lamellar patterns in electrodeposited selenium\u2013tellurium (Se\u2013Te) alloy films grown under noncoherent, uniform illumination on unpatterned substrates in an isotropic electrolyte solution. These inorganic nanostructures exhibited phototropic growth in which lamellar stripes grew toward the incident light source, adopted an orientation parallel to the light polarization direction with a period controlled by the illumination wavelength, and showed an increased growth rate with increasing light intensity. Furthermore, the patterns responded dynamically to changes during growth in the polarization, wavelength, and angle of the incident light, enabling the template-free and pattern-free synthesis, on a variety of substrates, of woodpile, spiral, branched, or zigzag structures, along with dynamically directed growth toward a noncoherent, uniform intensity light source. Full-wave electromagnetic simulations in combination with Monte Carlo growth simulations were used to model light\u2013matter interactions in the Se\u2013Te films and produced a model for the morphological evolution of the lamellar structures under phototropic growth conditions. The experiments and simulations are consistent with a phototropic growth mechanism in which the optical near-field intensity profile selects and reinforces the dominant morphological mode in the emergent nanoscale patterns.", "date": "2013-12-03", "date_type": "published", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "volume": "110", "number": "49", "publisher": "National Academy of Sciences", "pagerange": "19707-19712", "id_number": "CaltechAUTHORS:20131206-160205259", "issn": "0027-8424", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131206-160205259", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1073/pnas.1315539110", "pmcid": "PMC3856786", "primary_object": { "basename": "Sadtler_2013_PNAS.pdf", "url": "https://authors.library.caltech.edu/records/3q4pb-yja60/files/Sadtler_2013_PNAS.pdf" }, "related_objects": [ { "basename": "sapp.pdf", "url": "https://authors.library.caltech.edu/records/3q4pb-yja60/files/sapp.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Sadtler, Bryce; Burgos, Stanley P.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cjemv-sr524", "eprint_id": 43142, "eprint_status": "archive", "datestamp": "2023-08-19 22:20:35", "lastmod": "2023-10-25 23:18:42", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Chen-Yikai", "name": { "family": "Chen", "given": "Yikai" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Modeling an integrated photoelectrolysis system sustained by water vapor", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 The Royal Society of Chemistry.\n\nReceived 26th June 2013;\nAccepted 20th September 2013;\nFirst published online 23 Sep 2013.\n\nThis material is based upon work performed by the Joint Center\nfor Artificial Photosynthesis, a DOE Energy Innovation Hub,\nsupported through the Office of Science of the U.S. Department\nof Energy under Award number DE-SC0004993.\n\nPublished - c3ee42143k.pdf
", "abstract": "Two designs for an integrated photoelectrolysis system sustained by water vapor have been investigated using a multi-physics numerical model that accounts for charge and species conservation, electron and ion transport, and electrochemical processes. Both designs leverage the use of a proton-exchange membrane that provides conductive pathways for reactant/product transport and prevents product crossover. The resistive losses, product gas transport, and gas crossovers as a function of the geometric parameters of the two designs have been evaluated systematically. In these designs, minimization of pathways in the membrane that can support the diffusive transport of product gases from the catalyst to the gas-collecting chamber was required to prevent supersaturation of hydrogen or oxygen gases at the Nafion/catalyst interface. Due to the small, thin membrane layer that was required, a small electrode width (<300 \u03bcm) was also required to produce low resistive losses in the system. Alternatively, incorporation of a structured membrane that balances the gas transport and ionic transport allows the maximum electrode width to be increased to dimensions as large as a few millimeters. Diffusive gas transport between the cathode and anode was the dominant source for crossover of the product gases under such circumstances. The critical dimension of the electrode required to produce acceptably low rates of product crossover was also investigated through the numerical modeling and device simulations.", "date": "2013-12", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "6", "number": "12", "publisher": "Royal Society of Chemistry", "pagerange": "3713-3721", "id_number": "CaltechAUTHORS:20131223-104331588", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131223-104331588", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "doi": "10.1039/c3ee42143k", "primary_object": { "basename": "c3ee42143k.pdf", "url": "https://authors.library.caltech.edu/records/cjemv-sr524/files/c3ee42143k.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Xiang, Chengxiang; Chen, Yikai; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jwtmz-ngq09", "eprint_id": 43166, "eprint_status": "archive", "datestamp": "2023-08-19 22:20:41", "lastmod": "2023-10-25 23:19:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Haussener-S", "name": { "family": "Haussener", "given": "Sophia" }, "orcid": "0000-0002-3044-1662" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Weber-A-Z", "name": { "family": "Weber", "given": "Adam Z." }, "orcid": "0000-0002-7749-1624" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Simulations of the irradiation and temperature dependence of the efficiency of tandem photoelectrochemical water-splitting systems", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 The Royal Society of Chemistry. \n\nReceived 17th April 2013; Accepted 17th June 2013. First published online 17 Jun 2013.\n\nWe acknowledge the Joint Center for Artificial Photosynthesis, a\nDOE Energy Innovation Hub, supported through the Office of\nScience of the U.S. Department of Energy under Award Number\nDE-SC0004993. We thank Harry Atwater for fruitful discussions\non temperature-dependent analysis of realistic systems.\n\nPublished - c3ee41302k.pdf
Supplemental Material - c3ee41302k_si.pdf
", "abstract": "The instantaneous efficiency of an operating photoelectrochemical solar-fuel-generator system is a complicated function of the tradeoffs between the light intensity and temperature-dependence of the photovoltage and photocurrent, as well as the losses associated with factors that include ohmic resistances, concentration overpotentials, kinetic overpotentials, and mass transport. These tradeoffs were evaluated quantitatively using an advanced photoelectrochemical device model comprised of an analytical device physics model for the semiconducting light absorbers in combination with a multi-physics device model that solved for the governing conservation equations in the various other parts of the system. The model was used to evaluate the variation in system efficiency due to hourly and seasonal variations in solar irradiation as well as due to variation in the isothermal system temperature. The system performance characteristics were also evaluated as a function of the band gaps of the dual-absorber tandem component and its properties, as well as the device dimensions and the electrolyte conductivity. The modeling indicated that the system efficiency varied significantly during the day and over a year, exhibiting local minima at midday and a global minimum at midyear when the solar irradiation is most intense. These variations can be reduced by a favorable choice of the system dimensions, by a reduction in the electrolyte ohmic resistances, and/or by utilization of very active electrocatalysts for the fuel-producing reactions. An increase in the system temperature decreased the annual average efficiency and led to less rapid ramp-up and ramp-down phases of the system, but reduced midday and midyear instantaneous efficiency variations. Careful choice of the system dimensions resulted in minimal change in the system efficiency in response to degradation in the quality of the light absorbing materials. The daily and annually averaged mass of hydrogen production for the optimized integrated system compared favorably to the daily and annually averaged mass of hydrogen that was produced by an optimized stand-alone tandem photovoltaic array connected electrically to a stand-alone electrolyzer system. The model can be used to predict the performance of the system, to optimize the design of solar-driven water splitting devices, and to guide the development of components of the devices as well as of the system as a whole.", "date": "2013-12", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "6", "number": "12", "publisher": "Royal Society of Chemistry", "pagerange": "3605-3618", "id_number": "CaltechAUTHORS:20131224-102701042", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131224-102701042", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c3ee41302k", "primary_object": { "basename": "c3ee41302k.pdf", "url": "https://authors.library.caltech.edu/records/jwtmz-ngq09/files/c3ee41302k.pdf" }, "related_objects": [ { "basename": "c3ee41302k_si.pdf", "url": "https://authors.library.caltech.edu/records/jwtmz-ngq09/files/c3ee41302k_si.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Haussener, Sophia; Hu, Shu; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nmnzs-3pq69", "eprint_id": 117441, "eprint_status": "archive", "datestamp": "2023-08-22 10:55:01", "lastmod": "2023-10-24 22:31:46", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nielander-Adam-C", "name": { "family": "Nielander", "given": "Adam C." }, "orcid": "0000-0002-3639-2427" }, { "id": "Bierman-Matthew-J", "name": { "family": "Bierman", "given": "Matthew J." }, "orcid": "0000-0002-9053-6356" }, { "id": "Petrone-Nicholas-W", "name": { "family": "Petrone", "given": "Nicholas" }, "orcid": "0000-0003-1995-4077" }, { "id": "Strandwitz-Nicholas-C", "name": { "family": "Strandwitz", "given": "Nicholas C." }, "orcid": "0000-0001-6159-9430" }, { "id": "Ardo-Shane", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Yang-Fan", "name": { "family": "Yang", "given": "Fan" } }, { "id": "Hone-James", "name": { "family": "Hone", "given": "James" }, "orcid": "0000-0002-8084-3301" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemical Behavior of n-Type Si(111) Electrodes Coated With a Single Layer of Graphene", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "N.S.L. and A.C.N. acknowledge the NSF, Grant CHE-1214152, for support and the Beckman Institute Molecular Materials Resource Center for facilities. A.C.N. acknowledges support from the Dept. of Defense through the National Defense Science & Engineering Graduate Fellowship Program. S.A. acknowledges support from a U.S. Dept. of Energy, Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under EERE Fuel Cell Technologies Program. N.P. and J.H. acknowledge the Center for Re-Defining Photovoltaic Efficiency Through Molecular-Scale Control, an Energy Frontier Research Center funded by the U.S. Dept. of Energy, Office of Science, Office of Basic Energy Sciences under Award DE-SC0001085.", "abstract": "The behavior of graphene-coated n-type Si(111) photoanodes was compared to the behavior of H-terminated n-type Si(111) photoanodes in contact with aqueous K\u2083[Fe(CN)\u2086]/K\u2084[Fe(CN)\u2086] as well as in contact with a series of outer-sphere, one-electron redox couples in nonaqueous electrolytes. The n-Si/Graphene electrodes exhibited stable short-circuit photocurrent densities of over 10 mA cm\u207b\u00b2 for >1000 s of continuous operation in aqueous electrolytes, whereas n-Si\u2013H electrodes yielded a nearly complete decay of the current density within \u223c100 s. The values of the open-circuit photovoltages and the flat-band potentials of the Si were a function of both the Fermi level of the graphene and the electrochemical potential of the electrolyte solution, indicating that the n-Si/Graphene did not form a buried junction with respect to the solution contact.", "date": "2013-11-20", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "135", "number": "46", "publisher": "American Chemical Society", "pagerange": "17246-17249", "id_number": "CaltechAUTHORS:20221017-72823300.1", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221017-72823300.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001085" } ] }, "doi": "10.1021/ja407462g", "resource_type": "article", "pub_year": "2013", "author_list": "Nielander, Adam C.; Bierman, Matthew J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qg8s9-6d047", "eprint_id": 42844, "eprint_status": "archive", "datestamp": "2023-08-22 10:43:35", "lastmod": "2023-10-25 23:05:15", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Garc\u00eda-Berr\u00edos-E", "name": { "family": "Garc\u00eda-Berr\u00edos", "given": "Edgardo" } }, { "id": "Theriot-J-C", "name": { "family": "Theriot", "given": "Jordan C." } }, { "id": "Woodka-M-D", "name": { "family": "Woodka", "given": "Marc D." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Detection of ammonia, 2,4,6-trinitrotoluene, and common organic vapors using thin-film carbon black-metalloporphyrin composite chemiresistors", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Porphyrins; Carbon black composites; Electronic nose; Principal components analysis (PCA); 2,4,6 Trinitrotoluene", "note": "\u00a9 2013 Published by Elsevier B.V.\n\nReceived 12 January 2011; Received in revised form 21 June 2013; Accepted 5 July 2013; Available online 13 July 2013.\n\nThe authors thank Professor S. Maldonado, Dr. B.S. Brunschwig and Dr. W.J. Royea for helpful discussions. We gratefully acknowledge the DHS, the NSF, the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology, and Boeing Inc. for financial support, in addition to Next Dimension Technologies for donation of materials used in this work. The NSF is acknowledged for a graduate fellowship to Edgardo Garc\u00eda-Berr\u00edos.", "abstract": "Thin-film chemiresistive composites of octaethylporphine-based transition-metal complexes (Ph(M), M = Co, Cu and Zn) and carbon black (CB) have been fabricated and tested as chemical vapor sensors. The sensing performance of such sensor composites was compared to the sensing performance of composites of metallophthalocyanines (Phtc(M)) and CB. The relative differential resistance response of Ph(M)/CB sensor films upon exposure to organic vapors, such as n-hexane, n-heptane, n-octane, iso-octane, cyclohexane, toluene, ethyl acetate and ethanol, was dependent on the nature of the metal center. An array of chemiresistive Ph(M)/CB vapor sensors therefore provided discrimination between the organic vapor analytes that had different polarities, specifically classifying non-polar vapors, aprotic polar vapors and protic polar vapors. However, discrimination was not observed for analytes that had mutually similar polarities. The Ph(M)/CB sensors showed reversible responses toward ammonia, NH_3(g), at concentrations below the 8 h permissible exposure level (50 ppm). Ph(M)/CB composites exhibited a slightly larger resistance response than Phtc(M)/CB composites, consistent with the Ph(M) species having less \u03c0-stacked molecular aggregates, resulting in an increase in the number of adsorption sites relative to the Phtc(M)/CB composites. Resistance responses with a signal-to-noise ratio value of \u223c900 were obtained upon exposure to vapor pulses saturated with 2,4,6-trinitrotoluene.", "date": "2013-11", "date_type": "published", "publication": "Sensors and Actuators B: Chemical", "volume": "188", "publisher": "Elsevier", "pagerange": "761-767", "id_number": "CaltechAUTHORS:20131205-080859215", "issn": "0925-4005", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131205-080859215", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "DHS" }, { "agency": "NSF" }, { "agency": "Caltech Molecular Materials Research Center" }, { "agency": "Boeing Inc." }, { "agency": "NSF Graduate Fellowship" } ] }, "doi": "10.1016/j.snb.2013.07.006", "resource_type": "article", "pub_year": "2013", "author_list": "Garc\u00eda-Berr\u00edos, Edgardo; Theriot, Jordan C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/x55pf-b7h51", "eprint_id": 42409, "eprint_status": "archive", "datestamp": "2023-08-19 21:54:24", "lastmod": "2023-10-25 15:54:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nielander-A-C", "name": { "family": "Nielander", "given": "Adam C." }, "orcid": "0000-0002-3639-2427" }, { "id": "Bierman-M-J", "name": { "family": "Bierman", "given": "Matthew J." } }, { "id": "Petrone-N", "name": { "family": "Petrone", "given": "Nicholas" } }, { "id": "Strandwitz-N-C", "name": { "family": "Strandwitz", "given": "Nicholas C." } }, { "id": "Ardo-S", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Yang-Fan", "name": { "family": "Yang", "given": "Fan" } }, { "id": "Hone-J", "name": { "family": "Hone", "given": "James" }, "orcid": "0000-0002-8084-3301" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemical Behavior of n\u2011Type Si(111) Electrodes Coated With a Single Layer of Graphene", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Chemical Society. Received: July 20, 2013. Just Accepted Manuscript October 14, 2013. N.S.L. and A.C.N. acknowledge the NSF, Grant CHE-1214152,\nfor support and the Beckman Institute Molecular Materials\nResource Center for facilities. A.C.N. acknowledges support\nfrom the Dept. of Defense through the National Defense\nScience & Engineering Graduate Fellowship Program. S.A.\nacknowledges support from a U.S. Dept. of Energy, Office of\nEnergy Efficiency and Renewable Energy (EERE) Postdoctoral\nResearch Award under EERE Fuel Cell Technologies Program.\nN.P. and J.H. acknowledge the Center for Re-Defining\nPhotovoltaic Efficiency Through Molecular-Scale Control, an\nEnergy Frontier Research Center funded by the U.S. Dept. of\nEnergy, Office of Science, Office of Basic Energy Sciences\nunder Award DE-SC0001085.\n\nSupplemental Material - ja407462g_si_001.pdf
", "abstract": "The behavior of graphene-coated n-type Si(111) photoanodes was compared to the behavior of H-terminated n-type Si(111) photoanodes in contact with aqueous K_3[Fe(CN)_6]/K_4[Fe(CN)_6] as well as in contact with a series of outer-sphere, one-electron redox couples in nonaqueous electrolytes. The n-Si/Graphene electrodes exhibited stable short-circuit photocurrent densities of over 10 mA cm^(\u20132) for >1000 s of continuous operation in aqueous electrolytes, whereas n-Si\u2013H electrodes yielded a nearly complete decay of the current density within 100 s. The values of the open-circuit photovoltages and the flat-band potentials of the Si were a function of both the Fermi level of the graphene and the electrochemical potential of the electrolyte solution, indicating that the n-Si/Graphene did not form a buried junction with respect to the solution contact.", "date": "2013-10-14", "date_type": "published", "publication": "Journal of the American Chemical Society", "publisher": "American Chemical Society", "id_number": "CaltechAUTHORS:20131113-084041726", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131113-084041726", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Caltech Beckman Institute" }, { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" }, { "agency": "EERE Fuel Cell Technologies Program" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001085" } ] }, "doi": "10.1021/ja407462g", "primary_object": { "basename": "ja407462g_si_001.pdf", "url": "https://authors.library.caltech.edu/records/x55pf-b7h51/files/ja407462g_si_001.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Nielander, Adam C.; Bierman, Matthew J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/j3j2v-49s47", "eprint_id": 42538, "eprint_status": "archive", "datestamp": "2023-08-19 21:39:10", "lastmod": "2023-10-25 16:45:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Haussener-S", "name": { "family": "Haussener", "given": "Sophia" }, "orcid": "0000-0002-3044-1662" }, { "id": "Berger-A-D", "name": { "family": "Berger", "given": "Alan D." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "An analysis of the optimal band gaps of light absorbers in integrated tandem photoelectrochemical water-splitting systems", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 Royal Society of Chemistry. \n\nReceived 7th February 2013; Accepted 11th April 2013; Published online 10th May 2013. \n\nThis work was supported through the Office of Science of the U.S. Department of Energy under Award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub.\n\nPublished - c3ee40453f.pdf
Supplemental Material - c3ee40453f_si.pdf
", "abstract": "The solar-to-hydrogen (STH) efficiency limits, along with the maximum efficiency values and the corresponding optimal band gap combinations, have been evaluated for various combinations of light absorbers arranged in a tandem configuration in realistic, operational water-splitting prototypes. To perform the evaluation, a current\u2013voltage model was employed, with the light absorbers, electrocatalysts, solution electrolyte, and membranes coupled in series, and with the directions of optical absorption, carrier transport, electron transfer and ionic transport in parallel. The current density vs. voltage characteristics of the light absorbers were determined by detailed-balance calculations that accounted for the Shockley\u2013Queisser limit on the photovoltage of each absorber. The maximum STH efficiency for an integrated photoelectrochemical system was found to be ~31.1% at 1 Sun (=1 kW m\u207b\u00b2, air mass 1.5), fundamentally limited by a matching photocurrent density of 25.3 mA cm\u207b\u00b2 produced by the light absorbers. Choices of electrocatalysts, as well as the fill factors of the light absorbers and the Ohmic resistance of the solution electrolyte also play key roles in determining the maximum STH efficiency and the corresponding optimal tandem band gap combination. Pairing 1.6\u20131.8 eV band gap semiconductors with Si in a tandem structure produces promising light absorbers for water splitting, with theoretical STH efficiency limits of >25%.", "date": "2013-10", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "6", "number": "10", "publisher": "Royal Society of Chemistry", "pagerange": "2984-2993", "id_number": "CaltechAUTHORS:20131118-152050309", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131118-152050309", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c3ee40453f", "primary_object": { "basename": "c3ee40453f.pdf", "url": "https://authors.library.caltech.edu/records/j3j2v-49s47/files/c3ee40453f.pdf" }, "related_objects": [ { "basename": "c3ee40453f_si.pdf", "url": "https://authors.library.caltech.edu/records/j3j2v-49s47/files/c3ee40453f_si.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Hu, Shu; Xiang, Chengxiang; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/497sv-eyh40", "eprint_id": 41896, "eprint_status": "archive", "datestamp": "2023-08-19 21:16:09", "lastmod": "2023-10-25 14:53:23", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ardo-S", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Roske-C-W", "name": { "family": "Roske", "given": "Chris W." } }, { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Demonstration of artificial photosynthesis with peeled silicon microrod arrays", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "The sustained use of solar energy is plagued by the intermittency of sunlight. If the energy from fleeting solar photons can be\nstored in chem. bonds through electrochem. reactions, this intermittency can be levelized to power demands. Although water is\noften proposed as the electron source for these reactions, myriad electron sources exist that may be better matched to the\nvoltage output of existing photovoltaics. In light of this, peeled silicon microrod arrays, partially embedded in a Nafion\nproton-exchange membrane, were used to drive solar hydroiodic-acid splitting (i.e. HI --> H_2 + I_3-). Open-circuit photovoltages\nmeasured for p-type and n-type microrod arrays driving aq. H_2 evolution and iodide oxidn., resp., were 450 - 500 mV.\nCorrosion of Si was attenuated through methylation of Si atop sites via a two-step chlorination-alkylation surface chem.\nprocedure. This resulted in stable iodide oxidn. under continuous simulated sunlight illumination for weeks. Amorphous MoSx,\nPt, or PEDOT:PSS electrocatalysts were deposited on the microrods to catalyze H2 evolution and iodide oxidn. Si microrod\narrays were partially embedded in Nafion and mech. removed from the Si substrate to yield free-standing, flexible devices.\nSolar-to-hydrogen efficiencies and faradaic yields for product formation were quantified. These systems are sustainable\nbecause the HI fuel precursor is inorg., thus not capable of liberating CO2, and HI can be regenerated in a flow battery or fuel\ncell as H_2 + I_3-/I_2.", "date": "2013-09", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20131011-113955668", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131011-113955668", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Ardo, Shane; Roske, Chris W.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4thqb-5tr89", "eprint_id": 41099, "eprint_status": "archive", "datestamp": "2023-08-19 21:13:00", "lastmod": "2023-10-24 23:27:31", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Mi-Qixi", "name": { "family": "Mi", "given": "Qixi" } }, { "id": "Coridan-R-H", "name": { "family": "Coridan", "given": "Robert H." }, "orcid": "0000-0003-1916-4446" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemical oxidation of anions by WO_3 in aqueous and nonaqueous electrolytes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 The Royal Society of Chemistry. \n\nReceived 1st March 2013; Accepted 18th June 2013. First published online 18 Jun 2013. \n\nWe acknowledge the National Science Foundation (NSF) Powering the Planet Center for Chemical Innovation (CCI-Solar),\nGrants CHE-0802907 and CHE-0947829, and the Molecular Materials Research Center of the Beckman Institute at the\nCalifornia Institute of Technology, for support. QM acknowledges Dr Elizabeth A. Santori for assistance with the spectral response experiments, and the NSF for support as a CCI-Solar Postdoctoral Fellow.\n\nPublished - c3ee40712h.pdf
Supplemental Material - c3ee40712h_si.pdf
", "abstract": "The behavior of WO_3 photoanodes has been investigated in contact with a combination of four anions (Cl\u2212, CH_3SO_3\u2212, HSO_4\u2212, and ClO_4\u2212) and three solvents (water, acetonitrile, and propylene carbonate), to elucidate the role of the semiconductor surface, the electrolyte, and redox kinetics on the current density vs. potential properties of n-type WO_3. In 1.0 M aqueous strong acids, although the flat-band potential (E_(fb)) of WO_3 was dominated by electrochemical intercalation of protons into WO_3, the nature of the electrolyte influenced the onset potential (E_(on)) of the anodic photocurrent. In aprotic solvents, the electrolyte anion shifted both E_(fb) and E_(on), but did not significantly alter the overall profile of the voltammetric data. For 0.50 M tetra(n-butyl)ammonium perchlorate in propylene carbonate, the internal quantum yield exceeded unity at excitation wavelengths of 300\u2013390 nm, indicative of current doubling. A regenerative photoelectrochemical cell based on the reversible redox couple B_(10)Br_(10)^(\u02d9\u2212/2\u2212) in acetonitrile, with a solution potential of 1.7 V vs. the normal hydrogen electrode, exhibited an open-circuit photovoltage of 1.32 V under 100 mW cm^(\u22122) of simulated Air Mass 1.5 global illumination.", "date": "2013-09", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "6", "number": "9", "publisher": "Royal Society of Chemistry", "pagerange": "2646-2653", "id_number": "CaltechAUTHORS:20130905-093517424", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130905-093517424", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "NSF", "grant_number": "CHE-0947829" }, { "agency": "Caltech Beckman Institute" }, { "agency": "NSF Postdoctoral Fellowship" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1039/c3ee40712h", "primary_object": { "basename": "c3ee40712h.pdf", "url": "https://authors.library.caltech.edu/records/4thqb-5tr89/files/c3ee40712h.pdf" }, "related_objects": [ { "basename": "c3ee40712h_si.pdf", "url": "https://authors.library.caltech.edu/records/4thqb-5tr89/files/c3ee40712h_si.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Mi, Qixi; Coridan, Robert H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kwfpq-4pz13", "eprint_id": 41949, "eprint_status": "archive", "datestamp": "2023-08-19 21:17:09", "lastmod": "2023-10-25 14:57:09", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sadtler-B", "name": { "family": "Sadtler", "given": "Bryce" } }, { "id": "Burgos-S-P", "name": { "family": "Burgos", "given": "Stanley P." } }, { "id": "Batara-N-A", "name": { "family": "Batara", "given": "Nicolas A." } }, { "id": "Beardslee-J-A", "name": { "family": "Beardslee", "given": "Joseph A." } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Phototropic growth control of nanoscale pattern formation in photoelectrodeposited Se-Te films", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Photoresponsive materials that adapt their growth rates dynamically to the local incident electromagnetic field\nwould provide a remarkable route to the synthesis of complex three-dimensional mesoscale structures via\nfeedback between illumination and the morphol. that develops in response to the optical excitation. We report\nthe spontaneous development of ordered, complex nanoscale lamellar patterns in electrodeposited seleniumtellurium\n(Se-Te) alloy films that are grown under uniform illumination on unpatterned substrates in an isotropic\nelectrolyte soln. These inorg. nanostructures exhibited phototropic growth in which lamellar stripes grew\ntowards the incident light source, adopted an orientation parallel to the light polarization direction, and showed\nan increased growth rate with increasing light intensity. The illumination wavelength controlled the\nlamellar period, which varied from 130 nm for UV light to 412 nm for near-IR light. The height modulation of the\nlamellar morphol. was detd. by the ratio of the photocurrent-mediated growth rate to the growth rate\nmediated by the dark current at a given applied potential. Highly anisotropic features, exhibiting av. lamellar\nheights of 938 nm and widths of 164 nm, were formed under incident light intensities of 18.6 mW/cm2 at a\npotential of -0.40 V referenced to a std. calomel electrode. Furthermore, the patterns responded dynamically to\nchanges during growth in the polarization, wavelength, and angle of the incident light, enabling the templatefree\nand pattern-free synthesis of woodpile, spiral, or branched structures. Full-wave electromagnetic\nsimulations were used to model the light-matter interactions in Se-Te films. In combination with Monte Carlo\ngrowth simulations, this approach produced a model for the morphol. evolution of the lamellar structures under\nphototropic growth conditions. The simulations and expts. are consistent with a phototropic growth\nmechanism in which the optical near-field intensity profile selects and reinforces the dominant morphol. mode in\nthe developing nanoscale patterns.", "date": "2013-09", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20131016-130836053", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131016-130836053", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Sadtler, Bryce; Burgos, Stanley P.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/67szj-e5a08", "eprint_id": 120624, "eprint_status": "archive", "datestamp": "2023-08-22 10:09:33", "lastmod": "2023-10-18 17:55:42", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Haussener-Sophia", "name": { "family": "Haussener", "given": "Sophia" }, "orcid": "0000-0002-3044-1662" }, { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Weber-Adam-Z", "name": { "family": "Weber", "given": "Adam Z." }, "orcid": "0000-0002-7749-1624" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Simulations of the Irradiation and Temperature Dependence of the Efficiency of Tandem Photoelectrochemical Water-splitting Systems", "ispublished": "pub", "full_text_status": "public", "keywords": "General Medicine", "note": "We acknowledge the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. We thank Harry Atwater for fruitful discussions on temperature-dependent analysis of realistic systems.", "abstract": "The efficiency of an operating photoelectrochemical solar-fuels-generator system is determined by the system design, the properties and morphology of the system's components, and the operational conditions. We used a previously developed model comprising of i) the detailed balance limit to describe the currentpotential performance of the photoabsorber component, and ii) the detailed multi-physics device model solving for the governing conservation equations (mass, momentum, species and charge) spatially resolved in the device, to quantify the performance of photoelectrochemical devices. The investigated the performance and its variations as a function of operational conditions, i.e. daily and seasonal irradiation variations, concentration factor of irradiation, and isothermal device temperature. Additionally, the difference in performance of an integrated photoelectrochemical system and a photovoltaic array connected electrically to a standalone electrolyzer system was quantified.", "date": "2013-08-31", "date_type": "published", "publication": "ECS Transactions", "volume": "58", "number": "2", "publisher": "Electrochemical Society", "pagerange": "293-303", "id_number": "CaltechAUTHORS:20230329-637828000.2", "issn": "1938-5862", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-637828000.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1149/05802.0293ecst", "resource_type": "article", "pub_year": "2013", "author_list": "Haussener, Sophia; Hu, Shu; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9k7g8-vxp12", "eprint_id": 41469, "eprint_status": "archive", "datestamp": "2023-08-19 20:51:43", "lastmod": "2023-10-24 23:46:07", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Reyes-Gil-K-R", "name": { "family": "Reyes-Gil", "given": "Karla R." } }, { "id": "Wiggenhorn-C", "name": { "family": "Wiggenhorn", "given": "Craig" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparison between the Quantum Yields of Compact and Porous WO_3 Photoanodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Chemical Society. \n\nReceived: March 13, 2013; Revised: June 15, 2013; Published: June 17, 2013. \n\nThis work was funded by the NSF Powering the Planet Center for Chemical Innovation, grant CHE-0947829, and by the Defense Advanced Research Projects Agency. Use of facilities at the Molecular Materials Research Center (MMRC) at Caltech is gratefully acknowledged. The authors also acknowledge the technical work of Miguel Ortiz from California State University, Los Angeles.\n\nSupplemental Material - jp4025624_si_001.pdf
", "abstract": "Ordered structures offer the potential for producing photoanodes with enhanced minority-carrier collection. To evaluate this approach to visible-light-driven oxidation in aqueous electrolytes, porous WO_3 structures were synthesized by the potentiostatic anodization of W foil. The photoelectrochemical behavior of the porous WO_3 photoanodes was compared to that of compact WO_3 films. Relative to planar electrodes, the porous WO_3 electrodes exhibited a 6-fold increase in photocurrent density, from 0.12 to 0.75 mA cm^(\u20132), under 100 mW cm^(\u20132) of simulated solar illumination. Spectral response measurements indicated that the porous electrodes exhibited internal quantum yields of 0.5 throughout most of the region of WO_3 absorption. The external quantum yield of the porous WO_3 films was a function of the angle of incidence of the light, increasing from 0.25 at normal incidence to 0.50 at 65\u00b0 off normal. The porous WO_3 films showed excellent stability against photodegradation. This work demonstrates that morphological control can improve the internal quantum yield of photoanodes in contact with aqueous electrolytes.", "date": "2013-07-25", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "117", "number": "29", "publisher": "American Chemical Society", "pagerange": "14947-14957", "id_number": "CaltechAUTHORS:20130923-093622415", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130923-093622415", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0947829" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/jp4025624", "primary_object": { "basename": "jp4025624_si_001.pdf", "url": "https://authors.library.caltech.edu/records/9k7g8-vxp12/files/jp4025624_si_001.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Reyes-Gil, Karla R.; Wiggenhorn, Craig; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/gpyw6-dbv55", "eprint_id": 42400, "eprint_status": "archive", "datestamp": "2023-08-19 20:48:09", "lastmod": "2023-10-25 15:54:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Walter-M-G", "name": { "family": "Walter", "given": "Michael G." } }, { "id": "Liu-Xueliang", "name": { "family": "Liu", "given": "Xueliang" } }, { "id": "O'Leary-L-E", "name": { "family": "O'Leary", "given": "Leslie E." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electrical Junction Behavior of Poly(3,4-ethylenedioxythiophene) (PEDOT) Contacts to H\u2011Terminated and CH_3\u2011Terminated p\u2011, n\u2011, and n^+\u2011Si(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Chemical Society. \n\nReceived: February 20, 2013; Revised: May 6, 2013; Published: May 8, 2013. \n\nWe acknowledge the National Science Foundation Grant CHE-1214152 for financial support. We acknowledge critical support and infrastructure provided for this work by the Kavli Nanoscience Institute at Caltech. M.G.W. acknowledges support from a NSF American Competitiveness in Chemistry postdoctoral fellowship (CHE-0937048). \n\nAdditional information regarding the preparation and measurements of the PEDOT:PSS films and J\u2013V data of aged electrodes. This material is available free of charge via the Internet at http://pubs.acs.org.\n\nSupplemental Material - jp4018162_si_001.pdf
", "abstract": "The electronic and photovoltaic properties of junctions between the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and Si(111) surfaces have been investigated for a range of doping types, doping levels, and surface functionalization of the Si. PEDOT\u2013poly(styrenesulfonate) (PSS) formed ohmic, low resistance contacts to H-terminated and CH_3-terminated p-type Si(111) surfaces. In contrast, PEDOT formed high barrier height (0.8\u20131.0 V) contacts to n-Si(111) surfaces, with CH_3-terminated n-Si(111)/PEDOT contacts showing slightly higher barrier heights (1.01 eV) than H-terminated n-Si(111)/PEDOT contacts (0.89 V). PEDOT contacts to CH_3-terminated and H-terminated n-Si(111) surfaces both produced photovoltages under illumination in accord with the Shockley diode limit based on bulk/recombination diffusion in the semiconductor. Such devices produced solar energy-conversion efficiencies of 5.7% under 100 mW cm^(\u20132) of simulated air mass 1.5 illumination. The electrical properties of PEDOT contacts to CH_3-terminated Si surfaces were significantly more stable in an air ambient than the electrical properties of PEDOT contacts to H-terminated Si surfaces. PEDOT films produced a low resistance, tunnel-barrier type of ohmic contact to n^+-Si(111) surfaces. Hence, through various combinations of doping type, doping level, and surface functionalization, the PEDOT/Si contact system offers a wide range of opportunities for integration into monolithic photovoltaic and/or artificial photosynthetic systems.", "date": "2013-07-18", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "117", "number": "28", "publisher": "American Chemical Society", "pagerange": "14485-14492", "id_number": "CaltechAUTHORS:20131112-143252303", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131112-143252303", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "NSF Postdoctoral Fellowship", "grant_number": "CHE-0937048" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/jp4018162", "primary_object": { "basename": "jp4018162_si_001.pdf", "url": "https://authors.library.caltech.edu/records/gpyw6-dbv55/files/jp4018162_si_001.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Walter, Michael G.; Liu, Xueliang; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/y04h3-sts70", "eprint_id": 40989, "eprint_status": "archive", "datestamp": "2023-08-19 20:44:27", "lastmod": "2023-10-24 23:21:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "O'Leary-L-E", "name": { "family": "O'Leary", "given": "Leslie E." } }, { "id": "Rose-M-J", "name": { "family": "Rose", "given": "Michael J." } }, { "id": "Ding-Tina-X", "name": { "family": "Ding", "given": "Tina X." } }, { "id": "Johansson-E-M", "name": { "family": "Johansson", "given": "Erik" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Heck Coupling of Olefins to Mixed Methyl/Thienyl Monolayers on Si(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Chemical Society. \n\nReceived: March 10, 2013; Published: June 26, 2013. \n\nThis work was supported by the National Science Foundation (CHE-1214152) and the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology. The Link Foundation Energy fellowship (L.E.O.), the NSF ACC-F (M.J.R., CHE-1042009), and the John and Maria Laffin Trust SURF (T.X.D.) are gratefully acknowledged for graduate, postdoctoral, and undergraduate fellowship support. We acknowledge Dr. Ronald Grimm and Ms. Judith Lattimer for insightful discussions.\n\nSupplemental Material - ja402495e_si_001.pdf
", "abstract": "The Heck reaction has been used to couple olefins to a Si(111) surface that was functionalized with a mixed monolayer comprised of methyl and thienyl groups. The coupling method maintained a conjugated linkage between the surface and the olefinic surface functionality, to allow for facile charge transfer from the silicon surface. While a Si(111) surface terminated only with thienyl groups displayed a surface recombination velocity, S, of 670 \u00b1 190 cm s^(\u20131), the mixed CH_3/SC_4H_3\u2013Si(111) surfaces with a coverage of \u03b8_(SC_4H_3) = 0.15 \u00b1 0.02 displayed a substantially lower value of S = 27 \u00b1 9 cm s^(\u20131). Accordingly, CH_3/SC_4H_3\u2013Si(111) surfaces were brominated with N-bromosuccinimide, to produce mixed CH_3/SC_4H_2Br\u2013Si(111) surfaces with coverages of \u03b8_(Br\u2013Si) < 0.05. The resulting aryl halide surfaces were activated using [Pd(PPh_3)_4] as a catalyst. After activation, Pd(II) was selectively coordinated by oxidative addition to the surface-bound aryl halide. The olefinic substrates 4-fluorostyrene, vinylferrocene, and protoporphyrin IX dimethyl ester were then coupled (in dimethylformamide at 100 \u00b0C) to the Pd-containing functionalized Si surfaces. The porphyrin-modified surface was then metalated with Co, Cu, or Zn. The vinylferrocene-modified Si(111) surface showed a linear dependence of the peak current on scan rate in cyclic voltammetry, indicating that facile electron transfer had been maintained and providing evidence of a robust linkage between the Si surface and the tethered ferrocene. The final Heck-coupled surface exhibited S = 70 cm s^(\u20131), indicating that high-quality surfaces could be produced by this multistep synthetic approach for tethering small molecules to silicon photoelectrodes.", "date": "2013-07-10", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "135", "number": "27", "publisher": "American Chemical Society", "pagerange": "10081-10090", "id_number": "CaltechAUTHORS:20130829-095118486", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130829-095118486", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Link Foundation" }, { "agency": "NSF", "grant_number": "CHE-1042009" }, { "agency": "John and Maria Laffin Trust" }, { "agency": "Caltech Summer Undergraduate Research Fellowship (SURF)" } ] }, "doi": "10.1021/ja402495e", "primary_object": { "basename": "ja402495e_si_001.pdf", "url": "https://authors.library.caltech.edu/records/y04h3-sts70/files/ja402495e_si_001.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "O'Leary, Leslie E.; Rose, Michael J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qpzme-j2p64", "eprint_id": 42604, "eprint_status": "archive", "datestamp": "2023-08-19 20:44:36", "lastmod": "2023-10-25 16:56:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gleason-Rohrer-D-C", "name": { "family": "Gleason-Rohrer", "given": "David C." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Measurement of the Band Bending and Surface Dipole at Chemically Functionalized Si(111)/Vacuum Interfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Chemical Society. \n\nReceived: February 13, 2013; Revised: July 8, 2013; Published: July 10, 2013. \n\nWe gratefully acknowledge the National Science Foundation (CHE-0911682 and CHE-1214152), the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology, and Toyota for support of this work.\n\nSupplemental Material - jp401585s_si_001.pdf
", "abstract": "The core-level energy shifts observed using X-ray photoelectron spectroscopy (XPS) have been used to determine the band bending at Si(111) surfaces terminated with Si\u2013Br, Si\u2013H, and Si\u2013CH3 groups, respectively. The surface termination influenced the band bending, with the Si 2p3/2 binding energy affected more by the surface chemistry than by the dopant type. The highest binding energies were measured on Si(111)\u2013Br (whose Fermi level was positioned near the conduction band at the surface), followed by Si(111)\u2013H, followed by Si(111)\u2013CH3 (whose Fermi level was positioned near midgap at the surface). Si(111)\u2013CH3 surfaces exposed to Br2(g) yielded the lowest binding energies, with the Fermi level positioned between midgap and the valence band. The Fermi level position of Br2(g)-exposed Si(111)\u2013CH3 was consistent with the presence of negatively charged bromine-containing ions on such surfaces. The binding energies of all of the species detected on the surface (C, O, Br) shifted with the band bending, illustrating the importance of isolating the effects of band bending when measuring chemical shifts on semiconductor surfaces. The influence of band bending was confirmed by surface photovoltage (SPV) measurements, which showed that the core levels shifted toward their flat-band values upon illumination. Where applicable, the contribution from the X-ray source to the SPV was isolated and quantified. Work functions were measured by ultraviolet photoelectron spectroscopy (UPS), allowing for calculation of the sign and magnitude of the surface dipole in such systems. The values of the surface dipoles were in good agreement with previous measurements as well as with electronegativity considerations. The binding energies of the adventitious carbon signals were affected by band bending as well as by the surface dipole. A model of band bending in which charged surface states are located exterior to the surface dipole is consistent with the XPS and UPS behavior of the chemically functionalized Si(111) surfaces investigated herein.", "date": "2013-07-10", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "117", "number": "35", "publisher": "American Chemical Society", "pagerange": "18031-18042", "id_number": "CaltechAUTHORS:20131120-160424952", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131120-160424952", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0911682" }, { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Toyota" } ] }, "doi": "10.1021/jp401585s", "primary_object": { "basename": "jp401585s_si_001.pdf", "url": "https://authors.library.caltech.edu/records/qpzme-j2p64/files/jp401585s_si_001.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Gleason-Rohrer, David C.; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1mge0-dre42", "eprint_id": 39891, "eprint_status": "archive", "datestamp": "2023-08-19 20:29:39", "lastmod": "2023-10-24 17:17:33", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Popczun-E-J", "name": { "family": "Popczun", "given": "Eric J." } }, { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Read-C-G", "name": { "family": "Read", "given": "Carlos G." } }, { "id": "Biacchi-A-J", "name": { "family": "Biacchi", "given": "Adam J." } }, { "id": "Wiltrout-A-M", "name": { "family": "Wiltrout", "given": "Alex M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Schaak-R-E", "name": { "family": "Schaak", "given": "Raymond E." } } ] }, "title": "Nanostructured Nickel Phosphide as an Electrocatalyst for the Hydrogen Evolution Reaction", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Chemical Society.\n\nReceived: April 6, 2013;\nPublished: June 13, 2013.\n\nThis work was supported by the U.S. National Science\nFoundation \"Powering the Planet\" Center for Chemical\nInnovation (CHE-0802907). J.R.M. acknowledges the Department of Energy, Office of Science for a graduate research\nfellowship. TEM imaging was performed in the Electron\nMicroscopy Facility of the Huck Institutes of the Life Sciences,\nand HRTEM and SEM imaging was performed in the Materials\nCharacterization Lab of the Penn State Materials Research\nInstitute. The authors thank Melisa Yashinski, Julie Anderson,\nand Trevor Clark for assistance with SEM imaging, Josh\nStapleton for assistance with DRIFTS data collection and\ninterpretation, and Jason Binz and Robert Rioux for assistance\nwith the BET surface area measurements.\n\nSupplemental Material - ja403440e_si_001.pdf
", "abstract": "Nanoparticles of nickel phosphide (Ni_2P) have been investigated for electrocatalytic activity and stability for the hydrogen evolution reaction (HER) in acidic solutions, under which proton exchange membrane-based electrolysis is operational. The catalytically active Ni_2P nanoparticles were hollow and faceted to expose a high density of the Ni_2P(001) surface, which has previously been predicted based on theory to be an active HER catalyst. The Ni2P nanoparticles had among the highest HER activity of any non-noble metal electrocatalyst reported to date, producing H_2(g) with nearly quantitative faradaic yield, while also affording stability in aqueous acidic media.", "date": "2013-06-26", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "135", "number": "25", "publisher": "American Chemical Society", "pagerange": "9267-9270", "id_number": "CaltechAUTHORS:20130813-110523757", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130813-110523757", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "Department of Energy (DOE)" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/ja403440e", "primary_object": { "basename": "ja403440e_si_001.pdf", "url": "https://authors.library.caltech.edu/records/1mge0-dre42/files/ja403440e_si_001.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Popczun, Eric J.; McKone, James R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/773fn-pfn10", "eprint_id": 44275, "eprint_status": "archive", "datestamp": "2023-08-19 20:14:19", "lastmod": "2023-10-26 00:21:13", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "An Integrated, Systems Approach to the Development of Solar Fuel Generators", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 Electrochemical Society. Summer 2013. Support for solar fuels R&D by the NSF Powering the Planet Center for Chemical Innovation, CHE-0947829 (development of electrocatalysts), by the DOE DEFG02-03ER15483 (earth-abundant light absorbers), and by the Office of Science of\nthe U.S. Department of Energy under Award No. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy\nInnovation Hub (translational research in solar fuels generators), has enabled the preparation of this article.\n\nPublished - sum13_p043_049.pdf
", "abstract": "Two major technological challenges in the development of a sustainable, clean energy system are providing massive grid-scale energy storage and an ample supply of carbon-neutral, high energy-density, transportation fuels. The\ndevelopment and deployment of massive, grid-scale energy storage is imperative for reliably and robustly compensating for the intermittency involved with the utilization of very large amounts of wind energy and\nsolar energy.", "date": "2013-06", "date_type": "published", "publication": "Interface", "volume": "22", "number": "2", "publisher": "Electrochemical Society", "pagerange": "43-49", "id_number": "CaltechAUTHORS:20140312-095955949", "issn": "1064-8208", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140312-095955949", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Powering the Planet Center for Chemical Innovation (CCI)", "grant_number": "CHE-0947829" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "primary_object": { "basename": "sum13_p043_049.pdf", "url": "https://authors.library.caltech.edu/records/773fn-pfn10/files/sum13_p043_049.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/f9dcz-xm731", "eprint_id": 39416, "eprint_status": "archive", "datestamp": "2023-08-19 20:08:05", "lastmod": "2023-10-24 16:47:41", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hu-Shu", "name": { "family": "Hu", "given": "Shu" }, "orcid": "0000-0002-5041-0169" }, { "id": "Chi-Chun-Yung", "name": { "family": "Chi", "given": "Chun-Yung" } }, { "id": "Fountaine-K-T", "name": { "family": "Fountaine", "given": "Katherine T." }, "orcid": "0000-0002-0414-8227" }, { "id": "Yao-Maoqing", "name": { "family": "Yao", "given": "Maoqing" } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Dapkus-P-D", "name": { "family": "Dapkus", "given": "P. Daniel" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Zhou-Chongwu", "name": { "family": "Zhou", "given": "Chongwu" }, "orcid": "0000-0001-8448-8450" } ] }, "title": "Optical, electrical, and solar energy-conversion properties of gallium arsenide nanowire-array photoanodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 The Royal Society of Chemistry. \n\nReceived 23rd January 2013; Accepted 14th March 2013. First published online 17 Apr 2013. \n\nThe non-aqueous photoelectrochemistry and optical simulation\nwas supported by the Office of Science of the U.S. Department of Energy under Award no. DE-SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub; and the MOCVD growth was supported by the Center for Energy Nanoscience, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Basic Energy Sciences under Award Number DE-SC0001013. The authors acknowledge Professor Hans-Joachim Lewerenz, Professor Michelle Povinelli and Stanley Burgos for helpful discussions, and Dr Ron Grimm for assistance with the photoelectrochemical studies. Optical data were collected at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. M.Y. acknowledges a USC Provost's Ph.D. Fellowship and K. T. F. acknowledges the National Science Foundation for Graduate Research Fellowship under Grant no. DGE-1144469.\n\nSupplemental Material - c3ee40243f.pdf
", "abstract": "Periodic arrays of n-GaAs nanowires have been grown by selective-area metal\u2013organic chemical-vapor deposition on Si and GaAs substrates. The optical absorption characteristics of the nanowire-arrays were investigated experimentally and theoretically, and the photoelectrochemical energy-conversion properties of GaAs nanowire arrays were evaluated in contact with one-electron, reversible, redox species in non-aqueous solvents. The radial semiconductor/liquid junction in the nanowires produced near-unity external carrier-collection efficiencies for nanowire-array photoanodes in contact with non-aqueous electrolytes. These anodes exhibited overall inherent photoelectrode energy-conversion efficiencies of [similar]8.1% under 100 mW cm^\u22122 simulated Air Mass 1.5 illumination, with open-circuit photovoltages of 590 \u00b1 15 mV and short-circuit current densities of 24.6 \u00b1 2.0 mA cm^\u22122. The high optical absorption, and minimal reflection, at both normal and off-normal incidence of the GaAs nanowire arrays that occupy <5% of the fractional area of the electrode can be attributed to efficient incoupling into radial nanowire guided and leaky waveguide modes.", "date": "2013-06", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "6", "number": "6", "publisher": "Royal Society of Chemistry", "pagerange": "1879-1890", "id_number": "CaltechAUTHORS:20130717-111233079", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130717-111233079", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001013" }, { "agency": "University of Southern California" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1144469" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c3ee40243f", "primary_object": { "basename": "c3ee40243f.pdf", "url": "https://authors.library.caltech.edu/records/f9dcz-xm731/files/c3ee40243f.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Hu, Shu; Chi, Chun-Yung; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/v0fjb-44414", "eprint_id": 39621, "eprint_status": "archive", "datestamp": "2023-08-22 09:25:30", "lastmod": "2023-10-24 17:00:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bosco-J-P", "name": { "family": "Bosco", "given": "Jeffrey P." } }, { "id": "Scanlon-D-O", "name": { "family": "Scanlon", "given": "David O." } }, { "id": "Watson-G-W", "name": { "family": "Watson", "given": "Graeme W." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Energy-band alignment of II-VI/Zn_(3)P_2 heterojunctions from x-ray photoemission spectroscopy", "ispublished": "pub", "full_text_status": "public", "keywords": "ab initio calculations; conduction bands; core levels; density functional theory; electronic density of states; II-VI semiconductors, semiconductor heterojunctions, valence bands, X-ray photoelectron spectra, zinc compounds", "note": "\u00a9 2013 AIP Publishing LLC.\n\nReceived 18 March 2013; accepted 9 May 2013; published online 23 May 2013.\n\nThis work was supported by the Dow Chemical Company and by the Department of Energy, Office of Basic Energy Sciences under Grant No. DE-FG02-03ER15483. Computations were performed on the HECToR supercomputer through membership of the HPC Materials Chemistry Consortium under EPSRC (Grant No. EP/F067496), as well as the Kelvin supercomputer as maintained by TCHPC and supported by SFI through the PI programme (Grant Nos. 06/IN.1/I92 and 06/IN.1/I92/EC07). The authors would like to thank Joseph Beardslee for his assistance with the Kratos XPS measurements. J.P.B. acknowledges the NSF for a graduate research fellowship. D.O.S. acknowledges the Ramsay Memorial Trust and University College London for a Ramsay Fellowship.\n\nPublished - JApplPhys_113_203705.pdf
", "abstract": "The energy-band alignments for zb-ZnSe(001)/\u03b1-Zn_(3)P_2(001), w-CdS(0001)/\u03b1-Zn_(3)P_2(001), and w-ZnO(0001)/\u03b1-Zn_(3)P_2(001) heterojunctions have been determined using high-resolution x-ray photoelectron spectroscopy via the Kraut method. Ab initio hybrid density functional theory calculations of the valence-band density of states were used to determine the energy differences between the core level and valence-band maximum for each of the bulk materials. The ZnSe/Zn_(3)P_2 heterojunction had a small conduction-band offset, \u0394EC, of \u22120.03\u2009\u00b1\u20090.11\u2009eV, demonstrating a nearly ideal energy-band alignment for use in thin-film photovoltaic devices. The CdS/Zn_(3)P_2 heterojunction was also type-II but had a larger conduction-band offset of \u0394EC = \u22120.76\u2009\u00b1\u20090.10\u2009eV. A type-III alignment was observed for the ZnO/Zn_(3)P_2 heterojunction, with \u0394EC\u2009=\u2009\u22121.61\u2009\u00b1\u20090.16\u2009eV indicating the formation of a tunnel junction at the oxide\u2013phosphide interface. The data also provide insight into the role of the II-VI/Zn_(3)P_2 band alignment in the reported performance of Zn_(3)P_2 heterojunction solar cells.", "date": "2013-05-28", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "113", "number": "20", "publisher": "American Institute of Physics", "pagerange": "Art. No. 203705", "id_number": "CaltechAUTHORS:20130729-100531154", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130729-100531154", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Dow Chemical Company" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Ramsay Memorial Trust" }, { "agency": "University College London" } ] }, "doi": "10.1063/1.4807646", "primary_object": { "basename": "JApplPhys_113_203705.pdf", "url": "https://authors.library.caltech.edu/records/v0fjb-44414/files/JApplPhys_113_203705.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Bosco, Jeffrey P.; Scanlon, David O.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/18ckq-y7f69", "eprint_id": 38541, "eprint_status": "archive", "datestamp": "2023-08-19 19:33:20", "lastmod": "2023-10-23 20:33:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Coridan-R-H", "name": { "family": "Coridan", "given": "Robert H." }, "orcid": "0000-0003-1916-4446" }, { "id": "Shaner-M-R", "name": { "family": "Shaner", "given": "Matthew" }, "orcid": "0000-0003-4682-9757" }, { "id": "Wiggenhorn-C", "name": { "family": "Wiggenhorn", "given": "Craig" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electrical and Photoelectrochemical Properties of WO_3/Si Tandem Photoelectrodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Chemical Society. \n\nReceived: December 5, 2012; Revised: February 22, 2013; Published: March 15, 2013. Published In Issue April 11, 2013. \n\nWe acknowledge the Defense Advanced Research Projects Agency (DARPA) Grant W911NF-09-2-0011 for support of R.H.C. and N.S.L. and the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award DE-SC0004993, for support of M.S., B.S.B., and N.S.L. We also acknowledge BP and the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology for support.\n\nPublished - jp311947x.pdf
Supplemental Material - jp311947x_si_001.pdf
", "abstract": "Tungsten trioxide (WO_3) has been investigated as a photoanode for water oxidation reactions in acidic aqueous conditions. Though WO_3 is not capable of performing unassisted solar-driven water splitting, WO_3 can in principle be coupled with a low band gap semiconductor, such as Si, to produce a stand-alone, tandem photocathode/photoanode p-Si/n-WO_3 system for solar fuels production. Junctions between Si and WO_3, with and without intervening ohmic contacts, were therefore prepared and investigated in detail. Thin films of n-WO_3 that were prepared directly on p-Si and n-Si substrates exhibited an onset of photocurrent at a potential consistent with expectations based on the band-edge alignment of these two materials predicted by Andersen theory. However, n-WO_3 films deposited on Si substrates exhibited much lower anodic photocurrent densities (0.02 mA cm^(\u20132) at 1.0 V vs SCE) than identically prepared n-WO_3 films that were deposited on fluorine-doped tin oxide (FTO) substrates (0.45 mA cm^(\u20132) at 1.0 V vs SCE). Deposition of n-WO_3 onto a thin layer of tin-doped indium oxide (ITO) that had been deposited on a Si substrate yielded anodic photocurrent densities that were comparable to those observed for n-WO_3 films that had been deposited onto FTO-coated glass. An increased photovoltage was observed when an n-Si/ITO Schottky junction was formed in series with the n-WO_3 film, relative to when the WO_3 was deposited directly onto the Si. Hence, inclusion of the ITO layer allowed for tandem photoelectrochemical devices to be prepared using n-WO_3 and n-Si as the light absorbers.", "date": "2013-04-11", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "117", "number": "14", "publisher": "American Chemical Society", "pagerange": "6949-6957", "id_number": "CaltechAUTHORS:20130516-133146126", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130516-133146126", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "W911NF-09-2-0011" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "BP" }, { "agency": "Caltech Beckman Institute" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/jp311947x", "primary_object": { "basename": "jp311947x.pdf", "url": "https://authors.library.caltech.edu/records/18ckq-y7f69/files/jp311947x.pdf" }, "related_objects": [ { "basename": "jp311947x_si_001.pdf", "url": "https://authors.library.caltech.edu/records/18ckq-y7f69/files/jp311947x_si_001.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Coridan, Robert H.; Shaner, Matthew; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/a82zj-h3v43", "eprint_id": 38562, "eprint_status": "archive", "datestamp": "2023-08-19 19:32:03", "lastmod": "2023-10-23 20:35:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Brown-R-D", "name": { "family": "Brown", "given": "Ryan D." } }, { "id": "Hund-Z-M", "name": { "family": "Hund", "given": "Zachary M." } }, { "id": "Campi-D", "name": { "family": "Campi", "given": "Davide" } }, { "id": "O'Leary-L-E", "name": { "family": "O'Leary", "given": "Leslie E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Bernasconi-M", "name": { "family": "Bernasconi", "given": "M." } }, { "id": "Benedek-G", "name": { "family": "Benedek", "given": "G." } }, { "id": "Sibener-S-J", "name": { "family": "Sibener", "given": "S. J." } } ] }, "title": "Hybridization of Surface Waves with Organic Adlayer Librations: A Helium Atom Scattering and Density Functional Perturbation Theory Study of Methyl-Si(111)", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Physical Society.\n\nReceived 1 February 2013; published 9 April 2013.\n\nS. J. S. would like to acknowledge the support of the\nAir Force Office of Scientific Research Grant No. FA9550-10-1-0219, and the Material Research Science and\nEngineering Center at the University of Chicago for infrastructure support. N. S. L. acknowledges support from\nNSF-CHE1214152, and L. E. O. was funded by a Link foundation Energy fellowship.\n\nPublished - PhysRevLett.110.156102.pdf
Supplemental Material - README.TXT
Supplemental Material - lemental_Materials_032913_for_Upload_Submitted.pdf
", "abstract": "The interplay of the librations of a covalently bound organic adlayer with the lattice waves of an underlying semiconductor surface was characterized using helium atom scattering in conjunction with analysis by density functional perturbation teory. The Rayleigh wave dispersion relation of CH_(3)- and CD_(3)-terminated Si(111) surfaces was probed across the entire surface Brillouin zone by the use of inelastic helium atom time-of-flight experiments. The experimentally determined Rayleigh wave dispersion relations were in agreement with those predicted by density functional perturbation theory. The Rayleigh wave for the CH_(3)- and CD_(3)-terminated Si(111) surfaces exhibited a nonsinusoidal line shape, which can be attributed to the hybridization of overlayer librations with the vibrations of the underlying substrate. This combined synthetic, experimental, and theoretical effort clearly demonstrates the impact of hybridization between librations of the overlayer and the substrate lattice waves in determining the overall vibrational band structure of this complex interface.", "date": "2013-04-09", "date_type": "published", "publication": "Physical Review Letters", "volume": "110", "number": "15", "publisher": "American Physical Society", "pagerange": "Art. No. 156102", "id_number": "CaltechAUTHORS:20130517-131623698", "issn": "0031-9007", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130517-131623698", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-10-1-0219" }, { "agency": "University of Chicago Material Research Science and Engineering Center" }, { "agency": "NSF", "grant_number": "CHE1214152" }, { "agency": "Link Foundation Energy Fellowship" } ] }, "doi": "10.1103/PhysRevLett.110.156102", "primary_object": { "basename": "README.TXT", "url": "https://authors.library.caltech.edu/records/a82zj-h3v43/files/README.TXT" }, "related_objects": [ { "basename": "lemental_Materials_032913_for_Upload_Submitted.pdf", "url": "https://authors.library.caltech.edu/records/a82zj-h3v43/files/lemental_Materials_032913_for_Upload_Submitted.pdf" }, { "basename": "PhysRevLett.110.156102.pdf", "url": "https://authors.library.caltech.edu/records/a82zj-h3v43/files/PhysRevLett.110.156102.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Brown, Ryan D.; Hund, Zachary M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/e9m9c-znn61", "eprint_id": 39628, "eprint_status": "archive", "datestamp": "2023-08-19 19:22:27", "lastmod": "2023-10-24 17:00:47", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Architecture for a low-overpotential, gas-separated photoelectrolysis system", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "We are taking a modular, parallel approach to the development of an artificial photosynthetic system that will utilize sunlight and\nwater to produce hydrogen and oxygen. The three distinct components-the photoanode, the photocathode, and the productsepg.\nbut ion conducting membrane-are fabricated sep. before assembly into a complete water-splitting system. The\nphotoanode and photocathode will consist of rod-like semiconductor components, with attached heterogeneous multi-electron\ntransfer catalysts, which are needed to drive the oxidn. or redn. reactions at low overpotentials. Optimized mass transport of\nreactants and products, light absorption, and carrier collection in this system requires for these components to be engineered on\nlength scales from a few nanometers up to millimeters. The high aspect-ratio rod electrode architecture allows us to produce\nthese semiconductors using low cost methods and earth abundant materials without sacrificing energy conversion efficiency due\nto the orthogonalization of light absorption and charge-carrier collection. Addnl., the high surface-area design of the structured\nsemiconductor electrode inherently lowers the flux of charge carriers over the rod array surface relative to the projected\ngeometric surface of the photoelectrode. This lowers the photocurrent d. at the solid/liq. junction and thereby relaxing the\ndemands on the activity (and cost) of any electrocatalysts. A flexible composite polymer film will allow for the sepn. of gaseous\nproducts while simultaneously permitting electron and ion conduction between the photoanode and photocathode and providing\nstructural support. Sep. polymeric materials will be used to make elec. contact between the anode and cathode and to form\ninterspersed ion conducting patches to maintain charge balance between the two half-cells.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130729-104439335", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130729-104439335", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6fxpe-q1h31", "eprint_id": 39498, "eprint_status": "archive", "datestamp": "2023-08-19 19:20:23", "lastmod": "2023-10-24 16:51:55", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Chemical control over the electrical, electronic, and electrochemical properties of Si surfaces", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "We have developed mixed monolayer chem. that allows for incorporation of a versatile component and a 'filler' component to\nimpart simultaneous stability and function at Si surfaces. Optoelectronic device efficiency depends on control over chem. and\nelectronic properties. We were able to functionalize silicon surfaces with mixed thiophene/methyl monolayers. The mixed\nmonolayer method allowed for functionalization with thiophene groups while maintaining a low surface recombination velocity, S,\nof 27\u00b19 cm s^(-1), while the single component thiophene-functionalized Si(111) surface displayed S=670\u00b1190 cm s^(-1). Pd-catalyzed\nHeck coupling was achieved at mixed thienylBr/CH_3-Si(111) surfaces. Coverage of q = 0.11\u00b10.03 was achieved for Heckcoupled\nfluorostyrene. The Heck coupling reaction was versatile, vinylferrocene and protoporphyrin-IX were also successfully\ncoupled to the surface, and low surface recombination velocity was maintained after the coupling chem. Thienybromide\nfunctionalization induced an interfacial dipole, which was studied via spectroscopic and electronic experimentation and was\ninvestigated by ab initio methods. The band-edge positions were favorably shifted 400 mV from those at the CH_3-Si(111)\nsurfaces. The mixed monolayer technique can be similarly applied to attach protected aldehydes. Once deprotected, mixed\npropanal/methyl-Si(111) assisted at. layer deposition of Al_2O_3 and MnOx. Increased deposition and decreased surface electronic\ndefects were obsd. at propanal functionalized surfaces as compared to H-Si(111) surfaces. This has direct benefits for both\nsurface protection and field effect transistors. The mixed monolayer method was shown to increase synthetic versatility,\ndecrease electronic trap state d., and improve control of interfacial energetics.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130722-131748328", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130722-131748328", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/y1hzn-hey98", "eprint_id": 39380, "eprint_status": "archive", "datestamp": "2023-08-19 19:18:30", "lastmod": "2023-10-24 16:45:17", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Pieterick-A-P", "name": { "family": "Pieterick", "given": "Adam P." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Efficient and stable photoelectrochemical energy conversion using p-type WSe2 photocathodes implications", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "We have synthesized highly cryst. p-type WSe2 and characterized its electrochem. and photoelectrochem. behavior in a variety of\naq. redox couples. Energy conversion efficiencies of > 7% with respect to the thermodn. potential for hydrogen evolution have\nbeen achieved for p-WSe2 photocathodes deposited with a mixed Ru/Pt cocatalyst under 100 mW cm^(-2) white light illumination.\nAddnl., these photocathodes exhibit good stability during photoredn. of Me viologen for at least two hours under illumination at\npH values of 2 and 10. Spectral response measurements suggest that energy conversion efficiencies are limited by short\nminority-carrier diffusion lengths, but impedance spectroscopy indicates that the p-WSe2 band-edge positions are nearly ideal for\nattaining max. photovoltages for the hydrogen evolution reaction.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130716-081436296", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130716-081436296", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "McKone, James R.; Pieterick, Adam P.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8ktd5-7p471", "eprint_id": 39393, "eprint_status": "archive", "datestamp": "2023-08-19 19:18:51", "lastmod": "2023-10-24 16:46:22", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Blakemore-J-D", "name": { "family": "Blakemore", "given": "James D." }, "orcid": "0000-0003-4172-7460" }, { "id": "Lattimer-J-R-C", "name": { "family": "Lattimer", "given": "Judith R." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Molecular proton-reduction catalysis at silicon semiconductor surfaces", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Driving catalysis at semiconductor:liq. junctions with light enables the efficient conversion and storage of solar energy in chem.\nfuels. Hydrogen evolution from water is one possible path to fuel, as there are known heterogeneous and homogeneous\ncatalysts for proton redn. Homogeneous catalysts show the greatest promise for clarifying both (1) key mechanistic aspects of\nthe hydrogen-evolution reaction at the surface and (2) energetic considerations of the semiconductor band structure. Along this\nline, we are studying a family of rhodium complexes as model catalysts for hydrogen evolution at semiconductor:liq. junctions.\nBoth diffusional and silicon surface-attached systems have been developed, and will be compared. This approach has yielded\nnew information concerning the ambiguities of homogeneous vs. Heterogeneous catalysis, as well as the possible catalytic\nmechanism(s) of the surface-attached species.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130716-130435999", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130716-130435999", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Blakemore, James D.; Lattimer, Judith R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/egqq6-32965", "eprint_id": 39584, "eprint_status": "archive", "datestamp": "2023-08-19 19:21:37", "lastmod": "2023-10-24 16:58:04", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Sunlight-driven hydrogen formation by membrane-supported photoelectrochemical water splitting", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "We are developing an artificial photosynthetic system that will utilize sunlight and water as the inputs and produce hydrogen and\noxygen as the outputs. We are taking a modular, parallel development approach in which three distinct primary components-the\nphotoanode, the photocathode, and the product-sepg. but ion-conducting membrane-are fabricated and optimized sep. before\nassembly into a complete water-splitting system. The design principles incorporate two sep., photosensitive semiconductor/liq.\njunctions that will collectively generate the 1.7-1.9 V at open circuit necessary to support both the oxidn. of H_2O (or OH-) and\nthe redn. of H+ (or H_2O). The photoanode and photocathode will consist of rod-like semiconductor components, with attached\nheterogeneous multi-electron transfer catalysts, which are needed to drive the oxidn. or redn. reactions at low overpotentials.\nThe high aspect-ratio semiconductor rod electrode architecture allows for the use of low cost, earth abundant materials without\nsacrificing energy conversion efficiency due to the orthogonalization of light absorption and charge-carrier collection. Addnl., the\nhigh surface-area design of the rod-based semiconductor array electrode inherently lowers the flux of charge carriers over the\nrod array surface relative to the projected geometric surface of the photoelectrode, thus lowering the photocurrent d. at the\nsolid/liq. junction and thereby relaxing the demands on the activity (and cost) of any electrocatalysts. A flexible composite\npolymer film will allow for electron and ion conduction between the photoanode and photocathode while simultaneously\npreventing mixing of the gaseous products. Sep. polymeric materials will be used to make elec. contact between the anode and\ncathode, and also to provide structural support. Interspersed patches of an ion conducting polymer will maintain charge balance\nbetween the two half-cells.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130725-100410892", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130725-100410892", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/d061v-n4v76", "eprint_id": 39643, "eprint_status": "archive", "datestamp": "2023-08-19 19:22:41", "lastmod": "2023-10-24 17:02:21", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Systematic development of an artificial solar-fuel generation device", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "Addressing the world's energy challenges will require cost-competitive, globally scalable technologies for fuel prodn. that\nminimize impact on the environment. Despite decades of research focused on understanding and improving the efficiencies of\nnatural photosynthesis, the energy conversion efficiencies of the most productive biofuel crops remain too low for mass\nindustrialization of bioenergy. The Joint Center for Artificial Photosynthesis (JCAP) focuses on an alternative approach that aims\nto produce chem. fuels from sunlight, water, and carbon-dioxide using an engineered, non-biol. device that is cost-effective,\nrobust, and efficient. Research at JCAP involves the development of core technologies for artificial solar-fuels generation,\nincluding directed and combinatorial methods for the discovery of light-absorbing, semiconductor-based materials and watersplitting\nand carbon dioxide reducing catalysts, the design of ion-permeable, gas-sepg. membranes, and methods for efficiently\nintegrating and assembling these components into fully functional prototypes. Recent discoveries in JCAP have led to significant\nadvances towards com. viable, solar-fuel producing systems.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130730-091444738", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130730-091444738", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cszr6-gz289", "eprint_id": 39642, "eprint_status": "archive", "datestamp": "2023-08-19 19:22:34", "lastmod": "2023-10-24 17:02:16", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Technical and operational perspective on the DOE Energy Innovation Hub and fuels from sunlight, the Joint Center for Artificial Photosynthesis", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society.", "abstract": "The design of highly efficient, non-biol., mol.-level energy conversion \"machines\" that generate fuels directly from sunlight,\nwater, and carbon dioxide is both a formidable challenge and an opportunity that, if realized, could have a revolutionary impact\non our energy system. Basic research has already provided enormous advances in our understanding of the subtle and complex\nphotochem. behind the natural photosynthetic system, and in the use of inorg. photo-catalytic methods to split water or reduce\ncarbon dioxide-key steps in photosynthesis. Yet we still lack sufficient knowledge to design solar fuel generation systems with\nthe required efficiency, scalability, and sustainability to be economically viable.In the DOE Energy Innovation Hub, the Joint\nCenter for Artificial Photosynthesis, we are developing an artificial photosynthetic system that will only utilize sunlight and water\nas the inputs and will produce hydrogen and oxygen as the outputs. We are taking a modular, parallel development approach in\nwhich the three distinct primary components-the photoanode, the photocathode, and the product-sepg. but ion-conducting\nmembrane-are fabricated and optimized sep. before assembly into a complete water-splitting system. The design principles\nincorporate two sep., photosensitive semiconductor/liq. junctions that will collectively generate the 1.7-1.9 V at open circuit\nnecessary to support both the oxidn. of H_2O (or OH-) and the redn. of H+ (or H_2O). The photoanode and photocathode will\nconsist of rod-like semiconductor components, with attached heterogeneous multi-electron transfer catalysts, which are needed\nto drive the oxidn. or redn. reactions at low overpotentials. This talk will discuss a feasible and functional prototype and\nblueprint for an artificial photosynthetic system, composed of only inexpensive, earth-abundant materials, that is simultaneously\nefficient, durable, manufacturably scalable, and readily upgradeable, including both the operational and tech. scope of the JCAP\nHub, as well as tech. results towards this goal that has recently been developed at Caltech.", "date": "2013-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130730-091211252", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130730-091211252", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2013", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cj15p-fq416", "eprint_id": 37888, "eprint_status": "archive", "datestamp": "2023-08-19 19:03:19", "lastmod": "2023-10-23 19:05:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Li-Y", "name": { "family": "Li", "given": "Yan" } }, { "id": "O'Leary-L-E", "name": { "family": "O'Leary", "given": "Leslie E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Galli-G-A", "name": { "family": "Galli", "given": "Giulia A." } } ] }, "title": "Combined Theoretical and Experimental Study of Band-Edge Control of Si through Surface Functionalization", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Chemical Society.\n\nReceived: December 18, 2012; Revised: February 5, 2013;\nPublished: February 13, 2013.\n\nY.L. was supported by Brookhaven Science Associates, LLC\nunder Contract No. DE-AC02-98CH10886, with the U.S.\nDepartment of Energy. L.E.O. was supported through a Link\nFoundation Energy fellowship. Part of the work was funded by\nNSF-CHE-0802907. The calculations were performed at the\nNERSC and TeraGrid facilities. We thank M. Hybertsen for\nuseful discussions.\n\nPublished - jp3124583.pdf
Supplemental Material - jp3124583_si_001.pdf
", "abstract": "The band-edge positions of H-, Cl-, Br-, methyl-, and ethyl-terminated Si(111) surfaces were investigated through a combination of density functional theory (DFT) and many-body perturbation theory, as well as by photoelectron spectroscopy and electrical device measurements. The calculated trends in surface potential shifts as a function of the adsorbate type and coverage are consistent with the calculated strength and direction of the dipole moment of the adsorbate radicals in conjunction with simple electronegativity-based expectations. The quasi-particle energies, such as the ionization potential (IP), that were calculated by use of many-body perturbation theory were in good agreement with experiment. The IP values that were calculated by DFT exhibited substantial errors, but nevertheless, the IP differences, i.e., IP_(R\u2013Si(111))\u2013IP_(H\u2013Si(111)), computed using DFT were in good agreement with spectroscopic and electrical measurements.", "date": "2013-03-14", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "117", "number": "10", "publisher": "American Chemical Society", "pagerange": "5188-5194", "id_number": "CaltechAUTHORS:20130411-103710875", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130411-103710875", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-98CH10886" }, { "agency": "Link Foundation Energy fellowship" }, { "agency": "NSF", "grant_number": "CHE-0802907" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/jp3124583", "primary_object": { "basename": "jp3124583_si_001.pdf", "url": "https://authors.library.caltech.edu/records/cj15p-fq416/files/jp3124583_si_001.pdf" }, "related_objects": [ { "basename": "jp3124583.pdf", "url": "https://authors.library.caltech.edu/records/cj15p-fq416/files/jp3124583.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Li, Yan; O'Leary, Leslie E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/t9zy6-kvk31", "eprint_id": 37933, "eprint_status": "archive", "datestamp": "2023-08-19 19:03:24", "lastmod": "2023-10-23 19:33:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Strandwitz-N-C", "name": { "family": "Strandwitz", "given": "Nicholas C." } }, { "id": "Comstock-D-J", "name": { "family": "Comstock", "given": "David J." } }, { "id": "Grimm-R-L", "name": { "family": "Grimm", "given": "Ronald L." }, "orcid": "0000-0003-0407-937X" }, { "id": "Nielander-A-C", "name": { "family": "Nichols-Nielander", "given": "Adam C." }, "orcid": "0000-0002-3639-2427" }, { "id": "Elam-J", "name": { "family": "Elam", "given": "Jeffrey" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemical Behavior of n\u2011type Si(100) Electrodes Coated with Thin Films of Manganese Oxide Grown by Atomic Layer Deposition", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Chemical Society. \n\nPublished In Issue March 14, 2013. Article ASAP March 01, 2013. Just Accepted Manuscript February 06, 2013. Publication Date (Web): February 6, 2013. \n\nWe acknowledge support from the NSF (CHE-1214152) and N.C.S. acknowledges the NSF for an American Competitiveness in Chemistry postdoctoral fellowship (CHE-1042006). The authors declare no competing financial interest.\n\nPublished - jp311207x.pdf
Supplemental Material - jp311207x_si_001.pdf
", "abstract": "Thin (10 nm) films of manganese oxide have been deposited by atomic layer deposition (ALD) onto n-type silicon and onto degenerately doped p-type silicon. The photoelectrochemical properties of the resulting semiconductor/metal-oxide structures were evaluated in contact with aqueous 0.35 M K_4Fe(CN)_6\u22120.05 M\nK_3Fe(CN)_6, 1.0 M KOH(aq), as well as in contact with a series of nonaqueous one electron, reversible, outer-sphere redox systems. Under simulated air mass (AM) 1.5\nillumination in contact with 0.35 M K_4Fe(CN)_6\u22120.05 M K_3Fe(CN)_6(aq), MnO-coated n-Si photoanodes displayed open-circuit voltages of up to 550 mV and stable anodic\ncurrents for periods of hours at 0.0 V versus the solution potential. In contact with 1.0 M KOH(aq), at current densities of \u223c25 mA cm^(\u22122), MnO|Si photoanodes under 100 mW cm^(\u22122) of simulated AM 1.5 illuminationyielded stable oxygen evolution for 10\u221230 min. Variation in the thickness of the MnO films from 4 to 20 nm indicated the presence of a series resistance in the MnO film that limited the fill factor and thus the solar energy-conversion efficiency of the photoelectrodes. Open-circuit photovoltages of 30 and 450 mV, respectively, were observed in contact with cobaltocene^(+/0) or ferrocene^(+/0) in CH_3CN, indicating that the energetics of the MnO-coated Si surfaces were a function of the electrochemical potential of the contacting electrolyte solution.", "date": "2013-03-14", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "117", "number": "10", "publisher": "American Chemical Society", "pagerange": "4931-4936", "id_number": "CaltechAUTHORS:20130415-102414322", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130415-102414322", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "NSF Postdoctoral Fellowship", "grant_number": "CHE-1042006" } ] }, "doi": "10.1021/jp311207x", "primary_object": { "basename": "jp311207x.pdf", "url": "https://authors.library.caltech.edu/records/t9zy6-kvk31/files/jp311207x.pdf" }, "related_objects": [ { "basename": "jp311207x_si_001.pdf", "url": "https://authors.library.caltech.edu/records/t9zy6-kvk31/files/jp311207x_si_001.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Strandwitz, Nicholas C.; Comstock, David J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2kgqb-w9f98", "eprint_id": 37565, "eprint_status": "archive", "datestamp": "2023-08-19 14:38:24", "lastmod": "2023-10-23 17:45:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Fitch-A", "name": { "family": "Fitch", "given": "Anthony" } }, { "id": "Strandwitz-N-C", "name": { "family": "Strandwitz", "given": "Nicholas C." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A Comparison of the Behavior of Single Crystalline and Nanowire Array ZnO Photoanodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2013 American Chemical Society. \n\nReceived: October 4, 2012; Revised: December 10, 2012; Published: December 14, 2012. \n\nThis work was supported by the Department of Energy, Office of Basic Energy Sciences, DE-FG02-07ER46405. N.C.S. acknowledges the NSF for an American Competitiveness in Chemistry postdoctoral fellowship (CHE-1042006).\n\nPublished - jp3098457.pdf
Supplemental Material - jp3098457_si_002.pdf
", "abstract": "The photoelectrochemical behavior of n-type ZnO nanowire arrays was compared to the behavior of single crystalline n-ZnO photoelectrodes in contact with either 0.50 M K_(2)SO_4(aq) at pH 6.0 or Fe(CN)_(4)^(3\u2013/4\u2013)(aq). The use of a thin film of ZnO as a seed layer produced dense nanowire arrays in which the ZnO nanowires were preferentially oriented perpendicular to the substrate. The average diameter of the ZnO nanowires that were produced by two different growth conditions was ~125 and ~175 nm, respectively, with a nanowire length of 2\u20134 \u03bcm. Under simulated 1 Sun Air Mass 1.5 illumination conditions, the ZnO nanowire arrays exhibited open-circuit potentials, E_oc, and short-circuit photocurrent densities, J_sc, that were very close to the values observed from single crystal n-type ZnO photoanodes in contact with these same electrolytes. Device physics simulations were in accord with the experimentally observed behavior, indicating that, under certain combinations of materials properties and interface recombination velocities, the use of nanostructured light absorbers can provide an approach to efficient photoelectrochemical solar energy-conversion systems.", "date": "2013-02-07", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "117", "number": "5", "publisher": "American Chemical Society", "pagerange": "2008-2015", "id_number": "CaltechAUTHORS:20130319-115517593", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130319-115517593", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-07ER46405" }, { "agency": "NSF Postdoctoral Fellowship", "grant_number": "CHE-1042006" } ] }, "doi": "10.1021/jp3098457", "primary_object": { "basename": "jp3098457_si_002.pdf", "url": "https://authors.library.caltech.edu/records/2kgqb-w9f98/files/jp3098457_si_002.pdf" }, "related_objects": [ { "basename": "jp3098457.pdf", "url": "https://authors.library.caltech.edu/records/2kgqb-w9f98/files/jp3098457.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Fitch, Anthony; Strandwitz, Nicholas C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/z7ryh-8sk10", "eprint_id": 37403, "eprint_status": "archive", "datestamp": "2023-08-19 14:31:21", "lastmod": "2023-10-23 17:25:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Sadtler-B-F", "name": { "family": "Sadtler", "given": "Bryce F." } }, { "id": "Werlang-C-A", "name": { "family": "Werlang", "given": "Caroline A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Ni\u2013Mo Nanopowders for Efficient Electrochemical Hydrogen Evolution", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 American Chemical Society. \n\nReceived: October 26, 2012. Revised: November 30, 2012. Published: December 3, 2012. \n\nThis work was supported by the National Science Foundation\n\"Powering the Planet\" Center for Chemical Innovation (CHE-\n0802907). We thank Carol M. Garland for assistance with\ntransmission electron microscopy. J.R.M. acknowledges the\nDepartment of Energy, Office of Science for a graduate research\nfellowship. C.A.W. thanks the Caltech Summer Undergraduate\nResearch Fellowship (SURF) program for support during the\nsummer of 2012. B.F.S. acknowledges the Beckman Institute\nfor a postdoctoral fellowship.\n\nPublished - cs300691m.pdf
Supplemental Material - cs300691m_si_001.pdf
Supplemental Material - cs300691m_si_002.xlsx
", "abstract": "Earth-abundant metals are attractive alternatives to the noble metal composite catalysts that are used in water electrolyzers based on proton-exchange membrane technology. Ni\u2013Mo alloys have been previously developed for the hydrogen evolution reaction (HER), but synthesis methods to date have been limited to formation of catalyst coatings directly on a substrate. We report a method for generating unsupported nanopowders of Ni\u2013Mo, which can be suspended in common solvents and cast onto arbitrary substrates. The mass-specific catalytic activity under alkaline conditions approaches that of the most active reported non-noble HER catalysts, and the coatings display good stability under alkaline conditions. We have also estimated turnover frequencies per surface atom at various overpotentials and conclude that the activity enhancement for Ni\u2013Mo relative to pure Ni is due to a combination of increased surface area and increased fundamental catalytic activity.", "date": "2013-02", "date_type": "published", "publication": "ACS Catalysis", "volume": "3", "number": "2", "publisher": "American Chemical Society", "pagerange": "166-169", "id_number": "CaltechAUTHORS:20130308-080802822", "issn": "2155-5435", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130308-080802822", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "Department of Energy (DOE)" }, { "agency": "Caltech Summer Undergraduate Research Fellowship (SURF)" }, { "agency": "Caltech Beckman Institute" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/cs300691m", "primary_object": { "basename": "cs300691m.pdf", "url": "https://authors.library.caltech.edu/records/z7ryh-8sk10/files/cs300691m.pdf" }, "related_objects": [ { "basename": "cs300691m_si_001.pdf", "url": "https://authors.library.caltech.edu/records/z7ryh-8sk10/files/cs300691m_si_001.pdf" }, { "basename": "cs300691m_si_002.xlsx", "url": "https://authors.library.caltech.edu/records/z7ryh-8sk10/files/cs300691m_si_002.xlsx" } ], "resource_type": "article", "pub_year": "2013", "author_list": "McKone, James R.; Sadtler, Bryce F.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nghce-mw323", "eprint_id": 37124, "eprint_status": "archive", "datestamp": "2023-08-19 14:22:45", "lastmod": "2023-10-23 16:59:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Malyk-S", "name": { "family": "Malyk", "given": "Sergey" } }, { "id": "Shalhout-F-Y", "name": { "family": "Shalhout", "given": "Fadel Y." } }, { "id": "O'Leary-L-E", "name": { "family": "O'Leary", "given": "Leslie E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Benderskii-A-V", "name": { "family": "Benderskii", "given": "Alexander V." }, "orcid": "0000-0001-7031-2630" } ] }, "title": "Vibrational Sum Frequency Spectroscopic Investigation of the Azimuthal Anisotropy and Rotational Dynamics of Methyl-Terminated Silicon(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 American Chemical Society. \n\nReceived: July 6, 2012; Revised: November 9, 2012; Published: December 14, 2012. \n\nThis research was supported by the AFOSR, Grant No. FA9550-09-1-0547 (AVB), and by the NSF, CHE-0911682 (NSL). L.E.O. graciously thanks the financial support of the Link Foundation Energy Fellowship.\n\nPublished - jp3067298.pdf
Supplemental Material - jp3067298_si_001.pdf
", "abstract": "Polarization-selected vibrational sum frequency generation spectroscopy (SFG) has been used to investigate the molecular orientation of methyl groups on CH_(3)-terminated Si(111) surfaces. The symmetric and asymmetric C\u2013H stretch modes of the surface-bound methyl group were observed by SFG. Both methyl stretches showed a pronounced azimuthal anisotropy of the 3-fold symmetry in registry with the signal from the Si(111) substrate, indicating that the propeller-like rotation of the methyl groups was hindered at room temperature. The difference in the SFG line widths for the CH_3 asymmetric stretch that was observed for different polarization combinations (SPS and PPP for SFG, visible, and IR) indicated that the rotation proceeded on a 1\u20132 ps time scale, as compared to the 100 fs rotational dephasing of a free methyl rotor at room temperature.", "date": "2013-01-17", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "117", "number": "2", "publisher": "American Chemical Society", "pagerange": "935-944", "id_number": "CaltechAUTHORS:20130225-163026469", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130225-163026469", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-09-1-0547" }, { "agency": "NSF", "grant_number": "CHE-0911682" }, { "agency": "Link Foundation" } ] }, "doi": "10.1021/jp3067298", "primary_object": { "basename": "jp3067298.pdf", "url": "https://authors.library.caltech.edu/records/nghce-mw323/files/jp3067298.pdf" }, "related_objects": [ { "basename": "jp3067298_si_001.pdf", "url": "https://authors.library.caltech.edu/records/nghce-mw323/files/jp3067298_si_001.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Malyk, Sergey; Shalhout, Fadel Y.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/z66mk-19785", "eprint_id": 36881, "eprint_status": "archive", "datestamp": "2023-08-22 08:19:52", "lastmod": "2023-10-23 15:53:40", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bosco-J-P", "name": { "family": "Bosco", "given": "Jeffrey P." } }, { "id": "Kimball-G-M", "name": { "family": "Kimball", "given": "Gregory M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Pseudomorphic growth and strain relaxation of \u03b1-Zn_(3)P_(2) on GaAs(001) by molecular beam epitaxy", "ispublished": "pub", "full_text_status": "restricted", "keywords": "A1. Pseudomorphic growth; A1. X-ray diffraction; A3. Molecular beam epitaxy; B1. Phosphides; B3. Solar cells", "note": "\u00a9 2012 Elsevier B.V.\n\nReceived 10 January 2012; Received in revised form 6 September 2012; Accepted 21 October 2012; Communicated by A.Brown Available online 3 November 2012.\n\nThis work was supported by the Dow Chemical Company and by the Department of Energy, Office of Basic Energy Sciences under Grant no. DE-FG02-03ER15483. The authors would like to thank Steve Rozeveld for his assistance with the TEM and SAED measurements. J.P.B. acknowledges support under an NSF graduate research fellowship, and G.M.K. acknowledges support under an NDSEG fellowship.", "abstract": "Tetragonal zinc phosphide (\u03b1-Zn3P2) was grown pseudomorphically, by compound-source molecular-beam epitaxy on GaAs(001). The films grew coherently strained, with epitaxial relationships of Zn_(3)P_(2)(004)\u2016GaAs(002) and Zn_(3)P_(2)(202)\u2016GaAs(111). Partial relaxation of the Zn3P2 lattice was observed for films that were >150 nm in thickness. Van der Pauw and Hall effect measurements indicated that the films were intrinsically p-type, presumably due to the incorporation of phosphorus interstitials. The carrier mobilities in strained films (>40 cm^2 V^(\u22121) s^(\u22121)) were comparable to the carrier mobilities that have been reported for bulk Zn_(3)P_(2) single crystals. The carrier densities and mobilities of holes decreased significantly upon film relaxation, consistent with the evolution of compensating dislocations.", "date": "2013-01-15", "date_type": "published", "publication": "Journal of Crystal Growth", "volume": "363", "publisher": "Elsevier", "pagerange": "205-210", "id_number": "CaltechAUTHORS:20130212-131336765", "issn": "0022-0248", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130212-131336765", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Dow Chemical Company" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" } ] }, "doi": "10.1016/j.jcrysgro.2012.10.054", "resource_type": "article", "pub_year": "2013", "author_list": "Bosco, Jeffrey P.; Kimball, Gregory M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/eg4r2-9gw60", "eprint_id": 36773, "eprint_status": "archive", "datestamp": "2023-08-19 14:20:11", "lastmod": "2023-10-23 15:45:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Peiterick-A-P", "name": { "family": "Peiterick", "given": "Adam P." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Hydrogen Evolution from Pt/Ru-Coated p-Type WSe_2 Photocathodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 American Chemical Society. \n\nReceived: August 29, 2012; published: November 30, 2012. \n\nThis material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. The contributions from JRM and HBG were supported by CCSER (the Gordon and Betty Moore Foundation). JRM is supported by a graduate research fellowship from the Office of Science of the U.S. Department of Energy.\n\nPublished - ja308581g.pdf
Supplemental Material - ja308581g_si_001.pdf
", "abstract": "Crystalline p-type WSe_2 has been grown by a chemical vapor transport method. After deposition of noble metal catalysts, p-WSe_2 photocathodes exhibited thermodynamically based photoelectrode energy-conversion efficiencies of >7% for the hydrogen evolution reaction under mildly acidic conditions, and were stable under cathodic conditions for at least 2 h in acidic as well as in alkaline electrolytes. The open circuit potentials of the photoelectrodes in contact with the H^(+)/H_2 redox couple were very close to the bulk recombination/diffusion limit predicted from the Shockley diode equation. Only crystals with a prevalence of surface step edges exhibited a shift in flat-band potential as the pH was varied. Spectral response data indicated effective minority-carrier diffusion lengths of ~1 \u03bcm, which limited the attainable photocurrent densities in the samples to ~15 mA cm^(\u20132) under 100 mW cm^(\u20132) of Air Mass 1.5G illumination.", "date": "2013-01-09", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "135", "number": "1", "publisher": "American Chemical Society", "pagerange": "223-231", "id_number": "CaltechAUTHORS:20130205-103231488", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130205-103231488", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Gordon and Betty Moore Foundation" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1021/ja308581g", "primary_object": { "basename": "ja308581g.pdf", "url": "https://authors.library.caltech.edu/records/eg4r2-9gw60/files/ja308581g.pdf" }, "related_objects": [ { "basename": "ja308581g_si_001.pdf", "url": "https://authors.library.caltech.edu/records/eg4r2-9gw60/files/ja308581g_si_001.pdf" } ], "resource_type": "article", "pub_year": "2013", "author_list": "McKone, James R.; Peiterick, Adam P.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/tfqmg-abx66", "eprint_id": 47525, "eprint_status": "archive", "datestamp": "2023-08-19 14:03:35", "lastmod": "2024-01-13 16:06:57", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James" }, "orcid": "0000-0001-6445-7884" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan" }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Structured Materials for Photoelectrochemical Water Splitting", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2013 The Royal Society of Chemistry. \n\nThis work was supported in part by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. The contribution from NSL was supported through the Office of Science of the U.S. Department of Energy under award No. DE-SC0004993; the contributions from JRM and RLG were supported by BP and by the U.S. Department of Energy under award No. DEFG02-03ER15483. JRM additionally acknowledges the U.S. Department of Energy Office of Science for a graduate research fellowship.\n\nPublished - 9781849737739-00052.pdf
", "abstract": "Efficient and economical photoelectrochemical water splitting requires innovation\non several fronts. Tandem solar absorbers could increase the overall efficiency\nof a water splitting device, but economic considerations motivate\nresearch that employs cheap materials combinations. The need to manage\nsimultaneously light absorption, photogenerated carrier collection, ion transport,\ncatalysis, and gas collection drives efforts toward structuring solar absorber\nand catalyst materials.\nThis chapter divides the subject of structured solar materials into two principal\nsections. The first section investigates the motivations, benefits, and\ndrawbacks of structuring materials for photoelectrochemical water splitting.\nWe introduce the fundamental elements of light absorption, photogenerated\ncarrier collection, photovoltage, electrochemical transport, and catalytic behavior.\nFor each of these elements, we discuss the figures of merit, the critical\nlength scales associated with each process and the way in which these length\nscales must be balanced for efficient generation of solar fuels. This discussion assumes a working knowledge of the fundamentals of semiconductor-liquid\njunctions; for more details the reader is encouraged to consult review articles.\nThe second section of this chapter reviews recent approaches for generating\nstructured semiconductor light absorbers and structured absorber-catalyst\ncomposites. This literature review emphasizes the insights gained in the last\nsix years that are specifically related to photoelectrochemical water splitting,\nrather than to general photoelectrochemistry or photovoltaic applications.\nThis chapter concludes with perspectives and an outlook for future efforts\naimed at solar water splitting using structured materials. The realization of a\npractical, efficient, and useful water splitting device requires significant\nnew developments in materials synthesis as well as deeper understanding of the\nrelevant chemistry and physics. This chapter is intended to motivate such\ndevelopments.", "date": "2013", "date_type": "published", "publisher": "Royal Society of Chemistry", "place_of_pub": "Cambridge", "pagerange": "52-82", "id_number": "CaltechAUTHORS:20140728-125520169", "isbn": "978-1-84973-647-3", "book_title": "Photoelectrochemical Water Splitting: Materials, Processes and Architectures", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140728-125520169", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "BP" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "contributors": { "items": [ { "id": "Lewerenz-H-J", "name": { "family": "Lewerenz", "given": "Hans-Joachim" } }, { "id": "Peter-L", "name": { "family": "Peter", "given": "Laurence" } } ] }, "doi": "10.1039/9781849737739-00052", "primary_object": { "basename": "9781849737739-00052.pdf", "url": "https://authors.library.caltech.edu/records/tfqmg-abx66/files/9781849737739-00052.pdf" }, "resource_type": "book_section", "pub_year": "2013", "author_list": "McKone, James and Lewis, Nathan" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/p54mg-sp418", "eprint_id": 36198, "eprint_status": "archive", "datestamp": "2023-08-19 13:37:19", "lastmod": "2023-10-20 22:21:53", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yahyaie-I", "name": { "family": "Yahyaie", "given": "Iman" } }, { "id": "Ardo-S", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Oliver-D-R", "name": { "family": "Oliver", "given": "Derek R." } }, { "id": "Thomson-D-J", "name": { "family": "Thomson", "given": "Douglas J." } }, { "id": "Freund-M-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparison between the electrical junction properties of H-terminated and methyl-terminated individual Si microwire/polymer assemblies for photoelectrochemical fuel production", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 The Royal Society of Chemistry.\n\nReceived 8th August 2012, Accepted 24th September 2012.\nFirst published on the web 25 Sep 2012.\n\nFinancial support from the Natural Sciences and Engineering\nResearch Council (NSERC) of Canada, the Canada Foundation\nfor Innovation (CFI), the Manitoba Research and Innovation\nFund, and the University of Manitoba is gratefully acknowledged. \n\nThe work reported made use of surface characterization\ninfrastructure in the Manitoba Institute for Materials. This work\nwas supported by a National Science Foundation (NSF) Center\nfor Chemical Innovation (CCI) Powering the Planet (grants\nCHE-0802907, CHE-0947829, and NSF-ACCF) and made use\nof the Molecular Materials Research Center of the Beckman\nInstitute at Caltech and the Kavli Nanoscience Institute at Caltech. \n\nThis research was undertaken, in part, thanks to funding\nfrom the Canada Research Chairs Program. S. A. acknowledges\npartial support from a U. S. Department of Energy, Office of\nEnergy Efficiency and Renewable Energy (EERE) Postdoctoral\nResearch Award under the EERE Fuel Cell Technologies\nProgram.\n\nPublished - c2ee23115h.pdf
Supplemental Material - c2ee23115h_si.pdf
", "abstract": "The photoelectrical properties and stability of individual p-silicon (Si) microwire/polyethylenedioxythiophene/polystyrene sulfonate:Nafion/n-Si microwire structures, designed for use as arrays for solar fuel production, were investigated for both H-terminated and CH_3-terminated Si microwires. Using a tungsten probe method, the resistances of individual wires, as well as between individual wires and the conducting polymer, were measured vs. time. For the H-terminated samples, the n-Si/polymer contacts were initially rectifying, whereas p-Si microwire/polymer contacts were initially ohmic, but the resistance of both the n-Si and p-Si microwire/polymer contacts increased over time. In contrast, relatively stable, ohmic behavior was observed at the junctions between CH_3-terminated p-Si microwires and conducting polymers. CH_3-terminated n-Si microwire/polymer junctions demonstrated strongly rectifying behavior, attributable to the work function mismatch between the Si and polymer. Hence, a balance must be found between the improved stability of the junction electrical properties achieved by passivation, and the detrimental impact on the effective resistance associated with the additional rectification at CH_3-terminated n-Si microwire/polymer junctions. Nevertheless, the current system under study would produce a resistance drop of ~20 mV during operation under 100 mW cm^(\u22122) of Air Mass 1.5 illumination with high quantum yields for photocurrent production in a water-splitting device.", "date": "2012-12", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "5", "number": "12", "publisher": "Royal Society of Chemistry", "pagerange": "9789-9794", "id_number": "CaltechAUTHORS:20130107-103859564", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130107-103859564", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "Canada Foundation for Innovation" }, { "agency": "Manitoba Research and Innovation Fund" }, { "agency": "University of Manitoba" }, { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "NSF", "grant_number": "CHE-0947829" }, { "agency": "Department of Energy (DOE)" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" }, { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/c2ee23115h", "primary_object": { "basename": "c2ee23115h.pdf", "url": "https://authors.library.caltech.edu/records/p54mg-sp418/files/c2ee23115h.pdf" }, "related_objects": [ { "basename": "c2ee23115h_si.pdf", "url": "https://authors.library.caltech.edu/records/p54mg-sp418/files/c2ee23115h_si.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Yahyaie, Iman; Ardo, Shane; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/q367t-vbq61", "eprint_id": 36203, "eprint_status": "archive", "datestamp": "2023-08-19 13:37:33", "lastmod": "2023-10-20 22:22:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Haussener-S", "name": { "family": "Haussener", "given": "Sophia" }, "orcid": "0000-0002-3044-1662" }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Ardo-S", "name": { "family": "Ardo", "given": "Shane" }, "orcid": "0000-0001-7162-6826" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Weber-A-Z", "name": { "family": "Weber", "given": "Adam Z." }, "orcid": "0000-0002-7749-1624" } ] }, "title": "Modeling, simulation, and design criteria for photoelectrochemical water-splitting systems", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 Royal Society of Chemistry.\n\nReceived 15th August 2012, Accepted 28th September 2012.\nFirst published on the web 01 Oct 2012. \n\nWe acknowledge the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under award number DE-SC0004993. S.A. acknowledges support from a U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under the EERE Fuel Cell Technologies Program. We thank Sivagaminathan Balasubramanian for fruitful discussions.\n\nSupplemental Material - c2ee23187e.pdf
", "abstract": "A validated multi-physics numerical model that accounts for charge and species conservation, fluid flow, and electrochemical processes has been used to analyze the performance of solar-driven photoelectrochemical water-splitting systems. The modeling has provided an in-depth analysis of conceptual designs, proof-of-concepts, feasibility investigations, and quantification of performance. The modeling has led to the formulation of design guidelines at the system and component levels, and has identified quantifiable gaps that warrant further research effort at the component level. The two characteristic generic types of photoelectrochemical systems that were analyzed utilized: (i) side-by-side photoelectrodes and (ii) back-to-back photoelectrodes. In these designs, small electrode dimensions (mm to cm range) and large electrolyte heights were required to produce small overall resistive losses in the system. Additionally, thick, non-permeable separators were required to achieve acceptably low rates of product crossover.", "date": "2012-12", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "5", "number": "12", "publisher": "Royal Society of Chemistry", "pagerange": "9922-9935", "id_number": "CaltechAUTHORS:20130107-104614254", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130107-104614254", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/c2ee23187e", "primary_object": { "basename": "c2ee23187e.pdf", "url": "https://authors.library.caltech.edu/records/q367t-vbq61/files/c2ee23187e.pdf" }, "resource_type": "article", "pub_year": "2012", "author_list": "Haussener, Sophia; Xiang, Chengxiang; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mcq6r-bmp38", "eprint_id": 36574, "eprint_status": "archive", "datestamp": "2023-08-22 07:47:48", "lastmod": "2023-10-20 23:20:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Beardslee-J-A", "name": { "family": "Beardslee", "given": "Joseph A." } }, { "id": "Sadtler-B", "name": { "family": "Sadtler", "given": "Bryce" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Magnetic Field Alignment of Randomly Oriented, High Aspect Ratio Silicon Microwires into Vertically Oriented Arrays", "ispublished": "pub", "full_text_status": "public", "keywords": "magnetic coatings; vapor\u2212liquid\u2212solid growth; Ni electrodeposition; X-ray diffraction; image analysis", "note": "\u00a9 2012 American Chemical Society.\n\nReceived for review September 10, 2012; accepted October 20, 2012; published online October 20, 2012.\n\nThis work was supported by the DOE \"Light-Material Interactions in Energy Conversion\" Energy Frontier Research Center under Grant DE-SC0001293. Research was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. B.S. acknowledges the Beckman Institute of the California Institute of Technology for a postdoctoral fellowship.\n\nPublished - nn304180k.pdf
Supplemental Material - nn304180k_si_001.pdf
", "abstract": "External magnetic fields have been used to vertically align ensembles of silicon microwires coated with ferromagnetic nickel films. X-ray diffraction and image analysis techniques were used to quantify the degree of vertical orientation of the microwires. The degree of vertical alignment and the minimum field strength required for alignment were evaluated as a function of the wire length, coating thickness, magnetic history, and substrate surface properties. Nearly 100% of 100 \u03bcm long, 2 \u03bcm diameter, Si microwires that had been coated with 300 nm of Ni could be vertically aligned by a 300 G magnetic field. For wires ranging from 40 to 60 \u03bcm in length, as the length of the wire increased, a higher degree of alignment was observed at lower field strengths, consistent with an increase in the available magnetic torque. Microwires that had been exposed to a magnetic sweep up to 300 G remained magnetized and, therefore, aligned more readily during subsequent magnetic field alignment sweeps. Alignment of the Ni-coated Si microwires occurred at lower field strengths on hydrophilic Si substrates than on hydrophobic Si substrates. The magnetic field alignment approach provides a pathway for the directed assembly of solution-grown semiconductor wires into vertical arrays, with potential applications in solar cells as well as in other electronic devices that utilize nano- and microscale components as active elements.", "date": "2012-11-27", "date_type": "published", "publication": "ACS Nano", "volume": "6", "number": "11", "publisher": "American Chemical Society", "pagerange": "10303-10310", "id_number": "CaltechAUTHORS:20130124-141635894", "issn": "1936-0851", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130124-141635894", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE) Energy Frontier Research Center", "grant_number": "DE-SC0001293" }, { "agency": "Caltech Beckman Institute postdoctoral fellowship" } ] }, "doi": "10.1021/nn304180k", "primary_object": { "basename": "nn304180k.pdf", "url": "https://authors.library.caltech.edu/records/mcq6r-bmp38/files/nn304180k.pdf" }, "related_objects": [ { "basename": "nn304180k_si_001.pdf", "url": "https://authors.library.caltech.edu/records/mcq6r-bmp38/files/nn304180k_si_001.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Beardslee, Joseph A.; Sadtler, Bryce; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/g3sfn-jz883", "eprint_id": 36211, "eprint_status": "archive", "datestamp": "2023-08-22 07:45:26", "lastmod": "2023-10-20 22:52:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kimball-G-M", "name": { "family": "Kimball", "given": "Gregory M." } }, { "id": "Bosco-J-P", "name": { "family": "Bosco", "given": "Jeffrey P." } }, { "id": "M\u00fcller-A-M", "name": { "family": "M\u00fcller", "given": "Astrid M." }, "orcid": "0000-0002-2785-6808" }, { "id": "Tajdar-S-F", "name": { "family": "Tajdar", "given": "Syed F." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Passivation of Zn_3P_2 substrates by aqueous chemical etching and air oxidation", "ispublished": "pub", "full_text_status": "public", "keywords": "etching; oxidation; passivation; photoluminescence; surface composition; surface recombination; time resolved spectra; wide band gap semiconductors; X-ray photoelectron spectra; zinc compounds", "note": "\u00a9 2012 American Institute of Physics. \n\nReceived 3 May 2012; accepted 12 October 2012; published online 21 November 2012. \n\nThis work was supported by the Department of Energy under Grant Nos. DE-FG02-03ER15483 and DE-FG36-08GO18006, by the Beckman Institute Laser Resource Center, and by the Dow Chemical Company. GMK acknowledges support by an NDSEG graduate fellowship and Jeffery W. Lefler is acknowledged for fabrication of a custom time-resolved photoluminescence chamber.\n\nPublished - JApplPhys_112_106101.pdf
", "abstract": "Surface recombination velocities measured by time-resolved photoluminescence and compositions of Zn_(3)P_2 surfaces measured by x-ray photoelectron spectroscopy (XPS) have been correlated for a series of wet chemical etches of Zn_(3)P_2 substrates. Zn_(3)P_2 substrates that were etched with Br_2 in methanol exhibited surface recombination velocity values of 2.8\u2009\u00d7\u200910^4\u2009cm s^(\u22121), whereas substrates that were further treated by aqueous HF\u2013H_(2)O_2 exhibited surface recombination velocity values of 1.0\u2009\u00d7\u200910^4\u2009cm s^(\u22121). Zn_(3)P_2 substrates that were etched with Br_2 in methanol and exposed to air for 1 week exhibited surface recombination velocity values of 1.8\u2009\u00d7\u200910^3\u2009cm s^(\u22121), as well as improved ideality in metal/insulator/semiconductor devices.", "date": "2012-11-15", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "112", "number": "10", "publisher": "American Institute of Physics", "pagerange": "Art. No. 106101", "id_number": "CaltechAUTHORS:20130107-153109324", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130107-153109324", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG36-08GO18006" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Dow Chemical Company" }, { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" } ] }, "doi": "10.1063/1.4765030", "primary_object": { "basename": "JApplPhys_112_106101.pdf", "url": "https://authors.library.caltech.edu/records/g3sfn-jz883/files/JApplPhys_112_106101.pdf" }, "resource_type": "article", "pub_year": "2012", "author_list": "Kimball, Gregory M.; Bosco, Jeffrey P.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/99ewh-q5161", "eprint_id": 36630, "eprint_status": "archive", "datestamp": "2023-08-19 13:27:05", "lastmod": "2023-10-20 23:25:15", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Grimm-R-L", "name": { "family": "Grimm", "given": "Ronald L." }, "orcid": "0000-0003-0407-937X" }, { "id": "Bierman-M-J", "name": { "family": "Bierman", "given": "Matthew J." } }, { "id": "O'Leary-L-E", "name": { "family": "O'Leary", "given": "Leslie E." } }, { "id": "Strandwitz-N-C", "name": { "family": "Strandwitz", "given": "Nicholas C." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparison of the Photoelectrochemical Behavior of H\u2011Terminated and Methyl-Terminated Si(111) Surfaces in Contact with a Series of One-Electron, Outer-Sphere Redox Couples in CH_3CN", "ispublished": "pub", "full_text_status": "public", "keywords": "Electrochemistry", "note": "\u00a9 2012 American Chemical Society. \n\nReceived: September 11, 2012; Revised: October 12, 2012; Published: October 13, 2012. \n\nWe acknowledge the National Science Foundation (CHE-1214152 and CHE-0911682) and the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology for supporting this work. The authors thank Dr. David Knapp for his synthesis of 1,1\u2032-dicarbomethoxycobaltocene^(+/0) as well as Dr. Chengxiang Xiang and Professor Erik Johansson for helpful discussions.\n\nPublished - Grimm_2012p23569.pdf
Supplemental Material - jp308461q_si_001.pdf
", "abstract": "The photoelectrochemical behavior of methyl-terminated p-type and n-type Si(111) surfaces was determined in contact with a series of one-electron, outer-sphere, redox\ncouples that span >1 V in the Nernstian redox potential, E(A/A^\u2212), of the solution. The dependence of the current vs potential data, as well as of the open-circuit photovoltage, V_(OC), on E(A/A^\u2212) was compared to the behavior of H-terminated p-type and n-type Si(111) surfaces in contact with these same electrolytes. For a particular E(A/A^\u2212) value, CH_3-terminated p-Si(111) electrodes showed lower V_(OC) values than Hterminated\np-Si(111) electrodes, whereas CH_3-terminated n-Si(111) electrodes showed higher V_(OC) values than H-terminated n-Si(111) electrodes. Under 100 mW cm^(\u22122) of ELH-simulated Air Mass 1.5 illumination, n-type H\u2212Si(111) and CH_3\u2212Si(111) electrodes both demonstrated nonrectifying behavior with no photovoltage at very negative values of E(A/A^\u2212) and produced\nlimiting V_(OC) values of >0.5 V at very positive values of E(A/A^\u2212). Illuminated p-type H\u2212Si(111) and CH_3\u2212Si(111) electrodes produced no photovoltage at positive values of E(A/A^\u2212) and produced limiting V_(OC) values in excess of 0.5 V at very negative\nvalues of E(A/A^\u2212). In contact with CH_3CN-octamethylferrocene^(+/0), differential capacitance vs potential experiments yielded a \u22120.40 V shift in flat-band potential for CH_3-terminated n-Si(111) surfaces relative to H-terminated n-Si(111) surfaces. Similarly,\nin contact with CH_3CN-1,1\u2032-dicarbomethoxycobaltocene^(+/0), the differential capacitance vs potential data indicated a \u22120.25 V shift in the flat-band potential for CH_3-terminated p-Si(111) electrodes relative to H-terminated p-Si(111) electrodes. The observed trends in V_(OC) vs E(A/A^\u2212), and the trends in the differential capacitance vs potential data are consistent with a negative shift in the interfacial dipole as a result of methylation of the Si(111) surface. The negative dipole shift is consistent with a body\nof theoretical and experimental comparisons of the behavior of CH_3\u2212Si(111) surfaces vs H\u2212Si(111) surfaces, including density functional theory of the sign and magnitude of the surface dipole, photoemission spectroscopy in ultrahigh vacuum, the electrical\nbehavior of Hg/Si contacts, and the pH dependence of the current\u2212potential behavior of Si electrodes in contact with aqueous\nelectrolytes.", "date": "2012-11-08", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "116", "number": "44", "publisher": "American Chemical Society", "pagerange": "23569-23576", "id_number": "CaltechAUTHORS:20130128-141927544", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130128-141927544", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-1214152" }, { "agency": "NSF", "grant_number": "CHE-0911682" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/jp308461q", "primary_object": { "basename": "jp308461q_si_001.pdf", "url": "https://authors.library.caltech.edu/records/99ewh-q5161/files/jp308461q_si_001.pdf" }, "related_objects": [ { "basename": "Grimm_2012p23569.pdf", "url": "https://authors.library.caltech.edu/records/99ewh-q5161/files/Grimm_2012p23569.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Grimm, Ronald L.; Bierman, Matthew J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/bqm2e-ej654", "eprint_id": 36870, "eprint_status": "archive", "datestamp": "2023-08-19 13:26:45", "lastmod": "2023-10-23 15:53:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Mi-Qixi", "name": { "family": "Mi", "given": "Qixi" } }, { "id": "Ping-Yuan", "name": { "family": "Ping", "given": "Yuan" } }, { "id": "Li-Yan", "name": { "family": "Li", "given": "Yan" } }, { "id": "Cao-Bingfei", "name": { "family": "Cao", "given": "Bingfei" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Khalifah-P-G", "name": { "family": "Khalifah", "given": "Peter G." } }, { "id": "Galli-G-A", "name": { "family": "Galli", "given": "Giulia A." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Thermally Stable N_2-Intercalated WO_3 Photoanodes for Water Oxidation", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 American Chemical Society. \n\nReceived: July 14, 2012. Published: September 28, 2012. \n\nWe thank Prof. George R. Rossman for discussions and for assistance with the Raman microscope, and Prof. Francois Gygi for discussions of ab initio calculations. This work was supported by the National Science Foundation (NSF) Powering the Planet Center for Chemical Innovation (CCISolar), Grants CHE-0802907 and CHE-0947829. Q.M. was a CCI-Solar Postdoctoral Fellow. P.G.K. thanks the support of the U.S. Department of Energy under the Hydrogen Fuel Initiative. Research was in part carried out in the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology, and in part carried out at Brookhaven National Laboratory under No. DE-AC02-98CH10886 with the U.S. Department of Energy. Use of the Teragrid computational facilities is gratefully acknowledged.\n\nSupplemental Material - ja3067622_si_001.pdf
", "abstract": "We describe stable intercalation compounds of the composition xN_2\u2022WO_3 (x = 0.034\u20130.039), formed by trapping N_2 in WO_3. The incorporation of N_2 significantly reduced the absorption threshold of WO_3; notably, 0.039N_2\u2022WO_3 anodes exhibited photocurrent under illumination at wavelengths \u2264640 nm with a faradaic efficiency for O_2 evolution in 1.0 M HClO_4(aq) of nearly unity. Spectroscopic and computational results indicated that deformation of the WO3 host lattice, as well as weak electronic interactions between trapped N_2 and the WO_3 matrix, contributed to the observed red shift in optical absorption. Noble-gas-intercalated WO_3 materials similar to xN_2\u2022WO_3 are predicted to function as photoanodes that are responsive to visible light.", "date": "2012-11-07", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "134", "number": "44", "publisher": "American Chemical Society", "pagerange": "18318-18324", "id_number": "CaltechAUTHORS:20130212-095922217", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130212-095922217", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "NSF", "grant_number": "CHE-0947829" }, { "agency": "NSF Postdoctoral Fellowship" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-98CH10886" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/ja3067622", "primary_object": { "basename": "ja3067622_si_001.pdf", "url": "https://authors.library.caltech.edu/records/bqm2e-ej654/files/ja3067622_si_001.pdf" }, "resource_type": "article", "pub_year": "2012", "author_list": "Mi, Qixi; Ping, Yuan; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sqej5-2pz27", "eprint_id": 36298, "eprint_status": "archive", "datestamp": "2023-08-22 07:42:54", "lastmod": "2023-10-20 22:59:18", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bosco-J-P", "name": { "family": "Bosco", "given": "Jeffrey P." } }, { "id": "Demers-S-B", "name": { "family": "Demers", "given": "Steven B." } }, { "id": "Kimball-G-M", "name": { "family": "Kimball", "given": "Gregory M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Band alignment of epitaxial ZnS/Zn_(3)P_2 heterojunctions", "ispublished": "pub", "full_text_status": "public", "keywords": "binding energy; current density; density functional theory; electronic density of states; II-VI semiconductors; MIS structures; molecular beam epitaxial growth; semiconductor epitaxial layers; valence bands; wide band gap semiconductors; zinc compounds", "note": "\u00a9 2012 American Institute of Physics.\n\nReceived 10 September 2012; accepted 25 September 2012; published online 2 November 2012.\n\nThis work was supported by the Dow Chemical Company and by the Department of Energy, Office of Basic Energy Sciences under Grant No. DE-FG02-03ER15483. The authors would like to thank Joseph Beardslee for his assistance with the Kratos XPS measurements. J.P.B. acknowledges the NSF for a graduate research fellowship.\n\nPublished - JApplPhys_112_093703.pdf
", "abstract": "The energy-band alignment of epitaxial zb-ZnS(001)/\u03b1-Zn_(3)P_(2)(001) heterojunctions has been determined by measurement of shifts in the phosphorus 2p and sulfur 2p core-level binding energies for various thicknesses (0.6\u20132.2\u2009nm) of ZnS grown by molecular beam epitaxy on Zn_(3)P_(2). In addition, the position of the valence-band maximum for bulk ZnS and Zn3P2 films was estimated using density functional theory calculations of the valence-band density-of-states. The heterojunction was observed to be type I, with a valence-band offset, \u0394E_V, of \u22121.19\u2009\u00b1\u20090.07\u2009eV, which is significantly different from the type II alignment based on electron affinities that is predicted by Anderson theory. n^(+)-ZnS/p-Zn_(3)P_(2) heterojunctions demonstrated open-circuit voltages of >750\u2009mV, indicating passivation of the Zn_(3)P_(2) surface due to the introduction of the ZnS overlayer. Carrier transport across the heterojunction devices was inhibited by the large conduction-band offset, which resulted in short-circuit current densities of <0.1\u2009mA\u2009cm^(\u22122) under 1 Sun simulated illumination. Hence, constraints on the current density will likely limit the direct application of the ZnS/Zn_(3)P_(2) heterojunction to photovoltaics, whereas metal-insulator-semiconductor structures that utilize an intrinsic ZnS insulating layer appear promising.", "date": "2012-11-01", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "112", "number": "9", "publisher": "American Institute of Physics", "pagerange": "Art. No. 093703", "id_number": "CaltechAUTHORS:20130110-104540834", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130110-104540834", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Dow Chemical Company" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1063/1.4759280", "primary_object": { "basename": "JApplPhys_112_093703.pdf", "url": "https://authors.library.caltech.edu/records/sqej5-2pz27/files/JApplPhys_112_093703.pdf" }, "resource_type": "article", "pub_year": "2012", "author_list": "Bosco, Jeffrey P.; Demers, Steven B.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kpwsg-dwn92", "eprint_id": 35514, "eprint_status": "archive", "datestamp": "2023-08-19 13:16:51", "lastmod": "2023-10-20 16:26:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Hydrogen-evolution characteristics of Ni\u2013Mo-coated, radial junction, n+p-silicon microwire array photocathodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 Royal Society of Chemistry. \n\nReceived 16 August 2012; Accepted 13 September 2012; First published on the web 08 October 2012. \n\nELW and NSL acknowledge support from the Department of\nEnergy (DE-FG02-05ER15754) for Si MW growth and device\nfabrication. JRM and HBG acknowledge support from the\nNational Science Foundation (NSF) Powering the Planet Center\nfor Chemical Innovation (CHE-0802907) for catalyst preparation and characterization. The authors would like to thank Hal Emmer, Dan Turner-Evans, and Elizabeth Santori for help with device fabrication and spectral response data collection. We acknowledge critical support and infrastructure provided for this work by the Kavli Nanoscience Institute at Caltech. JRM would like to thank the Department of Energy, Office of Science, for a graduate research fellowship.\n\nSupplemental Material - c2ee23192a.pdf
", "abstract": "The photocathodic H_2-evolution performance of Ni\u2013Mo-coated radial n+p junction Si microwire (Si MW) arrays has been evaluated on the basis of thermodynamic energy-conversion efficiency as well as solar cell figures of merit. The Ni\u2013Mo-coated n^(+)p-Si MW electrodes yielded open-circuit photovoltages (V_oc) of 0.46 V, short-circuit photocurrent densities (J_sc) of 9.1 mA cm^(\u22122), and thermodynamically based energy-conversion efficiencies (\u03b7) of 1.9% under simulated 1 Sun illumination. Under nominally the same conditions, the efficiency of the Ni\u2013Mo-coated system was comparable to that of Pt-coated n+p-Si MW array photocathodes (V_oc = 0.44 V, J_sc = 13.2 mA cm^(\u22122_, \u03b7 = 2.7%). This demonstrates that, at 1 Sun light intensity on high surface area microwire arrays, earth-abundant electrocatalysts can provide performance comparable to noble-metal catalysts for photoelectrochemical hydrogen evolution. The formation of an emitter layer on the microwires yielded significant improvements in the open-circuit voltage of the microwire-array-based photocathodes relative to Si MW arrays that did not have a buried n^(+)p junction. Analysis of the spectral response and light-intensity dependence of these devices allowed for optimization of the catalyst loading and photocurrent density. The microwire arrays were also removed from the substrate to create flexible, hydrogen-evolving membranes that have potential for use in a solar water-splitting device.", "date": "2012-11", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "5", "number": "11", "publisher": "Royal Society of Chemistry", "pagerange": "9653-9661", "id_number": "CaltechAUTHORS:20121116-105842933", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121116-105842933", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-05ER15754" }, { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "Kavli Nanoscience Institute" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1039/C2EE23192A", "primary_object": { "basename": "c2ee23192a.pdf", "url": "https://authors.library.caltech.edu/records/kpwsg-dwn92/files/c2ee23192a.pdf" }, "resource_type": "article", "pub_year": "2012", "author_list": "Warren, Emily L.; McKone, James R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/abnhg-8a095", "eprint_id": 34812, "eprint_status": "archive", "datestamp": "2023-08-19 11:10:40", "lastmod": "2023-10-19 21:59:19", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Wilson-S-S", "name": { "family": "Wilson", "given": "Samantha S." } }, { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Tolstova-Y", "name": { "family": "Tolstova", "given": "Yulia" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Thin, free-standing Cu_2O substrates via thermal oxidation for photovoltaic devices", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "copper compounds, materials handling, oxygen, photovoltaic cells and semiconductor materials", "note": "\u00a9 2011 IEEE. \n\nDate of Current Version: 04 October 2012. \n\nThe authors acknowledge The Dow Chemical Company for funding and collaborating in this work.", "abstract": "Cu_2O is a promising, earth-abundant alternative to traditional photovoltaic materials (CIGS, CdTe, etc.) because of its low cost, high availability, and straightforward processing. We report a method to fabricate Cu_2O substrates with thicknesses of less than 20 microns which may be handled and processed into devices. Development of thinner Cu_2O substrates is essential as extrinsic doping has been impossible thus far, and intrinsic Cu_2O is highly resistive. Hall measurements indicate that the substrates had Hall mobilities of 10\u201320 cm^2V^(\u22121)s^(\u22121) and carrier concentrations on the order of 10^(14) cm^(\u22123). Current-voltage characteristics of these Cu_2O substrates were derived from liquid junction Schottky barrier device measurements which indicate open circuit voltages of Voc \u223c 600 mV.", "date": "2012-10-10", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "3191-3194", "id_number": "CaltechAUTHORS:20121010-091657887", "isbn": "978-1-4673-0064-3", "book_title": "38th IEEE Photovoltaic Specialists Conference", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121010-091657887", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Dow Chemical Company" } ] }, "doi": "10.1109/PVSC.2012.6318256", "resource_type": "book_section", "pub_year": "2012", "author_list": "Wilson, Samantha S.; Xiang, Chengxiang; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7z932-j0p12", "eprint_id": 34789, "eprint_status": "archive", "datestamp": "2023-08-19 11:10:09", "lastmod": "2023-10-19 21:52:39", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "Daniel B." } }, { "id": "Grimm-R-L", "name": { "family": "Grimm", "given": "Ronald L." }, "orcid": "0000-0003-0407-937X" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemical characterization of Si microwire array solar cells", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "material characterization, Silicon microwire,\nphotoelectrochemistry, photovoltaic", "note": "\u00a9 2011 IEEE. \n\nDate of Current Version: 04 October 2012. \n\nThe Department of Energy (DE-FG02-03ER15483) is acknowledged for financial support. We gratefully acknowledge critical support and infrastructure provided for this work by the Kavli Nanoscience Institute at Caltech. D. B. Turner-Evans acknowledges support from a National Science Foundation graduate fellowship.", "abstract": "Many proposed next-generation photovoltaic devices have complicated nano- and micro-structured architectures that are designed to simultaneously optimize carrier collection and light absorption. Characterization of the electrical properties of these highly structured materials can be challenging due to the difficulty of creating electrical contacts, as well as the need to decouple the properties of the contact from that of the semiconductor. Regenerative photoelectrochemistry is a powerful technique to characterize the electrical properties of such systems, providing a conformal liquid contact that can be ohmic or rectifying, depending on the system used. We demonstrate the use of the methyl viologen regenerative electrochemical system to characterize different stages of the fabrication of radial junction Si microwire (SiMW) solar cells. Photoelectrochemical characterization, combined with other more traditional measurements allows evaluation of how the different processing steps affect the device performance, without having to construct a fully integrated device. We describe the operating principle of this technique, and demonstrate that it can be applied to semiconductor materials with complex architectures.", "date": "2012-10-09", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "1-5", "id_number": "CaltechAUTHORS:20121009-114239624", "isbn": "978-1-4673-0064-3", "book_title": "38th IEEE Photovoltaic Specialists Conference", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121009-114239624", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "NSF Graduate Fellowship" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1109/PVSC.2012.6317731", "resource_type": "book_section", "pub_year": "2012", "author_list": "Warren, Emily L.; Turner-Evans, Daniel B.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zvrkb-fkj65", "eprint_id": 35250, "eprint_status": "archive", "datestamp": "2023-08-22 06:57:36", "lastmod": "2023-10-20 15:54:06", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Meng-A-C", "name": { "family": "Meng", "given": "Andrew C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Evaluation and optimization of mass transport of redox species in silicon microwire-array photoelectrodes", "ispublished": "pub", "full_text_status": "public", "keywords": "semiconductor/liquid junctions; Si microwire arrays; COMSOL Multiphysics", "note": "\u00a9 2012 National Academy of Sciences. \n\nEdited by Thomas J. Meyer, University of North Carolina at Chapel Hill, Chapel Hill, NC, and approved July 23, 2012 (received for review December 14, 2011). Published online before print August 16, 2012. \n\nThis work was supported by the U.S. Department of Energy, Grant DE-FG0203ER15483 and by the Caltech Center for Sustainable Energy Research (CCSER). One of us (A.C.M.) acknowledges support from Caltech's Summer Undergraduate Research Fellowship program. \n\nAuthor contributions: C.X., A.C.M., and N.S.L. designed research; C.X. and A.C.M. performed research; C.X. and A.C.M. analyzed data; and C.X., A.C.M., and N.S.L. wrote the paper.\n\nPublished - PNAS-2012-Xiang-15622-7.pdf
Supplemental Material - pnas.1118338109_SI.pdf
", "abstract": "Physical integration of a Ag electrical contact internally into a metal/substrate/microstructured Si wire array/oxide/Ag/electrolyte photoelectrochemical solar cell has produced structures that display relatively low ohmic resistance losses, as well as highly efficient mass transport of redox species in the absence of forced convection. Even with front-side illumination, such wire-array based photoelectrochemical solar cells do not require a transparent conducting oxide top contact. In contact with a test electrolyte that contained 50 mM/5.0 mM of the cobaltocenium^(+/0) redox species in CH_3CN\u20131.0 M LiClO_4, when the counterelectrode was placed in the solution and separated from the photoelectrode, mass transport restrictions of redox species in the internal volume of the Si wire array photoelectrode produced low fill factors and limited the obtainable current densities to 17.6 mA cm^(-2) even under high illumination. In contrast, when the physically integrated internal Ag film served as the counter electrode, the redox couple species were regenerated inside the internal volume of the photoelectrode, especially in regions where depletion of the redox species due to mass transport limitations would have otherwise occurred. This behavior allowed the integrated assembly to operate as a two-terminal, stand-alone, photoelectrochemical solar cell. The current density vs. voltage behavior of the integrated photoelectrochemical solar cell produced short-circuit current densities in excess of 80 mA cm^(-2) at high light intensities, and resulted in relatively low losses due to concentration overpotentials at 1 Sun illumination. The integrated wire array-based device architecture also provides design guidance for tandem photoelectrochemical cells for solar-driven water splitting.", "date": "2012-09-25", "date_type": "published", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "volume": "109", "number": "39", "publisher": "National Academy of Sciences", "pagerange": "15622-15627", "id_number": "CaltechAUTHORS:20121101-150325621", "issn": "0027-8424", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121101-150325621", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "Caltech Center for Sustainable Energy Research" }, { "agency": "Caltech Summer Undergraduate Research Fellowship (SURF)" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1073/pnas.1118338109", "pmcid": "PMC3465373", "primary_object": { "basename": "PNAS-2012-Xiang-15622-7.pdf", "url": "https://authors.library.caltech.edu/records/zvrkb-fkj65/files/PNAS-2012-Xiang-15622-7.pdf" }, "related_objects": [ { "basename": "pnas.1118338109_SI.pdf", "url": "https://authors.library.caltech.edu/records/zvrkb-fkj65/files/pnas.1118338109_SI.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Xiang, Chengxiang; Meng, Andrew C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kr91j-m9394", "eprint_id": 35226, "eprint_status": "archive", "datestamp": "2023-08-22 06:26:49", "lastmod": "2023-10-20 15:52:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Strandwitz-N-C", "name": { "family": "Strandwitz", "given": "Nicholas C." } }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "Daniel B." } }, { "id": "Tamboli-A-C", "name": { "family": "Tamboli", "given": "Adele C." } }, { "id": "Chen-Christopher-T", "name": { "family": "Chen", "given": "Christopher T." }, "orcid": "0000-0001-5848-961X" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemical Behavior of Planar and Microwire-Array Si|GaP Electrodes", "ispublished": "pub", "full_text_status": "restricted", "keywords": "semiconductors; composites; electrodes; electro-optical materials", "note": "\u00a9 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Received: November 29, 2011.\nPublished online: June 15, 2012. We acknowledge the National Science Foundation (NSF) Center for Chemical Innovation (CHE-0802907) and DARPA for support. NCS\nacknowledges the NSF for an American Competitiveness in Chemistry\npostdoctoral fellowship (CHE-1042006). DBTE acknowledges the NSF\nfor a Graduate Research Fellowship. The authors acknowledge helpful\ndiscussions from Dr. Chengxiang Xiang and Prof. Shannon W. Boettcher.", "abstract": "Gallium phosphide exhibits a short diffusion length relative to its optical absorption length, and is thus a candidate for use in wire array geometries that allow light absorption to be decoupled from minority carrier collection. Herein is reported the photoanodic performance of heteroepitaxially grown gallium phosphide on planar and microwire-array Si substrates. The n-GaP|n-Si heterojunction results in a favorable conduction band alignment for electron collection in the silicon. A conformal electrochemical contact to the outer GaP layer is produced using the ferrocenium/ferrocene (Fc^+/Fc) redox couple in acetonitrile. Photovoltages of \u223c750 mV under 1 sun illumination are observed and are attributed to the barrier formed at the (Fc^+/Fc)|n-GaP junction. The short-circuit current densities of the composite microwire-arrays are similar to those observed using single-crystal n-GaP photoelectrodes. Spectral response measurements along with a finite-difference-time-domain optical model indicate that the minority carrier diffusion length in the GaP is \u223c80 nm. Solid-state current\u2013voltage measurements show that shunting occurs through thin GaP layers that are present near the base of the microwire-arrays. The results provide guidance for further studies of 3D multi-junction photoelectrochemical cells.", "date": "2012-09", "date_type": "published", "publication": "Advanced Energy Materials", "volume": "2", "number": "9", "publisher": "Wiley", "pagerange": "1109-1116", "id_number": "CaltechAUTHORS:20121101-091407028", "issn": "1614-6832", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121101-091407028", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "NSF American Competitiveness in Chemistry Postdoctoral Fellowship", "grant_number": "CHE-1042006" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1002/aenm.201100728", "resource_type": "article", "pub_year": "2012", "author_list": "Strandwitz, Nicholas C.; Turner-Evans, Daniel B.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/82p84-bnt81", "eprint_id": 33434, "eprint_status": "archive", "datestamp": "2023-08-19 11:50:55", "lastmod": "2023-10-18 19:53:49", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sadtler-B", "name": { "family": "Sadtler", "given": "Bryce" } }, { "id": "Burgos-S-P", "name": { "family": "Burgos", "given": "Stanley P." } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Light-mediated growth of chalcogenide nanostructures", "ispublished": "unpub", "full_text_status": "restricted", "abstract": "The synthesis of inorg. materials whose morphologies respond to changing illumination conditions can enable the development of complex nanostructures with tailored optical responses. We have developed a method for light-mediated pattern formation during the electrodeposition of photoresponsive selenium-tellurium (Se-Te) alloys. While no long-range structure is obsd. for Se-Te films prepd. in the dark, those deposited under illumination display a nanoscale lamellar pattern that is continuous over the entire growth substrate. We attribute the light-induced pattern formation to interference between scattered waves at the surface of the growing film, which produces a periodic modulation in the light intensity. The deposition rate of the Se-Te alloy is increased in regions of greater local intensity making the resulting patterns highly sensitive to the wavelength, polarization, and angle of the incident illumination. Further structural complexity can be built into the Se-Te nanostructures by changing the illumination conditions during the electrodeposition process.", "date": "2012-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20120822-080735000", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120822-080735000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2012", "author_list": "Sadtler, Bryce; Burgos, Stanley P.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/p845f-z9419", "eprint_id": 38847, "eprint_status": "archive", "datestamp": "2023-08-22 06:08:01", "lastmod": "2023-10-23 23:32:07", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tamboli-A-C", "name": { "family": "Tamboli", "given": "Adele C." } }, { "id": "Chen-Christopher-T", "name": { "family": "Chen", "given": "Christopher T." }, "orcid": "0000-0001-5848-961X" }, { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "Daniel B." } }, { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Wafer-Scale Growth of Silicon Microwire Arrays for\n Photovoltaics and Solar Fuel Generation", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Microwire; nanowire; photoelectrochemical; photovoltaic", "note": "\u00a9 2012 IEEE. \n\nManuscript received July 11, 2011; revised March 7, 2012; accepted March 19, 2012. Date of publication April 19, 2012; date of current version June 18, 2012. \n\nThis work was supported in part by the Defense Advanced Research Projects Agency under Contract W911NF-09-2-0011 and in part by the U.S. Department of Energy under Grant DE-FG02-05ER15754. \n\nThe authors would like to thank A. Leenheer for assistance with confocal microscopy measurements. Facilities for wafer preparation were provided by the Kavli Nanoscience Institute at Caltech. D. B. Turner-Evans acknowledges support from a National Science Foundation graduate fellowship.", "abstract": "Silicon microwire arrays have recently demonstrated\ntheir potential for low-cost, high-efficiency photovoltaics and photoelectrochemical\nfuel generation. A remaining challenge to making\nthis technology commercially viable is scaling up of microwirearray\ngrowth. We discuss here a technique for vapor\u2013liquid\u2013solid\ngrowth of microwire arrays on the scale of six-inch wafers using\na cold-wall radio-frequency heated chemical vapor deposition furnace,\nenabling fairly uniform growth over large areas with rapid\ncycle time and improved run-to-run reproducibility. We have also\ndeveloped a technique to embed these large-area wire arrays in\npolymer and to peel them intact from the growth substrate, which\ncould enable lightweight, flexible solar cells with efficiencies as high\nas multicrystalline Si solar cells. We characterize these large-area\nmicrowire arrays using scanning electronmicroscopy and confocal\nmicroscopy to assess their structure and fidelity, and we test their\nenergy-conversion properties using a methyl viologen (MV^(2+/+) )\nliquid junction contact in a photoelectrochemical cell. Initial photoelectrochemical\nconversion efficiencies suggest that the material\nquality of these microwire arrays is similar to smaller (\u223c1 cm^2 )\nwire arrays that we have grown in the past, indicating that this\ntechnique is a viable way to scale up microwire-array devices.", "date": "2012-07", "date_type": "published", "publication": "IEEE Journal of Photovoltaics", "volume": "2", "number": "3", "publisher": "IEEE", "pagerange": "294-297", "id_number": "CaltechAUTHORS:20130607-081714418", "issn": "2156-3381", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130607-081714418", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "W911NF-09-2-0011" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-05ER15754" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1109/JPHOTOV.2012.2191941", "resource_type": "article", "pub_year": "2012", "author_list": "Tamboli, Adele C.; Chen, Christopher T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/h52ra-tt269", "eprint_id": 32012, "eprint_status": "archive", "datestamp": "2023-08-19 11:21:11", "lastmod": "2023-10-17 22:21:57", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Cho-Clara-J", "name": { "family": "Cho", "given": "Clara J." } }, { "id": "O'Leary-L-E", "name": { "family": "O'Leary", "given": "Leslie" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Greer-J-R", "name": { "family": "Greer", "given": "Julia R." }, "orcid": "0000-0002-9675-1508" } ] }, "title": "In Situ Nanomechanical Measurements of Interfacial Strength in Membrane-Embedded Chemically Functionalized Si Microwires for Flexible Solar Cells", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 American Chemical Society.\n\nReceived: April 14, 2012;\nRevised: May 9, 2012;\nPublished: May 21, 2012.\n\nC.J.C. gratefully acknowledges the financial support of the\nResnick Institute at Caltech through her graduate fellowship\nand E. Warren for help with wafer patterning. L.O'L. thanks the\nfinancial support of the Link Foundation Energy fellowship.\nN.S.L.'s portion of this work was supported by the National\nScience Foundation (NSF-CHE-0911682) and (NSF-CHE-0802907). J.R.G. is grateful to the Caltech's CI-2 Innovation\nGrant for supporting this work.\n\nSupplemental Material - nl3014007_si_001.pdf
Supplemental Material - nl3014007_si_002.mp4
Supplemental Material - nl3014007_si_003.mp4
", "abstract": "Arrays of vertically aligned Si microwires embedded in polydimethylsiloxane (PDMS) have emerged as a promising candidate for use in solar energy conversion devices. Such structures are lightweight and concurrently demonstrate competitive efficiency and mechanical flexibility. To ensure reliable functioning under bending and flexing, strong interfacial adhesion between the nanowire and the matrix is needed. In situ uniaxial tensile tests of individual, chemically functionalized, Si microwires embedded in a compliant PDMS matrix reveal that chemical functionality on Si microwire surfaces is directly correlated with interfacial adhesion strength. Chemical functionalization can therefore serve as an effective methodology for accessing a wide range of interfacial adhesion between the rigid constituents and the soft polymer matrix; the adhesion can be quantified by measuring the mechanical strength of such systems.", "date": "2012-06-13", "date_type": "published", "publication": "Nano Letters", "volume": "12", "number": "6", "publisher": "American Chemical Society", "pagerange": "3296-3301", "id_number": "CaltechAUTHORS:20120621-133116661", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120621-133116661", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Resnick Institute" }, { "agency": "Link Foundation Energy fellowship" }, { "agency": "NSF", "grant_number": "CHE-0911682" }, { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "Caltech's CI-2 Innovation Grant" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/nl3014007", "primary_object": { "basename": "nl3014007_si_001.pdf", "url": "https://authors.library.caltech.edu/records/h52ra-tt269/files/nl3014007_si_001.pdf" }, "related_objects": [ { "basename": "nl3014007_si_002.mp4", "url": "https://authors.library.caltech.edu/records/h52ra-tt269/files/nl3014007_si_002.mp4" }, { "basename": "nl3014007_si_003.mp4", "url": "https://authors.library.caltech.edu/records/h52ra-tt269/files/nl3014007_si_003.mp4" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Cho, Clara J.; O'Leary, Leslie; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jdynb-hk364", "eprint_id": 32835, "eprint_status": "archive", "datestamp": "2023-08-19 11:07:54", "lastmod": "2023-10-18 16:21:41", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Anglada-Escud\u00e9-G", "name": { "family": "Anglada-Escud\u00e9", "given": "Guillem" }, "orcid": "0000-0002-3645-5977" }, { "id": "Plavchan-P", "name": { "family": "Plavchan", "given": "Peter" }, "orcid": "0000-0002-8864-1667" }, { "id": "Mills-S-M", "name": { "family": "Mills", "given": "Sean" }, "orcid": "0000-0002-4535-6241" }, { "id": "Gao-Peter", "name": { "family": "Gao", "given": "Peter" }, "orcid": "0000-0002-8518-9601" }, { "id": "Garc\u00eda-Berr\u00edos-E", "name": { "family": "Garc\u00eda-Berr\u00edos", "given": "Edgardo" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Sung-Keeyoon", "name": { "family": "Sung", "given": "Keeyoon" } }, { "id": "Ciardi-D-R", "name": { "family": "Ciardi", "given": "David" }, "orcid": "0000-0002-5741-3047" }, { "id": "Beichman-C-A", "name": { "family": "Beichman", "given": "Chas" }, "orcid": "0000-0002-5627-5471" }, { "id": "Brinkworth-C-S", "name": { "family": "Brinkworth", "given": "Carolyn" } }, { "id": "Johnson-J-A", "name": { "family": "Johnson", "given": "John" }, "orcid": "0000-0001-9808-7172" }, { "id": "Davisson-C", "name": { "family": "Davison", "given": "Cassy" } }, { "id": "White-R-J", "name": { "family": "White", "given": "Russel" }, "orcid": "0000-0001-5313-7498" }, { "id": "Prato-L", "name": { "family": "Prato", "given": "Lisa" } } ] }, "title": "Design and Construction of Absorption Cells for Precision Radial Velocities in the K Band Using Methane Isotopologues", "ispublished": "pub", "full_text_status": "public", "keywords": "Exoplanets", "note": "\u00a9 2012 The Astronomical Society of the Pacific.\n\nReceived 2011 August 18; accepted 2012 April 24; published 2012 May 22.\n\nBoth G. Anglada-Escud\u00e9 and P. Plavchan contributed equally\nto this work. G. A. would like to acknowledge the Carnegie\nPostdoctoral Fellowship Program and the support provided by\nthe NASA Astrobiology Institute grant NNA09DA81A. Peter\nPlavchan would like acknowledge Wes Traub and Stephen Unwin\nfor funding provided by the Jet Propulsion Laboratory's\n(JPL's) Center for Exoplanet Science and NASA Exoplanet\nScience Institute. K. Sung acknowledges the Planetary Atmospheric Research Program to support the laboratory spectroscopic calibrations. Part of the research at the JPL and California Institute of Technology was performed under contracts with National Aeronautics and Space Administration. We thank Anu Dudhia for making the Reference Forward Model code available to us and for his assistance with adapting it for gas cell spectral calculations. The stellar synthetic spectra were graciously\nprovided by Peter Hauschildt (University of\nHamburg) and the PHOENIX group. We also thank Linda\nBrown from JPL's Laboratory Studies and Modeling group\nand Pin Chen from the Planetary Chemistry and Astrobiology\ngroup for their advice and support using the Fourier-transformed infrared spectrometer. We would like to thank Paul Butler (Carnegie Institution of Washington) and Gilian Nave (NIST) for their advice in gas optimization parameters and molecular spectroscopy in general. We would like to thank Stephen Kane (NExScI), Kaspar von Braun (NExScI), and Steve Osterman (University of Colorado) for their valuable discussions. We also thank John Rayner, Morgan Bonnet, George Koenig, and Alan Tokunaga from IfA, Hawaii, for their support during the CSHELL/IRTF cell design review, integration, and commissioning. We thank Rick Gerhart (California Institute of Technology), Scot Howell (Mindrum Precision), and Thurston Levy (Glass Instruments, Inc.) for their work in helping construct and fill the gas cells, as well as Joeff Zolkower (California Institute of Technology) for mechanical engineering advise.\n\nPublished - AngladaEscude2012p18966Publ_Astron_Soc_Pac.pdf
", "abstract": "We present a method to optimize absorption cells for precise wavelength calibration in the near-infrared. We apply it to design and optimize methane isotopologue cells for precision radial velocity measurements in the K band. We also describe the construction and installation of two such cells for the CSHELL spectrograph at NASA's IRTF. We have obtained their high-resolution laboratory spectra, which we can then use in precision radial velocity measurements and which can also have other applications. In terms of obtainable RV precision, methane should outperform other proposed cells, such as the ammonia cell (^(14)NH_3) recently demonstrated on CRIRES/VLT. The laboratory spectra of the ammonia and methane cells show strong absorption features in the H band that could also be exploited for precision Doppler measurements. We present spectra and preliminary radial velocity measurements obtained during our first-light run. These initial results show that a precision down to 20-30 m s^(-1)can be obtained using a wavelength interval of only 5 nm in the K band and S/N \u223c 150. This supports the prediction that a precision down to a few meters per second can be achieved on late-M dwarfs using the new generation of NIR spectrographs, thus enabling the detection of terrestrial planets in their habitable zones. Doppler measurements in the NIR can also be used to mitigate the radial velocity jitter due to stellar activity, enabling more efficient surveys on young active stars.", "date": "2012-06", "date_type": "published", "publication": "Publications of the Astronomical Society of the Pacific", "volume": "124", "number": "916", "publisher": "Astronomical Society of the Pacific", "pagerange": "586-597", "id_number": "CaltechAUTHORS:20120801-111847565", "issn": "0004-6280", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120801-111847565", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Carnegie Trust" }, { "agency": "NASA", "grant_number": "NNA09DA81A" }, { "agency": "JPL" } ] }, "local_group": { "items": [ { "id": "Infrared-Processing-and-Analysis-Center-(IPAC)" } ] }, "doi": "10.1086/666489", "primary_object": { "basename": "AngladaEscude2012p18966Publ_Astron_Soc_Pac.pdf", "url": "https://authors.library.caltech.edu/records/jdynb-hk364/files/AngladaEscude2012p18966Publ_Astron_Soc_Pac.pdf" }, "resource_type": "article", "pub_year": "2012", "author_list": "Anglada-Escud\u00e9, Guillem; Plavchan, Peter; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/b1aqt-fpy78", "eprint_id": 31567, "eprint_status": "archive", "datestamp": "2023-08-19 10:44:49", "lastmod": "2023-10-17 18:40:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Santori-E-A", "name": { "family": "Santori", "given": "Elizabeth A." } }, { "id": "Maiolo-J-R-III", "name": { "family": "Maiolo", "given": "James R., III" } }, { "id": "Bierman-M-J", "name": { "family": "Bierman", "given": "Matthew J." } }, { "id": "Strandwitz-N-C", "name": { "family": "Strandwitz", "given": "Nicholas C." } }, { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoanodic behavior of vapor-liquid-solid\u2013grown, lightly doped, crystalline Si microwire arrays", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 Royal Society of Chemistry. \n\nReceived 15th December 2011, Accepted 14th February 2012. First published on the web 20 Feb 2012. \n\nWe acknowledge BP, the Gordon and Betty Moore Foundation, Toyota, and the U.S. Department of Energy for financial support.\nNCS acknowledges the NSF for an American Competitiveness in\nChemistry postdoctoral fellowship (CHE-1042006). The angle-resolved optical characterization work was supported by the US Department of Energy 'Light\u2013Material Interactions in Energy Conversion' Energy Frontier Research Center Award (grant DESC0001293). We acknowledge critical support and infrastructure provided for this work by the Kavli Nanoscience Institute at Caltech.\n\nPublished - Santori2012p18191Energ_Environ_Sci.pdf
Supplemental Material - c2ee03468a.pdf
", "abstract": "Arrays of n-Si microwires have to date exhibited low efficiencies when measured as photoanodes in contact with a 1-1\u2032-dimethylferrocene (Me_2Fc^(+/0))\u2013CH_3OH solution. Using high-purity Au or Cu catalysts, arrays of crystalline Si microwires were grown by a vapor-liquid-solid process without dopants, which produced wires with electronically active dopant concentrations of 1 \u00d7 10^(13) cm^(\u22123). When measured as photoanodes in contact with a Me_2Fc^(+/0)\u2013CH_3OH solution, the lightly doped Si microwire arrays exhibited greatly increased fill factors and efficiencies as compared to n-Si microwires grown previously with a lower purity Au catalyst. In particular, the Cu-catalyzed Si microwire array photoanodes exhibited open-circuit voltages of ~0.44 V, carrier-collection efficiencies exceeding ~0.75, and an energy-conversion efficiency of 1.4% under simulated air mass 1.5 G illumination. Lightly doped Cu-catalyzed Si microwire array photoanodes have thus demonstrated performance that is comparable to that of optimally doped p-type Si microwire array photocathodes in photoelectrochemical cells.", "date": "2012-05", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "5", "number": "5", "publisher": "Royal Society of Chemistry", "pagerange": "6867-6871", "id_number": "CaltechAUTHORS:20120521-102643994", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120521-102643994", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Gordon and Betty Moore Foundation" }, { "agency": "NSF Postdoctoral Fellowship", "grant_number": "CHE-1042006" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "Kavli Nanoscience Institute" }, { "agency": "BP" }, { "agency": "Toyota" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/c2ee03468a", "primary_object": { "basename": "Santori2012p18191Energ_Environ_Sci.pdf", "url": "https://authors.library.caltech.edu/records/b1aqt-fpy78/files/Santori2012p18191Energ_Environ_Sci.pdf" }, "related_objects": [ { "basename": "c2ee03468a.pdf", "url": "https://authors.library.caltech.edu/records/b1aqt-fpy78/files/c2ee03468a.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Santori, Elizabeth A.; Maiolo, James R., III; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/g8d20-k7103", "eprint_id": 29496, "eprint_status": "archive", "datestamp": "2023-08-19 09:45:18", "lastmod": "2023-10-24 22:15:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Mi-Qixi", "name": { "family": "Mi", "given": "Qixi" } }, { "id": "Zhanaidarova-A", "name": { "family": "Zhanaidarova", "given": "Almagul" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A quantitative assessment of the competition between water and anion oxidation at WO_3 photoanodes in acidic aqueous electrolytes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 The Royal Society of Chemistry. \n\nReceived 19th October 2011, Accepted 7th December 2011. First published on the web 03 Jan 2012. \n\nWe acknowledge the National Science Foundation (NSF) Powering the Planet Center for Chemical Innovation (CCI-Solar), Grants CHE-0802907 and CHE-0947829, and the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology, for support. QM also acknowledges the NSF for support as a CCI-Solar Postdoctoral Fellow.\n\nPublished - Mi2012p17291Energ_Environ_Sci.pdf
", "abstract": "The faradaic efficiency for O_2(g) evolution at thin-film WO_3 photoanodes has been evaluated in a series of acidic aqueous electrolytes. In 1.0 M H_2SO_4, persulfate was the predominant photoelectrochemical oxidation product, and no O_2 was detected unless catalytic quantities of Ag^+(aq) were added to the electrolyte. In contact with 1.0 M HClO_4, dissolved O_2 was observed with nearly unity faradaic efficiency, but addition of a hole scavenger, 4-cyanopyridine N-oxide, completely suppressed O_2 formation. In 1.0 M HCl, Cl_2(g) was the primary oxidation product. These results indicate that at WO_3 photoanodes, water oxidation is dominated by oxidation of the acid anions in 1.0 M HCl, H_2SO_4, and HClO_4, respectively.", "date": "2012-02", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "5", "number": "2", "publisher": "Royal Society of Chemistry", "pagerange": "5694-5700", "id_number": "CaltechAUTHORS:20120228-074506627", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120228-074506627", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "NSF", "grant_number": "CHE-0947829" }, { "agency": "Caltech Beckman Institute" }, { "agency": "NSF Postdoctoral Fellowship" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1039/c2ee02929d", "primary_object": { "basename": "Mi2012p17291Energ_Environ_Sci.pdf", "url": "https://authors.library.caltech.edu/records/g8d20-k7103/files/Mi2012p17291Energ_Environ_Sci.pdf" }, "resource_type": "article", "pub_year": "2012", "author_list": "Mi, Qixi; Zhanaidarova, Almagul; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/btcxc-yt720", "eprint_id": 33499, "eprint_status": "archive", "datestamp": "2023-09-14 19:28:24", "lastmod": "2023-10-23 20:52:02", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "O'Leary-L-E", "name": { "family": "O'Leary", "given": "Leslie E." } }, { "id": "Johansson-E-M", "name": { "family": "Johansson", "given": "Erik" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Chemical Stability of Organic Monolayers Formed in Solution", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2012 John Wiley & Sons, Inc.", "abstract": "The H- Si surface is important to the electronics and photovoltaics industries\nbecause Si-H is the starting point for many Si-based devices. In tum, the electronic\nand chemical properties of the H-terminated Si surface affect the properties of\nsubsequent Si surfaces and interfaces [1-3]. Dangling or weak bonds present at the\nsurface will affect minority-carrier (\"excited-state\") processes, and will thus affect\ndevices such as field-effect transistors and pbotovoltaics. Furthermore, the topography\nof, as well as the presence of adsorbed chemical contaminants on, a\nH-terminated Si surface greatly affects the electronic properties of Si/SiO_x interfaces\nformed from this initial H-terminated Si surface [4, 5]. Organic contaminants are\ndifficult to remove from the Si surface, and different cleaning procedures have been\nshown to result in a variety of contaminant fingerprints. Hence, significant effort has\nbeen directed to understand the reactivity of the H-Si surface.\nThis section will explore the reactivity of the H-terminated Si surface with O_2,\nH_2O, alcohols, metals, amines, and thiols. The synthesis, as well as the physical and\nelectronic characterization, of the H-Si surfaces will be reviewed briefly, but the\nreader is encouraged to consult Chapter 3 for a more detailed account of the\npreparation and characterization of H-terminated Si surfaces.", "date": "2012", "date_type": "published", "publisher": "John Wiley & Sons, Inc.", "place_of_pub": "Hoboken, NJ", "pagerange": "339-399", "id_number": "CaltechAUTHORS:20120824-082317316", "isbn": "9780470562949", "book_title": "Functionalization of semiconductor surfaces", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120824-082317316", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Tao-F", "name": { "family": "Tao", "given": "Feng" } }, { "id": "Bemasek-S-L", "name": { "family": "Bemasek", "given": "Steven L." } } ] }, "resource_type": "book_section", "pub_year": "2012", "author_list": "O'Leary, Leslie E.; Johansson, Erik; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qqhfx-nq382", "eprint_id": 36778, "eprint_status": "archive", "datestamp": "2023-08-22 04:30:24", "lastmod": "2023-10-23 15:46:16", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Anz-S-J", "name": { "family": "Anz", "given": "Samir J." } }, { "id": "Fajardo-A-M", "name": { "family": "Fajardo", "given": "Arnel M." } }, { "id": "Royea-W-J", "name": { "family": "Royea", "given": "William J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Morris-A-J", "name": { "family": "Morris", "given": "Amanda J." } } ] }, "title": "Semiconductor photoelectrochemistry", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "photoconductivity; intensity modulated photocurrent and photovoltage spectroscopy; time-resolved microwave conductivity; semiconductor-liquid junctions; laser spot scanning; charge transfer; band gap; electrochemistry", "note": "\u00a9 2012 John Wiley & Sons, Inc.\nPublished Online: 12 Oct. 2012.\n\nA. Morris would like to acknowledge Virginia Polytechnic\nInstitute and State University for their generous support.\nWe acknowledge the Department of Energy, Office\nof Basic Energy Sciences, and the National Science\nFoundation for their generous support of semiconductor\nelectrochemistry that is incorporated partly in this work.\nIn addition, we acknowledge helpful discussions with G.\nCoia, G. Walker, and O. Kr\u00fcger during the preparation of\nthis article.", "abstract": "This article discusses methods and experimental\nprotocols in semiconductor electrochemistry. We first\nintroduce the basic principles that govern the energetics\nand kinetics of charge flow at a semiconductor\u2013liquid\ncontact. The principal electrochemical techniques of\nphotocurrent and photovoltage measurements used to\nobtain important interfacial energetic and kinetic\nquantities of such contacts are then described in detail.\nAfter this basic description of concepts and methods\nin semiconductor electrochemistry, we describe methods\nfor characterizing the optical, electrical, and chemical\nproperties of semiconductors through use of the\nelectrochemical properties of semiconductor\u2013liquid\ninterfaces.", "date": "2012", "date_type": "published", "publisher": "John Wiley & Sons", "place_of_pub": "Hoboken, NJ", "pagerange": "864-898", "id_number": "CaltechAUTHORS:20130205-105735010", "isbn": "978-1-1181-1074-4", "book_title": "Characterization of Materials", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130205-105735010", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Virginia Polytechnic Institute and State University" }, { "agency": "Department of Energy (DOE) Office of Basic Energy Sciences" }, { "agency": "NSF" } ] }, "contributors": { "items": [ { "id": "Kaufmann-E-N", "name": { "family": "Kaufmann", "given": "Elton N." } } ] }, "doi": "10.1002/0471266965.com052.pub2", "resource_type": "book_section", "pub_year": "2012", "author_list": "Anz, Samir J.; Fajardo, Arnel M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2mrmt-zsv17", "eprint_id": 85903, "eprint_status": "archive", "datestamp": "2023-08-22 04:23:45", "lastmod": "2023-10-18 19:05:29", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tan-Ming-X", "name": { "family": "Tan", "given": "Ming X." } }, { "id": "Bansal-A", "name": { "family": "Bansal", "given": "Ashish" } }, { "id": "Lauermann-I", "name": { "family": "Lauermann", "given": "Iver" } }, { "id": "Shreve-G-A", "name": { "family": "Shreve", "given": "Gary A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Semiconductor Interfaces", "ispublished": "unpub", "full_text_status": "public", "keywords": "Schottky barrier; barrier height; band bending; interfaces; built\u2010in voltage; space\u2010charge region; semiconductor junctions; semiconductor contacts", "note": "\u00a9 2011 John Wiley & Sons, Ltd. \n\nPublished Online: 15 December 2011.", "abstract": "This article describes the properties of semiconductors that are responsible for the operation of rectifiers, transistors, photovoltaic devices, and light emitting. The penetration of the electric field and the electric potential into a bulk semiconductor phase yields a nonuniform carrier concentration in the sample, and produces contacts that either attract or repel specific types of charge carriers. Chemical control over these electric fields is crucial to the technology of semiconductor contacts. In principle, such control can be established through a simple variation in the electrochemical potential of the contacting phase. In practice, this ideal model often does not apply, and other factors influence or completely determine the interfacial electric field strength. The application of these principles is described for semiconductor/semiconductor, semiconductor/metal, semiconductor/liquid, and semiconductor/polymer contacts, making the approach valuable for understanding the operational principles of a variety of technologically important semiconductor devices.", "date": "2011-12-15", "date_type": "published", "publisher": "Wiley", "place_of_pub": "Hoboken, NJ", "pagerange": "1-17", "id_number": "CaltechAUTHORS:20180417-110631790", "isbn": "9781119951438", "book_title": "Encyclopedia of Inorganic and Bioinorganic Chemistry", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180417-110631790", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Scott-R-A", "name": { "family": "Scott", "given": "Robert A." } } ] }, "doi": "10.1002/9781119951438.eibc0200", "resource_type": "book_section", "pub_year": "2011", "author_list": "Tan, Ming X.; Bansal, Ashish; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/q0ek3-sra03", "eprint_id": 86025, "eprint_status": "archive", "datestamp": "2023-08-22 04:24:25", "lastmod": "2023-10-18 19:11:50", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Stanton-C-E", "name": { "family": "Stanton", "given": "Colby E." } }, { "id": "Nguyen-SonBinh-T", "name": { "family": "Nguyen", "given": "SonBinh T." } }, { "id": "Kesselman-J-M", "name": { "family": "Kesselman", "given": "Janet M." } }, { "id": "Laibinis-P-E", "name": { "family": "Laibinis", "given": "Paul E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Semiconductors", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "semiconductors; band structure; electrons; holes; mobility; solids", "note": "\u00a9 2011 John Wiley & Sons, Ltd. \n\nPublished Online: 15 December 2011. \n\nWe acknowledge the National Science Foundation, grant\nCHE-8814694, and the Department of Energy, Office of\nBasic Energy Sciences, grant DE-FG03-88ER13932, for\nsupport of work in photoelectrochemistry. Janet M. Kesselman\nacknowledges the National Science Foundation and SonBinh\nT. Nguyen acknowledges the Department of Defense, Office\nof Army Research for pre-doctoral fellowships. This is\ncontribution 8755 from the Caltech Division of Chemistry\nand Chemical Engineering.", "abstract": "The structural, electronic, optical, and electrical properties of semiconductors are treated within a common framework. The bonding in the lattice determines the band structure of the solid, which is used to describe the chemical, optical, and electrical properties of the semiconductor. These concepts enable this process to be understood from a qualitative, chemically based viewpoint.", "date": "2011-12-15", "date_type": "published", "publisher": "Wiley", "place_of_pub": "Hoboken, NJ", "pagerange": "1-16", "id_number": "CaltechAUTHORS:20180424-140059084", "isbn": "9781119951438", "book_title": "Encyclopedia of Inorganic and Bioinorganic Chemistry", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180424-140059084", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-8814694" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG03-88ER13932" }, { "agency": "Army Research Office (ARO)" } ] }, "other_numbering_system": { "items": [ { "id": "8755", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "contributors": { "items": [ { "id": "Scott-R-A", "name": { "family": "Scott", "given": "Robert A." } } ] }, "doi": "10.1002/9781119951438.eibc0201", "resource_type": "book_section", "pub_year": "2011", "author_list": "Stanton, Colby E.; Nguyen, SonBinh T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ttgkk-qp696", "eprint_id": 27678, "eprint_status": "archive", "datestamp": "2023-08-22 04:10:26", "lastmod": "2023-10-24 17:19:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Garc\u00eda-Berr\u00edos-E", "name": { "family": "Garc\u00eda-Berr\u00edos", "given": "Edgardo" } }, { "id": "Gao-Ting", "name": { "family": "Gao", "given": "Ting" } }, { "id": "Walker-D", "name": { "family": "Walker", "given": "Don" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Composites of carboxylate-capped TiO_2 nanoparticles and carbon black as chemiresistive vapor sensors", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Titanium (IV) dioxide nanoparticles; Carbon black composites; Electronic nose; Principal components analysis (PCA)", "note": "\u00a9 2011 Elsevier B.V. \n\nReceived 11 November 2010; Accepted 6 April 2011. Available online 14 April 2011. \n\nThe authors thank Dr. Marc D. Woodka for helpful discussions and data analysis, Heather Agnew for helping with the FTIR analysis, Carol M. Garland for the TEM analysis and Juan S. Ramirez for the centrifugation of the nanoparticles. Edgardo Garc\u00eda-Berr\u00edos acknowledges the NSF for a graduate fellowship. Ting Gao acknowledges the support from Tyco Electronics. Research was carried out in the Molecular Materials Research Center of the Beckman Institute at Caltech. This work was supported by the NSF, grant CHE-0604894, and by DHS, grant HSARPA 2008-ST-061-ED0002.", "abstract": "Titanium (IV) dioxide (TiO_2) nanoparticles (NPs) with a 1\u20135 nm diameter were synthesized by a sol\u2013gel method, functionalized with carboxylate ligands, and combined with carbon black (CB) to produce chemiresistive chemical vapor sensor films. The TiO_2 acted as an inorganic support phase for the swellable, organic capping groups of the NPs, and the CB imparted electrical conductivity to the film. Such sensor composite films exhibited a reproducible, reversible change in relative differential resistance upon exposure to a series of organic test vapors. The response of such chemiresistive composites was comparable to, but generally somewhat smaller than, that of thiol-capped Au NPs. For a given analyte, the resistance response and signal-to-noise ratio of the capped TiO_2-NP/CB composites varied with the identity of the capping ligand. Hence, an array of TiO_2-NP/CB composites, with each film having a compositionally different carboxylate capping ligand, provided good vapor discrimination and quantification when exposed to a series of organic vapors. Principal components analysis of the relative differential resistance response of the sensor array revealed a clear clustering of the response for each analyte tested. This approach expands the options for composite-based chemiresistive vapor sensing, from use of organic monomeric or polymeric sorbent phases, to use of electrically insulating capped inorganic NPs as the nonconductive phase of chemiresistive composite vapor sensors.", "date": "2011-11-15", "date_type": "published", "publication": "Sensors and Actuators B: Chemical", "volume": "158", "number": "1", "publisher": "Elsevier", "pagerange": "17-22", "id_number": "CaltechAUTHORS:20111108-132622961", "issn": "0925-4005", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111108-132622961", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Fellowship" }, { "agency": "Tyco Electronics Corporation" }, { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "Department of Homeland Security", "grant_number": "HSARPA 2008-ST-061-ED0002" } ] }, "doi": "10.1016/j.snb.2011.04.022", "resource_type": "article", "pub_year": "2011", "author_list": "Garc\u00eda-Berr\u00edos, Edgardo; Gao, Ting; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/gvbez-y4017", "eprint_id": 25490, "eprint_status": "archive", "datestamp": "2023-08-19 07:52:06", "lastmod": "2023-10-24 15:54:52", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Bierman-M-J", "name": { "family": "Bierman", "given": "Matthew J." } }, { "id": "Boettcher-S-W", "name": { "family": "Boettcher", "given": "Shannon W." }, "orcid": "0000-0001-8971-9123" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Evaluation of Pt, Ni, and Ni\u2013Mo electrocatalysts for hydrogen evolution on crystalline Si electrodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2011 The Royal Society of Chemistry. \n\nReceived 19 Apr 2011, Accepted 22 Jun 2011. First published on the web 01 Aug 2011. \n\nThis work was supported by the National Science Foundation (NSF) Powering the Planet Center for Chemical Innovation (CCI), Grants CHE-0802907 and CHE-0947829, and by the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology. The authors would like to acknowledge Joseph Beardslee for assistance with XPS analysis. JRM would like to thank the Department of Energy, Office of Science, for a graduate research fellowship. SWB gratefully acknowledges fellowship support from the Kavli Nanoscience Institute.\n\nPublished - McKone2011p15897Energ_Environ_Sci.pdf
Supplemental Material - c1ee01488a.pdf
", "abstract": "The dark electrocatalytic and light photocathodic hydrogen evolution properties of Ni, Ni\u2013Mo alloys, and Pt on Si electrodes have been measured, to assess the viability of earth-abundant electrocatalysts for integrated, semiconductor coupled fuel formation. In the dark, the activities of these catalysts deposited on degenerately doped p^+-Si electrodes increased in the order Ni < Ni\u2013Mo \u2264 Pt. Ni\u2013Mo deposited on degenerately doped Si microwires exhibited activity that was very similar to that of Pt deposited by metal evaporation on planar Si electrodes. Under 100 mW cm^(\u22122) of Air Mass 1.5 solar simulation, the energy conversion efficiencies of p-type Si/catalyst photoelectrodes ranged from 0.2\u20131%, and increased in the order Ni \u2248 Ni\u2013Mo < Pt, due to somewhat lower photovoltages and photocurrents for p-Si/Ni\u2013Mo relative to p-Si/Ni and p-Si/Pt photoelectrodes. Deposition of the catalysts onto microwire arrays resulted in higher apparent catalytic activities and similar photoelectrode efficiencies than were observed on planar p-Si photocathodes, despite lower light absorption by p-Si in the microwire structures.", "date": "2011-09", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "4", "number": "9", "publisher": "Royal Society of Chemistry", "pagerange": "3573-3583", "id_number": "CaltechAUTHORS:20110929-104011152", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110929-104011152", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "NSF", "grant_number": "CHE-0947829" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Kavli Nanoscience Institute" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1039/c1ee01488a", "primary_object": { "basename": "McKone2011p15897Energ_Environ_Sci.pdf", "url": "https://authors.library.caltech.edu/records/gvbez-y4017/files/McKone2011p15897Energ_Environ_Sci.pdf" }, "related_objects": [ { "basename": "c1ee01488a.pdf", "url": "https://authors.library.caltech.edu/records/gvbez-y4017/files/c1ee01488a.pdf" } ], "resource_type": "article", "pub_year": "2011", "author_list": "McKone, James R.; Warren, Emily L.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7h3f4-hya27", "eprint_id": 25219, "eprint_status": "archive", "datestamp": "2023-08-19 07:47:57", "lastmod": "2023-10-24 15:42:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Knapp-D", "name": { "family": "Knapp", "given": "David" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Transmission Infrared Spectra of CH_3-, CD_3-, and\n C_(10)H_(21)-Ge(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2011 American Chemical Society. \n\nReceived: November 4, 2010. Revised: June 7, 2011. Publication Date (Web): June 16, 2011. \n\nWe acknowledge the National Science Foundation, Grant No. CHE-0911682, and the Beckman Institute for support of this work. We are also grateful to Dr. Erik Johansson for helpful discussions. XPS and FTIR data were collected at the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology.\n\nSupplemental Material - jp110550t_si_001.pdf
", "abstract": "The surface chemistry of CH_3\u2013, CD_3\u2013, and C_(10)H_(21)\u2013Ge(111) surfaces prepared through a bromination/alkylation method have been investigated by infrared spectroscopy. Well-ordered CH_3\u2013Ge(111) surfaces could be prepared only if, prior to bromination, the surface was etched with 6.0 M HCl or with a two-step etch of H_2O_2 (1.5 M)/HF (5.1 M) followed by a short HF (6.0 M) etch. The etching method used to make the Ge precursor surface, and the formation of a bromine-terminated intermediate Ge surface, were of critical importance to obtain clear, unambiguous infrared absorption peaks on the methyl-terminated Ge surfaces. Polarization-dependent absorption peaks observed at 1232 cm^(\u20131) for CH_3\u2013Ge(111) surfaces and at 951 cm^(\u20131) for CD_3\u2013Ge(111) surfaces were assigned to the methyl \"umbrella\" vibrational mode. A polarization-dependent peak at 2121 cm^(\u20131) for CD_3\u2013Ge(111) surfaces was assigned to the symmetric methyl stretching mode. Polarization-independent absorption peaks at 755 cm^(\u20131) for CH_3\u2013Ge(111) and at 577 cm^(\u20131) for CD_3\u2013Ge(111) were assigned to the methyl rocking mode. These findings provide spectroscopic evidence that the methyl monolayer structure on the alkylated Ge is well-ordered and similar to that on analogous Si(111) surfaces, despite differences in the composition of the precursor surfaces. The X-ray photoelectron spectra of CH_3\u2013Ge(111) surfaces, however, were not highly dependent upon the etching method and showed a constant C 1s:Ge 3d ratio, independent of the etching method. The infrared spectra of C_(10)H_(21)\u2013Ge(111) surfaces were also not sensitive to the initial etching method. Hence, while the final packing density of the alkyl groups on the surface was similar for all etch methods studied, not all methods yielded a well-ordered Ge(111)/overlayer interface.", "date": "2011-08-25", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "115", "number": "33", "publisher": "American Chemical Society", "pagerange": "16389-16397", "id_number": "CaltechAUTHORS:20110906-070404983", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110906-070404983", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0911682" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/jp110550t", "primary_object": { "basename": "jp110550t_si_001.pdf", "url": "https://authors.library.caltech.edu/records/7h3f4-hya27/files/jp110550t_si_001.pdf" }, "resource_type": "article", "pub_year": "2011", "author_list": "Knapp, David; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/t4fhb-89y46", "eprint_id": 24842, "eprint_status": "archive", "datestamp": "2023-08-19 07:33:44", "lastmod": "2023-10-24 14:58:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Proton exchange membrane electrolysis sustained by water vapor", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2011 The Royal Society of Chemistry. Received 21st February 2011, Accepted 19th April 2011. \nFirst published on the web 02 Jun 2011.\nThis work was performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub that is supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. We acknowledge use of facilities supported by the Caltech Center for Science and Engineering of Materials, an NSF MRSEC, and the Caltech Center for Sustainable Energy Research.\n\nPublished - Spurgeon2011p15485Energ_Environ_Sci.pdf
", "abstract": "The current\u2013voltage characteristics of a proton exchange membrane (PEM) electrolyzer constructed with an IrRuOx water oxidation catalyst and a Pt black water reduction catalyst, under operation with water vapor from a humidified carrier gas, have been investigated as a function of the gas flow rate, the relative humidity, and the presence of oxygen. The performance of the system with water vapor was also compared to the performance when the device was immersed in liquid water. With a humidified Ar(g) input stream at 20 \u00b0C, an electrolysis current density of 10 mA cm^(\u22122) was sustained at an applied voltage of ~ 1.6 V, with a current density of 20 mA cm^(\u22122) observed at ~ 1.7 V. In the system evaluated, at current densities >40 mA cm^(\u22122) the electrolysis of water vapor was limited by the mass flux of water to the PEM. At <40 mA cm^(\u22122), the electrolysis of water vapor supported a given current density at a lower applied bias than did the electrolysis of liquid water. The relative humidity of the input carrier gas strongly affected the current\u2013voltage behavior, with lower electrolysis current density attributed to dehydration of the PEM at reduced humidity values. The results provide a proof-of-concept that, with sufficiently active catalysts, an efficient solar photoelectrolyzer could be operated only with water vapor as the feedstock, even at the low operating temperatures that may result in the absence of active heating. This approach therefore offers a route to avoid the light attenuation and mass transport limitations that are associated with bubble formation in these systems.", "date": "2011-08", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "4", "number": "8", "publisher": "Royal Society of Chemistry", "pagerange": "2993-2998", "id_number": "CaltechAUTHORS:20110815-074658754", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110815-074658754", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Science of the Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Caltech Center for the Science and Engineering of Materials" }, { "agency": "NSF MRSEC" }, { "agency": "Caltech Center for Sustainable Energy Research" } ] }, "doi": "10.1039/c1ee01203g", "primary_object": { "basename": "Spurgeon2011p15485Energ_Environ_Sci.pdf", "url": "https://authors.library.caltech.edu/records/t4fhb-89y46/files/Spurgeon2011p15485Energ_Environ_Sci.pdf" }, "resource_type": "article", "pub_year": "2011", "author_list": "Spurgeon, Joshua M. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qdkdp-8gr62", "eprint_id": 93647, "eprint_status": "archive", "datestamp": "2023-08-19 07:02:39", "lastmod": "2023-10-20 17:18:51", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kimball-G-M", "name": { "family": "Kimball", "given": "Gregory M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Direct evidence of Mg-Zn-P alloy formation in Mg/Zn_3P_2 solar cells", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2011 IEEE. \n\nWe acknowledge Yunbin Guan and the Division of Geological and Planetary Sciences at Caltech for assistance collecting SIMS data. This work was supported by the Office of Energy Efficiency and Renewable Energy, US Department of Energy under grant DE-FG36-08GO18006, the Molecular Materials Research Center (MMRC) of the Beckman Institute at the California Institute of Technology, as well as a partnership with the Dow Chemical Company. One of us (GMK) acknowledges support under an NDSEG graduate fellowship.", "abstract": "Zinc phosphide (Zn_3P_2) is a promising and earth-abundant alternative to traditional materials (e.g. CdTe, CIGS, a-Si) for thin film photovoltaics. The record solar energy conversion efficiency for Zn_3P_2 cells of 6% (M. Bhushan et al., Appl. Phys. Lett., 1980) used a Mg/Zn_3P_2 device geometry that required annealing to reach peak performance. Here we report photovoltaic device results and junction composition profiles as a function of annealing treatment for ITO/Mg/Zn_3P_2 devices. Mild annealing at 100 \u00b0C in air dramatically increases V_(oc) values from ~150 mV to 550 mV, exceeding those of the record cell (V_(oc, record) = 490 mV). In devices with thinner Mg films we achieved J_(sc) values reaching 26 mA cm^(-2), significantly greater than those of the record cell (J_(sc, record) = 14.9 mA cm^(-2)). Junction profiling by secondary ion mass spectrometry (SIMS) and x-ray photoelectron spectroscopy (XPS) both show evidence of MgO and Mg-Zn-P alloy formation at the active photovoltaic junction in annealed ITO/Mg/Zn_3P_2 devices. These results indicate that high efficiency should be realizable by optimization of Mg treatment in Mg/Zn_3P_2 solar cells.", "date": "2011-06", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "3381-3384", "id_number": "CaltechAUTHORS:20190308-090744484", "isbn": "978-1-4244-9966-3", "book_title": "37th IEEE Photovoltaic Specialists Conference", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190308-090744484", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG36-08GO18006" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Dow Chemical Company" }, { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" } ] }, "doi": "10.1109/PVSC.2011.6186672", "resource_type": "book_section", "pub_year": "2011", "author_list": "Kimball, Gregory M.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pks1z-32d32", "eprint_id": 93646, "eprint_status": "archive", "datestamp": "2023-08-19 07:02:32", "lastmod": "2023-10-20 17:18:49", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tamboli-A-C", "name": { "family": "Tamboli", "given": "Adele C." } }, { "id": "Chen-Christopher-T", "name": { "family": "Chen", "given": "Christopher T." }, "orcid": "0000-0001-5848-961X" }, { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "Daniel B." } }, { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Wafer-scale growth of silicon microwire arrays for photovoltaics", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2011 IEEE.", "abstract": "Silicon microwire arrays have recently demonstrated their potential for low cost, high efficiency photovoltaics. These high aspect ratio, radial junction wire arrays allow for the absorption of nearly all the incident sunlight while enabling efficient carrier extraction in the radial direction. One of the remaining challenges to make this technology commercially viable is scaling up of the microwire array growth. We discuss here a technique we have developed for vapor liquid solid growth of microwire arrays over full six-inch wafers using a cold-wall RF-heated chemical vapor deposition furnace. This geometry allows for fairly uniform growth over large areas, rapid cycle time, and improved run-to-run reproducibility. We have studied these large-area microwire arrays using scanning electron microscopy and confocal microscopy to assess their structural fidelity and uniformity. We have also developed a technique to embed these large-area arrays in polymer and peel them off the substrate, which could enable lightweight, flexible solar cells with efficiencies as high as crystalline Si solar cells. We have tested the energy conversion properties of these microwire array samples grown using a liquid junction contact and a photoelectrochemical cell. Initial efficiencies measured in this way suggest that the material quality of these microwire arrays is similar to earlier small-area wire arrays that we have grown, meaning that this technique is a viable way to scale up microwire array devices.", "date": "2011-06", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "3390", "id_number": "CaltechAUTHORS:20190308-090237420", "isbn": "978-1-4244-9966-3", "book_title": "37th IEEE Photovoltaic Specialists Conference", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190308-090237420", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1109/PVSC.2011.6186674", "resource_type": "book_section", "pub_year": "2011", "author_list": "Tamboli, Adele C.; Chen, Christopher T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7499x-ve426", "eprint_id": 23608, "eprint_status": "archive", "datestamp": "2023-08-19 06:28:46", "lastmod": "2023-10-23 19:48:00", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Johansson-E", "name": { "family": "Johansson", "given": "Erik" } }, { "id": "Boettcher-S-W", "name": { "family": "Boettcher", "given": "Shannon W." }, "orcid": "0000-0001-8971-9123" }, { "id": "O'Leary-L-E", "name": { "family": "O'Leary", "given": "Leslie E." } }, { "id": "Poletayev-A-D", "name": { "family": "Poletayev", "given": "Andrey D." } }, { "id": "Maldonado-S", "name": { "family": "Maldonado", "given": "Stephen" }, "orcid": "0000-0002-2917-4851" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Control of the pH-Dependence of the Band Edges of Si(111) Surfaces Using Mixed Methyl/Allyl Monolayers", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2011 American Chemical Society. \n\nReceived: October 12, 2010; revised: February 22, 2011; published: April 8, 2011. \n\nThis work was supported by the National Science Foundation\n(CHE-0911682) and the Molecular Materials Research Center\nof the Beckman Institute at the California Institute of Technology. The Kavli Nanoscience Institute (S.W.B) and the Betty and Gordon Moore Foundation (S. M.) are gratefully acknowledged for postdoctoral fellowship support.", "abstract": "The open-circuit potentials of p-Si/((MV^(2+)/MV^(+))(aq)) junctions with Si(111) surfaces functionalized with H\u2212, CH_(3)\u2212, CH_(2)CHCH_(2)\u2212, or mixed CH_(3)\u2212/CH_(2)CHCH_(2)\u2212 monolayers have been investigated as the solution pH was changed from 2.5 to 11. The pH sensitivity of the open-circuit potentials, and therefore the band-edge positions, was anticorrelated with the total fraction of Si atop sites that were terminated by Si\u2212C bonds. This behavior is consistent with the hypothesis that the non Si\u2212C terminated atop sites were initially H-terminated and were unstable to oxide growth under aqueous conditions with the oxidation-product inducing a pH-dependent dipole. Metal-semiconductor junctions between Hg and CH_(3)-, CH_(2)CHCH_(2)-, or mixed CH_(3)-/CH_(2)CHCH_(2)-terminated n-Si(111) surfaces formed rectifying Hg/Si Schottky junctions and exhibited mutually similar barrier-heights (~0.9 V), suggesting similar magnitudes and direction of the surface dipoles on all of these functionalized surfaces.", "date": "2011-05-05", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "115", "number": "17", "publisher": "American Chemical Society", "pagerange": "8594-8601", "id_number": "CaltechAUTHORS:20110510-104428314", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110510-104428314", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0911682" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Kavli Nanoscience Institute" }, { "agency": "Gordon and Betty Moore Foundation" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/jp109799e", "resource_type": "article", "pub_year": "2011", "author_list": "Johansson, Erik; Boettcher, Shannon W.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3jysn-xet46", "eprint_id": 23698, "eprint_status": "archive", "datestamp": "2023-08-19 06:19:38", "lastmod": "2023-10-23 19:52:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "MacFarlane-S-L", "name": { "family": "MacFarlane", "given": "Shaune L." } }, { "id": "Day-B-A", "name": { "family": "Day", "given": "Brittney A." } }, { "id": "McEleney-K", "name": { "family": "McEleney", "given": "Kevin" } }, { "id": "Freund-M-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Designing electronic/ionic conducting membranes for artificial photosynthesis", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2011 Royal Society of Chemistry. \n\nReceived 24 Aug 2010; Accepted 06 Dec 2010; First published on the web 10 Jan 2011. \n\nFinancial support from the following is gratefully acknowledged: The Natural Sciences and Engineering Research Council (NSERC) of Canada, the Canada Foundation for Innovation (CFI), the Manitoba Research and Innovation Fund, the University of Manitoba, and made use of the Manitoba Materials and Surface Characterization Facility. This work was also supported by the NSF through a Center for Chemical Innovation, by the Stanford Global Trust and Energy Program, and by Toyota, and made use of the Molecular Materials Research Center of the Beckman Institute at Caltech, and the Kavli Nanoscience Institute at Caltech. This research was undertaken, in part, thanks to funding from the Canada Research Chairs Program. We thank Michael McDonald for the artwork in Fig. 1.\n\nPublished - McFarlane2011p13840Energ_Environ_Sci.pdf
Supplemental Material - c0ee00384k.pdf
", "abstract": "We discuss the figures of merit for conducting membranes in artificial photosynthetic systems and describe an electronically and ionically conducting polymer composite with attractive performance characteristics.", "date": "2011-05", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "4", "number": "5", "publisher": "Royal Society of Chemistry", "pagerange": "1700-1703", "id_number": "CaltechAUTHORS:20110517-152016582", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110517-152016582", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "Canada Foundation for Innovation" }, { "agency": "Manitoba Research and Innovation Fund" }, { "agency": "University of Manitoba" }, { "agency": "NSF" }, { "agency": "Stanford Global Trust and Energy Program" }, { "agency": "Toyota" }, { "agency": "Canada Research Chairs Program" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1039/c0ee00384k", "primary_object": { "basename": "McFarlane2011p13840Energ_Environ_Sci.pdf", "url": "https://authors.library.caltech.edu/records/3jysn-xet46/files/McFarlane2011p13840Energ_Environ_Sci.pdf" }, "related_objects": [ { "basename": "c0ee00384k.pdf", "url": "https://authors.library.caltech.edu/records/3jysn-xet46/files/c0ee00384k.pdf" } ], "resource_type": "article", "pub_year": "2011", "author_list": "MacFarlane, Shaune L.; Day, Brittney A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ng84d-5pv83", "eprint_id": 23726, "eprint_status": "archive", "datestamp": "2023-08-19 06:19:43", "lastmod": "2023-10-23 19:53:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Walter-M-G", "name": { "family": "Walter", "given": "Michael G." } }, { "id": "Zhou-J", "name": { "family": "Zhou", "given": "Junfeng" } }, { "id": "Kohl-P-A", "name": { "family": "Kohl", "given": "Paul A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electrical conductivity, ionic conductivity, optical absorption, and gas separation properties of ionically conductive polymer membranes embedded with Si microwire arrays", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2011 Royal Society of Chemistry.\n\nReceived 11th January 2011, Accepted 23rd February 2011.\nFirst published on the web 28 Mar 2011.\nThis work was supported by the Department of Energy, Office of Basic Energy Sciences, DE-FG02-07ER46405 and by DARPA\ncontract #W911NF-09-2-0011. We acknowledge use of \nfacilities supported by the Caltech Center for Science and Engineering of Materials, an NSF MRSEC, and the Caltech Center for Sustainable Energy Research. The financial support (J.Z. and P.K.) from the Army Research Laboratory, contract LCHS22067 is gratefully acknowledged. M.G.W. acknowledges the financial support from an NSF-ACCF postdoctoral fellowship (CHE-0937048).\n\nPublished - Spurgeon2011p13838Energ_Environ_Sci.pdf
", "abstract": "The optical absorption, ionic conductivity, electronic conductivity, and gas separation properties have been evaluated for flexible composite films of ionically conductive polymers that contain partially embedded arrays of ordered, crystalline, p-type Si microwires. The cation exchange ionomer Nafion, and a recently developed anion exchange ionomer, poly(arylene ether sulfone) that contains quaternary ammonium groups (QAPSF), produced composite microwire array/ionomer membrane films that were suitable for operation in acidic or alkaline media, respectively. The ionic conductivity of the Si wire array/Nafion composite films in 2.0 M H_(2)SO_4(aq) was 71 mS cm^(\u22121), and the conductivity of the Si wire array/QAPSF composite films in 2.0 M KOH(aq) was 6.4 mS cm^(\u22121). Both values were comparable to the conductivities observed for films of these ionomers that did not contain embedded Si wire arrays. Two Si wire array/Nafion membranes were electrically connected in series, using a conducting polymer, to produce a trilayer, multifunctional membrane that exhibited an ionic conductivity in 2.0 M H_(2)SO)4(aq) of 57 mS cm^(\u22121) and an ohmic electrical contact, with an areal resistance of ~0.30 \u03a9 cm^2, between the two physically separate embedded Si wire arrays. All of the wire array/ionomer composite membranes showed low rates of hydrogen crossover. Optical measurements indicated very low absorption (<3%) in the ion-exchange polymers but high light absorption (up to 80%) by the wire arrays even at normal incidence, attesting to the suitability of such multifunctional membranes for application in solar fuels production.", "date": "2011-05", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "4", "number": "5", "publisher": "Royal Society of Chemistry", "pagerange": "1772-1780", "id_number": "CaltechAUTHORS:20110519-094752518", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110519-094752518", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE) Office of Basic Energy Sciences", "grant_number": "DE-FG02-07ER46405" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "W911NF-09-2-0011" } ] }, "doi": "10.1039/C1EE01028J", "primary_object": { "basename": "Spurgeon2011p13838Energ_Environ_Sci.pdf", "url": "https://authors.library.caltech.edu/records/ng84d-5pv83/files/Spurgeon2011p13838Energ_Environ_Sci.pdf" }, "resource_type": "article", "pub_year": "2011", "author_list": "Spurgeon, Joshua M.; Walter, Michael G.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/f4jq4-jmb88", "eprint_id": 23444, "eprint_status": "archive", "datestamp": "2023-08-19 06:12:42", "lastmod": "2023-10-23 19:35:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Garc\u00eda-Berr\u00edos-E", "name": { "family": "Garc\u00eda-Berr\u00edos", "given": "Edgardo" } }, { "id": "Gao-Ting", "name": { "family": "Gao", "given": "Ting" } }, { "id": "Theriot-J-C", "name": { "family": "Theriot", "given": "Jordan C." } }, { "id": "Woodka-M-D", "name": { "family": "Woodka", "given": "Marc D." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Response and Discrimination Performance of Arrays of Organothiol-Capped Au Nanoparticle Chemiresistive Vapor Sensors", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2011 American Chemical Society. \n\nReceived: November 11, 2010. Revised: January 06, 2011. Article ASAP March 15, 2011. Published In Issue April 14, 2011. This article was published ASAP on March 15, 2011. \n\nFigures 5, 6, and 7 and their captions have been modified. The correct version was published on March 21, 2011. \n\nT.G. acknowledges the support from Tyco Electronics Corp. Research was carried out in the Molecular Materials Research Center of the Beckman Institute at Caltech. This work was\nsupported by the NSF and by DHS. NSF is acknowledged for a graduate fellowship to E.G.-B.\n\nSupplemental Material - jp110793h_si_001.pdf
", "abstract": "The response and discrimination performance of an array that consisted of 20 different organothiol-capped Au nanoparticle chemiresistive vapor sensors was evaluated during exposure to 13 different organic vapors. The passivating organothiol ligand library consisted of collections of straight-chain alkanethiols, branched alkanethiols, and aromatic thiols. A fourth collection of sensors was formed from composites of 2-phenylethanethiol-capped Au nanoparticles and nonpolymeric aromatic materials that were coembedded in a sensor film. The organic vapors consisted of six hydrocarbons (n-hexane, n-heptane, n-octane, isooctane, cyclohexane, and toluene), three polar aprotic vapors (chloroform, tetrahydrofuran, and ethyl acetate), and four alcohols (methanol, ethanol, isopropanol, and 1-butanol). Trends in the resistance response of the sensors were consistent with expected trends in sorption due to the properties of the test vapor and the molecular structure of the passivating ligands in the sensor films. Classification algorithms including principal components analysis and Fisher's linear discriminant were used to evaluate the discrimination performance of an array of such sensors. Each collection of sensors produced accurate classification of most vapors, with misclassification occurring primarily for vapors that had mutually similar polarity. The classification performance for an array that contained all of the sensor collections produced nearly perfect discrimination for all vapors studied. The dependence of the array size (i.e., the number of sensors) and the array chemical diversity on the discrimination performance indicated that, for an array of 20 sensors, an array size of 13 sensors or more produced the maximum discrimination performance.", "date": "2011-04-14", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "115", "number": "14", "publisher": "American Chemical Society", "pagerange": "6208-6217", "id_number": "CaltechAUTHORS:20110425-094627953", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110425-094627953", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Tyco Electronics Corporation" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Department of Homeland Security" } ] }, "doi": "10.1021/jp110793h", "primary_object": { "basename": "jp110793h_si_001.pdf", "url": "https://authors.library.caltech.edu/records/f4jq4-jmb88/files/jp110793h_si_001.pdf" }, "resource_type": "article", "pub_year": "2011", "author_list": "Garc\u00eda-Berr\u00edos, Edgardo; Gao, Ting; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3prmb-dte58", "eprint_id": 23410, "eprint_status": "archive", "datestamp": "2023-08-19 06:00:55", "lastmod": "2023-10-23 19:33:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Xiang-Chengxiang", "name": { "family": "Xiang", "given": "Chengxiang" }, "orcid": "0000-0002-1698-6754" }, { "id": "Kimball-G-M", "name": { "family": "Kimball", "given": "Gregory M." } }, { "id": "Grimm-R-L", "name": { "family": "Grimm", "given": "Ronald L." }, "orcid": "0000-0003-0407-937X" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "820 mV open-circuit voltages from Cu_(2)O/CH_(3)CN junctions", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2011 Royal Society of Chemistry. \n\nReceived 12th October 2010, Accepted 25th November 2010. \n\nThis work was supported by the Office of Energy Efficiency and Renewable Energy, US Department of Energy under Grant\nDE-FG36-08GO18006, the Caltech Center for Sustainable\nEnergy Research (CCSER), and the Dow Chemical Company.\nOne of us (GMK) acknowledges support under an NDSEG\ngraduate fellowship.\n\nPublished - Xiang2011p13479Energ_Environ_Sci.pdf
Supplemental Material - c0ee00554a.pdf
", "abstract": "P-Type cuprous oxide (Cu_(2)O) photoelectrodes prepared by the thermal oxidation of Cu foils exhibited open-circuit voltages in excess of 800 mV in nonaqueous regenerative photoelectrochemical cells. In contact with the decamethylcobaltocene^(+/0) (Me_(10)CoCp_(2)^(+/0)) redox couple, cuprous oxide yielded open-circuit voltage, V_(oc), values of 820 mV and short-circuit current density, J_(sc), values of 3.1 mA cm^(\u22122) under simulated air mass 1.5 illumination. The energy-conversion efficiency of 1.5% was limited by solution absorption and optical reflection losses that reduced the short-circuit photocurrent density. Spectral response measurements demonstrated that the internal quantum yield approached unity in the 400\u2013500 nm spectral range, but poor red response, attributable to bulk recombination, lowered the overall efficiency of the cell. X-Ray photoelectron spectroscopy and Auger electron spectroscopy indicated that the photoelectrodes had a high-quality cuprous oxide surface, and revealed no observable photocorrosion during operation in the nonaqueous electrolyte. The semiconductor/liquid junctions thus provide a noninvasive method to investigate the \nenergy-conversion properties of cuprous oxide without the confounding factors of deleterious surface reactions.", "date": "2011-04", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "4", "number": "4", "publisher": "Royal Society of Chemistry", "pagerange": "1311-1318", "id_number": "CaltechAUTHORS:20110421-100446025", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110421-100446025", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG36-08GO18006" }, { "agency": "Caltech Center for Sustainable Energy Research" }, { "agency": "Dow Chemical Company" }, { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/c0ee00554a", "primary_object": { "basename": "c0ee00554a.pdf", "url": "https://authors.library.caltech.edu/records/3prmb-dte58/files/c0ee00554a.pdf" }, "related_objects": [ { "basename": "Xiang2011p13479Energ_Environ_Sci.pdf", "url": "https://authors.library.caltech.edu/records/3prmb-dte58/files/Xiang2011p13479Energ_Environ_Sci.pdf" } ], "resource_type": "article", "pub_year": "2011", "author_list": "Xiang, Chengxiang; Kimball, Gregory M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/h4f38-k0660", "eprint_id": 23331, "eprint_status": "archive", "datestamp": "2023-08-19 05:53:27", "lastmod": "2023-10-23 19:00:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yahyaie-I", "name": { "family": "Yahyaie", "given": "Iman" } }, { "id": "McEleney-K", "name": { "family": "McEleney", "given": "Kevin" } }, { "id": "Walter-M", "name": { "family": "Walter", "given": "Michael" } }, { "id": "Oliver-D-R", "name": { "family": "Oliver", "given": "Derek R." } }, { "id": "Thomson-D-J", "name": { "family": "Thomson", "given": "Douglas J." } }, { "id": "Freund-M-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electrical Characterization of Si Microwires and of Si Microwire/Conducting Polymer Composite Junctions", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2011 American Chemical Society. \n\nReceived: January 28, 2011; Accepted: February 25, 2011. \n\nFinancial support from the following is gratefully acknowledged: The Technology International Collaboration Fund of Manitoba Innovation Energy and Mines, the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Canada Foundation for Innovation (CFI), the Manitoba Research and Innovation Fund, and the University of Manitoba. The work reported made use of the Manitoba Institute for Materials. This work was also supported by the NSF through a Center for Chemical Innovation, by the Stanford Global Trust and Energy Program, and by Toyota and made use of the Molecular Materials Research Center of the Beckman Institute at Caltech and the Kavli Nanoscience Institute at Caltech. This research was undertaken, in part, thanks to funding from the Canada Research Chairs Program.\n\nSupplemental Material - jz2001375_si_001.pdf
", "abstract": "The electrical (DC) behavior of single silicon microwires has been determined by the use of tungsten probes to make ohmic contact to the silicon microwires. The basic electrical properties of the microwires, such as their DC resistivity and the doping distribution along the length of the microwires, were investigated using this approach. The technique was also used to characterize the junction between silicon microwires and conducting polymers to assess the suitability of such contacts for use in a proposed artificial photosynthesis system.", "date": "2011-03-17", "date_type": "published", "publication": "Journal of Physical Chemistry Letters", "volume": "2", "number": "6", "publisher": "American Chemical Society", "pagerange": "675-680", "id_number": "CaltechAUTHORS:20110414-091143113", "issn": "1948-7185", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110414-091143113", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Technology International Collaboration Fund of Manitoba Innovation Energy and Mines" }, { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "Canada Foundation for Innovation" }, { "agency": "Manitoba Research and Innovation Fund" }, { "agency": "University of Manitoba" }, { "agency": "NSF" }, { "agency": "Stanford Global Trust and Energy Program" }, { "agency": "Toyota" }, { "agency": "Canada Research Chairs Program" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" }, { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/jz2001375", "primary_object": { "basename": "jz2001375_si_001.pdf", "url": "https://authors.library.caltech.edu/records/h4f38-k0660/files/jz2001375_si_001.pdf" }, "resource_type": "article", "pub_year": "2011", "author_list": "Yahyaie, Iman; McEleney, Kevin; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4tayg-1rh82", "eprint_id": 23062, "eprint_status": "archive", "datestamp": "2023-08-19 05:41:43", "lastmod": "2023-10-23 17:52:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "Daniel B." } }, { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "Morgan C." } }, { "id": "Boettcher-S-W", "name": { "family": "Boettcher", "given": "Shannon W." }, "orcid": "0000-0001-8971-9123" }, { "id": "Briggs-R-M", "name": { "family": "Briggs", "given": "Ryan M." } }, { "id": "Baek-Jae-Yeon", "name": { "family": "Baek", "given": "Jae Yeon" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "High-performance Si microwire photovoltaics", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2011 The Royal Society of Chemistry. \n\nReceived 12th October 2010, Accepted 24th November 2010. \n\nThis work was supported by BP and in part by the Department of Energy, Basic Energy Sciences Energy Frontier Research Center\nprogram under grant DE-SC0001293 as well as the Department of Energy under grant DE-FG02-07ER46405. The work made use of facilities supported by the Caltech Center for Sustainable Energy Research and by the Center for Science and Engineering of Materials, an NSF Materials Research Science and Engineering Center at Caltech. Research was in part carried out at the Kavli Nanoscience Institute (KNI) and at the Molecular Materials Research Center of the Beckman Institute at Caltech. S.W.B. acknowledges the KNI for fellowship support. D.B.T-E. acknowledges the NSF for fellowship support. The authors acknowledge the assistance of Bruce Brunschwig, Joshua Spurgeon, Emily Warren and the KNI staff.\n\nPublished - Kelzenberg2011p13117Energ_Environ_Sci.pdf
Supplemental Material - c0ee00549e.pdf
", "abstract": "Crystalline Si wires, grown by the vapor\u2013liquid\u2013solid (VLS)\nprocess, have emerged as promising candidate materials for lowcost, thin-film photovoltaics. Here, we demonstrate VLS-grown Si microwires that have suitable electrical properties for high-performance photovoltaic applications, including long minority-carrier diffusion lengths (L_n \u00bb 30 \u00b5m) and low surface recombination velocities (S \u00ab 70 cm\u00b7s^(-1)). Single-wire radial p\u2013n junction solar cells were fabricated with amorphous silicon and silicon nitride\nsurface coatings, achieving up to 9.0% apparent photovoltaic efficiency, and exhibiting up to ~600 mV open-circuit voltage with over 80% fill factor. Projective single-wire measurements and optoelectronic simulations suggest that large-area Si wire-array solar cells have the potential to exceed 17% energy-conversion efficiency, offering a promising route toward cost-effective crystalline Si photovoltaics.", "date": "2011-03", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "4", "number": "3", "publisher": "Royal Society of Chemistry", "pagerange": "866-871", "id_number": "CaltechAUTHORS:20110323-080918474", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110323-080918474", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-07ER46405" }, { "agency": "Kavli Nanoscience Institute" }, { "agency": "Caltech Beckman Institute" }, { "agency": "NSF" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/C0EE00549E", "primary_object": { "basename": "Kelzenberg2011p13117Energ_Environ_Sci.pdf", "url": "https://authors.library.caltech.edu/records/4tayg-1rh82/files/Kelzenberg2011p13117Energ_Environ_Sci.pdf" }, "related_objects": [ { "basename": "c0ee00549e.pdf", "url": "https://authors.library.caltech.edu/records/4tayg-1rh82/files/c0ee00549e.pdf" } ], "resource_type": "article", "pub_year": "2011", "author_list": "Kelzenberg, Michael D.; Turner-Evans, Daniel B.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ha62e-mjc77", "eprint_id": 22849, "eprint_status": "archive", "datestamp": "2023-08-19 05:31:12", "lastmod": "2023-10-23 17:15:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Boettcher-S-W", "name": { "family": "Boettcher", "given": "Shannon W." }, "orcid": "0000-0001-8971-9123" }, { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "Morgan C." } }, { "id": "Santori-E-A", "name": { "family": "Santori", "given": "Elizabeth A." } }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "Daniel" } }, { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Walter-M-G", "name": { "family": "Walter", "given": "Michael G." } }, { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemical Hydrogen Evolution Using Si Microwire Arrays", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2011 American Chemical Society. \n\nReceived: October 10, 2010. Published In Issue February 09, 2011. Article ASAP January 07, 2011. \n\nThe Department of Energy (DE-FG02-05ER15754), the\nStanford Global Climate and Energy Project, and Toyota are\nacknowledged for financial support. S.W.B thanks the Kavli\nNanoscience Institute for a postdoctoral fellowship. M.G.W\nacknowledges support from an NSF American Competitiveness\nin Chemistry postdoctoral fellowship (CHE-0937048).\n\nSupplemental Material - ja108801m_si_001.pdf
", "abstract": "Arrays of B-doped p-Si microwires, diffusion-doped with P to form a radial n+ emitter and subsequently coated with a 1.5-nm-thick discontinuous film of evaporated Pt, were used as photocathodes for H_2 evolution from water. These electrodes yielded thermodynamically based energy-conversion efficiencies >5% under 1 sun solar simulation, despite absorbing less than 50% of the above-band-gap incident photons. Analogous p-Si wire-array electrodes yielded efficiencies <0.2%, largely limited by the low photovoltage generated at the p-Si/H_2O junction.", "date": "2011-02-09", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "133", "number": "5", "publisher": "American Chemical Society", "pagerange": "1216-1219", "id_number": "CaltechAUTHORS:20110314-101144886", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110314-101144886", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-05ER15754" }, { "agency": "Stanford Global Climate and Energy Project" }, { "agency": "Toyota" }, { "agency": "Kavli Nanoscience Institute" }, { "agency": "NSF Postdoctoral Fellowship", "grant_number": "CHE-0937048" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/ja108801m", "primary_object": { "basename": "ja108801m_si_001.pdf", "url": "https://authors.library.caltech.edu/records/ha62e-mjc77/files/ja108801m_si_001.pdf" }, "resource_type": "article", "pub_year": "2011", "author_list": "Boettcher, Shannon W.; Warren, Emily L.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/g11fw-szy91", "eprint_id": 22649, "eprint_status": "archive", "datestamp": "2023-08-19 05:17:54", "lastmod": "2023-10-23 17:06:06", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Boettcher-S-W", "name": { "family": "Boettcher", "given": "Shannon W." }, "orcid": "0000-0001-8971-9123" }, { "id": "Walter-M-G", "name": { "family": "Walter", "given": "Michael G." } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "pH-Independent, 520 mV Open-Circuit Voltages of Si/Methyl Viologen^(2+/+) Contacts Through Use of Radial n^+p-Si Junction Microwire Array Photoelectrodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2010 American Chemical Society. \n\nReceived September 24, 2010; Revised Manuscript Received: November 26, 2010, Published on Web 12/23/2010. \n\nWe acknowledge the Stanford Global Climate and Energy Project and the U.S. Department of Energy (grant DE-FG02-05ER15754) for financial support. We acknowledge critical support and infrastructure provided for this work by the Kavli Nanoscience Institute at Caltech. S.W.B. thanks the Kavli Nanoscience Institute for a postdoctoral fellowship. M.G.W acknowledges support from an NSF American Competitiveness in Chemistry postdoctoral fellowship (CHE-0937048). D. Turner-Evans, J. Ku, and Dr. R. Grimm are thanked for their contributions.\n\nSupplemental Material - jp109147p_si_001.pdf
", "abstract": "The effects of introducing an n^+-doped emitter layer have been evaluated for both planar Si photoelectrodes and for radial junction Si microwire-array photoelectrodes. In contact with the pH-independent, one-electron, outer-sphere, methyl viologen redox system (denoted MV^(2+/+)), both planar and wire array p-Si photoelectrodes yielded open-circuit voltages, V_(oc), that varied with the pH of the solution. The highest V_(oc) values were obtained at pH = 2.9, with V_(oc) = 0.53 V for planar p-Si electrodes and V_(oc) = 0.42 V for vapor\u2212liquid\u2212solid catalyzed p-Si microwire array samples, under 60 mW cm^(\u22122) of 808 nm illumination. Increases in the pH of the electrolyte produced a decrease in V_(oc) by approximately \u221244 mV/pH unit for planar electrodes, with similar trends observed for the Si microwire array electrodes. In contrast, introduction of a highly doped, n^+ emitter layer produced V_(oc) = 0.56 V for planar Si electrodes and V_(oc) = 0.52 V for Si microwire array electrodes, with the photoelectrode properties in each system being essentially independent of pH over six pH units (3 < pH < 9). Hence, formation of an n^+ emitter layer not only produced nearly identical photovoltages for planar and Si microwire array photoelectrodes, but decoupled the band energetics of the semiconductor (and hence the obtainable photovoltage) from the value of the redox potential of the solution. The formation of radial junctions on Si microwire arrays thus provides an approach to obtaining Si-based photoelectrodes with high-photovoltages that can be used for a variety of photoelectrochemical processes, including potentially the hydrogen evolution reaction, under various pH conditions, regardless of the intrinsic barrier height and flat-band properties of the Si/liquid contact.", "date": "2011-01-20", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "115", "number": "2", "publisher": "American Chemical Society", "pagerange": "594-598", "id_number": "CaltechAUTHORS:20110303-152058659", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110303-152058659", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Stanford Global Climate and Energy Project (GCEP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-05ER15754" }, { "agency": "Kavli Nanoscience Institute" }, { "agency": "NSF Postdoctoral Fellowship", "grant_number": "CHE-0937048" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/jp109147p", "primary_object": { "basename": "jp109147p_si_001.pdf", "url": "https://authors.library.caltech.edu/records/g11fw-szy91/files/jp109147p_si_001.pdf" }, "resource_type": "article", "pub_year": "2011", "author_list": "Warren, Emily L.; Boettcher, Shannon W.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/m3687-qxw54", "eprint_id": 21775, "eprint_status": "archive", "datestamp": "2023-08-19 04:47:59", "lastmod": "2023-10-21 00:18:49", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Garc\u00eda-Berr\u00edos-E", "name": { "family": "Garc\u00eda-Berr\u00edos", "given": "Edgardo" } }, { "id": "Gao-Ting", "name": { "family": "Gao", "given": "Ting" } }, { "id": "Woodka-M-D", "name": { "family": "Woodka", "given": "Marc D." } }, { "id": "Maldonado-S", "name": { "family": "Maldonado", "given": "Stephen" }, "orcid": "0000-0002-2917-4851" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Ellsworth-M-W", "name": { "family": "Ellsworth", "given": "Mark W." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Response versus Chain Length of Alkanethiol-Capped Au Nanoparticle Chemiresistive Chemical Vapor Sensors", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2010 American Chemical Society. \n\nReceived: February 11, 2010; Revised Manuscript Received: August 12, 2010. Publication Date (Web): August 25, 2010. \n\nThe authors thank Carol M. Garland for the TEM measurements. E.G.-B. acknowledges support from the NSF for a graduate fellowship. T.G. and M.E. acknowledge support from Tyco Electronics Corporation. Research was carried out in the Molecular Materials Research Center of the Beckman Institute at Caltech. This work was supported by the NSF, Grant CHE-0604894.\n\nSupplemental Material - jp101331g_si_001.pdf
", "abstract": "Au nanoparticles capped with a homologous series of straight chain alkanethiols (containing 4\u221211 carbons in length) have been investigated as chemiresistive organic vapor sensors. The series of alkanethiols was used to elucidate the mechanisms of vapor detection by such capped nanoparticle chemiresistive films and to highlight the molecular design principles that govern enhanced detection. The thiolated Au nanoparticle chemiresistors demonstrated rapid and reversible responses to a set of test vapors (n-hexane, n-heptane, n-octane, iso-octane, cyclohexane, toluene, ethyl acetate, methanol, ethanol, isopropanol, and 1-butanol) that possessed a variety of analyte physicochemical properties. The resistance sensitivity to nonpolar and aprotic polar vapors systematically increased as the chain length of the capping reagent increased. Decreases in the nanoparticle film resistances, which produced negative values of the differential resistance response, were observed upon exposure of the sensor films to alcohol vapors. The response signals became more negative with higher alcohol vapor concentrations, producing negative values of the sensor sensitivity. Sorption data measured on Au nanoparticle chemiresistor films using a quartz crystal microbalance allowed for the measurement of the partition coefficients of test vapors in the Au nanoparticle films. This measurement assumed that analyte sorption only occurred at the organic interface and not the surface of the Au core. Such an assumption produced partition coefficient values that were independent of the length of the ligand. Furthermore, the value of the partition coefficient was used to obtain the particle-to-particle interfacial effective dielectric constant of films upon exposure to analyte vapors. The values of the dielectric constant upon exposure to alcohol vapors suggested that the observed resistance response changes observed were not significantly influenced by this dielectric change, but rather were primarily influenced by morphological changes and by changes in the interparticle spacing.", "date": "2010-12-23", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "114", "number": "50", "publisher": "American Chemical Society", "pagerange": "21914-21920", "id_number": "CaltechAUTHORS:20110118-092448027", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110118-092448027", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "Tyco Electronics Corporation" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1021/jp101331g", "primary_object": { "basename": "jp101331g_si_001.pdf", "url": "https://authors.library.caltech.edu/records/m3687-qxw54/files/jp101331g_si_001.pdf" }, "resource_type": "article", "pub_year": "2010", "author_list": "Garc\u00eda-Berr\u00edos, Edgardo; Gao, Ting; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/m28jg-h7g02", "eprint_id": 21380, "eprint_status": "archive", "datestamp": "2023-08-19 04:26:07", "lastmod": "2023-10-20 23:59:39", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "O'Leary-L-E", "name": { "family": "O'Leary", "given": "Leslie E." } }, { "id": "Johansson-E-M", "name": { "family": "Johansson", "given": "Erik" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Synthesis and Characterization of Mixed Methyl/Allyl Monolayers on Si(111)", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2010 American Chemical Society. \n\nReceived: November 30, 2009; Revised Manuscript Received: July 12, 2010. Publication Date (Web): August 19, 2010. \n\nPart of the \"Michael R. Wasielewski Festschrift\". \n\nThis work was supported by the National Science Foundation (CHE-0911682), BP, and the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology. The authors acknowledge Dr. Kate Plass, Dr. Shannon Boettcher, and Mr. Andrey Poletayev for insightful discussions.\n\nSupplemental Material - jp911379c_si_001.pdf
", "abstract": "The formation of mixed methyl/allyl monolayers has been accomplished through a two-step halogenation/alkylation reaction on Si(111) surfaces. The total coverage of alkylated Si, the surface recombination velocities, and the degree of surface oxidation as a function of time have been investigated using X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and microwave conductivity measurements. The total coverage of alkyl groups, the rate of oxidation, and the surface recombination velocities of Si(111) terminated by mixed monolayers were found to be close to those observed for CH_3\u2212Si(111) surfaces. Hence, the mixed-monolayer surfaces retained the beneficial properties of CH_3\u2212Si(111) surfaces while allowing for convenient secondary surface functionalization.", "date": "2010-11-18", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "114", "number": "45", "publisher": "American Chemical Society", "pagerange": "14298-14302", "id_number": "CaltechAUTHORS:20101215-114031395", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20101215-114031395", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0911682" }, { "agency": "Caltech Beckman Institute" }, { "agency": "BP" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1021/jp911379c", "primary_object": { "basename": "jp911379c_si_001.pdf", "url": "https://authors.library.caltech.edu/records/m28jg-h7g02/files/jp911379c_si_001.pdf" }, "resource_type": "article", "pub_year": "2010", "author_list": "O'Leary, Leslie E.; Johansson, Erik; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/93k21-0nz61", "eprint_id": 21330, "eprint_status": "archive", "datestamp": "2023-08-19 04:14:19", "lastmod": "2023-10-20 23:56:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Walter-M-G", "name": { "family": "Walter", "given": "Michael G." } }, { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Boettcher-S-W", "name": { "family": "Boettcher", "given": "Shannon W." }, "orcid": "0000-0001-8971-9123" }, { "id": "Mi-Qixi", "name": { "family": "Mi", "given": "Qixi" } }, { "id": "Santori-E-A", "name": { "family": "Santori", "given": "Elizabeth A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Solar Water Splitting Cells", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2010 American Chemical Society. \n\nReceived July 23, 2010. Publication Date (Web): November 10, 2010. \n\nThis work was supported by a National Science Foundation (NSF) Center for Chemical Innovation (CCI) Powering the Planet, Grants (CHE-0802907, CHE-0947829) and (NSFACCF) support for MGW (CHE-0937048). The authors would also like to thank Dr. Nick Strandwitz and Dr. Bruce Brunschwig for help reviewing the manuscript.", "abstract": "No abstract.", "date": "2010-11", "date_type": "published", "publication": "Chemical Reviews", "volume": "110", "number": "11", "publisher": "American Chemical Society", "pagerange": "6446-6473", "id_number": "CaltechAUTHORS:20101213-121533554", "issn": "0009-2665", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20101213-121533554", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0802907" }, { "agency": "NSF", "grant_number": "CHE-0947829" }, { "agency": "NSF Postdoctoral Fellowship", "grant_number": "CHE-0937048" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1021/cr1002326", "resource_type": "article", "pub_year": "2010", "author_list": "Walter, Michael G.; Warren, Emily L.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/w3t25-wtz04", "eprint_id": 20621, "eprint_status": "archive", "datestamp": "2023-08-22 00:58:14", "lastmod": "2023-10-20 23:15:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Li-Mo", "name": { "family": "Li", "given": "Mo" } }, { "id": "Myers-E-B", "name": { "family": "Myers", "given": "E. B." } }, { "id": "Tang-Hongxing", "name": { "family": "Tang", "given": "H. X." } }, { "id": "Aldridge-S-J", "name": { "family": "Aldridge", "given": "S. J." } }, { "id": "McCaig-H-C", "name": { "family": "McCaig", "given": "H. C." } }, { "id": "Whiting-J-J", "name": { "family": "Whiting", "given": "J. J." } }, { "id": "Simonson-R-J", "name": { "family": "Simonson", "given": "R. J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Roukes-M-L", "name": { "family": "Roukes", "given": "M. L." }, "orcid": "0000-0002-2916-6026" } ] }, "title": "Nanoelectromechanical Resonator Arrays for Ultrafast, Gas-Phase Chromatographic Chemical Analysis", "ispublished": "pub", "full_text_status": "public", "keywords": "NEMS; gas chromatography; gas detectors; mass sensing", "note": "\u00a9 2010 American Chemical Society.\nReceived for review: 05/4/2010.\nPublished on Web: 08/26/2010.\nThe authors thank X. L. Feng and I.\nBargatin for useful discussions and S. Stryker for machining\nassistance. We gratefully acknowledge support from the\nDefense Advanced Research Projects Agency via DARPA/\nMTO-MGA Grant NBCH1050001 and from the Department\nof Homeland Security. Sandia is a multiprogram laboratory\noperated by Sandia Corporation, a Lockheed Martin Company,\nfor the United States Department of Energy under\ncontract DE-AC04-94AL85000.\n\nAccepted Version - nihms-305220.pdf
Supplemental Material - nl101586s_si_001.pdf
", "abstract": "Miniaturized gas chromatography (GC) systems can provide fast, quantitative analysis of chemical vapors in an ultrasmall package. We describe a chemical sensor technology based on resonant nanoelectromechanical systems (NEMS) mass detectors that provides the speed, sensitivity, specificity, and size required by the microscale GC paradigm. Such NEMS sensors have demonstrated detection of subparts per billion (ppb) concentrations of a phosphonate analyte. By combining two channels of NEMS detection with an ultrafast GC front-end, chromatographic analysis of 13 chemicals was performed within a 5 s time window.", "date": "2010-10", "date_type": "published", "publication": "Nano Letters", "volume": "10", "number": "10", "publisher": "American Chemical Society", "pagerange": "3899-3903", "id_number": "CaltechAUTHORS:20101101-112952062", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20101101-112952062", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "NBCHI050001" }, { "agency": "Department of Homeland Security" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC04-94AL85000" } ] }, "doi": "10.1021/nl101586s", "pmcid": "PMC3839305", "primary_object": { "basename": "nihms-305220.pdf", "url": "https://authors.library.caltech.edu/records/w3t25-wtz04/files/nihms-305220.pdf" }, "related_objects": [ { "basename": "nl101586s_si_001.pdf", "url": "https://authors.library.caltech.edu/records/w3t25-wtz04/files/nl101586s_si_001.pdf" } ], "resource_type": "article", "pub_year": "2010", "author_list": "Li, Mo; Myers, E. B.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7zpbt-waw02", "eprint_id": 20590, "eprint_status": "archive", "datestamp": "2023-08-19 03:49:21", "lastmod": "2023-10-20 23:13:41", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Becker-J-S", "name": { "family": "Becker", "given": "James S." } }, { "id": "Brown-R-D", "name": { "family": "Brown", "given": "Ryan-D" } }, { "id": "Johansson-E-M", "name": { "family": "Johansson", "given": "Erik" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Sibener-S-J", "name": { "family": "Sibener", "given": "S. J." } } ] }, "title": "Helium atom diffraction measurements of the surface structure and vibrational dynamics of CH_3-Si(111) and CD_3-Si(111) surfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "Debye temperature, helium ions, lattice dynamics, long-range order, surface structure", "note": "\u00a9 2010 American Institute of Physics. \nReceived 13 July 2010; accepted 5 August 2010; published online 13 September 2010.\nThis work was supported at the University of Chicago by the Air Force Office of Scientific Research and the UChicago NSF Materials Research Science and Engineering Center\nand at Caltech by NSF Grant No. CHE-0911682.\n\nPublished - Becker2010p11638J_Chem_Phys.pdf
", "abstract": "The surface structure and vibrational dynamics of CH_3\u2013Si(111) and CD_3\u2013Si(111) surfaces were measured using helium atom scattering. The elastic diffraction patterns exhibited a lattice constant of 3.82 \u00c5, in accordance with the spacing of the silicon underlayer. The excellent quality of the observed diffraction patterns, along with minimal diffuse background, indicated a high degree of long-range ordering and a low defect density for this interface. The vibrational dynamics were investigated by measurement of the Debye\u2013Waller attenuation of the elastic diffraction peaks as the surface temperature was increased. The angular dependence of the specular (\u03b8_i=\u03b8_f) decay revealed\nperpendicular mean-square displacements of 1.0 x 10^(\u22125) \u00c5^2 K^(\u22121) for the CH_3\u2013Si(111) surface and 1.2 x 10^(\u22125) \u00c5^2 K^(\u22121) for the CD_3\u2013Si(111) surface, and a He-surface attractive well depth of ~7 meV. The effective surface Debye temperatures were calculated to be 983 K for the CH_3\u2013Si(111) surface and 824 K for the CD_3\u2013Si(111) surface. These relatively large Debye temperatures suggest that collisional energy accommodation at the surface occurs primarily through\nthe Si\u2013C local molecular modes. The parallel mean-square displacements were 7.1 x 10^(\u22124) and 7.2 x 10^(\u22124) \u00c5^2 K^(\u22121) for the CH_3\u2013Si(111) and CD_3\u2013Si(111) surfaces, respectively. The observed increase in thermal motion is consistent with the interaction between the helium atoms and Si\u2013CH_3 bending modes. These experiments have thus yielded detailed information on the dynamical properties of these robust and technologically interesting semiconductor interfaces.", "date": "2010-09-14", "date_type": "published", "publication": "Journal of Chemical Physics", "volume": "133", "number": "10", "publisher": "American Institute of Physics", "pagerange": "Art. No. 104705", "id_number": "CaltechAUTHORS:20101029-074325400", "issn": "0021-9606", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20101029-074325400", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research" }, { "agency": "University of Chicago NSF Materials Research Science and Engineering Center" }, { "agency": "NSF", "grant_number": "CHE-0911682" } ] }, "doi": "10.1063/1.3483465", "primary_object": { "basename": "Becker2010p11638J_Chem_Phys.pdf", "url": "https://authors.library.caltech.edu/records/7zpbt-waw02/files/Becker2010p11638J_Chem_Phys.pdf" }, "resource_type": "article", "pub_year": "2010", "author_list": "Becker, James S.; Brown, Ryan-D; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/w9yf5-1zs08", "eprint_id": 22938, "eprint_status": "archive", "datestamp": "2023-08-22 00:39:27", "lastmod": "2024-01-13 00:12:19", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Boettcher-S-W", "name": { "family": "Boettcher", "given": "Shannon W." }, "orcid": "0000-0001-8971-9123" }, { "id": "McKone-J-R", "name": { "family": "McKone", "given": "James R." }, "orcid": "0000-0001-6445-7884" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemical water splitting: silicon photocathodes for hydrogen evolution", "ispublished": "unpub", "full_text_status": "public", "keywords": "hydrogen; water-splitting; solar; silicon; photocathode", "note": "\u00a9 2010 SPIE. \n\nWe acknowledge Dr. Michael Kelzenberg, Dr. Josh Spurgeon, and Dr. Michael Walter for their contributions. We also thank the members of the NSF Powering the Planet Center for Chemical Innovation for their valuable contributions to this work. We gratefully acknowledge critical support and infrastructure provided for this work by the Kavli Nanoscience Institute at Caltech, the Stanford Global Climate and Energy Project and the U.S. Department of Energy (grant DE-FG02-05ER15754) for financial support.\n\nPublished - Warren2010p12912Adaptive_Optics_Systems_Pts_1-3.pdf
", "abstract": "The development of low cost, scalable, renewable energy technologies is one of today's most pressing scientific challenges. We report on progress towards the development of a photoelectrochemical water-splitting system that will use sunlight and water as the inputs to produce renewable hydrogen with oxygen as a by-product. This system is based on the design principle of incorporating two separate, photosensitive inorganic semiconductor/liquid junctions to collectively generate the 1.7-1.9 V at open circuit needed to support both the oxidation of H_2O (or OH^-) and the reduction of H^+ (or H_2O). Si microwire arrays are a promising photocathode material because the high aspect-ratio electrode architecture allows for the use of low cost, earth-abundant materials without sacrificing energy-conversion efficiency, due to the orthogonalization of light absorption and charge-carrier collection. Additionally, the high surfacearea design of the rod-based semiconductor array inherently lowers the flux of charge carriers over the rod array surface relative to the projected geometric surface of the photoelectrode, thus lowering the photocurrent density at the solid/liquid junction and thereby relaxing the demands on the activity (and cost) of any electrocatalysts. Arrays of Si microwires grown using the Vapor Liquid Solid (VLS) mechanism have been shown to have desirable electronic light absorption properties. We have demonstrated that these arrays can be coated with earth-abundant metallic catalysts and used for photoelectrochemical production of hydrogen. This development is a step towards the demonstration of a complete artificial photosynthetic system, composed of only inexpensive, earth-abundant materials, that is simultaneously efficient, durable, and scalable.", "date": "2010-08-24", "date_type": "published", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_pub": "Bellingham, WA", "pagerange": "Art. No. 77701F", "id_number": "CaltechAUTHORS:20110316-132846386", "isbn": "978-0-8194-8266-2", "book_title": "Solar hydrogen and nanotechnology V", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110316-132846386", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Kavli Nanoscience Institute" }, { "agency": "Stanford Global Climate and Energy Project (GCEP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-05ER15754" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "contributors": { "items": [ { "id": "Idriss-H", "name": { "family": "Idriss", "given": "Hicham" } }, { "id": "Wang-Heli", "name": { "family": "Wang", "given": "Heli" } } ] }, "doi": "10.1117/12.860994", "primary_object": { "basename": "Warren2010p12912Adaptive_Optics_Systems_Pts_1-3.pdf", "url": "https://authors.library.caltech.edu/records/w9yf5-1zs08/files/Warren2010p12912Adaptive_Optics_Systems_Pts_1-3.pdf" }, "resource_type": "book_section", "pub_year": "2010", "author_list": "Warren, Emily L.; Boettcher, Shannon W.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nw4y3-a2d82", "eprint_id": 19895, "eprint_status": "archive", "datestamp": "2023-08-22 00:34:40", "lastmod": "2023-10-20 22:01:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Boettcher-S-W", "name": { "family": "Boettcher", "given": "Shannon W." }, "orcid": "0000-0001-8971-9123" }, { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Flexible, Polymer-Supported, Si Wire Array Photoelectrodes", "ispublished": "pub", "full_text_status": "restricted", "keywords": "solar cells; microstructures; silicon nanowires; flexible electronics; photochemistry", "note": "\u00a9 2010 Wiley-Blackwell. \n\nReceived: February 16, 2010; Published online: June 29, 2010. \n\nThis work was financially supported by BP plc and by the Department of Energy, Office of Basic Energy Sciences, DE-FG02-07ER46405. BSB acknowledges support from the NSF Center for Chemical Innovation Grant No. 0802907 (Powering the Planet). We acknowledge use of facilities supported by the Caltech Center for Science and Engineering of Materials, an NSF MRSEC, and the Caltech Center for Sustainable Energy Research.", "abstract": "Arrays of oriented, crystalline Si wires are transferred into flexible, transparent polymer films. The polymer-supported Si wire arrays in liquid-junction photoelectrochemical cells yield current-potential behavior similar to the Si wires attached to the brittle growth substrate. These systems offer the potential for attaining high solar energy-conversion efficiencies using modest diffusion length, readily grown, crystalline Si in a flexible, processable form.", "date": "2010-08-10", "date_type": "published", "publication": "Advanced Materials", "volume": "22", "number": "30", "publisher": "Wiley", "pagerange": "3277-3281", "id_number": "CaltechAUTHORS:20100913-100004178", "issn": "0935-9648", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100913-100004178", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-07ER46405" }, { "agency": "NSF", "grant_number": "CHE-0802907" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "doi": "10.1002/adma.201000602", "resource_type": "article", "pub_year": "2010", "author_list": "Spurgeon, Joshua M.; Boettcher, Shannon W.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fgn61-eha98", "eprint_id": 19587, "eprint_status": "archive", "datestamp": "2023-08-19 03:21:53", "lastmod": "2023-10-20 21:10:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "Morgan C." } }, { "id": "Boettcher-S-W", "name": { "family": "Boettcher", "given": "Shannon W." }, "orcid": "0000-0001-8971-9123" }, { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "Daniel B." } }, { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Briggs-R-M", "name": { "family": "Briggs", "given": "Ryan M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Si microwire-array solar cells", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2010 The Royal Society of Chemistry. \n\nReceived 5th April 2010, Accepted 18th May 2010. \n\nThis work was supported by BP and in part by the Department of Energy (Basic Energy Sciences, Energy Frontier Research Center under grant DE-SC0001293 and also grant DE-FG02-07ER46405) and made use of facilities supported by the Caltech Center for Sustainable Energy Research, the Center for Science and Engineering of Materials\u2014an NSF Materials Research Science and Engineering Center at Caltech (DMR 0520565), the Molecular Materials Research Center of the Beckman Institute at Caltech, and the Kavli Nanoscience Institute at Caltech. S.W.B. acknowledges the Kavli Nanoscience Institute for fellowship support, and D.B.T.-E. acknowledges the National Science Foundation for fellowship support. The authors acknowledge Dr Michael Walter for helpful discussions.\n\nPublished - Putnam2010p11115Energ_Environ_Sci.pdf
Supplemental Material - C0EE00014K.pdf
", "abstract": "Si microwire-array solar cells with Air Mass 1.5 Global conversion efficiencies of up to 7.9% have been fabricated using an active volume of Si equivalent to a 4 \u03bcm thick Si wafer. These solar cells exhibited open-circuit voltages of 500 mV, short-circuit current densities (J_(sc)) of up to 24 mA cm^(-2), and fill factors >65% and employed Al_2O_3 dielectric particles that scattered light incident in the space between the wires, a Ag back reflector that prevented the escape of incident illumination from the back surface of the solar cell, and an a-SiN_x:H passivation/anti-reflection layer. Wire-array solar cells without some or all of these design features were also fabricated to demonstrate the importance of the light-trapping elements in achieving a high J_(sc). Scanning photocurrent microscopy images of the microwire-array solar cells revealed that the higher J_(sc) of the most advanced cell design resulted from an increased absorption of light incident in the space between the wires. Spectral response measurements further revealed that solar cells with light-trapping elements exhibited improved red and infrared response, as compared to solar cells without light-trapping elements.", "date": "2010-08", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "3", "number": "8", "publisher": "Royal Society of Chemistry", "pagerange": "1037-1041", "id_number": "CaltechAUTHORS:20100823-105710525", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100823-105710525", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "Department of Energy", "grant_number": "DE-FG02-07ER46405" }, { "agency": "Caltech Center for Sustainable Energy Research" }, { "agency": "NSF", "grant_number": "DMR-0520565" }, { "agency": "Kavli Nanoscience Institute" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1039/c0ee00014k", "primary_object": { "basename": "C0EE00014K.pdf", "url": "https://authors.library.caltech.edu/records/fgn61-eha98/files/C0EE00014K.pdf" }, "related_objects": [ { "basename": "Putnam2010p11115Energ_Environ_Sci.pdf", "url": "https://authors.library.caltech.edu/records/fgn61-eha98/files/Putnam2010p11115Energ_Environ_Sci.pdf" } ], "resource_type": "article", "pub_year": "2010", "author_list": "Putnam, Morgan C.; Boettcher, Shannon W.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dnzzx-6z932", "eprint_id": 19270, "eprint_status": "archive", "datestamp": "2023-08-19 03:17:44", "lastmod": "2023-10-20 20:10:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Knapp-D", "name": { "family": "Knapp", "given": "David" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Chemical, Electronic, and Electrical Properties of Alkylated Ge(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2010 American Chemical Society. \n\nReceived: February 13, 2010; Revised Manuscript Received: May 3, 2010. Publication Date (Web): June 28, 2010. \n\nWe acknowledge the National Science Foundation, Grant CHE-0604894, the Defense Advanced Research Projects Agency, Grant BAA-08-48, and the Beckman Institute for support of this work.\n\nSupplemental Material - jp101375x_si_001.txt
Supplemental Material - jp101375x_si_002.pdf
", "abstract": "The use of Ge in semiconductor electronics has been constrained by the lack of a simple method of passivating the crystal surface. Toward that end, we have explored the utility of chemically bonded hydrocarbon monolayers. Alkylated Ge(111) surfaces have been prepared by addition of 1-alkenes to the H-terminated Ge(111) surface as well as by a two-step halogenation/alkylation procedure. The chemical compositions of the resulting methyl-, ethyl-, and decyl-terminated surfaces have been evaluated using X-ray photoelectron spectroscopy (XPS). Thermal addition of 1-decene produced hydrophobic surfaces with 0.3 \u00b1 0.1 monolayer of Ge oxide detected by XPS, whereas no oxide was observed on the methyl-, ethyl-, or decyl-terminated surfaces that were prepared using the two-step halogenation/alkylation method. Methyl-terminated Ge(111) surfaces prepared by the two-step method displayed a well-resolved C 1s XPS peak at a binding energy of 284 eV, consistent with carbon bonded to a less electronegative element such as Ge. The electronic properties of all of the alkylated surfaces were characterized by measurements of the surface recombination velocity as a function of an externally applied gate voltage. Treatment of HF-etched Ge(111) surfaces with Br2 vapor, followed by reaction with alkylmagnesium or alkyllithium reagents, yielded air-stable surfaces that had surface recombination velocities of 100 cm s^(\u22121) or less under flat-band conditions. The field-dependent surface recombination velocity experiments indicated that, in contact with air, methyl-terminated n-type Ge(111) samples had a negative surface potential approaching 300 mV, in contrast to the oxidized Ge(111) surface, which exhibited a strongly positive surface potential under the same conditions. Mercury contacts to n-type methyl-, ethyl-, or decyl-terminated Ge(111) substrates that were alkylated using the two-step method formed rectifying junctions with barrier heights of 0.6 \u00b1 0.1 eV, whereas no measurable rectification was observed for Hg contacts to p-type Ge(111) substrates that were alkylated by the two-step method, to n-type Ge(111) substrates that were alkylated through addition of 1-decene, or to oxidized n-type Ge(111) samples.", "date": "2010-07-22", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "114", "number": "28", "publisher": "American Chemical Society", "pagerange": "12300-12307", "id_number": "CaltechAUTHORS:20100804-101624923", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100804-101624923", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "BAA-08-48" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/jp101375x", "primary_object": { "basename": "jp101375x_si_001.txt", "url": "https://authors.library.caltech.edu/records/dnzzx-6z932/files/jp101375x_si_001.txt" }, "related_objects": [ { "basename": "jp101375x_si_002.pdf", "url": "https://authors.library.caltech.edu/records/dnzzx-6z932/files/jp101375x_si_002.pdf" } ], "resource_type": "article", "pub_year": "2010", "author_list": "Knapp, David; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/aq1xj-zs594", "eprint_id": 85820, "eprint_status": "archive", "datestamp": "2023-08-22 00:23:00", "lastmod": "2024-01-14 19:35:48", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Fitch-A-G", "name": { "family": "Fitch", "given": "Anthony G." } }, { "id": "Walker-D", "name": { "family": "Walker", "given": "Don" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "The Kinetics of TiO_2-based Solar Cells Sensitized by Metal Complexes", "ispublished": "unpub", "full_text_status": "public", "keywords": "dye\u2010sensitized solar cells; titanium dioxide; metal complexes; kinetics", "note": "\u00a9 2010 Wiley\u2010VCH Verlag GmbH & Co. KGaA. \n\nPublished Online: 15 July 2010.", "abstract": "[no abstract]", "date": "2010-07-15", "date_type": "published", "publisher": "Wiley", "place_of_pub": "Weinheim", "id_number": "CaltechAUTHORS:20180413-095251245", "isbn": "9783527628698", "book_title": "Green Catalysis", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180413-095251245", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Anastas-P-T", "name": { "family": "Anastas", "given": "P. T." } } ] }, "doi": "10.1002/9783527628698.hgc020", "resource_type": "book_section", "pub_year": "2010", "author_list": "Fitch, Anthony G.; Walker, Don; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pg25t-zmv42", "eprint_id": 23288, "eprint_status": "archive", "datestamp": "2023-08-19 02:41:52", "lastmod": "2024-01-13 05:14:56", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kimball-G-M", "name": { "family": "Kimball", "given": "Gregory M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Mg doping and alloying in Zn_3P_2 heterojunction solar cells", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2010 IEEE.\nIssue Date: 20-25 June 2010.\nDate of Current Version: 01 November 2010.\n\nWe acknowledge Yunbin Guan and the Division of\nGeological and Planetary Sciences at Caltech for\nassistance collecting SIMS data. This work was\nsupported by the Office of Energy Efficiency and\nRenewable Energy, US Department of Energy under grant\nDE-FG36-08G018006, the Caltech Center for Sustainable\nEnergy Research (CCSER), as well as a partnership with\nthe Dow Chemical Company. One of us (GMK)\nacknowledges support under an NDSEG graduate\nfellowship.\n\nPublished - Kimball2010p13423Pvsc_2008_33Rd_Ieee_Photovoltaic_Specialists_Conference_Vols_1-4.pdf
", "abstract": "Zinc phosphide (Zn_3P_2) is a promising and earth-abundant\nalternative to traditional materials (e.g. CdTe, CIGS, a-Si)\nfor thin film photovoltaics. We report the fabrication of\nMg/Zn_3P_2 Schottky diodes with V_(oc) values reaching 550\nmV, J_(sc) values up to 21.8 mA/cm^2, and photovoltaic\nefficiency reaching 4.5%. Previous authors have\nsuggested that Mg impurities behave as n-type dopants in\nZn_3P_2, but combined Hall effect measurements and\nSecondary Ion Mass Spectrometry (SIMS) show that 10^(17)\nto 10^(19) cm^(-3)\nMg impurities compensate p-type doping to\nform highly resistive Zn_3P_2. Further device work with\nmodified ITO/Mg/Zn_3P_2 heterojunctions suggests that the\nITO capping layer improves a passivation reaction\nbetween Mg and Zn_3P_2 to yield high voltages > 500 mV\nwithout degradation in the blue response of the solar cell.\nThese results indicate that at least 8-10% efficiency cell is\nrealizable by the optimization of Mg treatment in Zn_3P_2\nsolar cells.", "date": "2010-06", "date_type": "published", "publisher": "IEEE", "place_of_pub": "New York", "pagerange": "1039-1043", "id_number": "CaltechAUTHORS:20110412-141058665", "isbn": "978-1-4244-5890-5", "book_title": "2010 35th IEEE Photovoltaic Specialists Conference (PVSC)", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110412-141058665", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG36-08G018006" }, { "agency": "Caltech Center for Sustainable Energy Research" }, { "agency": "Dow Chemical Company" }, { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" } ] }, "doi": "10.1109/PVSC.2010.5614641", "primary_object": { "basename": "Kimball2010p13423Pvsc_2008_33Rd_Ieee_Photovoltaic_Specialists_Conference_Vols_1-4.pdf", "url": "https://authors.library.caltech.edu/records/pg25t-zmv42/files/Kimball2010p13423Pvsc_2008_33Rd_Ieee_Photovoltaic_Specialists_Conference_Vols_1-4.pdf" }, "resource_type": "book_section", "pub_year": "2010", "author_list": "Kimball, Gregory M.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ynz76-qhx59", "eprint_id": 17688, "eprint_status": "archive", "datestamp": "2023-08-19 01:45:57", "lastmod": "2023-10-20 00:09:10", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Boettcher-S-W", "name": { "family": "Boettcher", "given": "Shannon W." }, "orcid": "0000-0001-8971-9123" }, { "id": "Petykiewicz-J-A", "name": { "family": "Petykiewicz", "given": "Jan A." } }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "Daniel B." } }, { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "Morgan C." } }, { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Briggs-R-M", "name": { "family": "Briggs", "given": "Ryan M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications", "ispublished": "pub", "full_text_status": "public", "keywords": "Optical, photonic and optoelectronic materials | Materials for energy | Nanoscale materials", "note": "\u00a9 2010 Macmillan Publishers Limited. \n\nReceived 4 September 2009; accepted 14 January 2010; published online 14 February 2010; corrected online 19 February 2010. \n\nThis work was supported by BP and in part by the Department of Energy EFRC program under grant DE-SC0001293, and made use of facilities supported by the Center for Science and Engineering of Materials, an NSF Materials Research Science and Engineering Center at Caltech. S.W.B. acknowledges the Kavli Nanoscience Institute for fellowship support. The authors acknowledge D. Pacifici for useful discussions and assistance in generating the quasi-periodic hole-array patterns, B. Kayes and M. Filler for their contributions at the outset of this project and M. Roy and S. Olson for their advice and skill in machining the components of the experimental apparatus. \n\nAuthor contributions: M.D.K. participated in the design and execution of the experiments, analysed the results and prepared the manuscript under the advisement of H.A.A. and the guidance of N.S.L. and S.W.B. J.A.P. contributed to the design and fabrication of the array template photomasks, the integrating-sphere apparatus and the image processing software. S.W.B., J.M.S., J.A.P., M.C.P. and D.B.T-E. assisted in the fabrication of the wire arrays and R.M.B. carried out the deposition and characterization of the SiNx antireflective coating. S.W.B., E.L.W. and J.M.S. assisted with the photoelectrochemical measurements and fabricated the electrodes. All authors discussed the results and commented on the manuscript.\n\nCorrigendum.\nNature Materials. Published online: 19 February 2010 | doi:10.1038/nmat2727\n\nNature Materials 9, 239\u2013244 (2010); published online: 14 February 2010; corrected after print: 19 February 2010.\n\nEnhanced absorption and carrier collection in Si wire arrays for photovoltaic applications\nMichael D. Kelzenberg, Shannon W. Boettcher, Jan A. Petykiewicz, Daniel B. Turner-Evans, Morgan C. Putnam, Emily L. Warren, Joshua M. Spurgeon, Ryan M. Briggs, Nathan S. Lewis & Harry A. Atwater\n\nSupplemental Material - nmat2635-s1.pdf
", "abstract": "Si wire arrays are a promising architecture for solar-energy-harvesting applications, and may offer a mechanically flexible alternative to Si wafers for photovoltaics. To achieve competitive conversion efficiencies, the wires must absorb sunlight over a broad range of wavelengths and incidence angles, despite occupying only a modest fraction of the array's volume. Here, we show that arrays having less than 5% areal fraction of wires can achieve up to 96% peak absorption, and that they can absorb up to 85% of day-integrated, above-bandgap direct sunlight. In fact, these arrays show enhanced near-infrared absorption, which allows their overall sunlight absorption to exceed the ray-optics light-trapping absorption limit18 for an equivalent volume of randomly textured planar Si, over a broad range of incidence angles. We furthermore demonstrate that the light absorbed by Si wire arrays can be collected with a peak external quantum efficiency of 0.89, and that they show broadband, near-unity internal quantum efficiency for carrier collection through a radial semiconductor/liquid junction at the surface of each wire. The observed absorption enhancement and collection efficiency enable a cell geometry that not only uses 1/100th the material of traditional wafer-based devices, but also may offer increased photovoltaic efficiency owing to an effective optical concentration of up to 20 times.", "date": "2010-03", "date_type": "published", "publication": "Nature Materials", "volume": "9", "number": "3", "publisher": "Nature Publishing Group", "pagerange": "239-244", "id_number": "CaltechAUTHORS:20100308-094625952", "issn": "1476-1122", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100308-094625952", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001293" }, { "agency": "NSF" }, { "agency": "Kavli Nanoscience Institute" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1038/NMAT2635", "primary_object": { "basename": "nmat2635-s1.pdf", "url": "https://authors.library.caltech.edu/records/ynz76-qhx59/files/nmat2635-s1.pdf" }, "resource_type": "article", "pub_year": "2010", "author_list": "Kelzenberg, Michael D.; Boettcher, Shannon W.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8f7nt-c6e02", "eprint_id": 19441, "eprint_status": "archive", "datestamp": "2023-08-19 01:40:13", "lastmod": "2023-10-20 20:41:55", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "M. D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "M. C." } }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "D. B." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "H. A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Predicted efficiency of Si wire array solar cells", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2009 IEEE.\nThe authors would like to thank Melissa Archer,\nShannon Boettcher, Stanley Burgos, Vivian Ferry, Michael\nFiller, Brendan Kayes, Jim Maiolo, Stephen Maldonado,\nEvan and April Neidholdt, Domenico Pacifici, Jan\nPetykiewicz, Katherine Plass, Jessica Roberts, Josh\nSpurgeon, Luke Sweatlock, and Emily Warren.\nThis work was supported by BP; the Department of\nEnergy, Office of Basic Energy Sciences; and the Center\nfor Science and Engineering of Materials, an NSF\nMaterials Research Science and Engineering Center at\nCaltech.\n\nPublished - Kelzenberg2009p11085Pvsc_2008_33Rd_Ieee_Photovoltaic_Specialists_Conference_Vols_1-4.pdf
", "abstract": "Solar cells based on arrays of CVD-grown Si nano- or micro-wires have attracted interest as potentially low-cost alternatives to conventional wafer-based Si photovoltaics [1-6], and single-wire solar cells have been reported with efficiencies of up to 3.4% [7]. We recently presented device physics simulations which predicted efficiencies exceeding 17%, based on experimentally observed diffusion lengths within our wires [8]. However, this model did not take into account the optical properties of a wire array device - in particular the inherently low packing fraction of wires within CVD-grown wire arrays, which might limit their ability to fully absorb incident sunlight. For this reason, we have combined a device physics model of Si wire solar cells with FDTD simulations of light absorption within wire arrays to investigate the potential photovoltaic efficiency of this cell geometry. We have found that even a sparsely packed array (14%) is expected to absorb moderate (66%) amounts of above-bandgap solar energy, yielding a simulated photovoltaic efficiency of 14.5%. Because the wire array comprises such a small volume of Si, the observed absorption represents an effective optical concentration, which enables greater operating voltages than previously predicted for Si wire array solar cells.", "date": "2010-02-17", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "391-396", "id_number": "CaltechAUTHORS:20100816-112503800", "isbn": "978-1-4244-2949-3", "book_title": "2009 34th IEEE Photovoltaic Specialists Conference", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100816-112503800", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NSF" } ] }, "collection": "CaltechAUTHORS", "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute", "value": "Kavli Nanoscience Institute" } ] }, "doi": "10.1109/PVSC.2009.5411542", "primary_object": { "basename": "Kelzenberg2009p11085Pvsc_2008_33Rd_Ieee_Photovoltaic_Specialists_Conference_Vols_1-4.pdf", "url": "https://authors.library.caltech.edu/records/8f7nt-c6e02/files/Kelzenberg2009p11085Pvsc_2008_33Rd_Ieee_Photovoltaic_Specialists_Conference_Vols_1-4.pdf" }, "resource_type": "book_section", "pub_year": "2010", "author_list": "Kelzenberg, M. D.; Putnam, M. C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/z58v4-sxr94", "eprint_id": 17347, "eprint_status": "archive", "datestamp": "2023-08-19 01:24:15", "lastmod": "2023-10-19 23:47:52", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Boettcher-S-W", "name": { "family": "Boettcher", "given": "Shannon W." }, "orcid": "0000-0001-8971-9123" }, { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "Morgan C." } }, { "id": "Warren-E-L", "name": { "family": "Warren", "given": "Emily L." }, "orcid": "0000-0001-8568-7881" }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "Daniel B." } }, { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Maiolo-J-R-III", "name": { "family": "Maiolo", "given": "James R." } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Energy-Conversion Properties of Vapor-Liquid-Solid\u2013Grown Silicon Wire-Array Photocathodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2010 American Association for the Advancement of Science. \n\nSubmitted 19 August 2009; accepted 10 November 2009. \n\nWe acknowledge the Stanford Global Climate and Energy Project and the U.S. Department of Energy (grant DE-FG02-05ER15754) for financial support. S.W.B. thanks the Kavli Nanoscience Institute for a postdoctoral fellowship. L. O'Leary is thanked for her contributions. The authors have filed U.S. patent applications (20090020150 and 20090020853) related to this work.\n\nSupplemental Material - Boettcher2010p6870Science_supp.pdf
", "abstract": "Silicon wire arrays, though attractive materials for use in photovoltaics and as photocathodes for hydrogen generation, have to date exhibited poor performance. Using a copper-catalyzed, vapor-liquid-solid\u2013growth process, SiCl_4 and BCl_3 were used to grow ordered arrays of crystalline p-type silicon (p-Si) microwires on p^+-Si(111) substrates. When these wire arrays were used as photocathodes in contact with an aqueous methyl viologen^(2+/+) electrolyte, energy-conversion efficiencies of up to 3% were observed for monochromatic 808-nanometer light at fluxes comparable to solar illumination, despite an external quantum yield at short circuit of only 0.2. Internal quantum yields were at least 0.7, demonstrating that the measured photocurrents were limited by light absorption in the wire arrays, which filled only 4% of the incident optical plane in our test devices. The inherent performance of these wires thus conceptually allows the development of efficient photovoltaic and photoelectrochemical energy-conversion devices based on a radial junction platform.", "date": "2010-01-08", "date_type": "published", "publication": "Science", "volume": "327", "number": "5962", "publisher": "American Association for the Advancement of Science", "pagerange": "185-187", "id_number": "CaltechAUTHORS:20100129-084339516", "issn": "0036-8075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100129-084339516", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Stanford Global Climate and Energy Project (GCEP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-05ER15754" }, { "agency": "Kavli Nanoscience Institute" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1126/science.1180783", "primary_object": { "basename": "Boettcher2010p6870Science_supp.pdf", "url": "https://authors.library.caltech.edu/records/z58v4-sxr94/files/Boettcher2010p6870Science_supp.pdf" }, "resource_type": "article", "pub_year": "2010", "author_list": "Boettcher, Shannon W.; Spurgeon, Joshua M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/avbv1-w4r60", "eprint_id": 16767, "eprint_status": "archive", "datestamp": "2023-08-19 00:23:55", "lastmod": "2023-10-19 22:32:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "Morgan C." } }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "Daniel B." } }, { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Boettcher-S-W", "name": { "family": "Boettcher", "given": "Shannon W." }, "orcid": "0000-0001-8971-9123" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "10 \u00b5m minority-carrier diffusion lengths in Si wires synthesized by Cu-catalyzed vapor-liquid-solid growth", "ispublished": "pub", "full_text_status": "public", "keywords": "carrier lifetime, catalysis, copper, elemental semiconductors, optical microscopy, photovoltaic cells, silicon, surface recombination, surface states, wires", "note": "\u00a9 2009 American Institute of Physics. \n\nReceived 5 August 2009; accepted 18 September 2009; published 23 October 2009. \n\nThe authors thank BP, the Department of Energy Office of Basic Energy Sciences, and the Caltech Center for Sustainable Energy Research for support, as well as the Kavli Nanoscience Institute at Caltech, the Molecular Materials Research Center at Caltech, and the Center for the Science of Materials and Engineering NSF MRSEC: DMR 0520565 for use of facilities, and thank Emily Warren, Josh Spurgeon, Brendan Kayes, and Michael Filler for their contributions.\n\nPublished - Putnam2009p6371Appl_Phys_Lett.pdf
", "abstract": "The effective electron minority-carrier diffusion length, L_(n,eff), for 2.0 \u00b5m diameter Si wires that were synthesized by Cu-catalyzed vapor-liquid-solid growth was measured by scanning photocurrent microscopy. In dark, ambient conditions, L_(n,eff) was limited by surface recombination to a value of \u2264 0.7 \u00b5m. However, a value of L_(n,eff) = 10.5\u00b11 \u00b5m was measured under broad-area illumination in low-level injection. The relatively long minority-carrier diffusion length observed under illumination is consistent with an increased surface passivation resulting from filling of the surface states of the Si wires by photogenerated carriers. These relatively large L_(n,eff) values have important implications for the design of high-efficiency, radial-junction photovoltaic cells from arrays of Si wires synthesized by metal-catalyzed growth processes.", "date": "2009-10-23", "date_type": "published", "publication": "Applied Physics Letters", "volume": "95", "number": "16", "publisher": "American Institute of Physics", "pagerange": "Art. No. 163116", "id_number": "CaltechAUTHORS:20091119-144726009", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20091119-144726009", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Department of Energy (DOE)" }, { "agency": "Caltech Center for Sustainable Energy Research" }, { "agency": "NSF", "grant_number": "DMR-0520565" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "doi": "10.1063/1.3247969", "primary_object": { "basename": "Putnam2009p6371Appl_Phys_Lett.pdf", "url": "https://authors.library.caltech.edu/records/avbv1-w4r60/files/Putnam2009p6371Appl_Phys_Lett.pdf" }, "resource_type": "article", "pub_year": "2009", "author_list": "Putnam, Morgan C.; Turner-Evans, Daniel B.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hfsxx-63q09", "eprint_id": 16318, "eprint_status": "archive", "datestamp": "2023-08-19 00:04:24", "lastmod": "2023-10-19 22:06:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kimball-G-M", "name": { "family": "Kimball", "given": "Gregory M." } }, { "id": "M\u00fcller-A-M", "name": { "family": "M\u00fcller", "given": "Astrid M." }, "orcid": "0000-0002-2785-6808" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Photoluminescence-based measurements of the energy gap and diffusion length of Zn_3P_2", "ispublished": "pub", "full_text_status": "public", "keywords": "carrier lifetime, dielectric function, energy gap, photoluminescence, time resolved spectra, zinc compounds", "note": "\u00a92009 American Institute of Physics. \n\nReceived 29 June 2009; accepted 20 August 2009; published 14 September 2009. \n\nThis work was supported by the Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy under Grant No. DE-FG36-08GO18006, as well as Caltech Center for Sustainable Energy Research (CCSER). We acknowledge use of facilities supported by the Beckman Institute Laser Resource Center (BILRC). One of us (G.M.K.) acknowledges support under an NDSEG graduate fellowship.\n\nPublished - ApplPhysLett_95_112103.pdf
", "abstract": "The steady-state photoluminescence spectra of zinc phosphide (Zn_3P_2) wafers have revealed a fundamental indirect band gap at 1.38 eV, in close proximity to the direct band gap at 1.50 eV. These values are consistent with the values for the indirect and direct band gaps obtained from analysis of the complex dielectric function deduced from spectroscopic ellipsometric measurements. Bulk minority carrier lifetimes of 20 ns were observed by time-resolved photoluminescence decay measurements, implying minority-carrier diffusion lengths of \u2265 7 \u00b5m.", "date": "2009-09-14", "date_type": "published", "publication": "Applied Physics Letters", "volume": "95", "number": "11", "publisher": "American Institute of Physics", "pagerange": "Art. No. 112103", "id_number": "CaltechAUTHORS:20091013-093453282", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20091013-093453282", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG36-08GO18006" }, { "agency": "Caltech Center for Sustainable Energy Research" }, { "agency": "Caltech Beckman Institute" }, { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" } ] }, "doi": "10.1063/1.3225151", "primary_object": { "basename": "ApplPhysLett_95_112103.pdf", "url": "https://authors.library.caltech.edu/records/hfsxx-63q09/files/ApplPhysLett_95_112103.pdf" }, "resource_type": "article", "pub_year": "2009", "author_list": "Kimball, Gregory M.; M\u00fcller, Astrid M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/d7nkm-sma33", "eprint_id": 15458, "eprint_status": "archive", "datestamp": "2023-08-20 02:40:02", "lastmod": "2023-10-19 14:29:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Johansson-E-M", "name": { "family": "Johansson", "given": "Erik" } }, { "id": "Hurley-P-T", "name": { "family": "Hurley", "given": "Patrick T." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Infrared Vibrational Spectroscopy of Isotopically Labeled Ethyl-Terminated Si(111) Surfaces Prepared Using a Two-Step Chlorination/Alkylation Procedure", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2009 American Chemical Society. \n\nReceived: February 26, 2009; Revised Manuscript Received: June 22, 2009. Publication Date (Web): July 31, 2009. \n\nWe thank Dr. Katherine Plass for helpful discussions. We gratefully acknowledge the National Science Foundation (CHE-0604894) and the Molecular Materials Research Center in the Beckman Institute at Caltech for support of this work. \n\nSupporting Information: Subtraction results of the C\u2212H stretching region for 1,1-d2-ethyl-Si(111) and 2,2,2-d3-ethyl-Si(111). Subtraction result of the two spectra in Figure 6 and the C\u2212H stretching region of the subtraction result of the spectra from C_2D_5\u2212Si(111) surfaces synthesized using either all protic or all deuterated solvents. This information is available free of charge via the Internet at http://pubs.acs.org.\n\nSupplemental Material - Johanssonjp901792y_si_001.pdf
", "abstract": "Fourier transform infrared (FTIR) spectroscopy was used to investigate C_2H_5\u2212Si(111) surfaces prepared using a chlorination/alkylation method. After alkylation, in addition to ethyl groups, such surfaces showed the presence of hydrogen bonded to atop silicon surface atoms. Systematic isotopic substitution of protic solvents and reagents with their fully or partially deuterated counterparts revealed the origin of the surface-bound hydrogen on the C_2H_5\u2212Si(111) surfaces. The presence or absence of the Si\u2212H stretch at 2080 cm^(\u22121) and the Si\u2212D stretch at 1510 cm^(\u22121), respectively, indicated that the hydrogen originated from the methyl group of the ethyl Grignard reagent.", "date": "2009-08-27", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "113", "number": "34", "publisher": "American Chemical Society", "pagerange": "15239-15245", "id_number": "CaltechAUTHORS:20090828-231035223", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090828-231035223", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/jp901792y", "primary_object": { "basename": "Johanssonjp901792y_si_001.pdf", "url": "https://authors.library.caltech.edu/records/d7nkm-sma33/files/Johanssonjp901792y_si_001.pdf" }, "resource_type": "article", "pub_year": "2009", "author_list": "Johansson, Erik; Hurley, Patrick T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ga5yt-q6496", "eprint_id": 88058, "eprint_status": "archive", "datestamp": "2023-08-20 02:38:00", "lastmod": "2024-01-14 20:28:53", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Reyes-Gil-K-R", "name": { "family": "Reyes Gil", "given": "Karla R." } }, { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Silicon and tungsten oxide nanostructures for water splitting", "ispublished": "unpub", "full_text_status": "public", "keywords": "water splitting, silicon, tungsten oxide, solar cell, membrane, hydrogen production, semiconductor", "note": "\u00a9 2009 Society of Photo-Optical Instrumentation Engineers (SPIE). \n\nWe acknowledge every former and current member of the Lewis group for their contribution to this work. We also acknowledge all members of the Powering the Planet Center for Chemical Innovation (CCI Solar) for their valuable contribution to this project. In addition, we acknowledge the DOE, NSF and BP plc for financial support that has made this work possible.\n\nPublished - 74080S.pdf
", "abstract": "Inorganic semiconductors are promising materials for driving photoelectrochemical water-splitting reactions. However, there is not a single semiconductor material that can sustain the unassisted splitting of water into H_2 and O_2. Instead, we are developing a three part cell design where individual catalysts for water reduction and oxidation will be attached to the ends of a membrane. The job of splitting water is therefore divided into separate reduction and oxidation reactions, and each catalyst can be optimized independently for a single reaction. Silicon might be suitable to drive the water reduction. Inexpensive highly ordered Si wire arrays were grown on a single crystal wafer and transferred into a transparent, flexible polymer matrix. In this array, light would be absorbed along the longer axial dimension while the resulting electrons or holes would be collected along the much shorter radial dimension in a massively parallel array resembling carpet fibers on a microscale, hence the term \"solar carpet\". Tungsten oxide is a good candidate to drive the water oxidation. Self-organized porous tungsten oxide was successfully synthesized on the tungsten foil by anodization. This sponge-like structure absorbs light efficiently due to its high surface area; hence we called it \"solar sponge\".", "date": "2009-08-20", "date_type": "published", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_pub": "Bellingham, WA", "pagerange": "Art. No. 74080S", "id_number": "CaltechAUTHORS:20180720-110313872", "isbn": "9780819476982", "book_title": "Solar Hydrogen and Nanotechnology IV", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180720-110313872", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "NSF" }, { "agency": "BP plc" } ] }, "local_group": { "items": [ { "id": "CCI-Solar-Fuels" } ] }, "contributors": { "items": [ { "id": "Osterloh-F-E", "name": { "family": "Osterloh", "given": "Frank E." } } ] }, "doi": "10.1117/12.825545", "primary_object": { "basename": "74080S.pdf", "url": "https://authors.library.caltech.edu/records/ga5yt-q6496/files/74080S.pdf" }, "resource_type": "book_section", "pub_year": "2009", "author_list": "Reyes Gil, Karla R.; Spurgeon, Joshua M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/v6cvx-h7k04", "eprint_id": 120625, "eprint_status": "archive", "datestamp": "2023-08-21 21:29:39", "lastmod": "2023-10-18 17:55:44", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A Perspective on Forward Research and Development Paths for Cost-Effective Solar Energy Utilization", "ispublished": "pub", "full_text_status": "public", "keywords": "General Energy; General Materials Science; General Chemical Engineering; Environmental Chemistry", "note": "We acknowledge the Camille & Henry Dreyfus Foundation, the DOE, and the NSF for support that enabled the preparation of this work.", "abstract": "Solar electricity has long been recognized as a potential energy source that holds great promise. Several approaches towards converting sunlight into energy are elaborated in this Viewpoint, and discussed with respect to their feasibility for large-scale application.", "date": "2009-05-25", "date_type": "published", "publication": "ChemSusChem", "volume": "2", "number": "5", "publisher": "Wiley", "pagerange": "383-386", "id_number": "CaltechAUTHORS:20230329-683752000.1", "issn": "1864-5631", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-683752000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NSF" } ] }, "doi": "10.1002/cssc.200900039", "resource_type": "article", "pub_year": "2009", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dg79m-sxw66", "eprint_id": 13979, "eprint_status": "archive", "datestamp": "2023-08-21 21:05:50", "lastmod": "2023-10-18 16:00:40", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Katz-J-E", "name": { "family": "Katz", "given": "Jordan E." }, "orcid": "0000-0002-6242-2124" }, { "id": "Gingrich-T-R", "name": { "family": "Gingrich", "given": "Todd R." } }, { "id": "Santori-E-A", "name": { "family": "Santori", "given": "Elizabeth A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Combinatorial synthesis and high-throughput photopotential and photocurrent screening of mixed-metal oxides for photoelectrochemical water splitting", "ispublished": "pub", "full_text_status": "public", "keywords": "photoassisted electrolysis; electrochemical synthesis; energy-conversion; photoelectrolysis; semiconductor; systems; cells", "note": "\u00a9 2009 The Royal Society of Chemistry.\nReceived 16th July 2008, Accepted 28th August 2008.\nFirst published as an Advance Article on the web 6th November 2008.\nWe acknowledge the Stanford Global Energy and Climate\nProject, and the U.S. Department of Energy, Office of Basic\nEnergy Sciences, Basic Research for the Hydrogen Fuel Initiative,\nfor support of this work. We also gratefully acknowledge Dr\nMichael Woodhouse and Prof. Bruce Parkinson at Colorado\nState University, and Dr Bruce Brunschwig at Caltech, for\nnumerous valuable discussions. T.R.G. acknowledges financial\nsupport from the Carl and Shirley Larson SURF Fellowship and\nfrom an Amgen Scholars Fellowship.\n\nPublished - Katz2009p61910.1039b812177j.pdf
", "abstract": "A high-throughput method has been developed using a commercial piezoelectric inkjet printer for synthesis and characterization of mixed-metal oxide photoelectrode materials for water splitting. The printer was used to deposit metal nitrate solutions onto a conductive glass substrate. The deposited metal nitrate solutions were then pyrolyzed to yield mixed-metal oxides that contained up to eight distinct metals. The stoichiometry of the metal oxides was controlled quantitatively, allowing for the creation of vast libraries of novel materials. Automated methods were developed to measure the open-circuit potentials (Eoc), short-circuit photocurrent densities (Jsc), and current density vs. applied potential (J\u2013E) behavior under visible light irradiation. The high-throughput measurement of Eoc is particularly significant because open-circuit potential measurements allow the interfacial energetics to be probed regardless of whether the band edges of the materials of concern are above, close to, or below the values needed to sustain water electrolysis under standard conditions. The Eoc measurements allow high-throughput compilation of a suite of data that can be associated with the composition of the various materials in the library, to thereby aid in the development of additional screens and to form a basis for development of theoretical guidance in the prediction of additional potentially promising photoelectrode compositions.", "date": "2009-04", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "2", "number": "1", "publisher": "Royal Society of Chemistry", "pagerange": "103-112", "id_number": "CaltechAUTHORS:20090415-091958867", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090415-091958867", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech Summer Undergraduate Research Fellowship (SURF)" }, { "agency": "Amgen" } ] }, "doi": "10.1039/b812177j", "primary_object": { "basename": "Katz2009p61910.1039b812177j.pdf", "url": "https://authors.library.caltech.edu/records/dg79m-sxw66/files/Katz2009p61910.1039b812177j.pdf" }, "resource_type": "article", "pub_year": "2009", "author_list": "Katz, Jordan E.; Gingrich, Todd R.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/a8w5t-b7q50", "eprint_id": 15234, "eprint_status": "archive", "datestamp": "2023-08-21 21:01:20", "lastmod": "2023-10-18 21:34:13", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Paulauskas-I-E", "name": { "family": "Paulauskas", "given": "I. E." } }, { "id": "Katz-J-E", "name": { "family": "Katz", "given": "J. E." }, "orcid": "0000-0002-6242-2124" }, { "id": "Jellison-G-E-Jr", "name": { "family": "Jellison", "given": "G. E. Jr." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Boatner-L-A", "name": { "family": "Boatner", "given": "L. A." } }, { "id": "Brown-G-M", "name": { "family": "Brown", "given": "G. M." } } ] }, "title": "Growth, Characterization, and Electrochemical Properties of Doped n-Type KTaO_3 Photoanodes", "ispublished": "pub", "full_text_status": "public", "keywords": "barium, calcium, carrier density, carrier lifetime, electrochemical electrodes, electrolytes, energy gap, photoconductivity, photoelectrochemical cells, photoelectrochemistry, photovoltaic effects, potassium compounds, semiconductor materials; PACS: 82.47.Jk, 82.50.-m, 82.45.Fk, 82.45.Gj, 72.40.+w, 72.20.Jv, YEAR: 2009", "note": "\u00a9 2009 The Electrochemical Society. \n\nSubmitted 31 July 2008; revised 21 January 2009; published 10 March 2009. \n\nThis research was sponsored by the Division of Materials Science and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy, under contract no. DE-AC05-00OR22725 with Oak Ridge National Laboratory, managed and operated by UT-Battelle, LLC, and by the Office of Basic Energy Sciences, under grant no. DE-FG0Z-03ERI5483 with the California Institute of Technology. The authors acknowledge, with thanks, the contributions of J. O. Ramey, J. A. Kolopus, and H. E. Harmon to various aspects of this work. \n\nUniversity of Tennesse assisted in meeting the publication costs of this article. \n\n82.47.Jk\nPhotoelectrochemical cells, photoelectrochromic cells\n82.50.-m\nPhotochemistry\n82.45.Fk\nElectrochemical electrodes\n82.45.Gj\nElectrolytes\n72.40.+w\nPhotoconduction and photovoltaic effects\n72.20.Jv\nCharge carriers: generation, recombination, lifetime, and trapping (semiconductors/insulators)\n\nPublished - Paulauskas2009p1461J_Electrochem_Soc.pdf
", "abstract": "The effects of compositionally induced changes on the semiconducting properties, optical response, chemical stability, and overall performance of KTaO_3 photoanodes in photoelectrochemical (PEC) cells have been investigated. Single crystals of n-type Ca- and Ba-doped KTaO_3 with carrier concentrations ranging from 0.45 to 11.5\u00d710^(19) cm^(\u22123) were grown and characterized as photoanodes in basic aqueous electrolyte PEC cells. The PEC properties of the crystals, including the photocurrent, photovoltage, and flatband potential in contact with 8.5 M NaOH(aq) were relatively independent of whether Ca or Ba was used to produce the semiconducting form of KTaO_3. All of the Ca- or Ba-doped KTaO_3 single-crystal photoanodes were chemically stable in the electrolyte and, based on the open-circuit potential and the band-edge positions, were capable of unassisted photochemical H_2 and O_2 evolution from H_2O. The minority-carrier diffusion lengths values were small and comparable to the depletion region width. Photoanodic currents were only observed for photoanode illumination with light above the bandgap (i.e., \u03bb<340 nm). The maximum external quantum yield occurred at \u03bb=255 nm (4.85 eV), and the depletion width plus the minority-carrier diffusion length ranged from 20 to 65 nm for the various KTaO_3-based photoanode materials.", "date": "2009-03-10", "date_type": "published", "publication": "Journal of the Electrochemical Society", "volume": "156", "number": "5", "publisher": "Electrochemical Society", "pagerange": "B580-B587", "id_number": "CaltechAUTHORS:20090821-130313595", "issn": "0013-4651", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090821-130313595", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC05-00OR22725" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG0Z-03ERI5483" }, { "agency": "University of Tennessee" } ] }, "doi": "10.1149/1.3089281", "primary_object": { "basename": "Paulauskas2009p1461J_Electrochem_Soc.pdf", "url": "https://authors.library.caltech.edu/records/a8w5t-b7q50/files/Paulauskas2009p1461J_Electrochem_Soc.pdf" }, "resource_type": "article", "pub_year": "2009", "author_list": "Paulauskas, I. E.; Katz, J. E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qevnf-t4998", "eprint_id": 12494, "eprint_status": "archive", "datestamp": "2023-08-22 14:16:55", "lastmod": "2023-10-17 17:01:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Maldonado-S", "name": { "family": "Maldonado", "given": "Stephen" }, "orcid": "0000-0002-2917-4851" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Behavior of Electrodeposited Cd and Pb Schottky Junctions on CH3-Terminated n-Si(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "cadmium; electrodeposition; lead; passivation; Schottky barriers; surface treatment; X-ray photoelectron spectra", "note": "\u00a9 2008 The Electrochemical Society. \n\nManuscript submitted June 2, 2008; revised manuscript received October 13, 2008. Published December 9, 2008. \n\nWe thank the National Science Foundation (Grant CHE-0604894) for financial support and the Gordon and Betty Moore Foundation for postdoctoral fellowship support (S.M.). \n\nCalifornia Institute of Technology assisted in meeting the publication costs of this article.\n\nPublished - MALjes08.pdf
", "abstract": "n-Si/Cd and n-Si/Pb Schottky junctions have been prepared by electrodeposition of Cd or Pb from acidic aqueous solutions onto H-terminated and CH3-terminated n-type Si(111) surfaces. For both nondegenerately (n-) and degenerately (n+-) doped H\u2013Si(111) electrodes, Cd and Pb were readily electroplated and oxidatively stripped, consistent with a small barrier height (Phib) at the Si/solution and the Si/metal junctions. Electrodeposition of Cd or Pb onto degenerately doped CH3-terminated n+-Si(111) electrodes occurred at the same potentials as Cd or Pd electrodeposition onto H-terminated n+-Si(111). However, electrodeposition on nondegenerately doped CH3-terminated n-Si(111) surfaces was significantly shifted to more negative applied potentials (by \u2212130 and \u2212347 mV, respectively), and the anodic stripping of the electrodeposited metals was severely attenuated, indicating large values of Phib for contacts on nondegenerately doped n-type CH3\u2013Si(111) surfaces. With either Cd or Pb, current\u2013voltage measurements on the dry, electrodeposited Schottky junctions indicated that much larger values of Phib were obtained on CH3-terminated n-Si(111) surfaces than on H-terminated n-Si(111) surfaces. Chronoamperometric data indicated that CH3\u2013Si(111) surfaces possessed an order-of-magnitude lower density of nucleation sites for metal electrodeposition than did H\u2013Si(111) surfaces, attesting to the high degree of structural passivation afforded by the CH3\u2013Si surface modification.", "date": "2009-02", "date_type": "published", "publication": "Journal of the Electrochemical Society", "volume": "156", "number": "2", "publisher": "Electrochemical Society", "pagerange": "H123-H128", "id_number": "CaltechAUTHORS:MALjes09", "issn": "0013-4651", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:MALjes09", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "National Science Foundation", "grant_number": "CHE-0604894" }, { "agency": "Gordon and Betty Moore Foundation" } ] }, "collection": "CaltechAUTHORS", "doi": "10.1149/1.3021450", "primary_object": { "basename": "MALjes08.pdf", "url": "https://authors.library.caltech.edu/records/qevnf-t4998/files/MALjes08.pdf" }, "resource_type": "article", "pub_year": "2009", "author_list": "Maldonado, Stephen and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1pvt1-b0d51", "eprint_id": 14840, "eprint_status": "archive", "datestamp": "2023-08-22 14:14:32", "lastmod": "2023-10-18 19:57:07", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Plass-K-E", "name": { "family": "Plass", "given": "Katherine E." } }, { "id": "Filler-M-A", "name": { "family": "Filler", "given": "Michael A." }, "orcid": "0000-0003-4239-8558" }, { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Kayes-B-M", "name": { "family": "Kayes", "given": "Brendan M." } }, { "id": "Maldonado-S", "name": { "family": "Maldonado", "given": "Stephen" }, "orcid": "0000-0002-2917-4851" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Flexible polymer-embedded Si wire arrays", "ispublished": "pub", "full_text_status": "public", "keywords": "composite materials; electro-optical materials; flexible electronics; polymer composites; solar cells", "note": "\u00a9 2009 WILEY-VCH Verlag GmbH & Co. \n\nReceived: July 15, 2008. Revised: August 8, 2008. Published online: November 14, 2008. \n\nThis work was funded by BP Solar, the Department of Energy, and the Caltech Center for Sustainable Energy Research (CCSER). Use of facilities at the Center for Science and Engineering of Materials, and NSF MRSEC, is gratefully acknowledged. The authors also appreciate the assistance of Dr. Youli Li at the UC Santa Barbara Materials Research Laboratory. K. E. Plass and M. A. Filler contributed equally to this work. Supporting Information is available online from Wiley InterScience or from the author.\n\nSupplemental Material - Plass2009p33610.1002adma.200802006_supp.pdf
", "abstract": "Arrays of Si rods are embedded in PDMS and removed from the rigid growth substrate, resulting in a composite material that merges the benefits of single-crystalline silicon with the flexibility of a polymer. With this technique, solar cell absorber materials with the potential to achieve high efficiency can be prepared by high-temperature processing and transformed into a flexible, processable form.", "date": "2009-01-19", "date_type": "published", "publication": "Advanced Materials", "volume": "21", "number": "3", "publisher": "Wiley", "pagerange": "325-328", "id_number": "CaltechAUTHORS:20090806-092858359", "issn": "0935-9648", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090806-092858359", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP Solar" }, { "agency": "Caltech Center for Sustainable Energy Research" }, { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1002/adma.200802006", "primary_object": { "basename": "Plass2009p33610.1002adma.200802006_supp.pdf", "url": "https://authors.library.caltech.edu/records/1pvt1-b0d51/files/Plass2009p33610.1002adma.200802006_supp.pdf" }, "resource_type": "article", "pub_year": "2009", "author_list": "Plass, Katherine E.; Filler, Michael A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/c84ry-b2n41", "eprint_id": 12759, "eprint_status": "archive", "datestamp": "2023-08-20 00:00:21", "lastmod": "2023-10-17 20:54:15", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Traub-M-C", "name": { "family": "Traub", "given": "Matthew C." } }, { "id": "Biteen-J-S", "name": { "family": "Biteen", "given": "Julie S." }, "orcid": "0000-0003-2038-6484" }, { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Phosphine Functionalization of GaAs(111)A Surfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2008 American Chemical Society. \n\nReceived: May 6, 2008; Revised Manuscript Received: September 8, 2008. Publication Date (Web): October 31, 2008. \n\nWe gratefully acknowledge the Department of Energy, Office of Basic Energy Sciences, for support of this work. The research was carried out in part at the National Synchrotron Light Source, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Division of Materials Sciences and Division of Chemical Sciences, under Contract No. DE-AC02-98CH10886. This research was carried out in part at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. We thank Michael Sullivan for use of the N2(g)-purged glovebox at the NSLS.", "abstract": "Phosphorus-functionalized GaAs surfaces have been prepared by exposure of Cl-terminated GaAs(111)A surfaces to triethylphosphine (PEt3) or trichlorophosphine (PCl3), or by the direct functionalization of the native-oxide terminated GaAs(111)A surface with PCl3. The presence of phosphorus on each functionalized surface was confirmed by X-ray photoelectron spectroscopy. High-resolution, soft X-ray photoelectron spectroscopy was used to evaluate the As and Ga 3d regions of such surfaces. On PEt3 treated surfaces, the Ga 3d spectra exhibited a bulk Ga peak as well as peaks that were shifted to 0.35, 0.92 and 1.86 eV higher binding energy. These peaks were assigned to residual Cl-terminated Ga surface sites, surficial Ga2O and surficial Ga2O3, respectively. For PCl3-treated surfaces, the Ga 3d spectra displayed peaks ascribable to bulk Ga(As), Ga2O, and Ga2O3, as well as a peak shifted 0.30 eV to higher binding energy relative to the bulk signal. A peak corresponding to Ga(OH)3, observed on the Cl-terminated surface, was absent from all of the phosphine-functionalized surfaces. After reaction of the Cl-terminated GaAs(111)A surface with PCl3 or PEt3, the As 3d spectral region was free of As oxides and As0. Although native oxide-terminated GaAs surfaces were free of As oxides after reaction with PCl3, such surfaces contained detectable amounts of As0. Photoluminescence measurements indicted that phosphine-functionalized surfaces prepared from Cl-terminated GaAs(111)A surfaces had better electrical properties than the native-oxide capped GaAs(111)A surface, while the native-oxide covered surface treated with PCl3 showed no enhancement in PL intensity.", "date": "2008-11-27", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "112", "number": "47", "publisher": "American Chemical Society", "pagerange": "18467-18473", "id_number": "CaltechAUTHORS:TRAjpcc08", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:TRAjpcc08", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-98CH10886" } ] }, "doi": "10.1021/jp803992h", "resource_type": "article", "pub_year": "2008", "author_list": "Traub, Matthew C.; Biteen, Julie S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/vzvpj-q7v96", "eprint_id": 13496, "eprint_status": "archive", "datestamp": "2023-08-22 13:12:47", "lastmod": "2023-10-17 23:56:42", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "Morgan C." } }, { "id": "Filler-M-A", "name": { "family": "Filler", "given": "Michael A." }, "orcid": "0000-0003-4239-8558" }, { "id": "Kayes-B-M", "name": { "family": "Kayes", "given": "Brendan M." } }, { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Guan-Yunbin", "name": { "family": "Guan", "given": "Yunbin" }, "orcid": "0000-0002-7636-3735" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Eiler-J-M", "name": { "family": "Eiler", "given": "John M." } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Secondary ion mass spectrometry of vapor\u2212liquid\u2212solid grown, Au-catalyzed, Si wires", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2008 American Chemical Society.\n\nReceived April 30, 2008; Revised Manuscript Received July 18, 2008.\nThe authors thank BP and the Caltech\nCenter for Sustainable Energy Research for support and\nacknowledge use of facilities of the Center for the Science\nof Materials, an NSF MRSEC. The authors also thank Jen\nDionne for SEM support. \n\nSupporting Information Available: Further experimental\ndetails, sputtering volumes, and count rates. This material\nis available free of charge via the Internet at http://pubs.acs.org.\n\nSupplemental Material - PUTnl08_supp.pdf
", "abstract": "Knowledge of the catalyst concentration within vapor-liquid-solid (VLS) grown semiconductor wires is needed in order to assess potential limits to electrical and optical device performance imposed by the VLS growth mechanism. We report herein the use of secondary ion mass spectrometry to characterize the Au catalyst concentration within individual, VLS-grown, Si wires. For Si wires grown by chemical vapor deposition from SiCl_4 at 1000 \u00b0C, an upper limit on the bulk Au concentration was observed to be 1.7 x 10^16 atoms/cm^3, similar to the thermodynamic equilibrium concentration at the growth temperature. However, a higher concentration of Au was observed on the sidewalls of the wires.", "date": "2008-10", "date_type": "published", "publication": "Nano Letters", "volume": "8", "number": "10", "publisher": "American Chemical Society", "pagerange": "3109-3113", "id_number": "CaltechAUTHORS:PUTnl08", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:PUTnl08", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Caltech Center for Sustainable Energy Research" } ] }, "local_group": { "items": [ { "id": "Division-of-Geological-and-Planetary-Sciences" } ] }, "doi": "10.1021/nl801234y", "primary_object": { "basename": "PUTnl08_supp.pdf", "url": "https://authors.library.caltech.edu/records/vzvpj-q7v96/files/PUTnl08_supp.pdf" }, "resource_type": "article", "pub_year": "2008", "author_list": "Putnam, Morgan C.; Filler, Michael A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/p8s5x-3x231", "eprint_id": 13759, "eprint_status": "archive", "datestamp": "2023-08-22 13:09:36", "lastmod": "2023-10-18 00:07:15", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Paulauskas-I-E", "name": { "family": "Paulauskas", "given": "I. E." } }, { "id": "Katz-J-E", "name": { "family": "Katz", "given": "J. E." }, "orcid": "0000-0002-6242-2124" }, { "id": "Jellison-G-E-Jr", "name": { "family": "Jellison", "given": "G. E. Jr." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Boatner-L-A", "name": { "family": "Boatner", "given": "L. A." } } ] }, "title": "Photoelectrochemical studies of semiconducting photoanodes for hydrogen production via water dissociation", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Solar energy; Photoelectrochemical cells; Photoanodes; KTaO_3; BaTiO_3; SrTiO_3; ZnO", "note": "\u00a9 2008 Elsevier B.V. \n\nAvailable online 11 April 2008. \n\nThis research was sponsored by the DOE Office of Basic Energy Sciences, Division of Materials Sciences and Engineering. It was performed at the Oak Ridge National Laboratory, managed and operated by UT-Battelle, LLC.", "abstract": "Single crystals of various n-type semiconducting oxides have been investigated in order to better understand the relationship between their photoelectrochemical behavior and their optical properties. The single crystals used in this study were all n-type and consisted of: KTaO_3, BaTiO_3, SrTiO_3, and ZnO. Current density vs applied potential measurements indicated that all of the crystals exhibited diodic properties when in contact with a highly basic electrolyte (8.5 M NaOH at room temperature). The ZnO electrodes, however, exhibited some degradation after exposure to the operational cell environment. Results indicate that the spectral quantum yield of the crystals is related to the penetration depth of the incident light, meaning that electron\u2013hole pairs formed far from the semiconductor\u2013liquid junction are less likely to be collected than those formed near the surface (e.g. inside the depletion regions). Additionally the quantum yield was found to decrease with time. In the case of KTaO_3, the decay of the quantum yield was fit to a double exponential, which suggests that a complicated process is operative for this material. Ongoing research is directed toward understanding the influence of both temperature variations and the surface/electrolyte interface on the effects observed in the case of KTaO_3.", "date": "2008-09-30", "date_type": "published", "publication": "Thin Solid Films", "volume": "516", "number": "22", "publisher": "Elsevier", "pagerange": "8175-8178", "id_number": "CaltechAUTHORS:PAUtsf08", "issn": "0040-6090", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:PAUtsf08", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1016/j.tsf.2008.04.026", "resource_type": "article", "pub_year": "2008", "author_list": "Paulauskas, I. E.; Katz, J. E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wbg56-ajz23", "eprint_id": 13477, "eprint_status": "archive", "datestamp": "2023-08-22 13:08:37", "lastmod": "2023-10-17 23:55:33", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Maldonado-S", "name": { "family": "Maldonado", "given": "Stephen" }, "orcid": "0000-0002-2917-4851" }, { "id": "Garc\u00eda-Berr\u00edos-E", "name": { "family": "Garc\u00eda-Berr\u00edos", "given": "Edgardo" } }, { "id": "Woodka-M-D", "name": { "family": "Woodka", "given": "Marc D." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Detection of organic vapors and NH3(g) using thin-film carbon black-metallophthalocyanine composite chemiresistors", "ispublished": "pub", "full_text_status": "restricted", "keywords": "chemiresistor gas sensors; NH3; metallophthalocyanine; electronic nose", "note": "\u00a9 2008 Elsevier B.V. \n\nReceived 18 March 2008. Received in revised form 23 May 2008. Accepted 26 May 2008. Available online 12 June 2008. \n\nThe authors thank Dr. E. J. Severin and Dr. W. Z. Royea for helpful initial discussions. We gratefully acknowledge the Homeland Security Advanced Research Projects Agency, the Army Research Office, the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology, and Boeing Inc. for financial support, in addition to Next Dimension Technologies for donation of materials used in this work. The Ford Foundation, through the National Academy of Sciences, is acknowledged for a postdoctoral fellowship to S. M., and the National Science Foundation is acknowledged for a graduate fellowship to E. G.", "abstract": "Thin-film chemiresistive vapor sensors have been fabricated using composites of carbon black (CB) and metallophthalocyanines. The resulting sensors exhibited large, rapid, and reversible relative differential resistance changes upon exposure to a series of test organic vapors. The individual sensor responses, and collective sensor array properties for classification of a series of test organic vapors, were comparable to those of chemiresistor arrays made from composites of conductors and insulating organic polymers. In addition to displaying resistance responses to volatile organic compounds, the CB/metallophthalocyanine composite sensors exhibited a high sensitivity towards trace levels of NH_3(g) under ambient temperature and pressure conditions. No degradation in sensor response was observed after nearly 12 h of repeated exposure to 30 parts per million of NH_3(g) in air. Chemiresistors formed from composites of CB and zinc phthalocyanines demonstrated responses that were comparable to those of commercial NH_3(g) sensors. The CB/metallophthalocyanine composites thus broaden the types of materials that can be used for this type of low-power chemiresistive gas sensing, and broaden the types of analytes that can be sensitively detected to include inorganic gases as well as organic vapors.", "date": "2008-09-25", "date_type": "published", "publication": "Sensors and Actuators B: Chemical", "volume": "134", "number": "2", "publisher": "Elsevier", "pagerange": "521-531", "id_number": "CaltechAUTHORS:MALsab08", "issn": "0925-4005", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:MALsab08", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Homeland Security" }, { "agency": "Army Research Office (ARO)" }, { "agency": "Caltech Beckman Institute" }, { "agency": "Boeing Inc." }, { "agency": "Ford Foundation" }, { "agency": "National Academy of Sciences" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1016/j.snb.2008.05.047", "resource_type": "article", "pub_year": "2008", "author_list": "Maldonado, Stephen; Garc\u00eda-Berr\u00edos, Edgardo; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/z1e0e-qr391", "eprint_id": 13481, "eprint_status": "archive", "datestamp": "2023-08-22 13:03:56", "lastmod": "2024-01-12 23:30:57", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Crabtree-George-W", "name": { "family": "Crabtree", "given": "George W." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Solar energy conversion", "ispublished": "unpub", "full_text_status": "public", "keywords": "cells; efficiency; hydrogen; electricity", "note": "\u00a9 2008 American Institute of Physics. \n\nThis article is based on the conclusions contained in the report of the US Department of Energy Basic Energy Sciences Workshop on Solar Energy Utilization, April 18-21, 2005. We served as chair (Lewis) and co-chair (Crabtree) of the workshop and were principal editors of the report. We acknowledge the US Department of Energy for support of both the workshop and preparation of the manuscript. \n\nReprinted with permission from George W. Crabtree and Nathan S. Lewis, Physics Today, Vol. 60, March 2007, pages 37-42. Copyright 2007, American Institute of Physics\n\nPublished - CRAaipcp08.pdf
", "abstract": "If solar energy is to become a practical alternative to fossil fuels, we must have efficient ways to convert photons into electricity, fuel, and heat. The need for better conversion technologies is a driving force behind many recent developments in biology, materials, and especially nanoscience.", "date": "2008-09-12", "date_type": "published", "publisher": "American Institute of Physics", "place_of_pub": "Melville, NY", "pagerange": "309-321", "id_number": "CaltechAUTHORS:CRAaipcp08", "isbn": "9780735405721", "book_title": "Physics of sustainable energy : using energy efficiently and producing it renewably : Berkeley, California, 1-2 March 2008", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:CRAaipcp08", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Hafemeister-David", "name": { "family": "Hafemeister", "given": "David" } }, { "id": "Levi-Barbara-G", "name": { "family": "Levi", "given": "Barbara G." } }, { "id": "Levine-Mark-D", "name": { "family": "Levine", "given": "Mark D." } }, { "id": "Schwartz-Peter", "name": { "family": "Schwartz", "given": "Peter" } } ] }, "doi": "10.1063/1.2993729", "primary_object": { "basename": "CRAaipcp08.pdf", "url": "https://authors.library.caltech.edu/records/z1e0e-qr391/files/CRAaipcp08.pdf" }, "resource_type": "book_section", "pub_year": "2008", "author_list": "Crabtree, George W. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dkz0p-09h75", "eprint_id": 13077, "eprint_status": "archive", "datestamp": "2023-08-22 12:59:08", "lastmod": "2023-10-17 21:45:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Scanning tunneling microscopy studies of monolayer templates: alkylthioethers and alkylethers", "ispublished": "pub", "full_text_status": "restricted", "keywords": "SOLID-LIQUID INTERFACE; IMAGE-CONTRAST; PREFERENTIAL ADSORPTION; MOLECULAR-PATTERNS; FUNCTIONAL-GROUPS; STM IMAGES; N-ALKANES; GRAPHITE; HOPG; DYNAMICS", "note": "\u00a9 2008 American Chemical Society. \n\nReceived April 24, 2008. Revised manuscript received July 2, 2008. Published online on October 7, 2008. \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, and the Beckman Institute at the California Institute of Technology, for support of this work. K.M.P. acknowledges Karl Papadantonakis for his assistance with software design and debugging.", "abstract": "Scanning tunneling microscopy has been used to determine the molecular ordering in stable, ordered monolayers formed from long-chain normal and substituted alkanes in solution on highly oriented pyrolytic graphite surfaces. Monolayers were initially formed using an overlying solution of either a symmetrical dialkylthioether or a symmetrical dialkylether. Initially pure thioether solutions were then changed to nearly pure solutions of the identical chain-length ether, and vice versa. The direct application of a pure solution of long-chain symmetrical ethers onto graphite produced a lamellate monolayer within which the individual molecular axes were oriented at an angle of ~65\u00b0 to the lamellar axes. In contrast, a pure solution of long-chain symmetrical thioethers on graphite produced a monolayer within which the molecular axes were oriented perpendicular to the lamellar axes. When ethers were gradually added to solutions overlying pure thioether monolayers, the ethers substituted into the existing monolayer structure. Thus, the ether molecules could be forced to orient in the perpendicular thioether-like manner through the use of a thioether template monolayer. Continued addition of ethers to the solution ultimately produced a nearly pure ether monolayer that retained the orientation of the thioether monolayer template. However, a monolayer of thioether molecules formed by gradual substitution into an ether monolayer did not retain the 65\u00b0 orientation typical of dialkylethers, but exhibited the 90\u00b0 orientation typical of dialkylthioether monolayers. The thioethers and ethers were easily distinguished in images of mixed monolayers, allowing both an analysis of the distribution of the molecules within the mixed monolayers and a comparison of the monolayer compositions with those of the overlying solutions. Substitution of molecules into the template monolayer did not proceed randomly; instead, a molecule within a monolayer was more likely to be replaced by a molecule in the overlying solution if it was located next to a molecule that had already been replaced.", "date": "2008-09-03", "date_type": "published", "publication": "Langmuir", "volume": "24", "number": "19", "publisher": "American Chemical Society", "pagerange": "10543-10548", "id_number": "CaltechAUTHORS:PAPl08", "issn": "0743-7463", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:PAPl08", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/la801285u", "resource_type": "article", "pub_year": "2008", "author_list": "Papadantonakis, Kimberly M.; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cptb8-sgw20", "eprint_id": 79195, "eprint_status": "archive", "datestamp": "2023-08-19 23:28:42", "lastmod": "2023-10-26 14:40:49", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Smeigh-A-L", "name": { "family": "Smeigh", "given": "Amanda L." } }, { "id": "Katz-J-E", "name": { "family": "Katz", "given": "Jordan E." }, "orcid": "0000-0002-6242-2124" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "McCusker-J-K", "name": { "family": "McCusker", "given": "James K." } } ] }, "title": "Effect of the Presence of Iodide on the Electron Injection Dynamics of Dye-Sensitized TiO_2-Based Solar Cells", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2008 American Chemical Society. \n\nReceived 18 April 2008. Published online 23 July 2008. Published in print 1 August 2008. \n\nResearch was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. This work was supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Science, U.S. Department of Energy Grants DE-FG02-03ER15483 (N.S.L.) and DE-FG02-01ER15282 (J.K.M.).\n\nSupplemental Material - jp803402x-file001.pdf
", "abstract": "The electron injection dynamics of dye-sensitized TiO_2-based solar cells have been investigated to determine the effects of replacing the I_3^\u2212/I^\u2212 redox system by non-redox-active supporting electrolytes. TiO-2 films were sensitized with Ru(dcbpy)_2(NCS)_2, where dcbpy = 4,4\u2032-dicarboxylic acid-2,2\u2032-bipyridine (the \"N3\" dye), and placed in contact with either M(ClO_4) or M(I_3\u2212/I\u2212) solutions (M = Li^+ or (n-C_4H_9)_4N^+); cells that contained I_3\u2212/I\u2212 were fully functional solar cells whose steady-state photocurrents were directly measured. In (n-C_4H_9)_4N^+-containing solutions, significant differences were observed between the measured kinetics when ClO_4^\u2212 was replaced by the redox-active I3^\u2212/I^\u2212 system. In particular, a ps time scale loss of the metal-to-ligand charge-transfer excited-state of the N3 dye, associated with electron injection, that was observed in cells containing either LiClO_4 or [(n-C_4H_9)4N]ClO_4 was absent in fully functional solar cells that contained [(n-C_4H_9)_4N]I/I_2. These results underscore the importance of performing kinetics measurements on this class of solar cells under operational conditions if one is to obtain reliable correlations between the dynamics data and the steady-state performance metrics of the solar cell devices.", "date": "2008-08-14", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "112", "number": "32", "publisher": "American Chemical Society", "pagerange": "12065-12068", "id_number": "CaltechAUTHORS:20170719-090248351", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170719-090248351", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech Beckman Institute" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-03ER15483" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-01ER15282" } ] }, "doi": "10.1021/jp803402x", "primary_object": { "basename": "jp803402x-file001.pdf", "url": "https://authors.library.caltech.edu/records/cptb8-sgw20/files/jp803402x-file001.pdf" }, "resource_type": "article", "pub_year": "2008", "author_list": "Smeigh, Amanda L.; Katz, Jordan E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zf08j-0yf61", "eprint_id": 11229, "eprint_status": "archive", "datestamp": "2023-08-22 12:32:34", "lastmod": "2023-10-16 23:21:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Plass-K-E", "name": { "family": "Plass", "given": "Katherine E." } }, { "id": "Kayes-B-M", "name": { "family": "Kayes", "given": "Brendan M." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Repeated epitaxial growth and transfer of arrays of patterned, vertically aligned, crystalline Si wires from a single Si(111) substrate", "ispublished": "pub", "full_text_status": "public", "keywords": "catalysis, elemental semiconductors, epitaxial growth, nanowires, semiconductor growth, semiconductor quantum wires, silicon", "note": "\u00a9 2008 American Institute of Physics. \n\nReceived 26 May 2008; accepted 26 June 2008; published 25 July 2008. \n\nWe acknowledge the Department of Energy and BP plc for support of this work. We also acknowledge use of facilities supported by the Caltech Center for Science and Engineering of Materials, an NSF MRSEC, and the Caltech Center for Sustainable Energy Research.\n\nPublished - SPUapl08.pdf
", "abstract": "Multiple arrays of Si wires were sequentially grown and transferred into a flexible polymer film from a single Si(111) wafer. After growth from a patterned, oxide-coated substrate, the wires were embedded in a polymer and then mechanically separated from the substrate, preserving the array structure in the film. The wire stubs that remained were selectively etched from the Si(111) surface to regenerate the patterned substrate. Then the growth catalyst was electrodeposited into the holes in the patterned oxide. Cycling through this set of steps allowed regrowth and polymer film transfer of several wire arrays from a single Si wafer.", "date": "2008-07-21", "date_type": "published", "publication": "Applied Physics Letters", "volume": "93", "number": "3", "publisher": "American Institute of Physics", "pagerange": "Art. No. 032112", "id_number": "CaltechAUTHORS:SPUapl08", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:SPUapl08", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "BP plc" }, { "agency": "NSF" }, { "agency": "Caltech Center for Sustainable Energy Research" } ] }, "doi": "10.1063/1.2959184", "primary_object": { "basename": "SPUapl08.pdf", "url": "https://authors.library.caltech.edu/records/zf08j-0yf61/files/SPUapl08.pdf" }, "resource_type": "article", "pub_year": "2008", "author_list": "Spurgeon, Joshua M.; Plass, Katherine E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9mchq-ae242", "eprint_id": 14146, "eprint_status": "archive", "datestamp": "2023-08-19 22:59:32", "lastmod": "2023-10-18 16:09:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "The challenge and need for Energy & Environmental Science", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 The Royal Society of Chemistry 2008.\n\nPublished - Lewis2008p618Energ_Environ_Sci.pdf
", "abstract": "Progress in transitioning to a globally scalable and sustainable energy system is a world-wide problem and demands contributions from scientists, engineers, economists, policy makers, and decision makers around the world. Rapid progress on this urgent issue depends on the integration of perspectives in all of these areas, which is the underlying and unique charter of Energy & Environmental Science as a leading, interdisciplinary journal.", "date": "2008-07", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "1", "number": "1", "publisher": "Royal Society of Chemistry", "pagerange": "13-13", "id_number": "CaltechAUTHORS:20090504-112551203", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090504-112551203", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1039/b810864c", "primary_object": { "basename": "Lewis2008p618Energ_Environ_Sci.pdf", "url": "https://authors.library.caltech.edu/records/9mchq-ae242/files/Lewis2008p618Energ_Environ_Sci.pdf" }, "resource_type": "article", "pub_year": "2008", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/p6yz1-np309", "eprint_id": 75657, "eprint_status": "archive", "datestamp": "2023-08-19 22:38:42", "lastmod": "2023-10-25 15:11:35", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kayes-B-M", "name": { "family": "Kayes", "given": "B. M." } }, { "id": "Filler-M-A", "name": { "family": "Filler", "given": "M. A." }, "orcid": "0000-0003-4239-8558" }, { "id": "Henry-M-D", "name": { "family": "Henry", "given": "M. D." }, "orcid": "0000-0002-5201-0644" }, { "id": "Maiolo-J-R-III", "name": { "family": "Maiolo", "given": "J. R., III" } }, { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "M. D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "M. C." } }, { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "J. M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Plass-K-E", "name": { "family": "Plass", "given": "K. E." } }, { "id": "Scherer-A", "name": { "family": "Scherer", "given": "A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "H. A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Radial PN junction, wire array solar cells", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2008 IEEE. \n\nThis work was supported by BP, the Department of Energy, Office of Basic Energy Sciences, and the Center for Science and Engineering of Materials, an NSF Materi\u00adals Research Science and Engineering Center at Caltech. MDH thanks the Hertz Foundation for financial support.\n\nPublished - 04922460.pdf
", "abstract": "Radial pn junctions are of interest in photovoltaics because of their potential to reduce the materials costs associated with cell fabrication. However, devices fabricated to date based on Au-catalyzed vapor-liquid-solid growth have suffered from low open-circuit voltages (to our knowledge the highest reports are 260 mV in the solid state and 389 mV in solid-liquid junctions). Herein we report on the potential of low-cost catalysts such as Cu and Ni to fabricate Si wire arrays with potentially higher minority-carrier lifetimes than is possible with a Au catalyst, as well as on the use of reactive ion etching to fabricate high-purity analogs to vapor-liquid-solid grown arrays.", "date": "2008-05", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "id_number": "CaltechAUTHORS:20170403-171216874", "isbn": "978-1-4244-1640-0", "book_title": "33rd IEEE Photovoltaic Specialists Conference", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170403-171216874", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NSF" }, { "agency": "Fannie and John Hertz Foundation" } ] }, "doi": "10.1109/PVSC.2008.4922460", "primary_object": { "basename": "04922460.pdf", "url": "https://authors.library.caltech.edu/records/p6yz1-np309/files/04922460.pdf" }, "resource_type": "book_section", "pub_year": "2008", "author_list": "Kayes, B. M.; Filler, M. A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3y15j-bfb98", "eprint_id": 76492, "eprint_status": "archive", "datestamp": "2023-08-19 22:39:06", "lastmod": "2023-10-25 16:02:57", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "M. D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "D. B." } }, { "id": "Kayes-B-M", "name": { "family": "Kayes", "given": "B. M." } }, { "id": "Filler-M-A", "name": { "family": "Filler", "given": "M. A." }, "orcid": "0000-0003-4239-8558" }, { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "M. C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "H. A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Single-nanowire Si solar cells", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2008 IEEE. \n\nThis work was supported by BP, the Department of Energy, Office of Basic Energy Sciences, and the Center for Science and Engineering of Materials, an NSF Materi\u00adals Research Science and Engineering Center at Caltech.\n\nPublished - 04922736.pdf
", "abstract": "Solar cells based on arrays of CVD-grown Si nano- or micro-wires are being considered as a potentially low-cost route to implementing a vertical multijunction cell design via radial p-n junctions. This geometry has been predicted to enable efficiencies competitive with planar multicrystalline Si designs, while reducing the materials and processing costs of solar cell fabrication [1]. To further assess the potential efficiency of cells based on this design, we present here experimental measurements of minority carrier diffusion lengths and surface recombination rates within nanowires via fabrication and characterization of single-wire solar cell devices. Furthermore, we consider a potential Si wire array-based solar cell design, and present device physics modeling of single-wire photovoltaic efficiency. Based on experimentally observed diffusion lengths within our wires, we model a radial junction wire solar cell capable of 17% photovoltaic energy conversion efficiency.", "date": "2008-05", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "id_number": "CaltechAUTHORS:20170410-172724395", "isbn": "978-1-4244-1640-0", "book_title": "33rd IEEE Photovolatic Specialists Conference", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170410-172724395", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NSF" } ] }, "doi": "10.1109/PVSC.2008.4922736", "primary_object": { "basename": "04922736.pdf", "url": "https://authors.library.caltech.edu/records/3y15j-bfb98/files/04922736.pdf" }, "resource_type": "book_section", "pub_year": "2008", "author_list": "Kelzenberg, M. D.; Turner-Evans, D. B.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wzpvv-zs365", "eprint_id": 75760, "eprint_status": "archive", "datestamp": "2023-08-19 22:38:47", "lastmod": "2023-10-25 15:16:57", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kimball-G-M", "name": { "family": "Kimball", "given": "Gregory M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Synthesis and surface chemistry of Zn_3P_2", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2008 IEEE. \n\nThis work was supported by the Office of Energy Efficiency and Renewable Energy, US Department of Energy under grant DE-FG36-08G018006. One of us (GMK) acknowledges support under an NDSEG graduate fellowship. We also acknowledge use of facilities supported by the Center for Science and Engineering of Materials, an NSF MRSEC.\n\nPublished - 04922747.pdf
", "abstract": "Zinc phosphide (Zn_3P_2) is a promising alternative to traditional materials (e.g. CIGS, CdTe, a-Si) for thin film photovoltaics. Open circuit voltage in Zn_3P_2 cells has been limited by Fermi-level pinning due to surfaces states and heterojunction interdiffusion, motivating the need to prepare interfaces that are electrically passive and chemically inert. We investigated the surface chemistry of Zn_3P_2 via etching with bromine in methanol and passivation with ammonium sulfide in t-butanol. The treatment decreases surface oxidation as determined by x-ray photoelectron spectroscopy and provides a stable, low-defect interface as monitored by steady-state photoluminescence. Magnesium Schottky diodes fabricated with sulfur-passivated interfaces show evidence of enhanced barrier heights in comparison to control devices.", "date": "2008-05", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "id_number": "CaltechAUTHORS:20170405-165832245", "isbn": "978-1-4244-1640-0", "book_title": "33rd IEEE Photovolatic Specialists Conference", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170405-165832245", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG36-08G018006" }, { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" }, { "agency": "NSF" } ] }, "doi": "10.1109/PVSC.2008.4922747", "primary_object": { "basename": "04922747.pdf", "url": "https://authors.library.caltech.edu/records/wzpvv-zs365/files/04922747.pdf" }, "resource_type": "book_section", "pub_year": "2008", "author_list": "Kimball, Gregory M.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/87cjv-wp920", "eprint_id": 68686, "eprint_status": "archive", "datestamp": "2023-08-19 22:32:37", "lastmod": "2023-10-19 23:12:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A Comparison Between the Behavior of Nanorod Array and Planar Cd(Se, Te) Photoelectrodes", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2008 American Chemical Society. Publication Date (Web): March 25, 2008. \n\nWe acknowledge the Department of Energy and BP plc for financial support of this work and the NSF for a graduate research fellowship to J.M.S. We also gratefully acknowledge the assistance of J. E. Katz in performing spectral response experiments and acknowledge M. D. Kelzenberg for preparation of Figure 1. We are grateful to T. Mallouk of Penn State for discussion of results on CdTe nanorod arrays during the course of this work.", "abstract": "Analysis of the full device generation, transport, and recombination equations has shown that nanorod junction arrays can potentially offer improved photovoltaic performance relative to planar junctions for a carrier-collection limited absorber material not characterized by an excessively high rate of depletion-region recombination. To test this hypothesis, we have characterized planar and nanorod array photoelectrodes prepared by electrodeposition of Cd(Se, Te). The photoelectrochemical behavior of each type of photoelectrode was measured in contact with a liquid electrolyte consisting of aqueous 1 M S_2^(2-)/S^(2-), 1 M NaOH. The open-circuit photovoltage, V_(oc), short-circuit current density, J_(sc), fill factor, and overall energy conversion efficiency for both types of electrodes was measured under simulated 100 mW cm^(-2), Air Mass 1.5 conditions. V_(oc), J_(sc), and overall efficiencies were lower, on average, for nanorod array Cd(Se,Te) photoelectrodes, while the fill factors of the nanorod array photoelectrodes were generally superior to those of the planar junction devices. Importantly, the spectral response of the nanorod array photoelectrodes exhibited better quantum yields for collection of near-IR photons relative to collection of high-energy photons than did the planar photoelectrodes, in agreement with predictions of the theoretical model. The effects of surface recombination and junction area for both electrode designs have also been evaluated relative to planar photoelectrode junctions, using the Cd(Se,Te) electrode as a model system for the properties of nanorod array photoelectrodes.", "date": "2008-04-17", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "112", "number": "15", "publisher": "American Chemical Society", "pagerange": "6186-6193", "id_number": "CaltechAUTHORS:20160627-105252809", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160627-105252809", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "BP plc" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1021/jp077481u", "resource_type": "article", "pub_year": "2008", "author_list": "Spurgeon, Joshua M.; Atwater, Harry A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sq3mw-9e797", "eprint_id": 76661, "eprint_status": "archive", "datestamp": "2023-08-19 22:32:45", "lastmod": "2023-10-25 16:11:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Maiolo-J-R-III", "name": { "family": "Maiolo", "given": "James R., III" } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Macroporous Silicon as a Model for Silicon Wire Array Solar Cells", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2008 American Chemical Society. \n\nReceived: November 30, 2007; In Final Form: January 22, 2008. Publication Date (Web): March 26, 2008. \n\nWe thank the Department of Energy, Office of Basic Energy Sciences, and BP for support of this work and acknowledge the American Society for Engineering Education National Defense Science and Engineering Grant for a graduate fellowship to J.R.M.\n\nSupplemental Material - jp711340b-file003.pdf
", "abstract": "Macroporous silicon samples have been investigated in photoelectrochemical cells, and their behavior has been compared to that of conventional, planar, Si/liquid junctions. The liquid electrolyte junction provided a conformal contact to the macroporous Si and allowed assessment of the trade-offs between increased surface area and decreased carrier collection distances in such systems relative to the behavior of planar semiconductor/liquid photoelectrochemical junctions. The electrolyte contained the dimethylferrocene/dimethylferrocenium redox system in methanol because this system has been shown previously to produce bulk recombination-diffusion-limited contacts at planar Si(100) electrodes under 100 mW cm^(-2) of simulated air mass 1.5 illumination. Introduction of a network of \u223c2\u22123 \u03bcm diameter, \u223c80 \u03bcm long pores into the Si was found to slightly reduce the short-circuit photocurrent density and the open-circuit voltage of the system, but energy-conversion efficiencies in excess of 10% were nevertheless obtained from such samples. This system therefore validates the concept of using interpenetrating networks to produce efficient solar energy conversion devices in systems that do not have long carrier collection distances.", "date": "2008-04-17", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "112", "number": "15", "publisher": "American Chemical Society", "pagerange": "6194-6201", "id_number": "CaltechAUTHORS:20170419-085849940", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170419-085849940", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "BP" }, { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" } ] }, "doi": "10.1021/jp711340b", "primary_object": { "basename": "jp711340b-file003.pdf", "url": "https://authors.library.caltech.edu/records/sq3mw-9e797/files/jp711340b-file003.pdf" }, "resource_type": "article", "pub_year": "2008", "author_list": "Maiolo, James R., III; Atwater, Harry A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3n2z6-71s83", "eprint_id": 78298, "eprint_status": "archive", "datestamp": "2023-08-19 22:32:52", "lastmod": "2023-10-25 23:59:04", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Gstrein-F", "name": { "family": "Gstrein", "given": "Florian" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "The Role of Band Bending in Affecting the Surface Recombination Velocities for Si(111) in Contact with Aqueous Acidic Electrolytes", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2008 American Chemical Society. \n\nReceived 9 July 2007. Published online 27 March 2008. Published in print 1 April 2008. \n\nWe acknowledge the NSF, Grant CHE-0604894, for support of this work. D.J.M. also acknowledges the generous support of a Link Foundation Energy Fellowship.", "abstract": "The role of band bending in affecting surface recombination velocity measurements has been evaluated by combining barrier height data with charge-carrier lifetime measurements for Si(111) surfaces in contact with a variety of acidic aqueous electrolytes. Charge-carrier lifetimes and thus surface recombination velocities have been measured by contactless radio frequency photoconductivity decay techniques for long bulk lifetime n-Si(111) samples in contact with 11 M (40% by weight) NH_4F(aq), buffered (pH = 5) HF(aq), 27 M (48% by weight) HF(aq), or concentrated 18 M H_2SO_4. Regardless of the sample history or surface condition, long charge-carrier lifetimes were observed for n-Si(111) surfaces in contact with 11 M NH_4F(aq) or buffered HF(aq). On the basis of previous barrier height measurements, this behavior is consistent with the formation of an electrolyte-induced surface accumulation layer that reduces the rate of steady-state surface recombination even in the presence of a significant density of surface trap sites. A straightforward evaluation of the surface trap state density from the measured surface recombination velocities, S, is thus precluded for such Si/liquid contacts. In contrast, a wide range of S values, depending on the history of the sample and the state of the surface, were observed for n-Si(111) surfaces in contact with 27 M HF(aq). These results in conjunction with previously measured barrier height data indicate that the charge-carrier lifetimes measured for n-Si(111) in contact with 27 M HF(aq) can be directly correlated with the surface condition and the effective surface-state trap density. These conclusions were confirmed by measurements of the apparent S values of n-Si(111) surfaces in contact with various solutions in the presence of the known deep trap, Cu. For Si(111)/HF(aq) contacts, very high (\u2265920 \u00b1 270 cm s^(-1)) surface recombination velocities were observed when 0.16 mM (10 ppm) Cu^(2+) was in the solution and/or adsorbed onto the Si(111) surface as Cu^0 deposits, whereas low (100 \u00b1 75 or 225 \u00b1 20 cm s^(-1)) apparent surface recombination velocities were measured for Cu-contaminated Si(111) samples in contact with 0.16 mM (10 ppm) Cu^(2+)-containing 11 M NH_4F(aq) or BHF(aq) solutions, respectively.", "date": "2008-04-17", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "112", "number": "15", "publisher": "American Chemical Society", "pagerange": "5911-5921", "id_number": "CaltechAUTHORS:20170616-144405453", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170616-144405453", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "Link Foundation" } ] }, "doi": "10.1021/jp075354s", "resource_type": "article", "pub_year": "2008", "author_list": "Michalak, David J.; Gstrein, Florian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mv6c4-qq626", "eprint_id": 88133, "eprint_status": "archive", "datestamp": "2023-08-22 11:32:05", "lastmod": "2024-01-14 20:29:10", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Woodka-M-D", "name": { "family": "Woodka", "given": "Marc D." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Extraction of spatiotemporal response information from sorption-based cross-reactive sensor arrays for the identification and quantification of analyte mixtures", "ispublished": "unpub", "full_text_status": "public", "keywords": "electronic nose; sensor arrays; vapor detection; spatiotemporal response; carbon black composite sensors", "note": "\u00a9 2008 Society of Photo-Optical Instrumentation Engineers (SPIE). \n\nResearch was carried out in the Molecular Materials Research Center of the Beckman Institute at Caltech. This work was supported by the ARO ICB and Boeing.\n\nPublished - 69321M.pdf
", "abstract": "Linear sensor arrays made from small molecule/carbon black composite chemiresistors placed in a low headspace volume chamber, with vapor delivered at low flow rates, allowed for the extraction of chemical information that significantly increased the ability of the sensor arrays to identify vapor mixture components and to quantify their concentrations. Each sensor sorbed vapors from the gas stream to various degrees. Similar to gas chromatography, species having high vapor pressures were separated from species having low vapor pressures. Instead of producing typical sensor responses representative of thermodynamic equilibrium between each sensor and an unchanging vapor phase, sensor responses varied depending on the position of the sensor in the chamber and the time from the beginning of the analyte exposure. This spatiotemporal (ST) array response provided information that was a function of time as well as of the position of the sensor in the chamber. The responses to pure analytes and to multi-component analyte mixtures comprised of hexane, decane, ethyl acetate, chlorobenzene, ethanol, and/or butanol, were recorded along each of the sensor arrays. Use of a non-negative least squares (NNLS) method for analysis of the ST data enabled the correct identification and quantification of the composition of 2-, 3-, 4- and 5-component mixtures from arrays using only 4 chemically different sorbent films and sensor training on pure vapors only. In contrast, when traditional time- and position-independent sensor response information was used, significant errors in mixture identification were observed. The ability to correctly identify and quantify constituent components of vapor mixtures through the use of such ST information significantly expands the capabilities of such broadly cross-reactive arrays of sensors.", "date": "2008-04-08", "date_type": "published", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_pub": "Bellingham, WA", "pagerange": "Art. No. 69321M", "id_number": "CaltechAUTHORS:20180723-115437656", "isbn": "9780819471185", "book_title": "Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2008", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180723-115437656", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)" }, { "agency": "Boeing Corporation" } ] }, "local_group": { "items": [ { "id": "Kavli-Nanoscience-Institute" } ] }, "contributors": { "items": [ { "id": "Tomizuka-M", "name": { "family": "Tomizuka", "given": "Masayoshi" } } ] }, "doi": "10.1117/12.781517", "primary_object": { "basename": "69321M.pdf", "url": "https://authors.library.caltech.edu/records/mv6c4-qq626/files/69321M.pdf" }, "resource_type": "book_section", "pub_year": "2008", "author_list": "Woodka, Marc D.; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/54ynf-qtr05", "eprint_id": 74014, "eprint_status": "archive", "datestamp": "2023-08-19 22:25:15", "lastmod": "2023-10-24 22:00:15", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Plass-K-E", "name": { "family": "Plass", "given": "Katherine E." } }, { "id": "Liu-Xueliang", "name": { "family": "Liu", "given": "Xueliang" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Passivation and Secondary Functionalization of Allyl-Terminated Si(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2008 American Chemical Society. \n\nReceived 29 August 2007. Published online 20 February 2008. Published in print 1 March 2008. \n\nThis work was supported by the National Science Foundation (CHE-0604894), BP Solar, and the Molecular Materials Research Center of the Beckman Institute at the California Institute of Technology. The authors acknowledge Mr. David Knapp, Mr. David Gleason-Rohrer, and Dr. Stephen Maldonado for insightful discussions and experimental assistance.\n\nSupplemental Material - cm7024679-file002.pdf
", "abstract": "Synthesis of passivated silicon surfaces with tunable properties requires formation of a monolayer that includes a synthetically useful functional group, such as an alkene. Thus, Si(111) surfaces have been chemically and electrically passivated by attachment of an allyl monolayer. The structure of the monolayer was confirmed using infrared spectroscopy. The allyl-functionalized surface exhibited resistance to oxidation and had a low density of surface trap states. Metal-catalyzed reactions, in particular, Heck coupling and ruthenium-catalyzed olefin cross-metathesis, allowed attachment of small molecules despite the steric constraints of the dense surface-bound layer. Allyl-terminated silicon surfaces thus offer a means of attaching a variety of chemical moieties to a silicon surface through a short linking group, enabling applications in energy conversion, catalysis, and sensing.", "date": "2008-03-25", "date_type": "published", "publication": "Chemistry of Materials", "volume": "20", "number": "6", "publisher": "American Chemical Society", "pagerange": "2228-2233", "id_number": "CaltechAUTHORS:20170203-100736727", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170203-100736727", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "BP Solar" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/cm7024679", "primary_object": { "basename": "cm7024679-file002.pdf", "url": "https://authors.library.caltech.edu/records/54ynf-qtr05/files/cm7024679-file002.pdf" }, "resource_type": "article", "pub_year": "2008", "author_list": "Plass, Katherine E.; Liu, Xueliang; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/vavv9-da296", "eprint_id": 77498, "eprint_status": "archive", "datestamp": "2023-08-19 22:24:35", "lastmod": "2023-10-25 23:06:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Maldonado-S", "name": { "family": "Maldonado", "given": "Stephen" }, "orcid": "0000-0002-2917-4851" }, { "id": "Knapp-D", "name": { "family": "Knapp", "given": "David" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Near-Ideal Photodiodes from Sintered Gold Nanoparticle Films on Methyl-Terminated Si(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2008 American Chemical Society. \n\nReceived January 24, 2008. Publication Date (Web): February 27, 2008. \n\nWe gratefully acknowledge the National Science Foundation, grant No. CHE-0604894, for support of this work. S.M. also acknowledges financial support from the Ford Foundation, through the National Academies of Sciences.\n\nSupplemental Material - ja800603v-file001.pdf
", "abstract": "We report photocurrent-voltage data for improved n-Si/metal devices using CH_3-terminated n-Si(111) and Au nanoparticles (NPs). CH_3-terminated Si(111) surfaces maintain good electronic properties throughout device assembly, while the use of Au NPs as precursors to metal films circumvents the standard issues associated with interfacial reactivity of metals in Schottky barrier formation. Such devices demonstrate excellent photovoltaic properties, with photovoltages that approach the maximum values predicted for photodiodes that are limited by Si bulk diffusion/recombination processes rather than interfacial processes. These devices are compared to standard n-Si/Au devices made via thermally evaporated Au films which are well-known to be limited by junction-based recombination.", "date": "2008-03-19", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "130", "number": "11", "publisher": "American Chemical Society", "pagerange": "3300-3301", "id_number": "CaltechAUTHORS:20170516-110757358", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170516-110757358", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "Ford Foundation" }, { "agency": "National Academies of Sciences" } ] }, "doi": "10.1021/ja800603v", "primary_object": { "basename": "ja800603v-file001.pdf", "url": "https://authors.library.caltech.edu/records/vavv9-da296/files/ja800603v-file001.pdf" }, "resource_type": "article", "pub_year": "2008", "author_list": "Maldonado, Stephen; Knapp, David; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9xkwc-fw909", "eprint_id": 77656, "eprint_status": "archive", "datestamp": "2023-08-19 22:08:42", "lastmod": "2023-10-25 23:20:04", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Papadantonakis-Kimberly-M", "name": { "family": "Papadantonakis", "given": "Kimberly M." }, "orcid": "0000-0002-9900-5500" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Use of Alkane Monolayer Templates To Modify the Structure of Alkyl Ether Monolayers on Highly Ordered Pyrolytic Graphite", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2008 American Chemical Society. \n\nReceived August 21, 2007. In Final Form: September 20, 2007.\nPublication Date (Web): January 3, 2008. \n\nWe acknowledge the DOE Basic Energy Sciences and the Beckman Institute at the California Institute of Technology for partial support of this work.", "abstract": "Scanning tunneling microscopy (STM) has been used to investigate the structure of pure and mixed monolayers formed by adsorption of long-chain alkanes and/or ethers on highly ordered pyrolytic graphite. Application of a pure phenyloctane solution of simple alkanes, such as tritriacontane, CH_3(CH_2)_(31)CH_3, produced a monolayer within which the individual molecular axes were oriented perpendicular to the lamellar axes. In contrast, a pure solution of symmetrical long-chain ethers, such as di-n-hexadecyl ether, CH_3(CH_2)_(15)O(CH_2)_(15)CH_3, produced a monolayer within which the molecular axes were oriented at an angle of \u224865\u00b0 relative to the lamellar axes. The compositions of the overlying solutions were then gradually changed either from pure alkanes to nearly pure ethers or from pure ethers to nearly pure alkanes. When ethers replaced alkanes in the monolayer, the ethers conformed to the orientation within the existing alkane layer, rather than adopting the characteristic orientation of pure ether monolayers. However, when alkanes were incorporated into monolayers that had been formed from pure ether solutions, the orientation of the molecules within the monolayer converted to that characteristic of pure alkanes. Alkane monolayers thus acted as templates for subsequent ether layers, but ether monolayers did not act as templates for alkane layers.", "date": "2008-02-05", "date_type": "published", "publication": "Langmuir", "volume": "24", "number": "3", "publisher": "American Chemical Society", "pagerange": "857-861", "id_number": "CaltechAUTHORS:20170523-104012244", "issn": "0743-7463", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170523-104012244", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/la702585e", "resource_type": "article", "pub_year": "2008", "author_list": "Papadantonakis, Kimberly M.; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7y6pk-6ts11", "eprint_id": 77432, "eprint_status": "archive", "datestamp": "2023-08-19 22:06:49", "lastmod": "2023-10-25 23:02:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Turner-Evans-D-B", "name": { "family": "Turner-Evans", "given": "Daniel B." } }, { "id": "Kayes-B-M", "name": { "family": "Kayes", "given": "Brendan M." } }, { "id": "Filler-M-A", "name": { "family": "Filler", "given": "Michael A." }, "orcid": "0000-0003-4239-8558" }, { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "Morgan C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Photovoltaic Measurements in Single-Nanowire Silicon Solar Cells", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2008 American Chemical Society. \n\nReceived October 10, 2007. Publication Date (Web): February 13, 2008. \n\nThis work was supported by BP and in part by the National Science Foundation under Grant DMR 0606472 and also made use of facilities supported by the Center for Science and Engineering of Materials, an NSF Materials Research Science and Engineering Center at Caltech.", "abstract": "Single-nanowire solar cells were created by forming rectifying junctions in electrically contacted vapor\u2212liquid\u2212solid-grown Si nanowires. The nanowires had diameters in the range of 200 nm to 1.5 \u03bcm. Dark and light current\u2212voltage measurements were made under simulated Air Mass 1.5 global illumination. Photovoltaic spectral response measurements were also performed. Scanning photocurrent microscopy indicated that the Si nanowire devices had minority carrier diffusion lengths of \u223c2 \u03bcm. Assuming bulk-dominated recombination, this value corresponds to a minimum carrier lifetime of \u223c15 ns, or assuming surface-dominated recombination, to a maximum surface recombination velocity of approximately 1350 cm s^(-1). The methods described herein comprise a valuable platform for measuring the properties of semiconductor nanowires, and are expected to be instrumental when designing an efficient macroscopic solar cell based on arrays of such nanostructures.", "date": "2008-02", "date_type": "published", "publication": "Nano Letters", "volume": "8", "number": "2", "publisher": "American Chemical Society", "pagerange": "710-714", "id_number": "CaltechAUTHORS:20170512-150141056", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170512-150141056", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "NSF", "grant_number": "DMR-0606472" } ] }, "doi": "10.1021/nl072622p", "resource_type": "article", "pub_year": "2008", "author_list": "Kelzenberg, Michael D.; Turner-Evans, Daniel B.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4mq7b-2rr36", "eprint_id": 76958, "eprint_status": "archive", "datestamp": "2023-08-19 22:03:03", "lastmod": "2023-10-25 17:01:57", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Traub-M-C", "name": { "family": "Traub", "given": "Matthew C." } }, { "id": "Biteen-J-S", "name": { "family": "Biteen", "given": "Julie S." }, "orcid": "0000-0003-2038-6484" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Passivation of GaAs Nanocrystals by Chemical Functionalization", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2008 American Chemical Society. \n\nReceived August 10, 2007. Publication Date (Web): January 3, 2008. \n\nWe gratefully acknowledge the U.S. Department of Energy, Office of Basic Energy Sciences, for support of this work. We thank Dr. Carol Garland for assistance collecting TEM images. This research was carried out in part at the Molecular Materials Research Center in the Beckman Institute at Caltech.", "abstract": "The effective use of nanocrystalline semiconductors requires control of the chemical and electrical properties of their surfaces. We describe herein a chemical functionalization procedure to passivate surface states on GaAs nanocrystals. Cl-terminated GaAs nanocrystals have been produced by anisotropic etching of oxide-covered GaAs nanocrystals with 6 M HCl(aq). The Cl-terminated GaAs nanocrystals were then functionalized by reaction with hydrazine or sodium hydrosulfide. X-ray photoelectron spectroscopic measurements revealed that the surfaces of the Cl-, hydrazine-, and sulfide-treated nanocrystals were As-rich, due to significant amounts of As^0. However, no As^0 was observed in the photoelectron spectra after the hydrazine-terminated nanocrystals were annealed at 350\u00b0 C under vacuum. After the anneal, the N 1s peak of hydrazine-exposed GaAs nanocrystals shifted to 3.2 eV lower binding energy. This shift was accompanied by the appearance of a Ga 3d peak shifted 1.4 eV from the bulk value, consistent with the hypothesis that a gallium oxynitride capping layer had been formed on the nanocrystals during the annealing process. The band gap photoluminescence (PL) was weak from the Cl- and hydrazine- or sulfide-terminated nanocrystals, but the annealed nanocrystals displayed strongly enhanced band-edge PL, indicating that the surface states of GaAs nanocrystals were effectively passivated by this two-step, wet chemical treatment.", "date": "2008-01-23", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "130", "number": "3", "publisher": "American Chemical Society", "pagerange": "955-964", "id_number": "CaltechAUTHORS:20170426-143025493", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170426-143025493", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1021/ja076034p", "resource_type": "article", "pub_year": "2008", "author_list": "Traub, Matthew C.; Biteen, Julie S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/n2ybq-xc914", "eprint_id": 77655, "eprint_status": "archive", "datestamp": "2023-08-19 21:40:12", "lastmod": "2023-10-25 23:20:00", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Woodka-M-D", "name": { "family": "Woodka", "given": "Marc D." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Use of Spatiotemporal Response Information from Sorption-Based Sensor Arrays to Identify and Quantify the Composition of Analyte Mixtures", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2007 American Chemical Society. \n\nReceived August 29, 2007. Publication Date (Web): November 15, 2007. \n\nThe authors thank Dr. Michael C. Burl for valuable discussions regarding potential pattern recognition approaches. Research was carried out in the Molecular Materials Research Center of the Beckman Institute at Caltech. This work was supported by the ARO ICB, HSARPA, and Boeing.", "abstract": "Linear sensor arrays made from small molecule/carbon black composite chemiresistors placed in a low-headspace volume chamber, with vapor delivered at low flow rates, allowed for the extraction of new chemical information that significantly increased the ability of the sensor arrays to identify vapor mixture components and to quantify their concentrations. Each sensor sorbed vapors from the gas stream and, thereby, as in gas chromatography, separated species having high vapor pressures from species having low vapor pressures. Instead of producing only equilibrium-based sensor responses that were representative of the thermodynamic equilibrium partitioning of analyte between each sensor and the initial vapor phase, the sensor responses varied depending on the position of the sensor in the chamber and the time since the beginning of the analyte exposure. The concomitant spatiotemporal (ST) sensor array response therefore provided information that was a function of time, as well as of the position of the sensor in the chamber. The responses to pure analytes and to multicomponent analyte mixtures comprised of hexane, decane, ethyl acetate, chlorobenzene, ethanol, and/or butanol were recorded along each of the sensor arrays. Use of a non-negative least-squares (NNLS) method for analysis of the ST data enabled the correct identification and quantification of the composition of two-, three-, four-, and five-component mixtures from arrays using only four chemically different sorbent films. In contrast, when traditional time- and position-independent sensor response information was used, these same mixtures could not be identified or quantified robustly. The work has also demonstrated that, for ST data, NNLS yielded significantly better results than analyses using extended disjoint principal components modeling. The ability to correctly identify and quantify constituent components of vapor mixtures through the use of such ST information significantly expands the capabilities of such broadly cross-reactive arrays of sensors.", "date": "2007-12-18", "date_type": "published", "publication": "Langmuir", "volume": "23", "number": "26", "publisher": "American Chemical Society", "pagerange": "13232-13241", "id_number": "CaltechAUTHORS:20170523-101528170", "issn": "0743-7463", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170523-101528170", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)" }, { "agency": "Homeland Security Advanced Research Projects Agency" }, { "agency": "Boeing Corporation" } ] }, "doi": "10.1021/la7026708", "resource_type": "article", "pub_year": "2007", "author_list": "Woodka, Marc D.; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wtrsm-9wt42", "eprint_id": 79181, "eprint_status": "archive", "datestamp": "2023-08-19 21:39:53", "lastmod": "2023-10-26 14:39:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jaeckel-Bengt", "name": { "family": "Jaeckel", "given": "Bengt" } }, { "id": "Hunger-Ralf", "name": { "family": "Hunger", "given": "Ralf" } }, { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Jaegermann-Wolfram", "name": { "family": "Jaegermann", "given": "Wolfram" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "High-Resolution Synchrotron Photoemission Studies of the Electronic Structure and Thermal Stability of CH_(3-) and C_2H_(5-)functionalized Si(111) Surfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2007 American Chemical Society. \n\nReceived 2 July 2007. Published online 10 November 2007. Published in print 1 December 2007. \n\nWe gratefully acknowledge the National Science Foundation, Grant No. CHE-0604894, for support of this work (N.S.L. and L.J.W.) and for providing a graduate research fellowship to L.J.W. W.J. acknowledges the traveling support of the Deutsche Forschungsgemeinschaft, DFG Grant No. JA 85910-1. The BMBF is acknowledged for support for setting up and running SoLiAS at BESSY (Contracts 05 KS1RD1/0 and 05 KS4RD1/0, R.H. and W.J.) and for travelgrants (05 ES3XBA/5). This work was also supported by the European Network of Excellence FAME, WP6.", "abstract": "The relative coverage, thermal stability, and electronic properties of CH_(3-) and C_2H_(5-)functionalized Si(111) surfaces prepared by a two-step chlorination/alkylation procedure have been compared using high-resolution synchrotron photoemission spectroscopy. Whereas the CH_(3-) terminated Si(111) surface showed only one C 2s peak for the occupied \u03c3 orbitals, the C 2s spectra of C_2H_(5-)terminated Si(111) surfaces showed a symmetric splitting of the occupied \u03c3 orbitals, as expected for an ethyl moiety bonded to the surface. The C_2H_5 termination resulted in an unpinning of the Si surface Fermi level, with a band bending of \u223c0.2 eV, and produced a surface dipole potential step of \u22120.23(15) eV. The observed close-to-flat-band condition is similar to that of CH_3\u2212Si(111) and is consistent with H termination of the non-alkylated Si atop sites in the two-step chlorination/alkylation process. The C_2H_(5-)functionalized Si(111) surfaces decomposed at temperatures >300 \u00b0C, whereas CH_3\u2212Si(111) surfaces were stable up to at least 440 \u00b0C. The data clearly highlight the similarities and identify some significant differences between the behavior of the CH_3- and C_2H_(5-)functionalized Si(111) surfaces.", "date": "2007-12-13", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "111", "number": "49", "publisher": "American Chemical Society", "pagerange": "18204-18213", "id_number": "CaltechAUTHORS:20170719-065011465", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170719-065011465", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "Deutsche Forschungsgemeinschaft (DFG)", "grant_number": "JA 85910-1" }, { "agency": "Bundesministerium f\u00fcr Bildung und Forschung (BMBF)", "grant_number": "05 KS1RD1/0" }, { "agency": "Bundesministerium f\u00fcr Bildung und Forschung (BMBF)", "grant_number": "05 KS4RD1/0" }, { "agency": "Bundesministerium f\u00fcr Bildung und Forschung (BMBF)", "grant_number": "05 ES3XBA/5" }, { "agency": "European Network of Excellence FAME", "grant_number": "WP6" } ] }, "doi": "10.1021/jp0751413", "resource_type": "article", "pub_year": "2007", "author_list": "Jaeckel, Bengt; Hunger, Ralf; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/f3kqf-z9837", "eprint_id": 78190, "eprint_status": "archive", "datestamp": "2023-08-19 21:38:05", "lastmod": "2023-10-25 23:51:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Maldonado-S", "name": { "family": "Maldonado", "given": "Stephen" }, "orcid": "0000-0002-2917-4851" }, { "id": "Plass-K-E", "name": { "family": "Plass", "given": "Katherine E." } }, { "id": "Knapp-D", "name": { "family": "Knapp", "given": "David" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electrical Properties of Junctions between Hg and Si(111) Surfaces Functionalized with Short-Chain Alkyls", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2007 American Chemical Society. \n\nReceived 25 January 2007. Published online 1 September 2007. Published in print 1 December 2007. \n\nWe acknowledge the National Science Foundation, grant No. CHE-0604894, for support of this work. S.M. also acknowledges financial support from the Ford Foundation, through the National Academy of Sciences.\n\nSupplemental Material - jp070651isi20070629_022207.pdf
", "abstract": "Metal\u2212semiconductor junctions between Hg and chemically modified n- and p-Si(111) surfaces have been prepared and analyzed using current\u2212voltage and differential capacitance\u2212voltage methods. To understand the role of the interfacial dipole on interfacial charge transfer, silicon surfaces were modified with either nonstoichoimetric oxide (SiO_x), terminal monohydride, short (CnH_(2n+1)\u2212, n = 1, 2, 3) saturated alkyl chains, or propynyl (CH_3\u2212C\u2261C\u2212) groups. X-ray photoelectron spectra of the modified Si electrode surfaces taken before and after exposure to Hg contacts showed no evidence of irreversible chemical interactions between the Si and the Hg. Hg/Si contacts made using H-terminated Si(111) surfaces exhibited Schottky junctions having barrier heights (\u03a6_b) that were consistent with the known surface electron affinity of Si and the work function of Hg. In contrast, Si coated with a thin, chemically grown oxide formed Hg/Si junctions having barrier heights suggestive of Fermi level pinning. Si(111) surfaces modified with methyl groups yielded Hg junctions having barrier heights in accord with expectations based on the electron affinity (3.67 eV) and surface dipole (0.38 eV) measured on such surfaces by photoemission spectroscopy, attesting to the degree of chemical control that can be exerted over the barrier heights of such systems by surface functionalization methods. Incomplete coverages of functional groups produced by alkylation with ethyl or iso-propyl groups did not greatly impact the observed values of \u03a6_b relative to \u03a6_b values observed for CH_3-terminated Si(111) surfaces. However, the observed variation in \u03a6_b between nominally identical samples increased as the number of carbons in the functionalizing alkyl group increased. Junctions between Hg and Si(111) surfaces modified with propynyl groups showed nearly identical behavior to that of CH_3\u2212Si(111)/Hg contacts, both in average \u03a6_b values and standard deviation between samples. The behavior of Si/Hg interfaces modified with short organic functional groups is consistent with the efficacy and utility of passivated surfaces in modifying the properties of surface-based Si devices.", "date": "2007-12-06", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "111", "number": "48", "publisher": "American Chemical Society", "pagerange": "17690-17699", "id_number": "CaltechAUTHORS:20170614-082600888", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170614-082600888", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "Ford Foundation" } ] }, "doi": "10.1021/jp070651i", "primary_object": { "basename": "jp070651isi20070629_022207.pdf", "url": "https://authors.library.caltech.edu/records/f3kqf-z9837/files/jp070651isi20070629_022207.pdf" }, "resource_type": "article", "pub_year": "2007", "author_list": "Maldonado, Stephen; Plass, Katherine E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wt79r-ge344", "eprint_id": 78297, "eprint_status": "archive", "datestamp": "2023-08-19 21:26:16", "lastmod": "2023-10-25 23:58:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Gstrein-F", "name": { "family": "Gstrein", "given": "Florian" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Interfacial Energetics of Silicon in Contact with 11 M NH_4F(aq), Buffered HF(aq), 27 M HF(aq), and 18 M H_2SO_4", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2007 American Chemical Society. \n\nReceived 26 June 2007. Published online 12 October 2007. Published in print 1 November 2007. \n\nWe acknowledge the NSF, Grant CHE-0604894, for support of this work. DJM also acknowledges the generous support of a Link Foundation Energy Fellowship.", "abstract": "Open-circuit impedance spectra, channel impedance spectroscopy on solution-gated field-effect devices, and differential capacitance vs potential (Mott\u2212Schottky) measurements were used to determine the energetics of n-Si(111), n-Si(100), and p-Si(111) electrodes in contact with aqueous 11 M (40% by weight) NH_4F, buffered HF (BHF), 27 M (48%) HF(aq), and concentrated (18 M) H_2SO_4. A Mott\u2212Schottky analysis of A_s^2C_(sc)^(-2)-vs-E (where As is the interfacial area, and C_(sc) is the differential capacitance as a function of the electrode potential, E) data yielded reliable barrier heights for some silicon/liquid contacts in this work. Performing a Mott\u2212Schottky analysis, however, requires measurement of the differential capacitance under reverse bias, where oxidation or etching can occur for n-Si and where electroplating of metal contaminants can occur for p-Si. Hence, open-circuit methods would offer desirable, complementary approaches to probing the energetics of such contacts. Accordingly, open-circuit, near-surface channel conductance measurements have been performed using solution-gated n^+-p-Si(111)-n^+ and p^+-n-Si(100)-p^+ devices. Additionally, open-circuit impedance spectra were obtained for silicon electrodes in contact with these solutions. The combination of the three techniques indicated that the surfaces of n-Si(111) and n-Si(100) were under accumulation when in contact with either 11 M NH_4F(aq) or BHF(aq). The barrier heights for n-Si(111) and n-Si(100) in 11 M NH_4F(aq) were \u22120.065 \u00b1 0.084 V and \u22120.20 \u00b1 0.21 V, respectively, and were \u22120.03 \u00b1 0.19 V and \u22120.07 \u00b1 0.24 V, respectively, for these surfaces in contact with buffered HF(aq). Consistently, p-Si(111) surfaces were determined to be in inversion in contact with these electrolytes, exhibiting barrier heights of 0.984 \u00b1 0.078 V in contact with 11 M NH_4F(aq) and 0.97 \u00b1 0.22 V in contact with buffered HF(aq). In contact with 27 M HF(aq), n-Si(111) and n-Si(100) were in depletion, with barrier heights of 0.577 \u00b1 0.038 V and 0.400 \u00b1 0.057 V, respectively, and p-Si(111) was under inversion with a barrier height of 0.856 \u00b1 0.076 V. Measurements performed in 18 M H_2SO_4 revealed barrier heights of 0.75 \u00b1 0.11 V, 0.696 \u00b1 0.043 V, and 0.889 \u00b1 0.018 V for n-Si(111), n-Si(100), and p-Si(111), respectively, demonstrating that in 18 M H_2SO_4, the band edge positions of Si were different for different doping types. The barrier height data demonstrate that the observed low recombination rates of silicon in contact with 11 M NH_4F, BHF, or 18 M H_2SO_4 cannot necessarily be attributed to a reduction in the number of surface trap states. In part, low surface recombination rates are expected for such systems because the very large or very small barrier height for silicon in contact with these liquids provides a potential barrier that prevents one type of photogenerated carrier (either electrons or holes) from reaching the surface, thereby producing a low steady-state surface recombination rate.", "date": "2007-11-08", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "111", "number": "44", "publisher": "American Chemical Society", "pagerange": "16516-16532", "id_number": "CaltechAUTHORS:20170616-143033829", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170616-143033829", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "Link Foundation" } ] }, "doi": "10.1021/jp074971d", "resource_type": "article", "pub_year": "2007", "author_list": "Michalak, David J.; Gstrein, Florian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/tc5yb-s8078", "eprint_id": 76832, "eprint_status": "archive", "datestamp": "2023-08-19 21:08:25", "lastmod": "2023-10-25 16:54:25", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Maiolo-J-R-III", "name": { "family": "Maiolo", "given": "James R., III" } }, { "id": "Kayes-B-M", "name": { "family": "Kayes", "given": "Brendan M." } }, { "id": "Filler-M-A", "name": { "family": "Filler", "given": "Michael A." }, "orcid": "0000-0003-4239-8558" }, { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "Morgan C." } }, { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "High Aspect Ratio Silicon Wire Array Photoelectrochemical Cells", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2007 American Chemical Society. \n\nReceived July 3, 2007. Publication Date (Web): September 25, 2007. \n\nThis work was supported by BP and by the Department of Energy, Office of Basic Energy Sciences. This work was supported in part by the Center for Science and Engineering Materials, an NSF Materials Research Science and Engineering Center at Caltech. We acknowledge T. Mallouk and J. Redwing of Penn State for helpful discussions and for providing a preprint of their work, done concurrently, on Si nanowire arrays.\n\nSupplemental Material - ja074897csi20070910_021947.pdf
", "abstract": "In an effort to develop low-cost solar energy conversion techniques, high uniformity vertically oriented silicon wire arrays have been fabricated. These arrays, which allow for radial diffusion of minority charge carriers, have been measured in a photoelectrochemical cell. Large photovoltages (\u223c400 mV) have been measured, and these values are significantly greater than those obtained from the substrate alone. Additionally, the wire array samples displayed much higher current densities than the underlying substrate, demonstrating that significant energy conversion was occurring due to the absorption and charge-carrier transport in the vertically aligned Si wires. This method therefore represents a step toward the use of collection-limited semiconductor materials in a wire array format in macroscopic solar cell devices.", "date": "2007-10-17", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "129", "number": "41", "publisher": "American Chemical Society", "pagerange": "12346-12347", "id_number": "CaltechAUTHORS:20170421-155914069", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170421-155914069", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NSF" } ] }, "doi": "10.1021/ja074897c", "primary_object": { "basename": "ja074897csi20070910_021947.pdf", "url": "https://authors.library.caltech.edu/records/tc5yb-s8078/files/ja074897csi20070910_021947.pdf" }, "resource_type": "article", "pub_year": "2007", "author_list": "Maiolo, James R., III; Kayes, Brendan M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zd2nj-75281", "eprint_id": 9302, "eprint_status": "archive", "datestamp": "2023-08-22 10:10:25", "lastmod": "2023-10-16 22:08:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Powering the Planet [2007 MRS Spring Meeting Plenary Address]", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2007, Materials Research Society. \n\nThe following article is an edited transcript based on the plenary presentation given by Nathan S. Lewis (California Institute of Technology) on April 11, 2007, at the Materials Research Society Spring Meeting in San Francisco. \n\nI acknowledge the NSF and DOE for sustained support that has made this work possible.", "abstract": "I am humbled and honored to be here to tell you about a topic that is dear to everyone's heart \u2014 and vital to the future of our planet. My colleague, Richard Smalley, gave a presentation1 on this topic several years ago, at a similar MRS plenary session. Over the last few years of Dr. Smalley's life, he and I worked together, traveling across our country to deliver a message about a subject that we \u2014 like many others, both scientists and lay people \u2014 have come to believe is unequivocally the most important technological problem in the world: our global energy future. That is an incredibly powerful statement, one that during the next hour I hope to ably defend.", "date": "2007-10-01", "date_type": "published", "publication": "MRS Bulletin", "volume": "32", "number": "10", "publisher": "MRS Bulletin", "pagerange": "808-820", "id_number": "CaltechAUTHORS:LEWmrsb07", "issn": "0883-7694", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:LEWmrsb07", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "primary_object": { "basename": "LEWmrsb07.pdf", "url": "https://authors.library.caltech.edu/records/zd2nj-75281/files/LEWmrsb07.pdf" }, "resource_type": "article", "pub_year": "2007", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/88vd7-h8913", "eprint_id": 78199, "eprint_status": "archive", "datestamp": "2023-08-19 20:57:26", "lastmod": "2023-10-25 23:52:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Biteen-J-S", "name": { "family": "Biteen", "given": "Julie S." }, "orcid": "0000-0003-2038-6484" }, { "id": "Sweatlock-L-A", "name": { "family": "Sweatlock", "given": "Luke A." } }, { "id": "Mertens-H", "name": { "family": "Mertens", "given": "Hans" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Polman-A", "name": { "family": "Polman", "given": "Albert" }, "orcid": "0000-0002-0685-3886" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Plasmon-Enhanced Photoluminescence of Silicon Quantum Dots: Simulation and Experiment", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2007 American Chemical Society. \n\nReceived 30 May 2007. Published online 17 August 2007. Published in print 1 September 2007. \n\nThis work was partially supported by NSF Grant No. CHE-0604894 and by AFOSR MURI Award No. FA9550-04-1-0434. Work at AMOLF is part of the research program of FOM, supported by NWO and NANONED, a nanotechnology program of the Dutch Ministry of Economic Affairs. Metal nanoparticle arrays were fabricated and analyzed using the facilities of the Amsterdam nanoCenter.", "abstract": "The enhancement of photoluminescence emission from silicon quantum dots in the near field of cylindrical silver particles has been calculated using finite integration techniques. This computational method permitted a quantitative examination of the plasmon resonance frequencies and locally enhanced fields surrounding coupled arrays of silver particles having arbitrary shapes and finite sizes. We have studied Ag nanoparticles with diameters in the 50\u2212300 nanometer range and array pitches in the range of 50\u2212800 nm, near a plane of optical emitters spaced 10\u221240 nm from the arrays. The calculated and experimental plasmon resonance frequencies and luminescence enhancements are in good agreement. In the tens-of-nanometers size regime, for the geometries under investigation, two competing factors affect the photoluminescence enhancement; on one hand, larger field enhancements, which produce greater emission enhancements, exist around smaller silver particles. However, as the spacing of such particles is decreased to attain higher surface coverages, the interparticle coupling draws the enhanced field into the lateral gaps between particles and away from the emitters, leading to a decrease in the plasmonic emission enhancement. The computations have thus revealed the limitations of using arbitrarily dense arrays of plasmonic metal particles to enhance the emission from coplanar arrays of dipole-like emitters. For such a geometry, a maximum sixfold net emission enhancement is predicted for the situation in which the plasmonic layer is composed of 50 nm diameter Ag particles in an array having a 300 nm pitch.", "date": "2007-09-13", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "111", "number": "36", "publisher": "American Chemical Society", "pagerange": "13372-13377", "id_number": "CaltechAUTHORS:20170614-092803765", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170614-092803765", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "Air Force Office of Scientific Research (AFOSR) (MURI)", "grant_number": "FA9550-04-1-0434" }, { "agency": "Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)" }, { "agency": "Ministry of Economic Affairs (Netherlands)" } ] }, "doi": "10.1021/jp074160+", "resource_type": "article", "pub_year": "2007", "author_list": "Biteen, Julie S.; Sweatlock, Luke A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1cyzr-yfw73", "eprint_id": 77997, "eprint_status": "archive", "datestamp": "2023-08-19 20:56:04", "lastmod": "2023-10-25 23:38:40", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Rivillon-S", "name": { "family": "Rivillon Amy", "given": "Sandrine" } }, { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Chabal-Y-J", "name": { "family": "Chabal", "given": "Yves J." } }, { "id": "Wielunski-L", "name": { "family": "Wielunski", "given": "Leszek" } }, { "id": "Hurley-P-T", "name": { "family": "Hurley", "given": "Patrick T." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Investigation of the Reactions during Alkylation of Chlorine-Terminated Silicon (111) Surfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2007 American Chemical Society. \n\nReceived: March 5, 2007; In Final Form: May 29, 2007. Publication Date (Web): August 14, 2007. \n\nThis work was supported by the National Science Foundation (Grant CHE-0415652). The authors are grateful to Lauren J. Webb (Caltech) for fruitful discussions.", "abstract": "Absorption infrared spectroscopy (IRAS) and Rutherford backscattering (RBS) have been used to investigate the reaction of chlorine-terminated Si(111) surfaces with organometallic molecules (Grignard reagents). Although the predominant reaction leads to alkylation, with formation of covalent Si\u2212C bonds, evidenced by a 678 cm^(-1) feature assigned to the Si\u2212C stretch mode, solvents typically used during alkylation (tetrahydrofuran and methanol) can also react with Cl/Si(111) surfaces, either during the alkylation reaction or during the rinsing/cleaning process to form Si\u2212OC_nH_(2n+1) as observed by the presence of a SiO\u2212C stretch mode at 1090 cm^(-1). We also address the origin of some silicon oxidation observed after the methylation or ethylation reactions.", "date": "2007-09-06", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "111", "number": "35", "publisher": "American Chemical Society", "pagerange": "13053-13061", "id_number": "CaltechAUTHORS:20170607-101718449", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170607-101718449", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0415652" } ] }, "doi": "10.1021/jp071793f", "resource_type": "article", "pub_year": "2007", "author_list": "Rivillon Amy, Sandrine; Michalak, David J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/esrfq-97x88", "eprint_id": 8706, "eprint_status": "archive", "datestamp": "2023-08-22 09:57:40", "lastmod": "2023-10-16 21:40:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kayes-B-M", "name": { "family": "Kayes", "given": "Brendan M." } }, { "id": "Filler-M-A", "name": { "family": "Filler", "given": "Michael A." }, "orcid": "0000-0003-4239-8558" }, { "id": "Putnam-M-C", "name": { "family": "Putnam", "given": "Morgan C." } }, { "id": "Kelzenberg-M-D", "name": { "family": "Kelzenberg", "given": "Michael D." }, "orcid": "0000-0002-6249-2827" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Growth of vertically aligned Si wire arrays over large areas (>1 cm^2) with Au and Cu catalysts", "ispublished": "pub", "full_text_status": "public", "keywords": "annealing; catalysts; crystal growth from solution; crystal growth from vapour; elemental semiconductors; photolithography; semiconductor growth; silicon; wires", "note": "\u00a9 2007 American Institute of Physics. \n\n(Received 18 July 2007; accepted 12 August 2007; published online 5 September 2007) \n\nThis work was supported by BP, the Department of Energy, Office of Basic Energy Sciences, and the Center for Science and Engineering of Materials, an NSF Materials Research Science and Engineering Center at Caltech.\n\nPublished - KAYapl07.pdf
Supplemental Material - KAYapl07readme.txt
Supplemental Material - KAYapl07supp.pdf
", "abstract": "Arrays of vertically oriented Si wires with diameters of 1.5 \u00b5m and lengths of up to 75 \u00b5m were grown over areas >1 cm^2 by photolithographically patterning an oxide buffer layer, followed by vapor-liquid-solid growth with either Au or Cu as the growth catalyst. The pattern fidelity depended critically on the presence of the oxide layer, which prevented migration of the catalyst on the surface during annealing and in the early stages of wire growth. These arrays can be used as the absorber material in novel photovoltaic architectures and potentially in photonic crystals in which large areas are needed.", "date": "2007-09-03", "date_type": "published", "publication": "Applied Physics Letters", "volume": "91", "number": "10", "publisher": "American Institute of Physics", "pagerange": "Art. No. 103110", "id_number": "CaltechAUTHORS:KAYapl07", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:KAYapl07", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NSF" } ] }, "doi": "10.1063/1.2779236", "primary_object": { "basename": "KAYapl07.pdf", "url": "https://authors.library.caltech.edu/records/esrfq-97x88/files/KAYapl07.pdf" }, "related_objects": [ { "basename": "KAYapl07readme.txt", "url": "https://authors.library.caltech.edu/records/esrfq-97x88/files/KAYapl07readme.txt" }, { "basename": "KAYapl07supp.pdf", "url": "https://authors.library.caltech.edu/records/esrfq-97x88/files/KAYapl07supp.pdf" } ], "resource_type": "article", "pub_year": "2007", "author_list": "Kayes, Brendan M.; Filler, Michael A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/aehsf-x6438", "eprint_id": 120621, "eprint_status": "archive", "datestamp": "2023-08-22 09:31:56", "lastmod": "2023-10-18 17:55:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hunger-Ralf", "name": { "family": "Hunger", "given": "Ralf" } }, { "id": "Fritsche-Rainer", "name": { "family": "Fritsche", "given": "Rainer" } }, { "id": "Jaeckel-Bengt", "name": { "family": "Jaeckel", "given": "Bengt" } }, { "id": "Webb-Lauren-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Jaegermann-Wolfram", "name": { "family": "Jaegermann", "given": "Wolfram" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "High-resolution photoemission studies of the interfacial reactivity and interfacial energetics of Au and Cu Schottky barriers on methyl-terminated Si(111) surfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Surfaces, Coatings and Films; Surfaces and Interfaces; Condensed Matter Physics", "note": "We gratefully acknowledge the National Science Foundation, Grant CHE-0604894, for support of this work (N.S.L. and L.J.W.) and for providing a graduate research fellowship to L.J.W. W.J. acknowledges the travelling support of the Deutsche Forschungsgemeinschaft, DFG Grant No. JA 85910-1. The support of the BMBF for setting-up and running SoLiAS at BESSY (contracts 05 KS1RD1/0 and 05 KS4RD1/0, R.H. and W.J.) and travel Grants (05 ES3XBA/5) are gratefully acknowledged. This work was also supported by the European Network of Excellence FAME (WP 6).", "abstract": "The Schottky junction formation by the stepwise evaporation of gold and copper, respectively, onto methyl-terminated silicon, CH\u2083\u2013Si(1 1 1), was investigated by synchrotron X-ray photoelectron spectroscopy. During the junction formation process, interface reactions occurred as revealed by the appearance of chemically shifted Si 2p components. Upon deposition of Au, the formation of about one monolayer of gold silicide, SiAu\u2083, with a Si 2p chemical shift of +0.75(2) eV, was observed. The SiAu\u2083 floated on top of the growing gold layer. Similarly, for the deposition of Cu, the methyl termination layer was partially disrupted, as indicated by the appearance of a \u22120.28(2) eV chemically shifted Si 2p component attributable to an interfacial copper silicide phase, SiCu\u2083. Hence, the termination of the Si(1 1 1) surface by methyl groups did not completely prevent interfacial reactions, but did reduce the amount interfacial reaction products as compared to bare Si(1 1 1)-(7 \u00d7 7) surfaces. \n\nElectron Schottky barrier heights of 0.78(8) eV (Au) and 0.61(8) eV (Cu) were measured. Within the experimental uncertainty the observed Schottky barriers were identical to those ones obtained on non-passivated, (7 \u00d7 7)-reconstructed Si(1 1 1) surfaces. Thus, the modification of the electronic properties of the silicon\u2013metal contact requires the complete absence of interfacial reactions.", "date": "2007-07-15", "date_type": "published", "publication": "Surface Science", "volume": "601", "number": "14", "publisher": "Elsevier", "pagerange": "2896-2907", "id_number": "CaltechAUTHORS:20230329-400559000.2", "issn": "0039-6028", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-400559000.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Deutsche Forschungsgemeinschaft (DFG)", "grant_number": "JA 85910-1" }, { "agency": "Bundesministerium f\u00fcr Bildung und Forschung (BMBF)", "grant_number": "05 KS1RD1/0" }, { "agency": "Bundesministerium f\u00fcr Bildung und Forschung (BMBF)", "grant_number": "05 KS4RD1/0" }, { "agency": "Bundesministerium f\u00fcr Bildung und Forschung (BMBF)", "grant_number": "05 ES3XBA/5" } ] }, "doi": "10.1016/j.susc.2007.04.249", "resource_type": "article", "pub_year": "2007", "author_list": "Hunger, Ralf; Fritsche, Rainer; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/h8r07-dq052", "eprint_id": 76950, "eprint_status": "archive", "datestamp": "2023-08-19 20:29:05", "lastmod": "2023-10-25 17:01:21", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Traub-M-C", "name": { "family": "Traub", "given": "Matthew C." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Relationships between Nonadiabatic Bridged Intramolecular, Electrochemical, and Electrical Electron-Transfer Processes", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2007 American Chemical Society. \n\nReceived: August 25, 2006; In Final Form: October 27, 2006.\nPublication Date (Web): April 12, 2007. \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, and the Beckman Institute, for support of this work. We also acknowledge the extensive contributions and inspiration of Norman Sutin to the field of electron transfer which has provided the basis for this work. We specifically acknowledge the helpful comments Dr. Sutin provided on this manuscript.", "abstract": "Fermi's golden rule is used to develop relationships between rate constants for electron transfer in donor\u2212bridge\u2212acceptor and electrode\u2212bridge\u2212acceptor systems and resistances across metal\u2212bridge\u2212electrode and metal\u2212bridge\u2212tip junctions. Experimental data on electron-transfer rates through alkanethiolate, oligophenylene, and DNA bridges are used to calculate the electronic coupling matrix element per state through these moieties. The formulation is then used to predict the resistance of these bridges between two gold contacts. This approach provides a straightforward method for experimentalists to assess the self-consistency between intramolecular electron-transfer rate constants and low-bias resistances measured for molecularly bridged junctions between two metallic contacts. Reported resistances for alkanethiolate bridges vary by a factor of 20, with predicted resistances falling within this range. However, comparisons between carboxylato and directly linked alkanethiolate bridges suggest differences between the coupling at the interface to either the redox center or the gold electrode in such systems. Calculated resistances for oligophenylene bridges are close to those measured experimentally in a similar oligophenylene system.", "date": "2007-06-21", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "111", "number": "24", "publisher": "American Chemical Society", "pagerange": "6676-6683", "id_number": "CaltechAUTHORS:20170426-111951613", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170426-111951613", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/jp065520g", "resource_type": "article", "pub_year": "2007", "author_list": "Traub, Matthew C.; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sqfcd-z2a89", "eprint_id": 78050, "eprint_status": "archive", "datestamp": "2023-08-19 20:27:13", "lastmod": "2023-10-25 23:42:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gstrein-F", "name": { "family": "Gstrein", "given": "Florian" } }, { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Knapp-D-W", "name": { "family": "Knapp", "given": "David W." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Near-Surface Channel Impedance Measurements, Open-Circuit Impedance Spectra, and Differential Capacitance vs Potential Measurements of the Fermi Level Position at Si/CH_3CN Contacts", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2007 American Chemical Society. \n\nReceived 22 September 2006. Published online 15 May 2007. Published in print 1 June 2007. \n\nWe acknowledge the National Science Foundation, Grant CHE-0604894, for support of this work and the Link Energy Foundation for a graduate fellowship to D.J.M.", "abstract": "Near-surface channel impedance measurements, open-circuit impedance spectra, and differential capacitance vs potential measurements have been used to determine the barrier height of liquid contacts formed with n-type and p-type Si electrodes. Barrier heights were measured as the redox potential, E(A/A^-), of a metallocene-based, one-electron, outer-sphere, acceptor/donor (A/A^-) pair was varied in CH_3CN solvent. The barrier heights of p-Si(111) electrodes in contact with CH_3CN\u2212Me_(10)Fc^(+/0) (where Me_(10)Fc is decamethylferrocene) or CH_3CN-CoCp_2^(+/0) (where CoCp_2 is cobaltocene) were 0.69 \u00b1 0.1 and 1.1 \u00b1 0.1 V respectively. In contrast, barrier heights for n-Si(111)/CH_3CN\u2212Me_(10)Fc^(+/0) and n-Si(111)/CH_3CN-CoCp_2^(+/0) contacts were 0.66 \u00b1 0.1 and 0.09 \u00b1 0.01 V, respectively. These measurements indicate that the barrier heights closely track changes in the electrochemical potential of the contact, instead of being relatively invariant to changes in the Fermi level of the contacting phase, as is observed for Si/metal Schottky barriers. These measurements also demonstrate that the low effective surface recombination velocity, S, for silicon in contact with CoCp_2^(+/0) is primarily the result of an accumulation layer rather than solely being due to a low density of surface electrical defects.", "date": "2007-06-07", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "111", "number": "22", "publisher": "American Chemical Society", "pagerange": "8120-8127", "id_number": "CaltechAUTHORS:20170609-091424987", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170609-091424987", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "Link Foundation" } ] }, "doi": "10.1021/jp066226r", "resource_type": "article", "pub_year": "2007", "author_list": "Gstrein, Florian; Michalak, David J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/p8zwh-2jb02", "eprint_id": 7721, "eprint_status": "archive", "datestamp": "2023-08-22 08:40:25", "lastmod": "2023-10-16 21:04:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Crabtree-G-W", "name": { "family": "Crabtree", "given": "George W." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Solar energy conversion", "ispublished": "pub", "full_text_status": "public", "keywords": "CELLS; EFFICIENCY; HYDROGEN; ELECTRICITY", "note": "\u00a9 2007 by the American Institute of Physics. \n\nThis article is based on the conclusions contained in the report [1] of the US Department of Energy Basic Energy Sciences Workshop on Solar Energy Utilization, April 18\u201321, 2005. We served as chair (Lewis) and cochair (Crabtree) of the workshop and were principal editors of the report. We acknowledge the US Department of Energy for support of both the workshop and preparation of the manuscript.", "abstract": "If solar energy is to become a practical alternative to fossil fuels, we must have efficient ways to convert photons into electricity, fuel, and heat. The need for better conversion technologies is a driving force behind many recent developments in biology, materials, and especially nanoscience.", "date": "2007-03-01", "date_type": "published", "publication": "Physics Today", "volume": "60", "number": "3", "publisher": "Physics Today", "pagerange": "37-42", "id_number": "CaltechAUTHORS:CRApt07", "issn": "0031-9228", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:CRApt07", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1063/1.2718755", "primary_object": { "basename": "CRApt07.pdf", "url": "https://authors.library.caltech.edu/records/p8zwh-2jb02/files/CRApt07.pdf" }, "resource_type": "article", "pub_year": "2007", "author_list": "Crabtree, George W. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ad5c4-yay51", "eprint_id": 51743, "eprint_status": "archive", "datestamp": "2023-08-19 19:39:19", "lastmod": "2023-10-18 17:06:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Toward Cost-Effective Solar Energy Use", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2007 American Association for the Advancement of Science.\n\nSupported by the U.S. Department of Energy and NSF.", "abstract": "At present, solar energy conversion technologies face cost and scalability hurdles in the technologies required for a complete energy system. To provide a truly widespread primary energy source, solar energy must be captured, converted, and stored in a cost-effective fashion. New developments in nanotechnology, biotechnology, and the materials and physical sciences may enable step-change approaches to cost-effective, globally scalable systems for solar energy use.", "date": "2007-02-09", "date_type": "published", "publication": "Science", "volume": "315", "number": "5813", "publisher": "American Association for the Advancement of Science", "pagerange": "798-801", "id_number": "CaltechAUTHORS:20141114-085153920", "issn": "0036-8075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141114-085153920", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "NSF" } ] }, "doi": "10.1126/science.1137014", "resource_type": "article", "pub_year": "2007", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ydhnv-cg122", "eprint_id": 78977, "eprint_status": "archive", "datestamp": "2023-08-19 19:07:40", "lastmod": "2023-10-26 14:30:33", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hamann-T-W", "name": { "family": "Hamann", "given": "Thomas W." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparison of the Self-Exchange and Interfacial Charge-Transfer Rate Constants for Methyl- versustert-Butyl-Substituted Os(III) Polypyridyl Complexes", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society. \n\nReceived 2 August 2006. Published online 14 December 2006. Published in print 1 December 2006. \n\nWe thank Dr. Norman Sutin for very helpful discussions. We thank the Office of Basic Energy Sciences, Department of Energy, for support of this work, and acknowledge support from the Molecular Materials Resource Center of the Beckman Institute at the California Institute of Technology.", "abstract": "Differences in the self-exchange and interfacial electron-transfer rate constants have been evaluated for a relatively unhindered Os(III/II) redox system, osmium(III/II) tris(4,4'-di-methyl-2,2'-bipyridyl), [Os(Me_2bpy)_3]^(3+/2+), relative to those of a relatively hindered system, osmium(III/II) tris(4,4'-di-tert-butyl-2,2'-bipyridyl), [Os(t-Bu_2bpy)_3]^(3+/2+). In contrast to the predicted increase in rate constant by a factor of 2\u22123 due to the difference in reorganization energy of the two complexes, introduction of the tert-butyl functionality decreased the self-exchange rate constant, as measured by NMR line-broadening techniques, by a factor of \u223c50 as compared to that of the analogous methyl-substituted osmium complex. Steady-state current density versus potential measurements, in conjunction with differential capacitance versus potential measurements, were used to compare the interfacial electron-transfer rate constants at n-type ZnO electrodes of [Os(t-Bu_2bpy)_3]^(3+/2+) and [Os(Me_2bpy)_3]^(3+/2+). The interfacial electron-transfer rate constant for the reduction of [Os(t-Bu_2bpy)_3]^(3+) was 100 times smaller than that for [Os(Me_2bpy)_3]^(3+). The results indicate that the tert-butyl group can act as a spacer on an outer-sphere redox couple and significantly decrease the electronic coupling of the electron-transfer reaction in both self-exchange and interfacial electron-transfer processes.", "date": "2006-12-21", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "110", "number": "50", "publisher": "American Chemical Society", "pagerange": "25514-25520", "id_number": "CaltechAUTHORS:20170712-070026392", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170712-070026392", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/jp0649697", "resource_type": "article", "pub_year": "2006", "author_list": "Hamann, Thomas W.; Brunschwig, Bruce S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fqv9h-z9w54", "eprint_id": 78045, "eprint_status": "archive", "datestamp": "2023-08-19 18:57:19", "lastmod": "2023-10-25 23:41:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yu-Hongbin", "name": { "family": "Yu", "given": "Hongbin" } }, { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Solares-S-D", "name": { "family": "Solares", "given": "Santiago D." }, "orcid": "0000-0003-0895-8160" }, { "id": "Cao-Peigen", "name": { "family": "Cao", "given": "Peigen" } }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A., III" }, "orcid": "0000-0003-0097-5716" }, { "id": "Heath-J-R", "name": { "family": "Heath", "given": "James R." }, "orcid": "0000-0001-5356-4385" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Scanning Tunneling Microscopy of Ethylated Si(111) Surfaces Prepared by a Chlorination/Alkylation Process", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society. \n\nReceived 12 June 2006. Published online 9 November 2006. Published in print 1 November 2006. \n\nThe authors acknowledge the National Science Foundation, Grants CHE-0604894 (N.S.L.) and NSF-CCF-05204490, the MARCO Materials Structures and Devices Focus Center (J.R.H. and W.A.G), and the Department of Energy for support of this research. L.J.W. thanks the NSF for a graduate fellowship.", "abstract": "Scanning tunneling microscopy (STM) and computational modeling have been used to study the structure of ethyl-terminated Si(111) surfaces. The ethyl-terminated surface was prepared by treating the H-terminated Si(111) surface with PCl_5 to form a Cl-terminated Si(111) surface with subsequent exposure to C_2H_5MgCl in tetrahydrofuran to produce an alkylated Si(111) surface. The STM data at 77 K revealed local, close-packed, and relatively ordered regions with a nearest-neighbor spacing of 0.38 nm as well as disordered regions. The average spot density corresponded to \u224885% of the density of Si atop sites on an unreconstructed Si(111) surface. Molecular dynamics simulations of a Si(111) surface randomly populated with ethyl groups to a total coverage of \u224880% confirmed that the ethyl-terminated Si(111) surface, in theory, can assume reasonable packing arrangements to accommodate such a high surface coverage, which could be produced by an exoergic surface functionalization route such as the two-step chlorination/alkylation process. Hence, it is possible to consistently interpret the STM data within a model suggested by recent X-ray photoelectron spectroscopic data and infrared absorption data, which indicate that the two-step halogenation/alkylation method can provide a relatively high coverage of ethyl groups on Si(111) surfaces.", "date": "2006-11-30", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "110", "number": "47", "publisher": "American Chemical Society", "pagerange": "23898-23903", "id_number": "CaltechAUTHORS:20170609-082013306", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170609-082013306", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "NSF", "grant_number": "CCF-05204490" }, { "agency": "Microelectronics Advanced Research Corporation (MARCO)" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1021/jp063655g", "resource_type": "article", "pub_year": "2006", "author_list": "Yu, Hongbin; Webb, Lauren J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1sb2z-vp537", "eprint_id": 78005, "eprint_status": "archive", "datestamp": "2023-08-19 18:55:01", "lastmod": "2023-10-25 23:39:18", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Biteen-J-S", "name": { "family": "Biteen", "given": "Julie S." }, "orcid": "0000-0003-2038-6484" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Chan-Ally-S-Y", "name": { "family": "Chan", "given": "Ally S. Y." } }, { "id": "Knapp-D-W", "name": { "family": "Knapp", "given": "David W." } }, { "id": "Meyer-H-M-III", "name": { "family": "Meyer", "given": "Harry M., III" } }, { "id": "Nemanick-E-J", "name": { "family": "Nemanick", "given": "Eric J." }, "orcid": "0000-0002-4650-6491" }, { "id": "Traub-M-C", "name": { "family": "Traub", "given": "Matthew C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "High-Resolution Soft X-ray Photoelectron Spectroscopic Studies and Scanning Auger Microscopy Studies of the Air Oxidation of Alkylated Silicon(111) Surfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society. \n\nReceived 31 May 2006. Published online 31 October 2006. Published in print 1 November 2006. \n\nWe gratefully acknowledge the National Science Foundation for support of this work (grants CHE-0213589) and for providing a graduate research fellowship to L.J.W. A.C. acknowledges support from the Army Research Office. This research was carried out in part at the National Synchrotron Light Source, Brookhaven National Laboratory, which is supported by the U. S. Department of Energy, Division of Materials Sciences and Division of Chemical Sciences, under Contract No. DE-AC02-98CH10886. We thank Michael Sullivan for use of the N2(g)-purged glovebox at the NSLS. The scanning Auger microscopy was sponsored by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of FreedomCAR and Vehicle Technologies, as part of the High Temperature Materials Laboratory User Program, Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy under contract number DE-AC05-00OR22725. We also thank Y. Chabal for sharing a preprint of his manuscript on the oxidation of silicon in air.", "abstract": "High-resolution soft X-ray photoelectron spectroscopy was used to investigate the oxidation of alkylated silicon(111) surfaces under ambient conditions. Silicon(111) surfaces were functionalized through a two-step route involving radical chlorination of the H-terminated surface followed by alkylation with alkylmagnesium halide reagents. After 24 h in air, surface species representing Si^+, Si^(2+), Si^(3+), and Si^(4+) were detected on the Cl-terminated surface, with the highest oxidation state (Si^(4+)) oxide signal appearing at +3.79 eV higher in energy than the bulk Si 2p_(3/2) peak. The growth of silicon oxide was accompanied by a reduction in the surface-bound Cl signal. After 48 h of exposure to air, the Cl-terminated Si(111) surface exhibited 3.63 equivalent monolyers (ML) of silicon oxides. In contrast, after exposure to air for 48 h, CH_3-, C_2H_5-, or C_6H_5CH_2-terminated Si surfaces displayed <0.4 ML of surface oxide, and in most cases only displayed \u22480.20 ML of oxide. This oxide was principally composed of Si+ and Si^(3+) species with peaks centered at +0.8 and +3.2 eV above the bulk Si 2p_(3/2) peak, respectively. The silicon 2p SXPS peaks that have previously been assigned to surface Si\u2212C bonds did not change significantly, either in binding energy or in relative intensity, during such air exposure. Use of a high miscut-angle surface (7\u00b0 vs \u22640.5\u00b0 off of the (111) surface orientation) yielded no increase in the rate of oxidation nor change in binding energy of the resultant oxide that formed on the alkylated Si surfaces. Scanning Auger microscopy indicated that the alkylated surfaces formed oxide in isolated, inhomogeneous patches on the surface.", "date": "2006-11-23", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "110", "number": "46", "publisher": "American Chemical Society", "pagerange": "23450-23459", "id_number": "CaltechAUTHORS:20170607-132636106", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170607-132636106", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "Army Research Office (ARO)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-98CH10886" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC05-00OR22725" } ] }, "doi": "10.1021/jp063366s", "resource_type": "article", "pub_year": "2006", "author_list": "Webb, Lauren J.; Michalak, David J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dk22e-48e54", "eprint_id": 78047, "eprint_status": "archive", "datestamp": "2023-08-19 18:54:07", "lastmod": "2023-10-25 23:42:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hamann-T-W", "name": { "family": "Hamann", "given": "Thomas W." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Control of the Stability, Electron-Transfer Kinetics, and pH-Dependent Energetics of Si/H_2O Interfaces through Methyl Termination of Si(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2006 American Chemical Society. \n\nReceived 12 July 2006. Published online 24 October 2006. Published in print 1 November 2006. \n\nWe acknowledge the NSF, grant CHE-0604894, for support of this work. XPS data were collected at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology.\n\nPublished - jp064401y.pdf
", "abstract": "Methyl-terminated, n-type, (111)-oriented Si surfaces were prepared via a two-step chlorination-alkylation method. This surface modification passivated the Si surface toward electrochemical oxidation and thereby allowed measurements of interfacial electron-transfer processes in contact with aqueous solutions. The resulting semiconductor/liquid junctions exhibited interfacial kinetics behavior in accord with the ideal model of a semiconductor/liquid junction. In contrast to the behavior of H-terminated Si(111) surfaces, current density vs. potential measurements of CH_3-terminated Si(111) surfaces in contact with an electron acceptor having a pH-independent redox potential (methyl viologen^(2+/+)) were used to verify that the band edges of the modified Si electrode were fixed with respect to changes in solution pH. The results provide strong evidence that the energetics of chemically modified Si interfaces can be fixed with respect to pH and show that the band-edge energies of Si can be tuned independently of pH-derived variations in the electrochemical potential of the solution redox species.", "date": "2006-11-16", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "110", "number": "45", "publisher": "American Chemical Society", "pagerange": "22291-22294", "id_number": "CaltechAUTHORS:20170609-083755926", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170609-083755926", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" } ] }, "doi": "10.1021/jp064401y", "primary_object": { "basename": "jp064401y.pdf", "url": "https://authors.library.caltech.edu/records/dk22e-48e54/files/jp064401y.pdf" }, "resource_type": "article", "pub_year": "2006", "author_list": "Hamann, Thomas W. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sfsf7-3vs35", "eprint_id": 73950, "eprint_status": "archive", "datestamp": "2023-08-19 18:47:04", "lastmod": "2023-10-24 21:08:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gao-Ting", "name": { "family": "Gao", "given": "Ting" } }, { "id": "Woodka-M-D", "name": { "family": "Woodka", "given": "Marc D." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Chemiresistors for Array-Based Vapor Sensing Using Composites of Carbon Black with Low Volatility Organic Molecules", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society. \n\nReceived 19 April 2006. Published online 28 September 2006. Published in print 1 October 2006. \n\nThe authors thank Dr. Brian Sisk, Dr. Erik J. Severin, and Edgardo Garc\u00eda-Berr\u00edos for valuable discussions. Research was carried out in the Molecular Materials Research Center of the Beckman Institute at Caltech. This work was partially supported by the National Institutes of Health and by the ARO under the Institute for Collaborative Biotechnologies.", "abstract": "Chemically sensitive resistors have been fabricated from composites of carbon black and low volatility, nonpolymeric, organic molecules such as propyl gallate, lauric acid, and dioctyl phthalate. Sorption of organic vapors into the nonconductive phase of such composites produced rapid and reversible changes in the relative differential resistance response of the sensing films. Arrays of these sensors, in which each sensing film was comprised of carbon black and a chemically distinct nonpolymeric organic molecule or blend of organic molecules, produced characteristic response patterns upon exposure to a series of different organic test vapors. The use of nonpolymeric sorption phases allowed fabrication of sensors having a high density of randomly oriented functional groups and provided excellent discrimination between analytes. By comparison to carbon black\u2212polymer composite vapor sensors and sensor arrays, such sensors provided comparable detection limits as well as enhanced clustering and enhanced resolution ability between test analytes.", "date": "2006-10-31", "date_type": "published", "publication": "Chemistry of Materials", "volume": "18", "number": "22", "publisher": "American Chemical Society", "pagerange": "5193-5202", "id_number": "CaltechAUTHORS:20170201-141754490", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170201-141754490", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NIH" }, { "agency": "Army Research Office (ARO)" } ] }, "doi": "10.1021/cm060905x", "resource_type": "article", "pub_year": "2006", "author_list": "Gao, Ting; Woodka, Marc D.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/yef4b-49451", "eprint_id": 9790, "eprint_status": "archive", "datestamp": "2023-08-22 07:02:24", "lastmod": "2023-10-23 19:33:33", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Nocera-Daniel-G", "name": { "family": "Nocera", "given": "Daniel G." }, "orcid": "0000-0001-5055-320X" } ] }, "title": "Powering the planet: Chemical challenges in solar energy utilization", "ispublished": "pub", "full_text_status": "public", "keywords": "ELECTROCATALYTIC HYDROGEN EVOLUTION; COUPLED ELECTRON-TRANSFER; OXIDATIVE ADDITION; ELECTROCHEMICAL REDUCTION; HOMOGENEOUS CATALYSIS; WATER-OXIDATION; ACTIVE-SITE; PROTON REDUCTION; METAL-COMPLEXES; PHOTOSYSTEM-II", "note": "\u00a9 2006 by the National Academy of Sciences. \n\nEdited by Edward I. Solomon, Stanford University, Stanford, CA, and approved August 11, 2006 (received for review May 25, 2006). Published online on October 16, 2006, 10.1073/pnas.0603395103. \n\nWe acknowledge sustained support from the U.S. Department of Energy (Office of Basic Energy Sciences) and the National Science Foundation (and in particular, Chemical Bonding Center CP-CP0533150) for basic research in renewable energy and for facilitating our ongoing perspective on global energy options.\n\nAuthor contributions: N.S.L. and D.G.N wrote the paper. \n\nThe authors declare no conflict of interest. \n\nThis article is a PNAS direct submission.\n\nFor the article \"Powering the planet: Chemical challenges in solar energy utilization,\" by Nathan S. Lewis and Daniel G. Nocera, which appeared in issue 43, October 24, 2006, of Proc Natl Acad Sci USA (103:15729\u201315735; first published October 16, 2006; 10.1073/pnas.0603395103), the authors note that in Fig. 1, the charges shown in the solar fuel cell are on the wrong sides of the cell. The holes should be at the anode, and the electrons should be at the cathode. This error does not affect the conclusions of the article. The corrected figure and its legend appear below.\n\nPublished - LEWpnas06.pdf
", "abstract": "Global energy consumption is projected to increase, even in the face of substantial declines in energy intensity, at least 2-fold by midcentury relative to the present because of population and economic growth. This demand could be met, in principle, from fossil energy resources, particularly coal. However, the cumulative nature of CO2 emissions in the atmosphere demands that holding atmospheric CO2 levels to even twice their preanthropogenic values by midcentury will require invention, development, and deployment of schemes for carbon-neutral energy production on a scale commensurate with, or larger than, the entire present-day energy supply from all sources combined. Among renewable energy resources, solar energy is by far the largest exploitable resource, providing more energy in 1 hour to the earth than all of the energy consumed by humans in an entire year. In view of the intermittency of insolation, if solar energy is to be a major primary energy source, it must be stored and dispatched on demand to the end user. An especially attractive approach is to store solar-converted energy in the form of chemical bonds, i.e., in a photosynthetic process at a year-round average efficiency significantly higher than current plants or algae, to reduce land-area requirements. Scientific challenges involved with this process include schemes to capture and convert solar energy and then store the energy in the form of chemical bonds, producing oxygen from water and a reduced fuel such as hydrogen, methane, methanol, or other hydrocarbon species.", "date": "2006-10-24", "date_type": "published", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "volume": "103", "number": "43", "publisher": "National Academy of Sciences", "pagerange": "15729-15735", "id_number": "CaltechAUTHORS:LEWpnas06", "issn": "0027-8424", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:LEWpnas06", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "NSF", "grant_number": "CP-CP0533150" } ] }, "doi": "10.1073/pnas.0603395103", "pmcid": "PMC1635072", "primary_object": { "basename": "LEWpnas06.pdf", "url": "https://authors.library.caltech.edu/records/yef4b-49451/files/LEWpnas06.pdf" }, "resource_type": "article", "pub_year": "2006", "author_list": "Lewis, Nathan S. and Nocera, Daniel G." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/76s3a-wwc95", "eprint_id": 78943, "eprint_status": "archive", "datestamp": "2023-08-19 18:45:20", "lastmod": "2023-10-26 14:28:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Rivillon-S", "name": { "family": "Rivillon", "given": "Sandrine" } }, { "id": "Chabal-Y-J", "name": { "family": "Chabal", "given": "Yves J." } }, { "id": "Est\u00e8ve-A", "name": { "family": "Est\u00e8ve", "given": "A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Infrared Spectroscopic Investigation of the Reaction of Hydrogen-Terminated, (111)-Oriented, Silicon Surfaces with Liquid Methanol", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society. \n\nReceived 20 April 2006. Published online 15 September 2006. Published in print 1 October 2006. \n\nWe acknowledge the support of the National Science Foundation, through grants CHE-0604894 at Caltech and CHE-0415652 at Rutgers and through the U.S.\u2212France cooperative research program (NSF-INT-0341053) for facilitating the international collaboration with the LAAS at Toulouse. D.J.M. acknowledges the Link Energy Foundation for a graduate fellowship. The authors are grateful to Lauren J. Webb for stimulating discussions.", "abstract": "Fourier transform infrared spectroscopy and first principles calculations have been used to investigate the reaction of atomically smooth, hydrogen-terminated Si(111) (H\u2212Si) surfaces with anhydrous liquid methanol. After 10 min of reaction at room temperature, a sharp absorbance feature was apparent at \u223c1080 cm^(-1) that was polarized normal to the surface plane. Previous reports have identified this mode as a Si\u2212O\u2212C stretch; however, the first principles calculations, presented in this work, indicate that this mode is a combination of an O\u2212C stretch with a CH_3 rock. At longer reaction times, the intensity of the Si\u2212H stretching mode decreased, while peaks attributable to the O\u2212C coupled stretch and the CH_3 stretching modes, respectively, increased in intensity. Spectra of H\u2212Si(111) surfaces that had reacted with CD_3OD showed the appearance of Si\u2212D signals polarized normal to the surface as well as the appearance of vibrations indicative of Si\u2212OCD_3 surface species. The data are consistent with two surface reactions occurring in parallel, involving (a) chemical attack of hydrogen-terminated Si(111) terraces by CH_3OH, forming Si\u2212OCH_3 moieties having their Si\u2212O bond oriented normal to the Si(111) surface and (b) transfer of the acidic hydrogen of the methanol to the silicon surface, either through a direct H-to-D exchange mechanism or through a mechanism involving chemical step-flow etching of Si\u2212H step sites.", "date": "2006-10-19", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "110", "number": "41", "publisher": "American Chemical Society", "pagerange": "20426-20434", "id_number": "CaltechAUTHORS:20170711-105630751", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170711-105630751", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0604894" }, { "agency": "NSF", "grant_number": "CHE-0415652" }, { "agency": "NSF", "grant_number": "INT-0341053" }, { "agency": "Link Foundation" } ] }, "doi": "10.1021/jp0624303", "resource_type": "article", "pub_year": "2006", "author_list": "Michalak, David J.; Rivillon, Sandrine; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/bagmp-nn215", "eprint_id": 77705, "eprint_status": "archive", "datestamp": "2023-08-19 18:43:48", "lastmod": "2023-10-25 23:22:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Royea-W-J", "name": { "family": "Royea", "given": "William J." } }, { "id": "Hamann-T-W", "name": { "family": "Hamann", "given": "Thomas W." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A Comparison between Interfacial Electron-Transfer Rate Constants at Metallic and Graphite Electrodes", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society. \n\nReceived: April 5, 2006; In Final Form: June 12, 2006. Publication Date (Web): September 2, 2006. \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, for support of this work. We also acknowledge helpful discussions with Norman Sutin.", "abstract": "The Fermi golden rule formalism has been used to derive the rate constant for interfacial electron transfer from a semimetallic electrode, such as highly ordered pyrolytic graphite (HOPG), to a redox couple in solution. A simple expression is presented that semiquantitatively relates the electron-transfer rate constant at a semimetallic electrode to that at a metallic electrode. The approach allows for the estimation of the value of the rate constant for interfacial charge transfer to nonadsorbing outer-sphere redox species at semimetallic electrodes. Rate constants for interfacial electron transfer for a variety of one-electron redox couples at semimetallic electrodes have been calculated relative to the rate constant of the ferrocenium/ferrocene redox couple at a gold electrode. Good agreement is found, in general, between the calculated and observed rate constants.", "date": "2006-10-05", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "110", "number": "39", "publisher": "American Chemical Society", "pagerange": "19433-19442", "id_number": "CaltechAUTHORS:20170524-100829690", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170524-100829690", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1021/jp062141e", "resource_type": "article", "pub_year": "2006", "author_list": "Royea, William J.; Hamann, Thomas W.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/phmxr-ssh33", "eprint_id": 47576, "eprint_status": "archive", "datestamp": "2023-08-19 18:35:20", "lastmod": "2023-10-26 20:43:24", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hu-Xile", "name": { "family": "Hu", "given": "Xile" }, "orcid": "0000-0001-8335-1196" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce B." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Peters-J-C", "name": { "family": "Peters", "given": "Jonas C." }, "orcid": "0000-0002-6610-4414" } ] }, "title": "Electrocatalytic hydrogen evolution by cobalt complexes of macrocyclic imine ligands", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society.", "abstract": "A series of cobalt complexes with macrocyclic imine ligands such as difluoroboryldiglyxomime and [14]-Tetraene-N4 are\nsynthesized for electrochem. hydrogen evolution catalysis. The complexes catalyze the redn. of proton to dihydrogen at\npotentials in the range between -0.55 V to -0.20 V vs. SCE in acidic acetonitrile solns. A correlation between the rates of\nhydrogen evolution and the Co(II/I) potentials of the catalysts is established. The catalysis is triggered by the redn. of\ncobalt(II) precursors to cobalt(I) species, while have been synthesized and studied independently. Attempts are made to\nisolate important catalytic intermediates such as cobalt(III) hydride species.", "date": "2006-09-10", "date_type": "published", "publication": "Abstracts of Papers of the American Chemical Society", "volume": "232", "publisher": "American Chemical Society", "pagerange": "INOR 205", "id_number": "CaltechAUTHORS:20140730-080036421", "issn": "0065-7727", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140730-080036421", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "article", "pub_year": "2006", "author_list": "Hu, Xile; Brunschwig, Bruce B.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/z9zrk-rg145", "eprint_id": 79327, "eprint_status": "archive", "datestamp": "2023-08-19 18:29:13", "lastmod": "2023-10-26 14:48:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sisk-B-C", "name": { "family": "Sisk", "given": "Brian C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Vapor Sensing Using Polymer/Carbon Black Composites in the Percolative Conduction Regime", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society. \n\nReceived 5 December 2005. Published online 26 July 2006. Published in print 1 August 2006. \n\nWe acknowledge the ARO, NIH, HSARPA, and DARPA for support of this work.", "abstract": "To investigate the behavior of chemiresistive vapor sensors operating below or around the percolation threshold, chemiresistors have been formed from composites of insulating organic polymers and low mass fractions of conductive carbon black (CB, 1\u221212% w/w). Such sensors produced extremely large relative differential resistance changes above certain threshold vapor concentrations. At high analyte partial pressures, these sensors exhibited better signal/noise characteristics and were typically less mutually correlated in their vapor response properties than composites formed using higher mass fractions of CB in the same set of polymer sorption layers. The responses of the low-mass-fraction CB sensors were, however, less repeatable, and their nonlinear response as a function of analyte concentration required more complicated calibration schemes to identify and quantify analyte vapors to compensate for drift of a sensor array and to compensate for variability in response between sensor arrays. Because of their much larger response signals, the low-mass-fraction CB sensors might be especially well suited for use with low-precision analog-to-digital signal readout electronics. These sensors serve well as a complement to composites formed from higher mass fractions of CB and have yielded insight into the tradeoffs of signal-to-noise improvements vs complexity of signal processing algorithms necessitated by the use of nonlinearly responding detectors in array-based sensing schemes.", "date": "2006-08-29", "date_type": "published", "publication": "Langmuir", "volume": "22", "number": "18", "publisher": "American Chemical Society", "pagerange": "7928-7935", "id_number": "CaltechAUTHORS:20170725-100501150", "issn": "0743-7463", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170725-100501150", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)" }, { "agency": "NIH" }, { "agency": "Homeland Security Advanced Research Projects Agency (HSARPA)" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" } ] }, "doi": "10.1021/la053287s", "resource_type": "article", "pub_year": "2006", "author_list": "Sisk, Brian C. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/vdm5n-7jc05", "eprint_id": 75164, "eprint_status": "archive", "datestamp": "2023-08-19 18:26:58", "lastmod": "2023-10-25 14:48:18", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Traub-M-C", "name": { "family": "Traub", "given": "Matthew C." } }, { "id": "Biteen-J-S", "name": { "family": "Biteen", "given": "Julie S." }, "orcid": "0000-0003-2038-6484" }, { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "High-Resolution X-ray Photoelectron Spectroscopy of Chlorine-Terminated GaAs(111)A Surfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society. \n\nReceived: March 15, 2006; In Final Form: May 10, 2006. Publication Date (Web): July 22, 2006. \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, and the Beckman Institute for support of this work. The research was carried out in part at the National Synchrotron Light Source, Brookhaven National Laboratory, which is supported by the U. S. Department of Energy, Division of Materials Sciences and Division of Chemical Sciences, under contract no. DE-AC02-98CH10886. We thank Michael Sullivan for use of the N_2(g)-purged glovebox at the NSLS.", "abstract": "Oxide-terminated and Cl-terminated GaAs(111)A surfaces have been characterized in the As and Ga 3d regions by high-resolution, soft X-ray photoelectron spectroscopy. The Cl-terminated surface, formed by treatment with 6 M HCl(aq), showed no detectable As oxides or As^0 in the As 3d region. The Ga 3d spectrum of the Cl-terminated surface showed a broad, intense signal at 19.4 eV and a smaller signal at 21.7 eV. The Ga 3d peaks were fitted using three species, one representing bulk GaAs and the others representing two chemical species on the surface. The large peak was well-fitted by the bulk GaAs emission and by a second doublet, assigned to surface Ga atoms bonded to Cl, that was shifted by 0.34 eV from the bulk GaAs 3d emission. The smaller peak, shifted by 2.3 eV in binding energy relative to the bulk GaAs Ga 3d signal, is assigned to Ga(OH)_3. The data confirm that wet chemical etching allows for the formation of well-defined, Cl-terminated GaAs(111)A surfaces free of detectable elemental As, that can provide a starting point for further functionalization of GaAs.", "date": "2006-08-17", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "110", "number": "32", "publisher": "American Chemical Society", "pagerange": "15641-15644", "id_number": "CaltechAUTHORS:20170315-160649038", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170315-160649038", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-98CH10886" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/jp061623n", "resource_type": "article", "pub_year": "2006", "author_list": "Traub, Matthew C.; Biteen, Julie S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8shz0-cew73", "eprint_id": 76843, "eprint_status": "archive", "datestamp": "2023-08-19 18:25:25", "lastmod": "2023-10-25 16:54:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hurley-P-T", "name": { "family": "Hurley", "given": "Patrick T." } }, { "id": "Nemanick-E-J", "name": { "family": "Nemanick", "given": "E. Joseph" }, "orcid": "0000-0002-4650-6491" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Covalent Attachment of Acetylene and Methylacetylene Functionality to Si(111) Surfaces: Scaffolds for Organic Surface Functionalization while Retaining Si\u2212C Passivation of Si(111) Surface Sites", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society. \n\nReceived March 31, 2006. Publication Date (Web): July 13, 2006. \n\nWe acknowledge the Beckman Institute and NSF Grants CHE-0213589 and 0604894 for generous support.", "abstract": "Si(111) surfaces have been functionalized with Si\u2212C\u22eeC\u2212R species, where R = H or \u2013CH_3, using a two-step reaction sequence involving chlorination of H\u2212Si(111) followed by treatment with Na\u2212C\u22eeC\u2212H or CH_3\u2212C\u22eeC\u2212Na reagents. The resulting surfaces showed no detectable oxidation as evidenced by X-ray photoelectron spectroscopic (XPS) data in the Si 2p region, electrochemical measurements of Si\u2212H oxidation, or infrared spectroscopy. The Si\u2212C\u22eeC\u2212R-terminated surfaces exhibited a characteristic C\u22eeC stretch in the infrared at 2179 cm^(-1), which was strongly polarized perpendicular to the Si(111) surface plane. XPS measurements in the C 1s region showed a low binding energy peak indicative of Si\u2212C bonding, with a coverage that was, within experimental error, identical to that of the CH_3-terminated Si(111) surface, which has been shown to fully terminate the Si atop sites on an unreconstructed Si(111) surface. The Si\u2212C\u22eeC\u2212H-terminated surfaces were further functionalized by exposure to n-C_4H_9Li followed by exposure to para Br\u2212C_6H_5\u2212CF_3, allowing for introduction of para \u2013C_6H_5CF_3 groups while maintaining the desirable chemical and electrical properties that accompany complete Si\u2212C termination of the atop sites on the Si(111) surface.", "date": "2006-08-09", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "128", "number": "31", "publisher": "American Chemical Society", "pagerange": "9990-9991", "id_number": "CaltechAUTHORS:20170424-100851525", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170424-100851525", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech Beckman Institute" }, { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "NSF", "grant_number": "CHE-0604894" } ] }, "doi": "10.1021/ja061969b", "resource_type": "article", "pub_year": "2006", "author_list": "Hurley, Patrick T.; Nemanick, E. Joseph; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4ms7t-k2c58", "eprint_id": 78042, "eprint_status": "archive", "datestamp": "2023-08-19 18:24:55", "lastmod": "2023-10-25 23:41:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nemanick-E-J", "name": { "family": "Nemanick", "given": "E. Joseph" }, "orcid": "0000-0002-4650-6491" }, { "id": "Hurley-P-T", "name": { "family": "Hurley", "given": "Patrick T." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Chemical and Electrical Passivation of Silicon (111) Surfaces through Functionalization with Sterically Hindered Alkyl Groups", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society. \n\nReceived 5 December 2005. Published online 13 July 2006. Published in print 1 August 2006. \n\nWe gratefully acknowledge the NSF, Grant CHE-021358 and the Beckman Institute for support of this work.", "abstract": "Crystalline Si(111) surfaces have been alkylated in a two-step chlorination/alkylation process using sterically bulky alkyl groups such as (CH_3)_2CH\u2212 (iso-propyl), (CH_3)_3C\u2212 (tert-butyl), and C_6H_5\u2212 (phenyl) moieties. X-ray photoelectron spectroscopic (XPS) data in the C 1s region of such surfaces exhibited a low energy emission at 283.9 binding eV, consistent with carbon bonded to Si. The C 1s XPS data indicated that the alkyls were present at lower coverages than methyl groups on CH_3-terminated Si(111) surfaces. Despite the lower alkyl group coverage, no Cl was detected after alkylation. Functionalization with the bulky alkyl groups effectively inhibited the oxidation of Si(111) surfaces in air and produced low (<100 cm s^(-1)) surface recombination velocities. Transmission infrared spectroscopy indicated that the surfaces were partially H-terminated after the functionalization reaction. Application of a reducing potential, \u22122.5 V vs Ag^+/Ag, to Cl-terminated Si(111) electrodes in tetrahydrofuran resulted in the complete elimination of Cl, as measured by XPS. The data are consistent with a mechanism in which the reaction of alkyl Grignard reagents with the Cl-terminated Si(111) surfaces involves electron transfer from the Grignard reagent to the Si, loss of chloride to solution, and subsequent reaction between the resultant silicon radical and alkyl radical to form a silicon\u2212carbon bond. Sites sterically hindered by neighboring alkyl groups abstract a H atom to produce Si\u2212H bonds on the surface.", "date": "2006-08-03", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "110", "number": "30", "publisher": "American Chemical Society", "pagerange": "14800-14808", "id_number": "CaltechAUTHORS:20170609-073705620", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170609-073705620", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/jp057070i", "resource_type": "article", "pub_year": "2006", "author_list": "Nemanick, E. Joseph; Hurley, Patrick T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ey9wv-m7k61", "eprint_id": 78008, "eprint_status": "archive", "datestamp": "2023-08-19 18:24:48", "lastmod": "2023-10-25 23:39:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nemanick-E-J", "name": { "family": "Nemanick", "given": "E. Joseph" }, "orcid": "0000-0002-4650-6491" }, { "id": "Hurley-P-T", "name": { "family": "Hurley", "given": "Patrick T." } }, { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Knapp-D-W", "name": { "family": "Knapp", "given": "David W." } }, { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Chemical and Electrical Passivation of Single-Crystal Silicon(100) Surfaces through a Two-Step Chlorination/Alkylation Process", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society. \n\nReceived 22 November 2005. Published online 12 July 2006. Published in print 1 August 2006. \n\nWe gratefully acknowledge the NSF, grant CHE-021358, for support of this work. This work was carried out in part at the National Synchrotron Light Source, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Division of Materials Sciences and Division of Chemical Sciences, under contract DE-AC02-98CH 10866, and the Beckman Institute Molecular Materials Research Center at the California Institute of Technology.", "abstract": "Single-crystal Si(100) surfaces have been functionalized by using a two-step radical chlorination\u2212Grignard (R= MgCl, R = CH_3, C_2H_5, C_4H_9, C_6H_5, or CH_2C_6H_5) alkylation method. After alkylation, no chlorine was detectable on the surface by X-ray photoelectron spectroscopy (XPS), and the C 1s region showed a silicon-induced peak shift indicative of a Si\u2212C bond. The relative intensity of this peak decreased, as expected, as the steric bulk of the alkyl increased. Despite the lack of full alkyl termination of the atop sites of the Si(100) surface, functionalization significantly reduced the rate of surface oxidation in air compared to that of the H-terminated Si(100) surface, with alkylated surfaces forming less than half a monolayer of oxide after over one month of exposure to air. Studies of the charge-carrier lifetime with rf photoconductivity decay methods indicated a surface recombination velocity of <30 cm s^(-1) for methylated surfaces, and <60 cm s^(-1) for Si surfaces functionalized with the other alkyl groups evaluated. Soft X-ray photoelectron spectroscopic data indicated that the H\u2212Si(100) surfaces were terminated by SiH, SiH_2, and SiH_3 species, whereas Cl\u2212Si(100) surfaces were predominantly terminated by monochloro (SiCl and SiHCl) and dichloro (SiCl_2 and SiHCl_2) Si species. Methylation produced signals consistent with termination by Si\u2212alkyl bonding arising from SiH(CH_3)-, SiH_2(CH_3)-, and Si(CH_3)_2-type species.", "date": "2006-08-03", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "110", "number": "30", "publisher": "American Chemical Society", "pagerange": "14770-14778", "id_number": "CaltechAUTHORS:20170607-135111738", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170607-135111738", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-98CH 10866" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/jp056773x", "resource_type": "article", "pub_year": "2006", "author_list": "Nemanick, E. Joseph; Hurley, Patrick T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wwbga-96608", "eprint_id": 76677, "eprint_status": "archive", "datestamp": "2023-08-19 18:24:41", "lastmod": "2023-10-25 16:12:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Nemanick-E-J", "name": { "family": "Nemanick", "given": "E. Joseph" }, "orcid": "0000-0002-4650-6491" }, { "id": "Solares-S-D", "name": { "family": "Solares", "given": "Santiago D." }, "orcid": "0000-0003-0895-8160" }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A., III" }, "orcid": "0000-0003-0097-5716" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Quantum Mechanics Calculations of the Thermodynamically Controlled Coverage and Structure of Alkyl Monolayers on Si(111) Surfaces", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2006 American Chemical Society. \n\nReceived: January 30, 2006; In Final Form: April 5, 2006. Publication Date (Web): July 13, 2006. \n\nE.J.N. and N.S.L. gratefully acknowledge the NSF, Grant CHE-021358, for support of this work. S.D.S. and W.A.G. thank the Microelectronics Advanced Research Corporation (MARCO) and its Focus Center on NanoEngineered Architectonics (FENA).\n\nSupplemental Material - jp060640+si20060405_071852.pdf
", "abstract": "The heat of formation, \u0394E, for silicon (111) surfaces terminated with increasing densities of the alkyl groups CH_3- (methyl), C_2H_5- (ethyl), (CH_3)_2CH- (isopropyl), (CH_3)_3C- (tert-butyl), CH_3(CH_2)_5- (hexyl), CH_3(CH_2)_7- (octyl), and C_6H_5- (phenyl) was calculated using quantum mechanics (QM) methods, with unalkylated sites being H-terminated. The free energy, \u0394G, for the formation of both Si\u2212C and Si\u2212H bonds from Si\u2212Cl model componds was also calculated using QM, with four separate Si\u2212H formation mechanisms proposed, to give overall \u0394G_S values for the formation of alkylated Si(111) surfaces through a two step chlorination/alkylation method. The data are in good agreement with measurements of the packing densities for alkylated surfaces formed through this technique, for Si\u2212H free energies of formation, \u0394G_H, corresponding to a reaction mechanism including the elimination of two H atoms and the formation of a C C double bond in either unreacted alkyl Grignard groups or tetrahydrofuran solvent.", "date": "2006-08-03", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "110", "number": "30", "publisher": "American Chemical Society", "pagerange": "14842-14848", "id_number": "CaltechAUTHORS:20170419-102845785", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170419-102845785", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "Microelectronics Advanced Research Corporation (MARCO)" }, { "agency": "Focus Center on NanoEngineered Architectonics (FENA)" } ] }, "doi": "10.1021/jp060640+", "primary_object": { "basename": "jp060640+si20060405_071852.pdf", "url": "https://authors.library.caltech.edu/records/wwbga-96608/files/jp060640+si20060405_071852.pdf" }, "resource_type": "article", "pub_year": "2006", "author_list": "Nemanick, E. Joseph; Solares, Santiago D.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/q4qb2-w3438", "eprint_id": 77429, "eprint_status": "archive", "datestamp": "2023-08-19 18:18:47", "lastmod": "2023-10-25 23:01:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Haick-H", "name": { "family": "Haick", "given": "Hossam" } }, { "id": "Hurley-P-T", "name": { "family": "Hurley", "given": "Patrick T." } }, { "id": "Hochbaum-A-I", "name": { "family": "Hochbaum", "given": "Allon I." } }, { "id": "Yang-Peidong", "name": { "family": "Yang", "given": "Peidong" }, "orcid": "0000-0003-4799-1684" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electrical Characteristics and Chemical Stability of Non-Oxidized, Methyl-Terminated Silicon Nanowires", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2006 American Chemical Society. \n\nReceived 4 October 2005. Published online 27 June 2006. Published in print 1 July 2006. \n\nWe acknowledge the NSF, Grant CHE-0213589, for support of this work (N.S.L.), and DARPA-MARCO (P.Y.). H.H. thanks the Fulbright foundation for his postdoctoral fellowship, and A.H. thanks NSF for an IGERT fellowship.\n\nSupplemental Material - ja056785w_s.pdf
Supplemental Material - ja056785wsi20060623_125407.pdf
", "abstract": "Silicon nanowires (Si NWs) modified by covalent Si\u2212CH3 functionality, with no intervening oxide, show atmospheric stability, high conductance values, low surface defect levels, and allow for the formation of air-stable Si NW Field-Effect Transistors (FETs) having on\u2212off ratios in excess of 105 over a relatively small gate voltage swing (\u00b12 V).", "date": "2006-07-19", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "128", "number": "28", "publisher": "American Chemical Society", "pagerange": "8990-8991", "id_number": "CaltechAUTHORS:20170512-144735960", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170512-144735960", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Fulbright Foundation" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Microelectronics Advanced Research Corporation (MARCO)" } ] }, "doi": "10.1021/ja056785w", "primary_object": { "basename": "ja056785w_s.pdf", "url": "https://authors.library.caltech.edu/records/q4qb2-w3438/files/ja056785w_s.pdf" }, "related_objects": [ { "basename": "ja056785wsi20060623_125407.pdf", "url": "https://authors.library.caltech.edu/records/q4qb2-w3438/files/ja056785wsi20060623_125407.pdf" } ], "resource_type": "article", "pub_year": "2006", "author_list": "Haick, Hossam; Hurley, Patrick T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ejcf7-agf25", "eprint_id": 120619, "eprint_status": "archive", "datestamp": "2023-08-22 06:04:22", "lastmod": "2023-10-18 17:55:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hamann-Thomas-W", "name": { "family": "Hamann", "given": "Thomas W." }, "orcid": "0000-0001-6917-7494" }, { "id": "Gstrein-Florian", "name": { "family": "Gstrein", "given": "Florian" } }, { "id": "Brunschwig-Bruce-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Measurement of the driving force dependence of interfacial charge-transfer rate constants in response to pH changes at n-ZnO/H\u2082O interfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Physics and Astronomy", "note": "We acknowledge the Department of Energy, Office of Basic Energy Sciences, for support of this work.", "abstract": "Changes in pH have been used to shift the band-edge positions of n-type ZnO electrodes relative to solution-based electron acceptors having pH-independent redox potentials. Differential capacitance vs. potential and current density vs. potential measurements using [Co(bpy)\u2083]^(3+/2+) and [Ru(bpy)\u2082(MeIm)\u2082]^(3+/2+) (where bpy = 2,2\u2032-bipyridyl and MeIm = 1-methyl-imidazole) allowed investigation of the pH-induced driving-force dependence of the interfacial electron-transfer rate in the normal and inverted regions of electron transfer, respectively. All rate processes were observed to be kinetically first-order in the concentration of electrons at the ZnO surface and first-order in the concentration of dissolved redox acceptors. Measurements using [Co(bpy)\u2082]^(3+/2+), which has a low driving force and a high reorganization energy in contact with ZnO electrodes, and measurements of [Ru(bpy)\u2082(MeIm)\u2082]^(3+/2+), which has a high driving force and a low reorganization energy in contact with ZnO electrodes, allowed for the evaluation of both the normal and inverted regions of interfacial electron-transfer processes, respectively. The rate constant at optimum exoergicity was observed to be approximately 5 \u00d7 10\u207b\u00b9\u2077 cm\u2074 s\u207b\u00b9. The rate constant vs. driving-force dependence at n-type ZnO electrodes exhibited both normal and inverted regions, and the data were well-fitted by parabolas generated using classical electron-transfer theory.", "date": "2006-07-11", "date_type": "published", "publication": "Chemical Physics", "volume": "326", "number": "1", "publisher": "Elsevier", "pagerange": "15-23", "id_number": "CaltechAUTHORS:20230329-57074000.1", "issn": "0301-0104", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-57074000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1016/j.chemphys.2006.02.027", "resource_type": "article", "pub_year": "2006", "author_list": "Hamann, Thomas W.; Gstrein, Florian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cwa3y-dzs11", "eprint_id": 120617, "eprint_status": "archive", "datestamp": "2023-08-22 05:56:34", "lastmod": "2023-10-18 17:55:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Pardo-Matteo", "name": { "family": "Pardo", "given": "Matteo" } }, { "id": "Sisk-Brian-C", "name": { "family": "Sisk", "given": "Brian C." }, "orcid": "0000-0003-3156-9673" }, { "id": "Sberveglieri-Giorgio", "name": { "family": "Sberveglieri", "given": "Giorgio" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparison of Fisher's linear discriminant to multilayer perceptron networks in the classification of vapors using sensor array data", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Electrical and Electronic Engineering; Metals and Alloys; Surfaces, Coatings and Films; Condensed Matter Physics; Instrumentation; Electronic, Optical and Magnetic Materials", "note": "The NIH and an ARO/ICB are acknowledged for their generous support of this work.", "abstract": "Two different classification methods, Fisher's linear discriminant (FLD) and a multilayer perceptron neural network (MLP), were directly compared with respect to their abilities to differentiate response patterns arising from arrays of chemical vapor detectors. The algorithms were compared in five different types of tasks that had been selected because they produced classification problems of varying character and difficulty. In one task, an array of 20 compositionally distinct carbon black\u2013polymer composite vapor detectors was exposed to P/P\u2070 = 0.0075 1-propanol and P/P\u2070 = 0.0083 2-propanol, where P and P\u2070 are the partial pressure and standard vapor pressure, respectively, of a given analyte. The second task consisted of classification of a mixture of P/P\u2070 = 0.011 1-propanol and P/P\u2070 = 0.0090 2-propanol versus a mixture of P/P\u2070 = 0.0090 1-propanol and P/P\u2070 = 0.011 2-propanol. A third task consisted of multiple concentrations of three hydrocarbons, and a fourth task involved clustering two hydrocarbons in the presence of a variable background composition. An additional dataset was generated by exposing an array of five thin-film metal-oxide sensors to the headspace of seven different coffee blends. In each case, the MLP and FLD techniques were compared using the 5-sensor subset of the 20 available sensors that proved optimal for that dataset. The FLD and MLP algorithms yielded comparable performance on straightforward classification tasks, whereas the MLP technique yielded better performance on tasks that involved non-linear classification boundaries. In addition, for the four datasets produced by the carbon black\u2013polymer composite detector array, the performance of each possible 5-sensor subset was evaluated using both signal processing approaches. The performance of the best 5-sensor subset selected with MLP was found to be slightly better than the performance of the FLD-selected subsets, and the performance of the median 5-sensor subset using MLP was nearer to that of the optimal subset than the median sensor array selected by FLD. In one case, the optimal test set performance distribution was found to be significantly better with MLP than with FLD: MLP had a clear advantage (86% versus 57% correct classification rate) when applied to the \"coffees\" dataset, and this trend is likely applicable to other multi-cluster classification tasks that consisted of non-Gaussian shaped data in lower-dimensional spaces.", "date": "2006-06-26", "date_type": "published", "publication": "Sensors and Actuators B: Chemical", "volume": "115", "number": "2", "publisher": "Elsevier", "pagerange": "647-655", "id_number": "CaltechAUTHORS:20230329-347025000.2", "issn": "0925-4005", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-347025000.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NIH" }, { "agency": "Army Research Office (ARO)" } ] }, "doi": "10.1016/j.snb.2005.10.033", "resource_type": "article", "pub_year": "2006", "author_list": "Pardo, Matteo; Sisk, Brian C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/70mtn-aj483", "eprint_id": 3870, "eprint_status": "archive", "datestamp": "2023-08-22 05:55:20", "lastmod": "2023-10-16 16:11:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yu-Hongbin", "name": { "family": "Yu", "given": "Hongbin" } }, { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Heath-J-R", "name": { "family": "Heath", "given": "James R." }, "orcid": "0000-0001-5356-4385" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Scanning tunneling spectroscopy of methyl- and ethyl-terminated Si(111) surfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "organic compounds; silicon; elemental semiconductors; scanning tunnelling spectroscopy; energy gap; Fermi level", "note": "\u00a9 2006 American Institute of Physics \n\n(Received 15 December 2005; accepted 30 March 2006; published online 22 June 2006) \n\nThe authors acknowledge the National Science Foundation, Grant Nos. CHE-0213589 (NSL) and NSF-CCF-05204490, and the MARCO Materials Structures and Devices Focus Center (JRH) for support of this research. One of the authors (L.J.W.) thanks the NSF for a graduate fellowship. The authors thank Peigen Cao for helpful discussions and technical assistance.\n\nPublished - YUHapl06.pdf
", "abstract": "Methyl- and ethyl-terminated Si(111) surfaces prepared by a two-step chlorination/alkylation method were characterized by low temperature scanning tunneling spectroscopy (STS). The STS data showed remarkably low levels of midgap states on the CH3- and C2H5-terminated Si surfaces. A large conductance gap relative to the Si band gap was observed for both surfaces as well as for the hydrogen-terminated Si(111) surface. This large gap is ascribed to scanning tunneling microscope tip-induced band bending resulting from a low density of midgap states which avoid pinning of the Fermi levels on these passivated surfaces.", "date": "2006-06-19", "date_type": "published", "publication": "Applied Physics Letters", "volume": "88", "number": "25", "publisher": "American Institute of Physics", "pagerange": "Art. No. 252111", "id_number": "CaltechAUTHORS:YUHapl06", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:YUHapl06", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "NSF", "grant_number": "CCF-05204490" }, { "agency": "Microelectronics Advanced Research Corporation (MARCO)" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1063/1.2203968", "primary_object": { "basename": "YUHapl06.pdf", "url": "https://authors.library.caltech.edu/records/70mtn-aj483/files/YUHapl06.pdf" }, "resource_type": "article", "pub_year": "2006", "author_list": "Yu, Hongbin; Webb, Lauren J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mwn3z-ekh51", "eprint_id": 78011, "eprint_status": "archive", "datestamp": "2023-08-19 17:43:31", "lastmod": "2023-10-25 23:39:46", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Solares-S-D", "name": { "family": "Solares", "given": "Santiago D." }, "orcid": "0000-0003-0895-8160" }, { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A., III" }, "orcid": "0000-0003-0097-5716" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Theoretical Investigation of the Structure and Coverage of the Si(111)\u2212OCH_3 Surface", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2006 American Chemical Society. \n\nReceived 23 November 2005. Published online 1 April 2006. Published in print 1 April 2006. \n\nS.D.S. and W.A.G. received support from the Microelectronics Advanced Research Corporation (MARCO) and its Focus Center on Function Engineered Nano Architectonics (FENA). N.S.L. and D.J.M. acknowledge the NSF, grant CHE-0213589. D.J.M. also thanks the Link Foundation for a fellowship.\n\nSupplemental Material - jp056796bsi20060117_041127.pdf
", "abstract": "The surface structure, strain energy, and charge profile of the methoxylated Si(111) surface, Si(111)\u2212OCH_3, has been studied using quantum mechanics, and the results are compared to those obtained previously for Si(111)\u2212CH_3 and Si(111)\u2212C_2H_5. The calculations indicate that 100% coverage is feasible for Si(111)\u2212OCH_3 (similar to the methylated surface), as compared to only \u223c80% coverage for the ethylated surface. These differences can be understood in terms of nearest-neighbor steric and electrostatic interactions. Enthalpy and free energy calculations indicate that the formation of the Si(111)\u2212OCH_3 surface from Si(111)\u2212H and methanol is favorable at 300 K. The calculations have also indicated the conditions under which stacking faults can emerge on Si(111)\u2212OCH_3, and such conditions are contrasted with the behavior of Si(111)\u2212CH_3 and Si(111)\u2212CH_2CH_3 surfaces, for which stacking faults are calculated to be energetically feasible when etch pits with sufficiently long edges are present on the surface.", "date": "2006-04-27", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "110", "number": "16", "publisher": "American Chemical Society", "pagerange": "8171-8175", "id_number": "CaltechAUTHORS:20170607-140601075", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170607-140601075", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Microelectronics Advanced Research Corporation (MARCO)" }, { "agency": "Center on Functional Engineered NanoArchitectonics (FENA)" }, { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "Link Foundation" } ] }, "doi": "10.1021/jp056796b", "primary_object": { "basename": "jp056796bsi20060117_041127.pdf", "url": "https://authors.library.caltech.edu/records/mwn3z-ekh51/files/jp056796bsi20060117_041127.pdf" }, "resource_type": "article", "pub_year": "2006", "author_list": "Solares, Santiago D.; Michalak, David J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/a5cd5-fhe11", "eprint_id": 5413, "eprint_status": "archive", "datestamp": "2023-08-22 05:33:49", "lastmod": "2023-10-16 19:12:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hafeman-Dean-G", "name": { "family": "Hafeman", "given": "Dean G." } }, { "id": "Harkins-James-B-IV", "name": { "family": "Harkins", "given": "James B., IV" } }, { "id": "Witkowski-Charles-E-II", "name": { "family": "Witkowski", "given": "Charles E., II" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Warmarck-Robert-J", "name": { "family": "Warmack", "given": "Robert J." } }, { "id": "Brown-Gilbert-M", "name": { "family": "Brown", "given": "Gilbert M." } }, { "id": "Thundat-Thomas", "name": { "family": "Thundat", "given": "Thomas" } } ] }, "title": "Optically directed molecular transport and 3D isoelectric positioning of amphoteric biomolecules", "ispublished": "pub", "full_text_status": "public", "keywords": "electrophoresis; light; mass spectrometry; protein transport; proteomics", "note": "\u00a9 2006 by the National Academy of Sciences \n\nEdited by Calvin F. Quate, Stanford University, Stanford, CA, and approved February 24, 2006 (received for review November 14, 2005). Published online before print April 17, 2006, 10.1073/pnas.0509881103 \n\nWe thank Dr. Ring-Ling Chen for assistance and advice in construction of experimental equipment; Dr. Rubye Farahi for assistance in preparation of thin-film materials; Dr. Greg Hurst for assistance with MALDI mass spectrometry; and Drs. Kilian Dill, Bruce Jacobsen, Evelyn McGown, David Hachey, Richard Caprioli, Alfred Yergy, and Michael Sailor for helpful advice and assistance. This work was conducted under a cooperative research and development agreement between UT-Battelle and Protein Discovery, Inc., and was supported by National Institute on Drug Abuse Small Business Innovation Research Contract N43DA-3-7735 (to Protein Discovery, Inc.). In addition, partial support was received from the U.S. Department of Energy Office of Biological and Environmental Research and Environmental Management Science Program (T.T.). Oak Ridge National Laboratory is managed by UT-Battelle for the U.S. Department of Energy under contract DE-AC05-00OR22725. \n\nAuthor contributions: D.G.H., J.B.H., C.E.W., N.S.L., R.J.W., G.M.B., and T.T. designed research; D.G.H., J.B.H., and C.E.W. performed research; D.G.H., J.B.H., N.S.L., R.J.W., G.M.B., and T.T. contributed new reagents/analytic tools; D.G.H., J.B.H., C.E.W., N.S.L., R.J.W., G.M.B., and T.T. analyzed data; and D.G.H. wrote the paper. \n\nConflict of interest statement: D.G.H., J.B.H., C.E.W., and N.S.L. own either stock or stock options in Protein Discovery, Inc., which holds a license to a patent application pending in the U.S. Patent Office that may cover portions of the technology described in this paper. G.M.B. and T.T. are listed coinventors on the subject patent application. In addition, R.J.W., G.M.B., and T.T. are employed at the Oak Ridge National Laboratory by its contractor, UT-Battelle, which is the assignee of the subject patent application. \n\nThis paper was submitted directly (Track II) to the PNAS office.\n\nPublished - HAFpnas06.pdf
", "abstract": "We demonstrate the formation of charged molecular packets and their transport within optically created electrical force-field traps in a pH-buffered electrolyte. We call this process photoelectrophoretic localization and transport (PELT). The electrolyte is in contact with a photoconductive semiconductor electrode and a counterelectrode that are connected through an external circuit. A light beam directed to coordinates on the photoconductive electrode surface produces a photocurrent within the circuit and electrolyte. Within the electrolyte, the photocurrent creates localized force-field traps centered at the illuminated coordinates. Charged molecules, including polypeptides and proteins, electrophoretically accumulate into the traps and subsequently can be transported in the electrolyte by moving the traps over the photoconductive electrode in response to movement of the light beam. The molecules in a single trap can be divided into aliquots, and the aliquots can be directed along multiple routes simultaneously by using multiple light beams. This photoelectrophoretic transport of charged molecules by PELT resembles the electrostatic transport of electrons within force-field wells of solid-state charge-coupled devices. The molecules, however, travel in a liquid electrolyte rather than a solid. Furthermore, we have used PELT to position amphoteric biomolecules in three dimensions. A 3D pH gradient was created in an electrolyte medium by controlling the illumination position on a photoconductive anode where protons were generated electrolytically. Photoelectrophoretic transport of amphoteric molecules through the pH gradient resulted in accumulation of the molecules at their apparent 3D isoelectric coordinates in the medium.", "date": "2006-04-25", "date_type": "published", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "volume": "103", "number": "17", "publisher": "National Academy of Sciences", "pagerange": "6436-6441", "id_number": "CaltechAUTHORS:HAFpnas06", "issn": "0027-8424", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:HAFpnas06", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NIH", "grant_number": "N43DA-3-7735" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC05-00OR22725" } ] }, "doi": "10.1073/pnas.0509881103", "pmcid": "PMC1458903", "primary_object": { "basename": "HAFpnas06.pdf", "url": "https://authors.library.caltech.edu/records/a5cd5-fhe11/files/HAFpnas06.pdf" }, "resource_type": "article", "pub_year": "2006", "author_list": "Hafeman, Dean G.; Harkins, James B., IV; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dk7vx-v7f12", "eprint_id": 76949, "eprint_status": "archive", "datestamp": "2023-08-19 17:41:25", "lastmod": "2023-10-25 17:01:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Rivillon-S", "name": { "family": "Rivillon", "given": "Sandrine" } }, { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Chabal-Y-J", "name": { "family": "Chabal", "given": "Yves J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Transmission Infrared Spectroscopy of Methyl- and Ethyl-Terminated Silicon(111) Surfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society. \n\nReceived: August 16, 2005; In Final Form: November 9, 2005.\nPublication Date (Web): March 21, 2006. \n\nL.J.W. thanks the NSF for a Graduate Research Fellowship, and D.J.M. thanks the Link Foundation for an Energy Fellowship. We gratefully acknowledge the NSF, grants CHE-0213589 at Caltech and CHE-0415652 at Rutgers, for support of this work.", "abstract": "Transmission infrared spectroscopy (TIRS) has been used to investigate the surface-bound species formed in the two-step chlorination/alkylation reaction of crystalline (111)-oriented Si surfaces. Spectra were obtained after hydrogen termination, chlorine termination, and reaction of the Cl\u2212Si(111) surface with CH_3MgX or C_2H_5MgX (X = Cl, Br) to form methyl (CH_3)- or ethyl (C_2H_5)-terminated Si(111) surfaces, respectively. Freshly etched H-terminated Si(111) surfaces that were subsequently chlorinated by immersion in a saturated solution of PCl_5 in chlorobenzene were characterized by complete loss of the Si\u2212H stretching and bending modes at 2083 and 627 cm^(-1), respectively, and the appearance of Si\u2212Cl modes at 583 and 528 cm^(-1). TIRS of the CH_3-terminated Si(111) surface exhibited a peak at 1257 cm^(-1) polarized perpendicular to the surface assigned to the C\u2212H symmetrical bending, or \"umbrella\" motion, of the methyl group. A peak observed at 757 cm^(-1) polarized parallel to the surface was assigned to the C\u2212H rocking motion. Alkyl C\u2212H stretch modes on both the CH_3- and C_2H_5-terminated surfaces were observed near 2900 cm^(-1). The C_2H_5-terminated Si(111) surface additionally exhibited broad bands at 2068 and 2080 cm^(-1), respectively, polarized perpendicular to the surface, as well as peaks at 620 and 627 cm^(-1), respectively, polarized parallel to the surface. These modes were assigned to the Si\u2212H stretching and bending motions, respectively, resulting from H-termination of surface atoms that did not form Si\u2212C bonds during the ethylation reaction.", "date": "2006-04-13", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "110", "number": "14", "publisher": "American Chemical Society", "pagerange": "7349-7356", "id_number": "CaltechAUTHORS:20170426-110722627", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170426-110722627", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Link Foundation" }, { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "NSF", "grant_number": "CHE-0415652" } ] }, "doi": "10.1021/jp054618c", "resource_type": "article", "pub_year": "2006", "author_list": "Webb, Lauren J.; Rivillon, Sandrine; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/q0vn3-zrr98", "eprint_id": 77424, "eprint_status": "archive", "datestamp": "2023-08-19 17:35:02", "lastmod": "2023-10-25 23:01:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Solares-S-D", "name": { "family": "Solares", "given": "Santiago D." }, "orcid": "0000-0003-0895-8160" }, { "id": "Yu-Hongbin", "name": { "family": "Yu", "given": "Hongbin" } }, { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Heath-J-R", "name": { "family": "Heath", "given": "James R." }, "orcid": "0000-0001-5356-4385" }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A., III" }, "orcid": "0000-0003-0097-5716" } ] }, "title": "Chlorination\u2212Methylation of the Hydrogen-Terminated Silicon(111) Surface Can Induce a Stacking Fault in the Presence of Etch Pits", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2006 American Chemical Society. \n\nReceived 15 August 2005. Published online 4 March 2006. Published in print 1 March 2006. \n\nSupport for S.D.S. and W.A.G. was provided by NSF-CCF-05204490 and by the Microelectronics Advanced Research Corporation (MARCO) and its Focus Center on Function Engineered NanoArchitectonics (FENA). Support for L.J.W. and N.S.L. was provided by NSF-CHE-0213589. Support for H.Y. and J.R.H. was provided by the DOE and NSF-CCF-05204490.\n\nSupplemental Material - ja055408gsi20060210_010750.pdf
", "abstract": "Recently, we reported STM images of the methylated Si(111) surface [prepared through chlorination\u2212alkylation of the Si(111)\u2212H surface] taken at 4.7 K, indicating that the torsion angle of the methyl group with respect to the subsurface silicon layer is \u03c6 = 23 \u00b1 3\u00b0. Repulsions between H atoms in adjacent methyl groups are minimized at 30\u00b0, while repulsions between H atoms and second layer Si atoms are minimized at 60\u00b0. The experimental result of 23\u00b0 is surprising because it suggests a tendency of the methyl group toward the eclipsed configuration (0\u00b0) rather than staggered (60\u00b0). In contrast, extensive fully periodic quantum mechanical Density Functional Theory studies of this surface give an equilibrium torsion angle of 37.5\u00b0, indicating a tendency toward the staggered configuration. This discrepancy can be resolved by showing that the CH_3 on the step edges and etch pits interacts repulsively with the CH_3 on the surface terraces unless a stacking fault is introduced between the first and second silicon layers of the Si(111)\u2212CH_3 surface terraces. We propose that this could occur during the chlorination\u2212alkylation of the Si(111)\u2212H surface. This stacking fault model predicted \u03c6 = 22.5\u00b0 measured with respect to the bulk (corresponding to \u03c6 = 37.5\u00b0 with respect to the second layer Si atoms). This model can be tested by measuring the orientation of the CH_3 within the etch pits, which should have \u03c6 = 37.5\u00b0, or by making a surface without etch pits, which should have \u03c6 = 37.5\u00b0.", "date": "2006-03-29", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "128", "number": "12", "publisher": "American Chemical Society", "pagerange": "3850-3851", "id_number": "CaltechAUTHORS:20170512-133830648", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170512-133830648", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CCF-05204490" }, { "agency": "Microelectronics Advanced Research Corporation (MARCO)" }, { "agency": "Focus Center on Function Engineered NanoArchitectonics (FENA)" }, { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NSF", "grant_number": "CCF-05204490" } ] }, "doi": "10.1021/ja055408g", "primary_object": { "basename": "ja055408gsi20060210_010750.pdf", "url": "https://authors.library.caltech.edu/records/q0vn3-zrr98/files/ja055408gsi20060210_010750.pdf" }, "resource_type": "article", "pub_year": "2006", "author_list": "Solares, Santiago D.; Yu, Hongbin; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6g0en-cnw12", "eprint_id": 47565, "eprint_status": "archive", "datestamp": "2023-08-19 17:34:12", "lastmod": "2023-10-26 20:42:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hu-Xile", "name": { "family": "Hu", "given": "Xile" }, "orcid": "0000-0001-8335-1196" }, { "id": "Cossairt-B-M", "name": { "family": "Cossairt", "given": "Brandi M." }, "orcid": "0000-0002-9891-3259" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce B." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Peters-J-C", "name": { "family": "Peters", "given": "Jonas C." }, "orcid": "0000-0002-6610-4414" } ] }, "title": "Electrocatalytic hydrogen evolution by macrocyclic cobalt and nickel complexes", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society.", "abstract": "A series of cobalt and nickel complexes with macrocyclic imine ligands such as difluoroboryldiglyxomime and [14]-Tetraene-N4 were synthesized for electrochem. hydrogen evolution catalysis. The complexes catalyzed the redn. of proton to dihydrogen at potentials as pos. as -0.26 V vs. SCE in acidic acetonitrile solns. The catalysis by the cobalt complexes was triggered by the redn. of cobalt(II) precursors to cobalt(I) species, while the catalysis by the nickel complexes was mediated by the redn. of nickel(II) precursors to nickel(II) stabilized ligand radicals. The influence of acid strengths on catalysis was discussed: for the cobalt mediated catalysis, using stronger acids as the proton sources gave higher catalytic rates; for the nickel mediated catalysis, the catalytic rates did not vary significantly when using different acids. Structure-function study of the catalysts was also described: more electron-deficient complexes catalyzed hydrogen evolution at more pos. potentials, yet with lower reaction rates.", "date": "2006-03-26", "date_type": "published", "publication": "Abstracts of Papers of the American Chemical Society", "volume": "231", "publisher": "American Chemical Society", "pagerange": "INOR 668", "id_number": "CaltechAUTHORS:20140729-143617509", "issn": "0065-7727", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140729-143617509", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "article", "pub_year": "2006", "author_list": "Hu, Xile; Cossairt, Brandi M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/g7t1v-e9y53", "eprint_id": 3576, "eprint_status": "archive", "datestamp": "2023-08-22 05:24:18", "lastmod": "2023-10-16 16:00:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Biteen-J-S", "name": { "family": "Biteen", "given": "Julie S." }, "orcid": "0000-0003-2038-6484" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Mertens-H", "name": { "family": "Mertens", "given": "Hans" } }, { "id": "Polman-A", "name": { "family": "Polman", "given": "Albert" }, "orcid": "0000-0002-0685-3886" } ] }, "title": "Spectral tuning of plasmon-enhanced silicon quantum dot luminescence", "ispublished": "pub", "full_text_status": "public", "keywords": "silicon; elemental semiconductors; semiconductor quantum dots; photoluminescence; optical tuning; radiative lifetimes; silver; electron beam lithography; surface plasmon resonance", "note": "\u00a9 2006 American Institute of Physics \n\n(Received 9 November 2005; accepted 16 February 2006; published online 31 March 2006) \n\nWork at AMOLF is part of the research program of FOM, supported by NOW and NANONED, a nanotechnology program of the Dutch Ministry of Economic Affairs. Sample fabrication and characterization were done at the Amsterdam nanoCenter. This work was also partially supported by NSF Grant No. CHE-0213589 and by AFOSR MURI Award No. FA9550-04-1-0434. One of the authors (H.A.A.) acknowledges the support of a Joop Los Fellowship awarded by AMOLF.\n\nPublished - BITapl06.pdf
", "abstract": "In the presence of nanoscale silver island arrays, silicon quantum dots exhibit up to sevenfold luminescence enhancements at emission frequencies that correspond to the collective dipole plasmon resonance frequency of the Ag island array. Using electron-beam lithography to alter the pitch and particle diameter, this wavelength-selective enhancement can be varied as the metal array resonance wavelength is tuned from 600 to 900 nm. The luminescence intensity enhancement upon coupling is attributed to an increase in the radiative decay rate of the silicon quantum dots.", "date": "2006-03-26", "date_type": "published", "publication": "Applied Physics Letters", "volume": "88", "number": "13", "publisher": "American Institute of Physics", "pagerange": "Art. No. 131109", "id_number": "CaltechAUTHORS:BITapl06", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:BITapl06", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Stichting voor Fundamenteel Onderzoek der Materie (FOM)" }, { "agency": "Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)" }, { "agency": "Ministry of Economic Affairs (Netherlands)" }, { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-04-1-0434" } ] }, "doi": "10.1063/1.2191411", "primary_object": { "basename": "BITapl06.pdf", "url": "https://authors.library.caltech.edu/records/g7t1v-e9y53/files/BITapl06.pdf" }, "resource_type": "article", "pub_year": "2006", "author_list": "Biteen, Julie S.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2md0p-pf169", "eprint_id": 48280, "eprint_status": "archive", "datestamp": "2023-08-19 17:34:32", "lastmod": "2023-10-17 18:40:05", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Peters-J-C", "name": { "family": "Peters", "given": "Jonas C." }, "orcid": "0000-0002-6610-4414" }, { "id": "Hu-Xile", "name": { "family": "Hu", "given": "Xile" }, "orcid": "0000-0001-8335-1196" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nate" }, "orcid": "0000-0001-5245-0538" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce B." }, "orcid": "0000-0002-6135-6727" }, { "id": "Cossairt-B-M", "name": { "family": "Coissart", "given": "Brandi M." }, "orcid": "0000-0002-9891-3259" } ] }, "title": "Two electron redox couples for hydrogen production", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2006 American Chemical Society.", "abstract": "As part of a collaborative, NSF-supported initiative to help develop the basic chem. needed for producing solar\nfuels, our group has been studying relatively inexpensive, first row transition metals that mediate\nelectrocatalytic hydrogen evolution at unusually pos. potentials. These complexes constitute a severe\nstructural departure from the active sites of hydrogenase enzymes, but are attractive candidates for hydrogen\nevolution because they access reduced states at quite pos. potentials that then trigger the two-electron redn.\nof proton to hydride. The systems are unusual in that they display remarkable tolerance to the typical\nhydrogenase poison, carbon monoxide. Our efforts to more fully map the chem. of these types of systems will\nbe described.", "date": "2006-03-26", "date_type": "published", "publication": "Abstracts of Papers of the American Chemical Society", "volume": "231", "publisher": "American Chemical Society", "pagerange": "INOR 412", "id_number": "CaltechAUTHORS:20140811-083620961", "issn": "0065-7727", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140811-083620961", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "article", "pub_year": "2006", "author_list": "Peters, Jonas C.; Hu, Xile; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fbgt7-zq040", "eprint_id": 85729, "eprint_status": "archive", "datestamp": "2023-08-22 05:22:06", "lastmod": "2023-10-18 18:43:28", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tan-Ming-X", "name": { "family": "Tan", "given": "Ming X." } }, { "id": "Bansal-A", "name": { "family": "Bansal", "given": "Ashish" } }, { "id": "Lauermann-I", "name": { "family": "Lauermann", "given": "Iver" } }, { "id": "Shreve-G-A", "name": { "family": "Shreve", "given": "Gary A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Semiconductor Interfaces", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "Schottky barrier; barrier height; band bending; interfaces; built\u2010in voltage; space\u2010charge region; semiconductor junctions; semiconductor contacts", "note": "\u00a9 2006 John Wiley & Sons, Ltd. \n\nPublished Online: 15 March 2006.", "abstract": "This article describes the properties of semiconductors that are responsible for the operation of rectifiers, transistors, photovoltaic devices, and light emitting. The penetration of the electric field and the electric potential into a bulk semiconductor phase yields a nonuniform carrier concentration in the sample, and produces contacts that either attract or repel specific types of charge carriers. Chemical control over these electric fields is crucial to the technology of semiconductor contacts. In principle, such control can be established through a simple variation in the electrochemical potential of the contacting phase. In practice, this ideal model often does not apply, and other factors influence or completely determine the interfacial electric field strength. The application of these principles is described for semiconductor/semiconductor, semiconductor/metal, semiconductor/liquid, and semiconductor/polymer contacts, making the approach valuable for understanding the operational principles of a variety of technologically important semiconductor devices.", "date": "2006-03-15", "date_type": "published", "publisher": "Wiley", "place_of_pub": "New York, NY", "pagerange": "1-17", "id_number": "CaltechAUTHORS:20180410-133851649", "isbn": "9780470860786", "book_title": "Encyclopedia of Inorganic Chemistry", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180410-133851649", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "King-R-B", "name": { "family": "King", "given": "R. B." } }, { "id": "Crabtree-R-H", "name": { "family": "Crabtree", "given": "R. H." } }, { "id": "Lukehart-C-M", "name": { "family": "Lukehart", "given": "C. M." } }, { "id": "Atwood-D-A", "name": { "family": "Atwood", "given": "D. A." } }, { "id": "Scott-R-A", "name": { "family": "Scott", "given": "R. A." } } ] }, "doi": "10.1002/0470862106.ia216", "resource_type": "book_section", "pub_year": "2006", "author_list": "Tan, Ming X.; Bansal, Ashish; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/v82r5-bvn72", "eprint_id": 85802, "eprint_status": "archive", "datestamp": "2023-08-22 05:22:14", "lastmod": "2023-10-18 18:49:03", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Stanton-C-E", "name": { "family": "Stanton", "given": "Colby E." } }, { "id": "Nguyen-SonBinh-T", "name": { "family": "Nguyen", "given": "SonBinh T." } }, { "id": "Kesselman-J-M", "name": { "family": "Kesselman", "given": "Janet M." } }, { "id": "Laibinis-P-E", "name": { "family": "Laibinis", "given": "Paul E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Semiconductors", "ispublished": "unpub", "full_text_status": "public", "keywords": "semiconductors; band structure; electrons; holes; mobility; solids", "note": "\u00a9 2006 John Wiley & Sons, Ltd. \n\nPublished Online: 15 March 2006. \n\nWe acknowledge the National Science Foundation, grant\nCHE-8814694, and the Department of Energy, Office of\nBasic Energy Sciences, grant DE-FG03-88ER13932, for\nsupport of work in photoelectrochemistry. Janet M. Kesselman\nacknowledges the National Science Foundation and SonBinh\nT. Nguyen acknowledges the Department of Defense, Office\nof Army Research for pre-doctoral fellowships. This is\ncontribution 8755 from the Caltech Division of Chemistry\nand Chemical Engineering.", "abstract": "The structural, electronic, optical, and electrical properties of semiconductors are treated within a common framework. The bonding in the lattice determines the band structure of the solid, which is used to describe the chemical, optical, and electrical properties of the semiconductor. These concepts enable this process to be understood from a qualitative, chemically based viewpoint.", "date": "2006-03-15", "date_type": "published", "publisher": "Wiley", "place_of_pub": "Chichester", "pagerange": "1-16", "id_number": "CaltechAUTHORS:20180412-161816893", "isbn": "9780470860786", "book_title": "Encyclopedia of Inorganic Chemistry", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180412-161816893", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-8814694" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG03-88ER13932" }, { "agency": "Army Research Office (ARO)" } ] }, "other_numbering_system": { "items": [ { "id": "8755", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "contributors": { "items": [ { "id": "King-R-B", "name": { "family": "King", "given": "R. Bruce" } }, { "id": "Crabtree-R-H", "name": { "family": "Crabtree", "given": "R. H." } }, { "id": "Lukehart-C-M", "name": { "family": "Lukehart", "given": "C. M." } }, { "id": "Atwood-D-A", "name": { "family": "Atwood", "given": "D. A." } }, { "id": "Scott-R-A", "name": { "family": "Scott", "given": "R. A." } } ] }, "doi": "10.1002/0470862106.ia217", "resource_type": "book_section", "pub_year": "2006", "author_list": "Stanton, Colby E.; Nguyen, SonBinh T.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sqy0c-kd774", "eprint_id": 5517, "eprint_status": "archive", "datestamp": "2023-08-22 04:44:50", "lastmod": "2023-10-16 19:15:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Mayo-E-I", "name": { "family": "Mayo", "given": "Elizabeth I." } }, { "id": "Kils\u00e5-K", "name": { "family": "Kils\u00e5", "given": "Kristine" } }, { "id": "Tirrell-T", "name": { "family": "Tirrell", "given": "Timothy" } }, { "id": "Djurovich-P-I", "name": { "family": "Djurovich", "given": "Peter I." } }, { "id": "Tamayo-A", "name": { "family": "Tamayo", "given": "Arnold" } }, { "id": "Thompson-M-E", "name": { "family": "Thompson", "given": "Mark E." }, "orcid": "0000-0002-7764-4096" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Cyclometalated iridium(III)-sensitized titanium dioxide solar cells", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 The Royal Society of Chemistry and Owner Societies 2006 \n\nReceived 14th June 2006, Accepted 6th September 2006. First published on the web 20th September 2006 \n\nThis work was supported by the DOE, NREL, Global Photonic Energy Corp., the NSF, BP, the Carlsberg Foundation, and the Caltech Summer Undergraduate Research Program. \n\nThis paper was published as part of the special issue in honour of the late Professor George S. Hammond. Photochemical & Photobiological Sciences, volume 5, issue 10, 2006.", "abstract": "Ir(III) dyes used as sensitizers in dye-sensitized solar cells produced quantum yields approaching unity for conversion of absorbed photons to current under simulated air mass 1.0 sunlight, with current production resulting from ligand-to-ligand charge-transfer states, rather than the typical metal-to-ligand charge-transfer states in ruthenium-based cells.", "date": "2006", "date_type": "published", "publication": "Photochemical and Photobiological Sciences", "volume": "5", "number": "10", "publisher": "Photochemical and Photobiological Sciences", "pagerange": "871-873", "id_number": "CaltechAUTHORS:MAYpps06", "issn": "1474-905X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:MAYpps06", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1039/b608430c", "primary_object": { "basename": "medium.png", "url": "https://authors.library.caltech.edu/records/sqy0c-kd774/files/medium.png" }, "related_objects": [ { "basename": "small.png", "url": "https://authors.library.caltech.edu/records/sqy0c-kd774/files/small.png" }, { "basename": "MAYpps06.gif", "url": "https://authors.library.caltech.edu/records/sqy0c-kd774/files/MAYpps06.gif" }, { "basename": "MAYpps06.pdf", "url": "https://authors.library.caltech.edu/records/sqy0c-kd774/files/MAYpps06.pdf" } ], "resource_type": "article", "pub_year": "2006", "author_list": "Mayo, Elizabeth I.; Kils\u00e5, Kristine; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nk91d-v1p59", "eprint_id": 22820, "eprint_status": "archive", "datestamp": "2023-08-19 16:56:06", "lastmod": "2023-10-23 17:14:09", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kayes-B-M", "name": { "family": "Kayes", "given": "Brendan M." } }, { "id": "Spurgeon-J-M", "name": { "family": "Spurgeon", "given": "Joshua M." }, "orcid": "0000-0002-2987-0865" }, { "id": "Sadler-T-C", "name": { "family": "Sadler", "given": "Thomas C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Synthesis and Characterization of Silicon Nanorod Arrays for Solar Cell Applications", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2006 IEEE. Issue Date: May 2006, Date of Current Version: 15 January 2007. We would like to thank BP Solar, DOE, NSF, and Caltech's SURF program for financial support.\n\n", "abstract": "Silicon nanorods have been grown by chemical vapor deposition of silane, using both gold and indium as catalysts for the vapor liquid solid (VLS) process. Conditions for optimal rod morphology for each catalyst were identified by varying silane partial pressure and temperature in the range P = 0.05-1 Torr and T = 300-600 C, respectively. In most cases, catalyst particles were formed by partial de-wetting of evaporated films of the catalytic material to form droplets with diameters of tens to hundreds of nanometers. Also, periodic arrays of catalyst particles with controlled size and spacing were achieved both by the use of porous alumina membranes and also by electron-beam lithography. Using these techniques, silicon nanorods were grown with diameters of 100 nm to microns and lengths of microns to tens of microns. Four-point and gate-bias-dependent resistance measurements were made on single wires, and these indicate that rods we have grown with gold catalysts and phosphine doping have metal-like conductivity.", "date": "2006", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, N.J.", "pagerange": "221-224", "id_number": "CaltechAUTHORS:20110311-081313253", "isbn": "1-4244-0016-3", "book_title": "Conference record of the 2006 IEEE 4th World Conference on Photovoltaic Energy Conversion WCPEC-4", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110311-081313253", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP Solar" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NSF" }, { "agency": "Caltech Summer Undergraduate Research Fellowship (SURF)" } ] }, "doi": "10.1109/WCPEC.2006.279422", "primary_object": { "basename": "Kayes2006p9659Conference_Record_Of_The_2006_Ieee_4Th_World_Conference_On_Photovoltaic_Energy_Conversion_Vols_1_And_2.pdf", "url": "https://authors.library.caltech.edu/records/nk91d-v1p59/files/Kayes2006p9659Conference_Record_Of_The_2006_Ieee_4Th_World_Conference_On_Photovoltaic_Energy_Conversion_Vols_1_And_2.pdf" }, "resource_type": "book_section", "pub_year": "2006", "author_list": "Kayes, Brendan M.; Spurgeon, Joshua M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/97m4j-23z17", "eprint_id": 77493, "eprint_status": "archive", "datestamp": "2023-08-19 16:30:33", "lastmod": "2023-10-25 23:06:24", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hamann-T-W", "name": { "family": "Hamann", "given": "Thomas W." } }, { "id": "Gstrein-F", "name": { "family": "Gstrein", "given": "Florian" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Measurement of the Dependence of Interfacial Charge-Transfer Rate Constants on the Reorganization Energy of Redox Species at n-ZnO/H_2O Interfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2005 American Chemical Society. \n\nReceived 10 March 2005. Published online 16 September 2005. Published in print 1 October 2005. \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, for support of this work.", "abstract": "The interfacial energetic and kinetics behavior of n-ZnO/H_2O contacts have been determined for a series of compounds, cobalt trisbipyridine (Co(bpy)_3^(3+/2+)), ruthenium pentaamine pyridine (Ru(NH_3)_5py^(3+/2+)), cobalt bis-1,4,7-trithiacyclononane (Co(TTCN)_2^(3+/2+)), and osmium bis-dimethyl bipyridine bis-imidazole (Os(Me_2bpy)_2(Im)_2^(3+/2+)), which have similar formal reduction potentials yet which have reorganization energies that span approximately 1 eV. Differential capacitance vs potential and current density vs potential measurements were used to measure the interfacial electron-transfer rate constants for this series of one-electron outer-sphere redox couples. Each interface displayed a first-order dependence on the concentration of redox acceptor species and a first-order dependence on the concentration of electrons in the conduction band at the semiconductor surface, in accord with expectations for the ideal model of a semiconductor/liquid contact. Rate constants varied from 1 \u00d7 10^(-19) to 6 \u00d7 10^(-17) cm^4 s^(-1). The interfacial electron-transfer rate constant decreased as the reorganization energy, \u03bb, of the acceptor species increased, and a plot of the logarithm of the electron-transfer rate constant vs (\u03bb + \u0394G\u00b0')^2/4\u03bbk_BT (where \u0394G\u00b0' is the driving force for interfacial charge transfer) was linear with a slope of \u223c\u2009\u22121. The rate constant at optimal exoergicity was found to be \u223c5 \u00d7 10^(-17) cm^4 s^(-1) for this system. These results show that interfacial electron-transfer rate constants at semiconductor electrodes are in good agreement with the predictions of a Marcus-type model of interfacial electron-transfer reactions.", "date": "2005-10-12", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "127", "number": "40", "publisher": "American Chemical Society", "pagerange": "13949-13954", "id_number": "CaltechAUTHORS:20170516-102143971", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170516-102143971", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1021/ja0515452", "resource_type": "article", "pub_year": "2005", "author_list": "Hamann, Thomas W.; Gstrein, Florian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/as9jr-npp92", "eprint_id": 75153, "eprint_status": "archive", "datestamp": "2023-08-19 16:29:15", "lastmod": "2023-10-25 14:47:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Chemical Control of Charge Transfer and Recombination at Semiconductor Photoelectrode Surfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2005 American Chemical Society. \n\nReceived July 6, 2005; Publication Date (Web): September 26, 2005. \n\nWe acknowledge NSF Grant CHE-0213589 and the Office of Basic Energy Sciences, Department of Energy, for the sustained support that has made the research discussed herein possible. In addition, the author is extremely indebted to Tom W. Hamann and David J. Michalak for their invaluable help during the preparation of this manuscript.", "abstract": "Semiconductor/liquid contacts provide very efficient systems for converting sunlight into electrical and/or chemical energy. Until recently, relatively little was understood about the factors that control the rates of interfacial charge transfer in such systems. This Forum Article summarizes recent results that have elucidated the key factors that control such charge-transfer rates, including verification of the Marcus inverted region, identification of the maximum charge-transfer rate constant for outer-sphere, nonadsorbing redox couples at optimal exoergicity, the role of nuclear reorganization on the value of the interfacial charge-transfer rate constant at semiconductor electrodes, and the effects of pH-induced changes in the driving force on the rates of such systems. In addition, we discuss methods for using main group inorganic chemistry to control the electrical properties of surfaces of important semiconductors for solar energy conversion, with specific emphasis on alkylation of the (111)-oriented surface of Si. Control of the rates at which carriers cross such interfaces, along with control of the rates at which carriers recombine at such interfaces, forms the basis for exerting chemical control over the key solar energy conversion properties of semiconductor photoelectrode-based devices.", "date": "2005-10-03", "date_type": "published", "publication": "Inorganic Chemistry", "volume": "44", "number": "20", "publisher": "American Chemical Society", "pagerange": "6900-6911", "id_number": "CaltechAUTHORS:20170315-141210704", "issn": "0020-1669", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170315-141210704", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1021/ic051118p", "resource_type": "article", "pub_year": "2005", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ds9c8-0d275", "eprint_id": 79743, "eprint_status": "archive", "datestamp": "2023-08-19 16:19:48", "lastmod": "2023-10-20 22:04:15", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Biteen-Julie-S", "name": { "family": "Biteen", "given": "Julie S." }, "orcid": "0000-0003-2038-6484" }, { "id": "Pacifici-Domenico", "name": { "family": "Pacifici", "given": "Domenico" }, "orcid": "0000-0003-1050-7684" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Enhanced Radiative Emission Rate and Quantum Efficiency in Coupled Silicon Nanocrystal-Nanostructured Gold Emitters", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2005 American Chemical Society. \n\nReceived 25 June 2005. Published online 19 August 2005. Published in print 1 September 2005. \n\nThe acknowledgement should be the following:\u2009Expert scientific and technical assistance from Jonah Erlebacher are gratefully acknowledged. A portion of this work was supported by NSF Grant CHE-0213589. This work was also partially supported by the Air Force Office of Scientific Research (MURI award #FA9550-04-1-0434).\n\nPage 1773. The acknowledgement should be the following:\u2009 Expert scientific and technical assistance from Jonah Erlebacher are gratefully acknowledged. A portion of this work was supported by NSF Grant CHE-0213589. This work was also partially supported by the Air Force Office of Scientific Research (MURI award #FA9550-04-1-0434).09/17/2005\n\nSupplemental Material - nl051207zsi20050728_054658.pdf
", "abstract": "We report local-field-enhanced light emission from silicon nanocrystals close to a film of nanoporous gold. We resolve photoluminescence as the gold\u2212Si nanocrystal separation distance is varied between 0 and 20 nm and observe a fourfold luminescence intensity enhancement concomitant with increases in the coupled silicon nanocrystal/nanoporous gold absorbance cross section and radiative decay rate. A detailed analysis of the luminescence data indicated a local-field-enhanced quantum efficiency of 58% for the Si nanocrystals coupled to the nanoporous gold layer.", "date": "2005-09", "date_type": "published", "publication": "Nano Letters", "volume": "5", "number": "9", "publisher": "American Chemical Society", "pagerange": "1768-1773", "id_number": "CaltechAUTHORS:20170802-090931005", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170802-090931005", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-04-1-0434" } ] }, "doi": "10.1021/nl051207z", "primary_object": { "basename": "nl051207zsi20050728_054658.pdf", "url": "https://authors.library.caltech.edu/records/ds9c8-0d275/files/nl051207zsi20050728_054658.pdf" }, "resource_type": "article", "pub_year": "2005", "author_list": "Biteen, Julie S.; Pacifici, Domenico; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zpbab-e1w79", "eprint_id": 2420, "eprint_status": "archive", "datestamp": "2023-08-22 03:55:52", "lastmod": "2023-10-13 23:23:10", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hunger-Ralf", "name": { "family": "Hunger", "given": "Ralf" } }, { "id": "Fritsche-Rainer", "name": { "family": "Fritsche", "given": "Rainer" } }, { "id": "Jaeckel-Bengt", "name": { "family": "Jaeckel", "given": "Bengt" } }, { "id": "Jaegermann-Wolfram", "name": { "family": "Jaegermann", "given": "Wolfram" } }, { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Chemical and electronic characterization of methyl-terminated Si(111) surfaces by high-resolution synchrotron photoelectron spectroscopy", "ispublished": "pub", "full_text_status": "public", "keywords": "silicon; elemental semiconductors; surface reconstruction; X-ray photoelectron spectra; passivation; low energy electron diffraction; annealing; photoemission; dangling bonds; vibrational modes; core levels; binding energy; excited states; fine structure", "note": "\u00a9 2005 The American Physical Society. \n\n(Received 19 November 2004; accepted 15 March 2005; published 8 July 2005) \n\nWe gratefully acknowledge the National Science Foundation, grant No. CHE-0213589, for support of this work (N.S.L. and L.J.W.) and for providing financial assistance to L.J.W. W.J. acknowledges the travelling support of the Deutsche Forschungsgemeinschaft, DFG Grant No. JA 85910-1. The support of the BMBF for setting-up and running SoLiAS at BESSY (Contracts Nos. 05 KS1RD1/0 and 05 KS4RD1/0, R.H. and W.J.) and travel grants (05 ES3XBA/5) are gratefully\nacknowledged.\n\nPublished - HUNprb05.pdf
", "abstract": "The chemical state, electronic properties, and geometric structure of methyl-terminated Si(111) surfaces prepared using a two-step chlorination/alkylation process were investigated using high-resolution synchrotron photoelectron spectroscopy and low-energy electron diffraction methods. The electron diffraction data indicated that the methylated Si surfaces maintained a (1\u00d71) structure, where the dangling bonds of the silicon surface atoms were terminated by methyl groups. The surfaces were stable to annealing at 720 K. The high degree of ordering was reflected in a well-resolved vibrational fine structure of the carbon 1s photoelectron emission, with the fine structure arising from the excitation of C-H stretching vibrations having hnu=0.38\u00b10.01 eV. The carbon-bonded surface Si atoms exhibited a well-defined x-ray photoelectron signal having a core level shift of 0.30\u00b10.01 eV relative to bulk Si. Electronically, the Si surface was close to the flat-band condition. The methyl termination produced a surface dipole of \u20130.4 eV. Surface states related to piCH3 and sigmaSi-C bonding orbitals were identified at binding energies of 7.7 and 5.4 eV, respectively. Nearly ideal passivation of Si(111) surfaces can thus be achieved by methyl termination using the two-step chlorination/alkylation process.", "date": "2005-07-15", "date_type": "published", "publication": "Physical Review B", "volume": "72", "number": "4", "publisher": "American Physical Society", "pagerange": "Art. No. 045317", "id_number": "CaltechAUTHORS:HUNprb05", "issn": "1098-0121", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:HUNprb05", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Deutsche Forschungsgemeinschaft (DFG)", "grant_number": "JA 85910-1" }, { "agency": "Bundesministerium f\u00fcr Bildung und Forschung (BMBF)", "grant_number": "05 KS1RD1/0" }, { "agency": "Bundesministerium f\u00fcr Bildung und Forschung (BMBF)", "grant_number": "05 KS4RD1/0" }, { "agency": "Bundesministerium f\u00fcr Bildung und Forschung (BMBF)", "grant_number": "05 ES3XBA/5" } ] }, "doi": "10.1103/PhysRevB.72.045317", "primary_object": { "basename": "HUNprb05.pdf", "url": "https://authors.library.caltech.edu/records/zpbab-e1w79/files/HUNprb05.pdf" }, "resource_type": "article", "pub_year": "2005", "author_list": "Hunger, Ralf; Fritsche, Rainer; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4qerj-2qv38", "eprint_id": 9641, "eprint_status": "archive", "datestamp": "2023-08-22 03:49:31", "lastmod": "2023-10-16 22:24:08", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Rivillon-S", "name": { "family": "Rivillon", "given": "Sandrine" } }, { "id": "Chabal-Y-J", "name": { "family": "Chabal", "given": "Yves J." } }, { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Halls-M-D", "name": { "family": "Halls", "given": "Mathew D." } }, { "id": "Raghavachari-Krishnan", "name": { "family": "Raghavachari", "given": "Krishnan" } } ] }, "title": "Chlorination of hydrogen-terminated silicon (111) surfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "silicon; hydrogen; elemental semiconductors; infrared spectra; X-ray photoelectron spectra; ab initio calculations; surface dynamics; surface roughness; surface treatment; surface structure", "note": "\u00a9 2005 American Vacuum Society. \n\n(Received 7 October 2004; accepted 20 December 2004; published 28 June 2005) \n\nThis work was supported by the National Science Foundation (Grant Nos. CHE-0415652 and CHE-0213589, as well as providing a graduate research fellowship to L.J.W.) and by International Sematech (Contract No. #306106 with FEPS008). This research was carried out in part at the National Synchrotron Light Source, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Division of Materials Sciences and Division of Chemical Sciences, under Contract No. DE-AC02-98CH10886. The authors thank Michael Sullivan for use of the N2(g)-purged glovebox at the NSLS. The authors are grateful to Martin M. Frank, Fabrice Amy, Rhett T. Brewer and Eric Garfunkel for fruitful discussions.\n\nPublished - RIVjvsta05.pdf
", "abstract": "Infrared absorption spectroscopy was used to investigate the chlorination of hydrogen-terminated Si(111) surfaces by three different methods: (a) exposure to a saturated solution of phosphorus pentachloride (PCl5) in chlorobenzene; (b) exposure to chlorine gas, Cl2(g), and (c) exposure to Cl2(g) under UV illumination. X-ray photoelectron spectroscopy and first principles model (clusters) calculations were used to explore the structure and dynamics of these surfaces. The infrared spectra exhibited sharp chlorine-related vibrations at 586 and 527 cm^\u20131. The narrow full width at half maximum of these vibrations for all three preparation methods indicated that all functionalization schemes produced a nearly complete monolayer of Cl with little surface roughening or introduction of step edges. The 527 cm^\u20131 mode was at a much higher frequency than might be expected for the bending vibration of Si monochloride. Theoretical calculations show, however, that this vibration involves the displacement of the top Si atom parallel to the surface, subject to a relatively stiff potential, shifting its frequency to a value fairly close to that of the Si\u2013Cl stretching mode on a Si(111) surface.", "date": "2005-07", "date_type": "published", "publication": "Journal of the Vacuum Society of America A", "volume": "23", "number": "4", "publisher": "American Vacuum Society", "pagerange": "1100-1106", "id_number": "CaltechAUTHORS:RIVjvsta05", "issn": "0734-2101", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:RIVjvsta05", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0415652" }, { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Sematech", "grant_number": "306106" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-98CH10886" } ] }, "doi": "10.1116/1.1861941", "primary_object": { "basename": "RIVjvsta05.pdf", "url": "https://authors.library.caltech.edu/records/4qerj-2qv38/files/RIVjvsta05.pdf" }, "resource_type": "article", "pub_year": "2005", "author_list": "Rivillon, Sandrine; Chabal, Yves J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cxjes-xm359", "eprint_id": 4165, "eprint_status": "archive", "datestamp": "2023-08-22 03:44:59", "lastmod": "2023-10-16 17:38:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kayes-B-M", "name": { "family": "Kayes", "given": "Brendan M." } }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparison of the device physics principles of planar and radial p-n junction nanorod solar cells", "ispublished": "pub", "full_text_status": "public", "keywords": "silicon; gallium arsenide; elemental semiconductors; III-V semiconductors; solar cells; minority carriers; diffusion; semiconductor device models; carrier lifetime", "note": "\u00a9 2005 American Institute of Physics. \n\nReceived 7 October 2004; accepted 15 March 2005; published online 23 May 2005. \n\nThis work was supported by the National Renewable Energy Laboratory.\n\nPublished - KAYjap05.pdf
", "abstract": "A device physics model has been developed for radial p-n junction nanorod solar cells, in which densely packed nanorods, each having a p-n junction in the radial direction, are oriented with the rod axis parallel to the incident light direction. High-aspect-ratio (length/diameter) nanorods allow the use of a sufficient thickness of material to obtain good optical absorption while simultaneously providing short collection lengths for excited carriers in a direction normal to the light absorption. The short collection lengths facilitate the efficient collection of photogenerated carriers in materials with low minority-carrier diffusion lengths. The modeling indicates that the design of the radial p-n junction nanorod device should provide large improvements in efficiency relative to a conventional planar geometry p-n junction solar cell, provided that two conditions are satisfied: (1) In a planar solar cell made from the same absorber material, the diffusion length of minority carriers must be too low to allow for extraction of most of the light-generated carriers in the absorber thickness needed to obtain full light absorption. (2) The rate of carrier recombination in the depletion region must not be too large (for silicon this means that the carrier lifetimes in the depletion region must be longer than ~10 ns). If only condition (1) is satisfied, the modeling indicates that the radial cell design will offer only modest improvements in efficiency relative to a conventional planar cell design. Application to Si and GaAs nanorod solar cells is also discussed in detail.", "date": "2005-06-01", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "97", "number": "11", "publisher": "American Institute of Physics", "pagerange": "Art. No. 114302", "id_number": "CaltechAUTHORS:KAYjap05", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:KAYjap05", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "National Renewable Energy Laboratory" } ] }, "doi": "10.1063/1.1901835", "primary_object": { "basename": "KAYjap05.pdf", "url": "https://authors.library.caltech.edu/records/cxjes-xm359/files/KAYjap05.pdf" }, "resource_type": "article", "pub_year": "2005", "author_list": "Kayes, Brendan M.; Atwater, Harry A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nd12s-vp740", "eprint_id": 76925, "eprint_status": "archive", "datestamp": "2023-08-19 15:56:23", "lastmod": "2023-10-25 16:59:44", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hamann-T-W", "name": { "family": "Hamann", "given": "Thomas W." } }, { "id": "Gstrein-F", "name": { "family": "Gstrein", "given": "Florian" } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Measurement of the Free-Energy Dependence of Interfacial Charge-Transfer Rate Constants using ZnO/H_2O Semiconductor/Liquid Contacts", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2005 American Chemical Society.\n\nReceived October 20, 2004. Publication Date (Web): May 7, 2005. \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, for support of this work. Dr. Mona Shahgholi provided helpful assistance in acquiring mass spectroscopic data, and Drs. Nagarajan Srivatsan and Norman Sutin are acknowledged for helpful conversations.\n\nSupplemental Material - ja0436188si20050208_040445.pdf
", "abstract": "The dependence of electron-transfer rate constants on the driving force for interfacial charge transfer has been investigated using n-type ZnO electrodes in aqueous solutions. Differential capacitance versus potential and current density versus potential measurements were used to determine the energetics and kinetics, respectively, of the interfacial electron-transfer processes. A series of nonadsorbing, one-electron, outer-sphere redox couples with formal reduction potentials that spanned approximately 900 mV allowed evaluation of both the normal and Marcus inverted regions of interfacial electron-transfer processes. All rate processes were observed to be kinetically first-order in the concentration of surface electrons and first-order in the concentration of dissolved redox acceptors. The band-edge positions of the ZnO were essentially independent of the Nernstian potential of the solution over the range 0.106\u22121.001 V vs SCE. The rate constant at optimal exoergicity was observed to be approximately 10^(-16) cm4 s^(-1). The rate constant versus driving force dependence at n-type ZnO electrodes exhibited both normal and inverted regions, and the data were well-fit by a parabola generated using classical Marcus theory with a reorganization energy of 0.67 eV. NMR line broadening measurements of the self-exchange rate constants indicated that the redox couples had reorganization energies of 0.64\u22120.69 eV. The agreement between the reorganization energy of the ions in solution and the reorganization energy for the interfacial electron-transfer processes indicated that the reorganization energy was dominated by the redox species in the electrolyte, as expected from an application of Marcus theory to semiconductor electrodes.", "date": "2005-06-01", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "127", "number": "21", "publisher": "American Chemical Society", "pagerange": "7815-7824", "id_number": "CaltechAUTHORS:20170425-161159177", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170425-161159177", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1021/ja0436188", "primary_object": { "basename": "ja0436188si20050208_040445.pdf", "url": "https://authors.library.caltech.edu/records/nd12s-vp740/files/ja0436188si20050208_040445.pdf" }, "resource_type": "article", "pub_year": "2005", "author_list": "Hamann, Thomas W.; Gstrein, Florian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6jy1g-3e329", "eprint_id": 73921, "eprint_status": "archive", "datestamp": "2023-08-19 15:50:17", "lastmod": "2023-10-24 21:06:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gao-Ting", "name": { "family": "Gao", "given": "Ting" } }, { "id": "Tillman-E-S", "name": { "family": "Tillman", "given": "Eric S." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Detection and Classification of Volatile Organic Amines and Carboxylic Acids Using Arrays of Carbon Black-Dendrimer Composite Vapor Detectors", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2005 American Chemical Society. \n\nReceived 31 March 2004. Published online 7 May 2005. Published in print 1 May 2005. \n\nThe authors thank Mr. Brian Sisk for valuable discussion and assistance. This work was supported by the National Institutes of Health (NIH) and the NSF.\n\nSupplemental Material - cm049457osi20040331_073813.pdf
", "abstract": "Carbon black-insulator composite chemiresistive vapor detectors have been prepared using dendrimers as the polymeric constituent of the composite. Amino-terminated dendrimer-carbon black composites exhibited an enhancement in detection sensitivity of \u223c10^3 for volatile carboxylic acids as compared to nondendrimeric insulating polymer-carbon black composites. Similarly, protonated carboxylato-terminated and protonated amino-terminated dendrimer-carbon black composites showed an \u223c10^3\u221210^4 increase in sensitivity for detection of volatile amines relative to the response of nondendrimeric insulating polymer-carbon black composites. The protonated amino-terminated dendrimer carbon black composite detectors exhibited a signal-to-noise ratio (S/N) of 22.4 \u00b1 0.9 upon exposure to 2.7 ppb of butylamine in air, whereas poly(ethylene oxide)-carbon black composites exhibited a S/N of 3.5 \u00b1 1.2 at 54 ppm of butylamine. The protonated amino-terminated dendrimer-carbon black detectors additionally exhibited relatively small responses to water vapor. Compositional diversity in an array of protonated amino-terminated dendrimeric vapor detectors was obtained by varying the type and generation of the dendrimer, and the type and concentration of the acid dopant. Fifteen analytes chosen from primary amines, branched amines, anilines, and non-amine organic analyte vapors were all robustly discriminated from each other by their different response patterns on the dendrimer-containing detector array. The signals produced by these 15 analytes additionally clustered into groups based on the chemical class of the analyte.", "date": "2005-05-31", "date_type": "published", "publication": "Chemistry of Materials", "volume": "17", "number": "11", "publisher": "American Chemical Society", "pagerange": "2904-2911", "id_number": "CaltechAUTHORS:20170201-095440684", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170201-095440684", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NIH" }, { "agency": "NSF" } ] }, "doi": "10.1021/cm049457o", "primary_object": { "basename": "cm049457osi20040331_073813.pdf", "url": "https://authors.library.caltech.edu/records/6jy1g-3e329/files/cm049457osi20040331_073813.pdf" }, "resource_type": "article", "pub_year": "2005", "author_list": "Gao, Ting; Tillman, Eric S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/k0mk2-mmp41", "eprint_id": 77731, "eprint_status": "archive", "datestamp": "2023-08-19 15:29:26", "lastmod": "2023-10-25 23:24:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Nemanick-E-J", "name": { "family": "Nemanick", "given": "E. Joseph" }, "orcid": "0000-0002-4650-6491" }, { "id": "Biteen-J-S", "name": { "family": "Biteen", "given": "Julie S." }, "orcid": "0000-0003-2038-6484" }, { "id": "Knapp-D-W", "name": { "family": "Knapp", "given": "David W." } }, { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Traub-M-C", "name": { "family": "Traub", "given": "Matthew C." } }, { "id": "Chan-Ally-S-Y", "name": { "family": "Chan", "given": "Ally S. Y." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "High-Resolution X-ray Photoelectron Spectroscopic Studies of Alkylated Silicon(111) Surfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2005 American Chemical Society. \n\nReceived 28 June 2004. Published online 12 February 2005. Published in print 1 March 2005. \n\nWe gratefully acknowledge the National Science Foundation, Grant CHE-0213589, for support of this work and for providing a graduate research fellowship to L.J.W. A.C. acknowledges support from the Army Research Office. This research was carried out in part at the National Synchrotron Light Source, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Division of Materials Sciences and Division of Chemical Sciences, under Contract DE-AC02-98CH10886. We thank Michael Sullivan for use of the N_2(g)-purged glovebox at the NSLS.", "abstract": "Hydrogen-terminated, chlorine-terminated, and alkyl-terminated crystalline Si(111) surfaces have been characterized using high-resolution, soft X-ray photoelectron spectroscopy from a synchrotron radiation source. The H-terminated Si(111) surface displayed a Si 2p_(3/2) peak at a binding energy 0.15 eV higher than the bulk Si 2p_(3/2) peak. The integrated area of this shifted peak corresponded to one equivalent monolayer, consistent with the assignment of this peak to surficial Si\u2212H moieties. Chlorinated Si surfaces prepared by exposure of H-terminated Si to PCl_5 in chlorobenzene exhibited a Si 2p_(3/2) peak at a binding energy of 0.83 eV above the bulk Si peak. This higher-binding-energy peak was assigned to Si\u2212Cl species and had an integrated area corresponding to 0.99 of an equivalent monolayer on the Si(111) surface. Little dichloride and no trichloride Si 2p signals were detected on these surfaces. Silicon(111) surfaces alkylated with C_nH_(2n+1)^\u2212 (n = 1 or 2) or C_6H_5CH_2^\u2212 groups were prepared by exposing the Cl-terminated Si surface to an alkylmagnesium halide reagent. Methyl-terminated Si(111) surfaces prepared in this fashion exhibited a Si 2p_(3/2) signal at a binding energy of 0.34 eV above the bulk Si 2p_(3/2) peak, with an area corresponding to 0.85 of a Si(111) monolayer. Ethyl- and C_6H_5CH_2-terminated Si(111) surfaces showed no evidence of either residual Cl or oxidized Si and exhibited a Si 2p_(3/2) peak \u223c0.20 eV higher in energy than the bulk Si 2p_(3/2) peak. This feature had an integrated area of \u223c1 monolayer. This positively shifted Si 2p_(3/2) peak is consistent with the presence of Si\u2212C and Si\u2212H surface functionalities on such surfaces. The SXPS data indicate that functionalization by the two-step chlorination/alkylation process proceeds cleanly to produce oxide-free Si surfaces terminated with the chosen alkyl group.", "date": "2005-03-10", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "109", "number": "9", "publisher": "American Chemical Society", "pagerange": "3930-3937", "id_number": "CaltechAUTHORS:20170524-150224153", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170524-150224153", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "Army Research Office (ARO)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-98CH10886" } ] }, "doi": "10.1021/jp047199c", "resource_type": "article", "pub_year": "2005", "author_list": "Webb, Lauren J.; Nemanick, E. Joseph; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/v29my-r7455", "eprint_id": 120614, "eprint_status": "archive", "datestamp": "2023-08-22 03:04:57", "lastmod": "2023-10-18 17:55:21", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sisk-Brian-C", "name": { "family": "Sisk", "given": "Brian C." }, "orcid": "0000-0003-3156-9673" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparison of analytical methods and calibration methods for correction of detector response drift in arrays of carbon black-polymer composite vapor detectors", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Electrical and Electronic Engineering; Metals and Alloys; Surfaces, Coatings and Films; Condensed Matter Physics; Instrumentation; Electronic, Optical and Magnetic Materials", "note": "We acknowledge the NIH, NSF, and an Army MURI for their generous support of this work.", "abstract": "The responses of 15 carbon black-polymer composite chemiresistors have been analyzed during exposure to eight different analytes (n-hexane, tetrahydrofuran, ethanol, ethyl acetate, cyclohexane, n-heptane, n-octane, and isooctane) in random order at low concentration (0.5% of the vapor pressure of analyte at room temperature) over 4 months (8000 total analyte exposures) of data collection. Data were collected for periods during which the array was continuously exposed periodically to analytes and after long periods during which no analyte exposures had been performed. All but the most difficult separation tasks (for example, discrimination between low concentrations of straight-chain hydrocarbons) could be performed robustly over the entire 4 month time period based only on the use of a decision boundary formulated from an initial training set of 200 exposures, indicating the sensor drift had minimal effect on system performance in such classification tasks. For the remaining classification tasks, modeling the dynamics of sensor drift either through a linear regression or Fourier transform decomposition of the individual relative differential resistance responses versus time of each sensor yielded little improvement in classification performance, indicating that external events were largely responsible for changes in sensor response versus time. Six analytes that were not treated as unknowns for a binary separation task were individually treated as calibrants whose response was intermittantly used to renormalize the response of the sensor array. A simple linear sensor-by-sensor calibration scheme proved effective at restoring the classification performance of difficult binary separation tasks to the performance that was observed in the initial training set period. Calibrants that were mutually similar to the analytes being differentiated tended to be more effective than calibrants that were very chemically different from the analytes of interest. Evaluation of various calibration protocols indicated that an optimal tradeoff existed between the number of calibration exposures and the frequency of calibration periods. Condition-based calibration, in which calibration was only performed when the classification model exhibited a decline in classification performance below a predetermined threshold value, was observed to be superior to a time-based calibration approach or to interval-based, cyclic calibration protocols for this set of analytes exposed under the chosen analysis conditions.", "date": "2005-01-24", "date_type": "published", "publication": "Sensors and Actuators B: Chemical", "volume": "104", "number": "2", "publisher": "Elsevier", "pagerange": "249-268", "id_number": "CaltechAUTHORS:20230329-399374000.1", "issn": "0925-4005", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-399374000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NIH" }, { "agency": "NSF" }, { "agency": "Army Research Office (ARO)" } ] }, "doi": "10.1016/j.snb.2004.05.010", "resource_type": "article", "pub_year": "2005", "author_list": "Sisk, Brian C. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fw6t8-9n070", "eprint_id": 77726, "eprint_status": "archive", "datestamp": "2023-08-19 15:16:16", "lastmod": "2023-10-25 23:23:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Yu-Hongbin", "name": { "family": "Yu", "given": "Hongbin" } }, { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Ries-R-S", "name": { "family": "Ries", "given": "Ryan S." } }, { "id": "Solares-S-D", "name": { "family": "Solares", "given": "Santiago D." }, "orcid": "0000-0003-0895-8160" }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A., III" }, "orcid": "0000-0003-0097-5716" }, { "id": "Heath-J-R", "name": { "family": "Heath", "given": "James R." }, "orcid": "0000-0001-5356-4385" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Low-Temperature STM Images of Methyl-Terminated Si(111) Surfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2005 American Chemical Society. \n\nReceived 28 May 2004. Published online 16 September 2004. Published in print 1 January 2005. \n\nWe acknowledge the National Science Foundation, grant CHE-0213589 (N.S.L.), the DARPA Molectronics Program, and the MARCO Materials Structures and Devices Focus Center (J.R.H. and W.A.G.) for their support of this research. L.J.W. thanks the NSF for a graduate fellowship, and we are grateful to L. Henling for assistance with the X-ray diffraction experiments.", "abstract": "Low-temperature scanning tunneling microscopy (STM) has been used to image CH3-terminated Si(111) surfaces that were prepared through a chlorination/alkylation procedure. The STM data revealed a well-ordered structure commensurate with the atop sites of an unreconstructed 1 \u00d7 1 overlayer on the silicon (111) surface. Images collected at 4.7 K revealed bright spots, separated by 0.18 \u00b1 0.01 nm, which are assigned to adjacent H atoms on the same methyl group. The C\u2212H bonds in each methyl group were observed to be rotated by 7 \u00b1 3\u00b0 away from the center of an adjacent methyl group and toward an underlying Si atom. Hence, the predominant interaction that determines the surface structure arises from repulsions between hydrogen atoms on neighboring methyl groups, and secondary interactions unique to the surface are also evident.", "date": "2005-01-20", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "109", "number": "2", "publisher": "American Chemical Society", "pagerange": "671-674", "id_number": "CaltechAUTHORS:20170524-143033911", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170524-143033911", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Microelectronics Advanced Research Corporation (MARCO)" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1021/jp047672m", "resource_type": "article", "pub_year": "2005", "author_list": "Yu, Hongbin; Webb, Lauren J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hkdp2-taz93", "eprint_id": 24815, "eprint_status": "archive", "datestamp": "2023-08-19 15:11:12", "lastmod": "2023-10-24 14:57:29", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kayes-B-M", "name": { "family": "Kayes", "given": "Brendan M." } }, { "id": "Richardson-C-E", "name": { "family": "Richardson", "given": "Christine E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Radial pn junction nanorod solar cells: device physics principles and routes to fabrication in silicon", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2005 IEEE. Issue Date: 3-7 Jan. 2005.\nDate of Current Version: 08 August 2005. The authors would like to thank BP Solar and NREL for their financial support.\n\nPublished - KAYpsc05.pdf
", "abstract": "We have developed quantitative device-physics models for a radial pn junction nanorod solar cell, that is, a cell which consists of densely packed nanorods attached to a conducting substrate, each nanorod with a pn junction in the radial direction. It is found that this novel design shows large improvements over the planar geometry so long as two conditions are satisfied: a) a planar solar cell made from the same material is collection limited, i.e. the diffusion length of minority carriers is too low to allow for collection of most or all of the light-generated carriers in the conventional planar geometry, and b) recombination in the depletion region is not too high, or, equivalently, the lifetime of carriers in the depletion region is not too short. In order to experimentally validate this concept, the vapor-liquid-solid (VLS) growth of silicon (Si) nanorods has been explored using metal catalyst particles that are not as deleterious to the minority carrier lifetime of Si as gold (Au), the most commonly used wire growth catalyst.", "date": "2005-01", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "55-58", "id_number": "CaltechAUTHORS:20110811-144332965", "isbn": "0-7803-8707-4", "book_title": "Conference record of the Thirty-First IEEE Photovoltaic Specialists Conference", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110811-144332965", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP Solar" }, { "agency": "National Renewable Energy Laboratory" } ] }, "doi": "10.1109/PVSC.2005.1488067", "primary_object": { "basename": "KAYpsc05.pdf", "url": "https://authors.library.caltech.edu/records/hkdp2-taz93/files/KAYpsc05.pdf" }, "resource_type": "book_section", "pub_year": "2005", "author_list": "Kayes, Brendan M.; Richardson, Christine E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/e4905-h9847", "eprint_id": 8599, "eprint_status": "archive", "datestamp": "2023-08-22 02:54:02", "lastmod": "2023-10-16 21:34:53", "type": "book", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Crabtree-G-W", "name": { "family": "Crabtree", "given": "George W." }, "orcid": "0000-0002-8494-4468" } ] }, "title": "Basic Research Needs for Solar Energy Utilization: report of the Basic Energy Sciences Workshop on Solar Energy Utilization, April 18-21, 2005", "ispublished": "unpub", "full_text_status": "public", "note": "Published - SEU_rpt05.pdf
", "abstract": "This report of the Basic Energy Sciences Workshop on Solar Energy Utilization identifies the key scientific challenges and research directions that will enable efficient and economic use of the solar resource to provide a significant fraction of global primary energy by the mid 21st century. The report reflects the collective output of the workshop attendees, which included 200 scientists representing academia, national laboratories, and industry in the United States and abroad, and the U.S. Department of Energy's Office of Basic Energy Sciences and Office of Energy Efficiency and Renewable Energy. \n\nSolar energy conversion systems fall into three categories according to their primary energy product: solar electricity, solar fuels, and solar thermal systems. Each of the three generic approaches to exploiting the solar resource has untapped capability well beyond its present usage. Workshop participants considered the potential of all three approaches, as well as the potential of hybrid systems that integrate key components of individual technologies into novel cross-disciplinary paradigms.", "date": "2005", "date_type": "published", "publisher": "US Department of Energy, Office of Basic Energy Science", "id_number": "CaltechAUTHORS:LEWsolarenergyrpt05", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:LEWsolarenergyrpt05", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." } }, { "id": "Crabtree-G-W", "name": { "family": "Crabtree", "given": "George" } }, { "id": "Nozik-A-J", "name": { "family": "Nozik", "given": "Arthur J." } }, { "id": "Wasielewski-M-R", "name": { "family": "Wasielewski", "given": "Michael R." } }, { "id": "Alivisatos-A-P", "name": { "family": "Alivisatos", "given": "Paul" } } ] }, "primary_object": { "basename": "SEU_rpt05.pdf", "url": "https://authors.library.caltech.edu/records/e4905-h9847/files/SEU_rpt05.pdf" }, "resource_type": "book", "pub_year": "2005", "author_list": "Lewis, Nathan S. and Crabtree, George W." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4qknv-67316", "eprint_id": 4825, "eprint_status": "archive", "datestamp": "2023-08-22 02:53:42", "lastmod": "2023-10-16 17:57:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hu-Xile", "name": { "family": "Hu", "given": "Xile" }, "orcid": "0000-0001-8335-1196" }, { "id": "Cossairt-B-M", "name": { "family": "Cossairt", "given": "Brandi M." }, "orcid": "0000-0002-9891-3259" }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Peters-J-C", "name": { "family": "Peters", "given": "Jonas C." }, "orcid": "0000-0002-6610-4414" } ] }, "title": "Electrocatalytic hydrogen evolution by cobalt difluoroboryl-diglyoximate complexes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 Royal Society of Chemistry 2005 \n\nReceived (in Berkeley, CA, USA) 28th June 2005, Accepted 29th July 2005. First published on the web 23rd August 2005 \n\nFor financial support we acknowledge the NSF through a Chemical Bonding Center (CBC). We also thank Prof. Alex Sessions for his generous help with the gas chromatography experiments.\n\nPublished - HUXcc05.pdf
Supplemental Material - HUXcc05supp.pdf
", "abstract": "In the presence of moderately strong acids in CH3CN, cobalt complexes with BF2-bridged diglyoxime ligands are active catalysts for the reduction of protons to H2 at potentials as positive as \u20130.28 V vs. SCE.", "date": "2005", "date_type": "published", "publication": "Chemical Communications", "volume": "2005", "number": "37", "publisher": "Royal Society of Chemistry", "pagerange": "4723-4725", "id_number": "CaltechAUTHORS:HUXcc05", "issn": "1359-7345", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:HUXcc05", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" } ] }, "doi": "10.1039/b509188h", "primary_object": { "basename": "HUXcc05.gif", "url": "https://authors.library.caltech.edu/records/4qknv-67316/files/HUXcc05.gif" }, "related_objects": [ { "basename": "HUXcc05.pdf", "url": "https://authors.library.caltech.edu/records/4qknv-67316/files/HUXcc05.pdf" }, { "basename": "HUXcc05supp.pdf", "url": "https://authors.library.caltech.edu/records/4qknv-67316/files/HUXcc05supp.pdf" }, { "basename": "medium.png", "url": "https://authors.library.caltech.edu/records/4qknv-67316/files/medium.png" }, { "basename": "small.png", "url": "https://authors.library.caltech.edu/records/4qknv-67316/files/small.png" } ], "resource_type": "article", "pub_year": "2005", "author_list": "Hu, Xile; Cossairt, Brandi M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ypfst-6xm18", "eprint_id": 78016, "eprint_status": "archive", "datestamp": "2023-08-19 14:26:35", "lastmod": "2023-10-25 23:40:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kils\u00e5-K", "name": { "family": "Kils\u00e5", "given": "Kristine" } }, { "id": "Mayo-E-I", "name": { "family": "Mayo", "given": "Elizabeth I." } }, { "id": "Brunschwig-B-S", "name": { "family": "Brunschwig", "given": "Bruce S." }, "orcid": "0000-0002-6135-6727" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" } ] }, "title": "Anchoring Group and Auxiliary Ligand Effects on the Binding of Ruthenium Complexes to Nanocrystalline TiO_2 Photoelectrodes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2004 American Chemical Society. \n\nReceived: October 6, 2003; In Final Form: April 1, 2004.\nPublication Date (Web): September 11, 2004. \n\nThis work was supported by BP (H.B.G; J.R.W.) and DOE/NREL (N.S.L.). K.K. thanks the Carlsberg Foundation (Denmark) for a postdoctoral fellowship.\n\nSupplemental Material - jp0369995_s.pdf
", "abstract": "The thermodynamics and kinetics of binding to nanocrystalline TiO_2 were investigated for five ruthenium complexes that differed structurally in the number of possible anchoring carboxy groups (one, two, four, or six) attached to coordinated bipyridyl ligands and in the number of auxiliary ligands (bipyridine, CN-, or SCN-). Diffuse reflectance infrared spectroscopic data indicated that the dyes predominantly bound to TiO_2 in a bridging mode in which the oxygen atoms of an attached carboxy group were bound to separate titanium atoms on the TiO_2 surface. Furthermore, in the dry state, complexes with only one monocarboxy or dicarboxy ligand used essentially all of their available carboxy groups to bind to the surface. However, complexes having two or three dicarboxy ligands used on average two carboxylato groups in binding to TiO_2. The structural differences between the complexes were manifested chemically in that the five dyes yielded similar maximum coverages (>100 nmol cm^(-2)) on nanocrystalline TiO_2 electrodes, but exhibited different binding constants (10^3\u221210^5 M^(-1)) and different adsorption and desorption kinetics (3\u221211) \u00d7 10^3 M^(-1) h^(-1) and 1\u2212100 h, respectively). The binding constant for the monocarboxy dye was significantly lower than the binding constants for dyes with dicarboxy ligands, correlating primarily with an increase in the desorption rate of the monocarboxy complex. The adsorption rate constants were similar for all of the dyes, suggesting that formation of the first bond to TiO_2 was rate limiting. Binding of the dyes from an ethanolic solution that contained pyridine and pyridinium as an acidic proton activity buffer yielded lower coverages than binding from a nonbuffered ethanol solution, even though the binding constants were up to 100 times greater under buffered conditions. The lower equilibrium dye coverage in buffered ethanol did not correlate with changes in the protonation state of the dyes but rather indicated competition for, and/or deactivation of, TiO_2 active sites in buffered ethanol. The more weakly bound monocarboxy dye displayed the lowest short-circuit current density and open-circuit voltage under simulated solar illumination in a photoelectrochemical cell containing 0.50 M LiI, 0.040 M I_2, 0.020 M pyridine, and 0.020 M pyridinium triflate in acetonitrile. Additionally, even at constant coverage, the integrated quantum yield for photocurrent flow was lowest for TiO_2 sensitized with the monocarboxy dye. The potential required to drive 0.1 mA cm^(-2) of cathodic current density in the dark on dye-sensitized TiO_2 photoelectrodes was least negative for the monocarboxy dye, indicating more facile electron transfer between reduced TiO_2 and the solution redox couple. Hence, in this series of ruthenium carboxy-bipyridyl dyes, the most weakly bound species (i.e., the monocarboxy dye) yielded inferior photoelectrode properties, whereas differences between the dyes that contained at least one dicarboxy ligand resulted primarily from differences in the light absorption and energetic properties of the metal complexes. These observations suggest an important role for the linkage to the TiO_2 surface in achieving temporal stability as well as in tuning both the steady-state quantum yield and the magnitude of the predominant back-reaction rate in dye-sensitized TiO_2-based photoelectrochemical solar cells.", "date": "2004-10-07", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "108", "number": "40", "publisher": "American Chemical Society", "pagerange": "15640-15651", "id_number": "CaltechAUTHORS:20170607-151847856", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170607-151847856", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BP" }, { "agency": "Department of Energy (DOE)" }, { "agency": "Carlsberg Foundation" } ] }, "doi": "10.1021/jp0369995", "primary_object": { "basename": "jp0369995_s.pdf", "url": "https://authors.library.caltech.edu/records/ypfst-6xm18/files/jp0369995_s.pdf" }, "resource_type": "article", "pub_year": "2004", "author_list": "Kils\u00e5, Kristine; Mayo, Elizabeth I.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6db4b-9y788", "eprint_id": 73677, "eprint_status": "archive", "datestamp": "2023-08-19 14:10:45", "lastmod": "2023-10-24 15:35:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparisons between Mammalian and Artificial Olfaction Based on Arrays of Carbon Black\u2212Polymer Composite Vapor Detectors", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2004 American Chemical Society. \n\nReceived 19 November 2003. Published online 29 June 2004. Published in print 1 September 2004. \n\nThe investigations described herein were performed by an\nextremely talented group of graduate students and postdoctoral fellows. These people, cited as coauthors in the reference list, along with generous support from the ARO, DARPA, DOE, NASA, NIH, and NSF, have made this work possible.", "abstract": "Arrays of broadly cross-reactive vapor sensors provide a man-made implementation of an olfactory system, in which an analyte elicits a response from many receptors and each receptor responds to a variety of analytes. Pattern recognition methods are then used to detect analytes based on the collective response of the sensor array. With the use of this architecture, arrays of chemically sensitive resistors made from composites of conductors and insulating organic polymers have been shown to robustly classify, identify, and quantify a diverse collection of organic vapors, even though no individual sensor responds selectively to a particular analyte. The properties and functioning of these arrays are inspired by advances in the understanding of biological olfaction, and in turn, evaluation of the performance of the man-made array provides suggestions regarding some of the fundamental odor detection principles of the mammalian olfactory system.", "date": "2004-09", "date_type": "published", "publication": "Accounts of Chemical Research", "volume": "37", "number": "9", "publisher": "American Chemical Society", "pagerange": "663-672", "id_number": "CaltechAUTHORS:20170124-153154396", "issn": "0001-4842", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170124-153154396", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NASA" }, { "agency": "NIH" }, { "agency": "NSF" } ] }, "doi": "10.1021/ar030120m", "resource_type": "article", "pub_year": "2004", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fcgy3-5bb37", "eprint_id": 1717, "eprint_status": "archive", "datestamp": "2023-08-22 02:06:10", "lastmod": "2023-10-13 22:57:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Biteen-J-S", "name": { "family": "Biteen", "given": "J. S." }, "orcid": "0000-0003-2038-6484" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "H. A." }, "orcid": "0000-0001-9435-0201" }, { "id": "Polman-A", "name": { "family": "Polman", "given": "A." }, "orcid": "0000-0002-0685-3886" } ] }, "title": "Size-dependent oxygen-related electronic states in silicon nanocrystals", "ispublished": "pub", "full_text_status": "public", "keywords": "silicon; silicon compounds; nanocomposites; etching; oxidation; photoluminescence; spectral line shift", "note": "\u00a9 2004 American Institute of Physics. \n\nReceived 20 January 2004; accepted 29 April 2004; published online 17 June 2004. \n\nThis work was supported by NSF. The Dutch contribution to this work is part of the research program of FOM and is financially supported by NWO.\n\nPublished - BITapl04.pdf
", "abstract": "Silicon nanocrystals embedded in SiO2 were isolated with a selective etching procedure, and the isolated nanocrystals' excitonic emission energy was studied during controlled oxidation. Nanocrystals having initial diameters, d(0), of similar to 2.9-3.4 nm showed a photoluminescence (PL) blueshift upon oxidatively induced size reduction, as expected from models of quantum confinement. Oxidation of smaller Si nanocrystals (d(0)similar to 2.5-2.8 nm) also initially resulted in a PL blueshift, but a redshift in the PL was then observed after growth of similar to 0.3 monolayers of native oxide. This decrease in excitonic emission energy during oxidation is consistent with the theoretically predicted formation of an oxygen-related excitonic recombination state.", "date": "2004-06-28", "date_type": "published", "publication": "Applied Physics Letters", "volume": "84", "number": "26", "publisher": "American Institute of Physics", "pagerange": "5389-5391", "id_number": "CaltechAUTHORS:BITapl04", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:BITapl04", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "Stichting voor Fundamenteel Onderzoek der Materie (FOM)" }, { "agency": "Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)" } ] }, "doi": "10.1063/1.1765200", "primary_object": { "basename": "BITapl04.pdf", "url": "https://authors.library.caltech.edu/records/fcgy3-5bb37/files/BITapl04.pdf" }, "resource_type": "article", "pub_year": "2004", "author_list": "Biteen, J. S.; Lewis, N. S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9rs18-6x550", "eprint_id": 76171, "eprint_status": "archive", "datestamp": "2023-08-19 13:32:31", "lastmod": "2023-10-25 15:33:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Toh-Chee-Seng", "name": { "family": "Toh", "given": "Chee-Seng" } }, { "id": "Kayes-B-M", "name": { "family": "Kayes", "given": "Brendan M." }, "orcid": "0000-0002-4697-1713" }, { "id": "Nemanick-E-J", "name": { "family": "Nemanick", "given": "E. Joseph" }, "orcid": "0000-0002-4650-6491" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Fabrication of Free-Standing Nanoscale Alumina Membranes with Controllable Pore Aspect Ratios", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2004 American Chemical Society. \n\nReceived September 25, 2003; Revised Manuscript Received March 22, 2004. Publication Date (Web): April 23, 2004. \n\nWe acknowledge the National Science Foundation (grant CHE-0213589) for supporting this work and the National University of Singapore for providing a fellowship to C.S.T. We also thank J. Casperson for assistance with the ion-milling process.", "abstract": "Porous alumina films with controllable pore sizes and having submicrometer film thicknesses were fabricated by the anodization of Al overlayers. The Al was deposited by sputtering onto either glass or onto silicon that had been coated with a layer of silicon nitride. Alumina membranes having thicknesses between 300 and 1000 nm were prepared analogously using a lithographic process to produce free-standing porous alumina films that were peripherally supported on a 500-\u03bcm-thick silicon substrate.", "date": "2004-05", "date_type": "published", "publication": "Nano Letters", "volume": "4", "number": "5", "publisher": "American Chemical Society", "pagerange": "767-770", "id_number": "CaltechAUTHORS:20170408-162241423", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170408-162241423", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "National University of Singapore" } ] }, "doi": "10.1021/nl0348286", "resource_type": "article", "pub_year": "2004", "author_list": "Toh, Chee-Seng; Kayes, Brendan M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pce9p-6p087", "eprint_id": 77337, "eprint_status": "archive", "datestamp": "2023-08-19 13:29:43", "lastmod": "2023-10-25 22:05:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lee-Jae-Joon", "name": { "family": "Lee", "given": "Jae-Joon" } }, { "id": "Coia-G-M", "name": { "family": "Coia", "given": "George M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Current Density versus Potential Characteristics of Dye-Sensitized Nanostructured Semiconductor Photoelectrodes. 1. Analytical Expressions", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2004 American Chemical Society. \n\nReceived: May 2, 2003; In Final Form: September 25, 2003.\nPublication Date (Web): April 8, 2004. \n\nThe authors gratefully acknowledge the Department of Energy, Office of Basic Energy Sciences, for support of this work.", "abstract": "A closed-form analytical model is developed to describe the steady-state current density\u2212potential (J\u2212E) characteristics of dye-sensitized nanostructured semiconductor photoelectrodes. The basic components of the model are a set of differential equations that describe the generation, recombination, and transport of charge carriers in mesoporous semiconductor electrode systems. Charge-carrier transport is treated as a diffusion process, and semiclassical Marcus theory is used to describe the kinetics at the interfaces between the semiconductor and the contacting phase as well as the kinetics at the interfaces with adsorbed dye. The model relates explicitly, within a single formalism, the rate constants for charge transfer of the mesoporous membrane electrode system to conventional intramolecular and intermolecular electron-transfer rate constant expressions and to interfacial electron-transfer processes at planar metal or semiconductor electrodes. The near-equilibrium situation is considered by including the reverse electron-transfer pathways for each rate process of interest. The underlying physical and chemical factors that form the basis of the model are completely parameterized to facilitate input into a numerical simulation algorithm, thereby allowing facile generation of simulated J\u2212E curves for a wide range of experimental conditions.", "date": "2004-04-29", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "108", "number": "17", "publisher": "American Chemical Society", "pagerange": "5269-5281", "id_number": "CaltechAUTHORS:20170510-095259794", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170510-095259794", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1021/jp035194u", "resource_type": "article", "pub_year": "2004", "author_list": "Lee, Jae-Joon; Coia, George M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6bcss-6ke57", "eprint_id": 77684, "eprint_status": "archive", "datestamp": "2023-08-19 13:29:50", "lastmod": "2023-10-25 23:21:21", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lee-Jae-Joon", "name": { "family": "Lee", "given": "Jae-Joon" } }, { "id": "Coia-G-M", "name": { "family": "Coia", "given": "George M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Current Density versus Potential Characteristics of Dye-Sensitized Nanostructured Semiconductor Photoelectrodes. 2. Simulations", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2004 American Chemical Society. \n\nReceived 2 May 2003. Published online 8 April 2004. Published in print 1 April 2004. \n\nThe authors gratefully acknowledge the Department of Energy, Office of Basic Energy Sciences, for funding this work under Grant DE-FG03-88ER13932.", "abstract": "The impact of changes in various parameters on the steady-state current density\u2212potential (J\u2212E) characteristics of dye-sensitized nanostructured semiconductor photoelectrodes has been evaluated through a series of simulations. The model parameters can be divided into three classes, designated as type I, type II, and type III, respectively. Type I parameters primarily affect the open-circuit potential without changing the overall shape of the J\u2212E curves. Type II parameters primarily affect the limiting quantum yield for photocurrent production. Rate constants for injection and quenching of the excited state of the dye by the contacting phase are type II parameters, whereas the rate constant for the direct electrolyte reduction reaction, the reduced equilibrium constant for iodine formation, and the rate constant for recombination are type I parameters. The rate constant for regeneration affects both the shape of the J\u2212E curves and the limiting quantum yield for photocurrent flow, and it is therefore designated as a type III parameter. Variation of the diffusion coefficient parameter for electrons in the semiconducting membrane produces a mixed response having both type I and II characteristics. Comparisons between simulations and experimental data have delineated the factors that should be manipulated to increase the energy conversion efficiency of photoelectrochemical cells that utilize nanostructured TiO_2 electrodes.", "date": "2004-04-29", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "108", "number": "17", "publisher": "American Chemical Society", "pagerange": "5282-5293", "id_number": "CaltechAUTHORS:20170524-071407885", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170524-071407885", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG03-88ER13932" } ] }, "doi": "10.1021/jp035195m", "resource_type": "article", "pub_year": "2004", "author_list": "Lee, Jae-Joon; Coia, George M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rv1jb-ee507", "eprint_id": 78310, "eprint_status": "archive", "datestamp": "2023-08-19 13:26:49", "lastmod": "2023-10-25 23:59:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Prokopuk-N", "name": { "family": "Prokopuk", "given": "Nicholas" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Energetics and Kinetics of Interfacial Electron-Transfer Processes at Chemically Modified InP/Liquid Junctions", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2004 American Chemical Society. \n\nReceived 24 October 2002. Published online 16 March 2004. Published in print 1 April 2004. \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, for support of this work.", "abstract": "The electrochemical behavior of freshly etched (111)B-oriented InP surfaces was compared to that of (111)B-oriented InP surfaces that had been chemically modified by reaction with p-BrCH_2C_6H_4CF_3. Differential capacitance versus potential and current density versus potential techniques were used to measure the energetics and kinetics of interfacial electron-transfer reactions in contact with a 70:30 (v:v) mixture of CH_3CN\u2212tetrahydrofuran that contained either 1,1'-dimethylferrrocene^(+/0) or decamethylferrocene^(+/0). For both the etched and modified (111)B InP contacts, plots of differential capacitance versus potential measurements indicated a linear dependence of the equilibrium voltage drop (V_(bi)) in the semiconductor space-charge region, as a function of the redox potential (E(A/A-)) of the solution, with the slope of V_(bi) vs E(A/A-) \u2248 1.0, as expected for ideal behavior of a semiconductor/liquid junction. The barrier heights calculated for the chemically modified InP/liquid junctions were 100 \u00b1 20 mV higher than the barrier heights of freshly etched, unmodified (111)B InP surfaces in contact with the same electrolyte solutions. The higher barrier heights of the chemically modified surfaces are consistent with a shift in the InP band-edge energies induced by the surface modification process. The modified and etched surfaces both displayed interfacial electron-transfer kinetics that were first order in the concentration of acceptors in solution and first order in the concentration of electrons at the semiconductor surface. The interfacial electron-transfer rate constants for these systems were determined to be \u223c10^(-17)\u221210^(-18) cm^4 s^(-1).", "date": "2004-04-08", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "108", "number": "14", "publisher": "American Chemical Society", "pagerange": "4449-4456", "id_number": "CaltechAUTHORS:20170619-064106321", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170619-064106321", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1021/jp0223049", "resource_type": "article", "pub_year": "2004", "author_list": "Prokopuk, Nicholas and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/abyh3-4hz09", "eprint_id": 78911, "eprint_status": "archive", "datestamp": "2023-08-19 12:59:17", "lastmod": "2023-10-26 14:27:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Briglin-S-M", "name": { "family": "Briglin", "given": "Shawn M." } }, { "id": "Gao-Ting", "name": { "family": "Gao", "given": "Ting" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Detection of Organic Mercaptan Vapors Using Thin Films of Alkylamine-Passivated Gold Nanocrystals", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2004 American Chemical Society. \n\nReceived July 1, 2003. In Final Form: September 17, 2003. Publication Date (Web): December 11, 2003. \n\nWe acknowledge the NIH, an Army MURI, and the NSF for their generous support of this work.", "abstract": "Alkylamine-capped gold nanocrystals have been used as chemically sensitive resistors for the detection of volatile organic mercaptan vapors. Thin (<1 \u00d7 10^(-4) cm) films of dodecylamine-capped, 6\u22127 nm diameter Au nanocrystals produced dc electrical resistances of 10 k\u03a9 to 10 M\u03a9 when deposited onto interdigitated Au/Cr electrodes. These chemiresistive vapor detectors displayed a reversible increase in dc electrical resistance when exposed to non-thiol-containing vapors such as water, acetone, or toluene delivered at a constant fraction (0.05) of their vapor pressure, with relative differential resistance responses to these vapors of \u22485% under such conditions. In contrast, the amine-capped Au nanocrystal films exhibited a much larger, irreversible decrease in resistance upon exposure to vapors possessing the thiol (\u2212SH) functionality, including H_2S, CH_3SH, and propanethiol. Optical spectroscopic and transmission electron microscopy data indicated that the thiols displaced the amine caps, allowing the gold cores to move closer together and in some cases enter into contact, thereby lowering the film resistance. Consistently, the resistance of such films did not decrease upon exposure to octanethiol. For CH_3SH, the rate of resistance change under repeated experimental conditions allowed extraction of the concentration of analyte over the range 4 ppb to 1.5 ppm in air.", "date": "2004-01-20", "date_type": "published", "publication": "Langmuir", "volume": "20", "number": "2", "publisher": "American Chemical Society", "pagerange": "299-305", "id_number": "CaltechAUTHORS:20170710-151028847", "issn": "0743-7463", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170710-151028847", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NIH" }, { "agency": "Army Research Office (ARO)" }, { "agency": "NSF" } ] }, "doi": "10.1021/la0351717", "resource_type": "article", "pub_year": "2004", "author_list": "Briglin, Shawn M.; Gao, Ting; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/gay1q-nmm23", "eprint_id": 77009, "eprint_status": "archive", "datestamp": "2023-08-19 12:57:07", "lastmod": "2023-10-25 17:13:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Briseno-A-L", "name": { "family": "Briseno", "given": "Alejandro L." }, "orcid": "0000-0003-2981-9143" }, { "id": "Han-Shubo", "name": { "family": "Han", "given": "Shubo" } }, { "id": "Rauda-I-E", "name": { "family": "Rauda", "given": "Iris E." } }, { "id": "Zhou-Feimeng", "name": { "family": "Zhou", "given": "Feimeng" }, "orcid": "0000-0002-2568-765X" }, { "id": "Toh-Chee-Seng", "name": { "family": "Toh", "given": "Chee-Seng" } }, { "id": "Nemanick-E-J", "name": { "family": "Nemanick", "given": "E. Joseph" }, "orcid": "0000-0002-4650-6491" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electrochemical Polymerization of Aniline Monomers Infiltrated into Well-Ordered Truncated Eggshell Structures of Polyelectrolyte Multilayers", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2004 American Chemical Society. \n\nReceived 3 July 2003. Published online 10 December 2003. Published in print 1 January 2004. \n\nWe gratefully acknowledge support from the American Chemical Society-PRF funds (Grant 37899-AC5), a Henry Dreyfus Teacher-Scholar Award (TH-01-025), and a NSF-CRUI grant (DBI-9978806). We also thank the two anonymous reviewers for their constructive suggestions on some of our data interpretations", "abstract": "The use of nanosphere lithography to construct two-dimensional arrays of polystyrene (PS) particles coated with multilayered polyelectrolyte (PE) shells and truncated eggshell structures composed of PE thin layers is reported. The truncated eggshell PE structures were produced by extraction of the PS particle cores with toluene. The core-extraction process ruptures the apex of the PE coating and causes a slight expansion of the PE thin layers. Aniline hydrochloride was infiltrated into the PE shells and subsequently electropolymerized to yield an array of a composite containing polyaniline (PAni) and PE thin shells. Voltammetric, quartz crystal microbalance, and reflectance Fourier transform infrared spectroscopic measurements indicate that aniline monomers were confined within the thin PE shells and the electropolymerization occurred in the interior of the PE shell. The PE thickness governs the amount of infiltrated monomer and the ultimate loading of the PAni in the truncated eggshell structure. Surface-structure imaging by atomic force microscopy and scanning electron microscopy, carried out after each step of the fabrication process, shows the influence of the PE thickness on the organization and dimensions of the arrays. Thus, the PE thin shells composed of different layers can function as nanometer-sized vessels for the entrapment of charged species for further construction of composite materials and surface modifications. This approach affords a new avenue for the synthesis of new materials that combine the unique properties of conductive polymers and the controllability of template-directed surface reactions.", "date": "2004-01-06", "date_type": "published", "publication": "Langmuir", "volume": "20", "number": "1", "publisher": "American Chemical Society", "pagerange": "219-226", "id_number": "CaltechAUTHORS:20170427-114728343", "issn": "0743-7463", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170427-114728343", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "American Chemical Society Petroleum Research Fund", "grant_number": "37899-AC5" }, { "agency": "Camille and Henry Dreyfus Foundation", "grant_number": "TH-01-025" }, { "agency": "NSF", "grant_number": "DBI-9978806" } ] }, "doi": "10.1021/la035198q", "resource_type": "article", "pub_year": "2004", "author_list": "Briseno, Alejandro L.; Han, Shubo; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3yje8-dhe40", "eprint_id": 117426, "eprint_status": "archive", "datestamp": "2023-08-22 01:11:41", "lastmod": "2023-10-24 22:31:32", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Biteen-Julie-S", "name": { "family": "Biteen", "given": "Julie S." }, "orcid": "0000-0003-2038-6484" }, { "id": "Tchebotareva-Anna-L", "name": { "family": "Tchebotareva", "given": "Anna L." } }, { "id": "Polman-Albert", "name": { "family": "Polman", "given": "Albert" }, "orcid": "0000-0002-0685-3886" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Atwater-H-A", "name": { "family": "Atwater", "given": "Harry A." }, "orcid": "0000-0001-9435-0201" } ] }, "title": "Controlled Passivation and Luminescence Blue Shifts of Isolated Silicon Nanocrystals", "ispublished": "pub", "full_text_status": "public", "keywords": "General Medicine", "abstract": "We have performed a comparative study of oxide- and nonoxide-passivated silicon nanocrystals to probe the role of the silicon/oxygen interface in low coverage, non-interacting silicon nanocrystal systems. Ensembles of Si nanocrystals characterized by a narrow distribution and diameters of 2\u20135 nm were synthesized by ion implantation into SiO2 films followed by a high-temperature anneal in Ar. The nanocrystals were removed from the SiO2 film matrix and deposited on Si substrates using a chemical etch in HF, leaving a hydrogen-terminated surface. A natural oxide layer grows on these surfaces in air. We characterized the morphology of the samples with atomic force microscopy (AFM) and the spectroscopic properties with photoluminescence (PL) and X-Ray photoelectron spectroscopy. We found that the PL energy of Si nanocrystals can be shifted by particle size reduction and hydrogen or oxygen termination. Further, PL peak energy shifts upon etching and oxidation were consistent with the model of Wolkin et al. that proposes that for very small radii, a silicon-oxygen double bond will produce deep interface states which red shift the luminescence.", "date": "2003-12", "date_type": "published", "publication": "Materials Research Society symposia proceedings", "volume": "770", "publisher": "Materials Research Society", "pagerange": "Art. No. 62", "id_number": "CaltechAUTHORS:20221017-164761900.1", "issn": "0272-9172", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221017-164761900.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1557/proc-770-i6.2", "resource_type": "article", "pub_year": "2003", "author_list": "Biteen, Julie S.; Tchebotareva, Anna L.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2kq77-39m76", "eprint_id": 120608, "eprint_status": "archive", "datestamp": "2023-08-22 01:07:28", "lastmod": "2023-10-23 16:07:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sisk-Brian-C", "name": { "family": "Sisk", "given": "Brian C." }, "orcid": "0000-0003-3156-9673" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Estimation of chemical and physical characteristics of analyte vapors through analysis of the response data of arrays of polymer-carbon black composite vapor detectors", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Electrical and Electronic Engineering; Metals and Alloys; Surfaces, Coatings and Films; Condensed Matter Physics; Instrumentation; Electronic, Optical and Magnetic Materials", "note": "We acknowledge the NIH, NSF, and an Army MURI for their generous support of this work.", "abstract": "Analysis of the signals produced by a collection of organic polymer-carbon black composite vapor detectors has been performed to assess the ability to estimate various chemical and physical properties of analyte vapors based on information contained in the response patterns of the detector array. A diverse array of composite chemiresistive vapor detectors was exposed to a series of 75 test analytes that had been selected from among five different chemical classes: alcohols, halogenated hydrocarbons, aromatics, unsubstituted hydrocarbons, and esters. The algorithmic task of interest was to use the resulting array of response data to assign one of the five chemical class labels to a test analyte, despite having left that analyte out of the model used to generate the class labels. Algorithms evaluated for this purpose included principal components analysis (PCA) and k-nearest neighbor (k-NN) analysis employing either Euclidean or Mahalanobis distance calculations. Each data cluster that was produced by replicate exposures to an individual analyte was well resolved from all of the other 74 analyte clusters. Furthermore, with the exception of the halide cluster, the analyte response clusters could be robustly grouped into supersets such that each of the five individual chemical classes was well-separated from every other class of analytes in principal component space. Accordingly, using either of the k-nearest neighbor algorithms, in excess of 85% of the non-halide test analyte exposures were correctly assigned to their chemical classes, and halides were only routinely confused with aromatics or esters but not with alcohols or hydrocarbons. The detector array response data also was found to contain semi-quantitative information regarding physicochemical properties of the members of the test analyte series, such as the degree of unsaturation of the carbon chain, the dipole moment, the molecular weight, the number of halogen atoms, and type of aromatic ring in the test analytes. The performance in these types of tasks is relevant for applications of a semi-selective array of vapor detectors in situations when no prior knowledge of the analyte identity is available and when there is no assurance that the test analyte will have been contained in the training set database produced by a compiling a library of responses from the detector array.", "date": "2003-11-15", "date_type": "published", "publication": "Sensors and Actuators B: Chemical", "volume": "96", "number": "1-2", "publisher": "Elsevier", "pagerange": "268-282", "id_number": "CaltechAUTHORS:20230329-569117000.2", "issn": "0925-4005", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-569117000.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NIH" }, { "agency": "NSF" }, { "agency": "Army Research Office (ARO)" } ] }, "doi": "10.1016/s0925-4005(03)00543-4", "resource_type": "article", "pub_year": "2003", "author_list": "Sisk, Brian C. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/629kr-1bh31", "eprint_id": 77419, "eprint_status": "archive", "datestamp": "2023-09-22 22:38:42", "lastmod": "2023-10-23 23:25:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Briglin-S-M", "name": { "family": "Briglin", "given": "Shawn M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Characterization of the Temporal Response Profile of Carbon Black\u2212Polymer Composite Detectors to Volatile Organic Vapors", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2003 American Chemical Society. \n\nReceived: February 18, 2003; In Final Form: May 20, 2003.\nPublication Date (Web): September 16, 2003. \n\nWe acknowledge the NIH and an Army MURI for support of this work.\n\nSupplemental Material - jp030218i_s.pdf
", "abstract": "The relative differential resistance responses of carbon black\u2212poly(ethylene-co-vinyl acetate) (PEVA) composite vapor detectors were evaluated in response to short rise time (<2 ms for a 17 ms pulse length) square pulses of acetone, n-hexane, methanol, 2-propanol, or toluene, in a background of synthetic air. The use of ultrathin films, along with a rapid vapor delivery system, facilitated measurement of the rapid time response available from this exemplary carbon black\u2212polymer composite chemiresistive film for the detection of common organic vapors. Detectors formed from very thin (<200 nm) PEVA\u2212carbon black composites produced steady-state responses within 17 ms upon exposure to methanol and produced steady-state responses within 90 ms upon exposure to toluene, acetone, and n-hexane. In accord with Fickian diffusion, the response times of the relative differential resistance of PEVA\u2212carbon black detectors to analyte exposures were proportional to the square of the film thickness, l, in the range 510 \u2264 l \u2264 5700 nm. Additionally, the relative differential resistance versus time profiles of PEVA\u2212carbon black detectors were well fit by a simple finite difference model based on Fickian analyte diffusion, using a single analyte diffusion coefficient, for a variety of different film thicknesses and analyte concentrations.", "date": "2003-10-09", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "107", "number": "40", "publisher": "American Chemical Society", "pagerange": "11031-11042", "id_number": "CaltechAUTHORS:20170512-133726724", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170512-133726724", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NIH" }, { "agency": "Army Research Office (ARO)" } ] }, "doi": "10.1021/jp030218i", "primary_object": { "basename": "jp030218i_s.pdf", "url": "https://authors.library.caltech.edu/records/629kr-1bh31/files/jp030218i_s.pdf" }, "resource_type": "article", "pub_year": "2003", "author_list": "Briglin, Shawn M. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zd6gm-bhf16", "eprint_id": 78002, "eprint_status": "archive", "datestamp": "2023-08-19 11:37:14", "lastmod": "2023-10-25 23:39:06", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Webb-L-J", "name": { "family": "Webb", "given": "Lauren J." }, "orcid": "0000-0001-9999-5500" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparison of the Electrical Properties and Chemical Stability of Crystalline Silicon(111) Surfaces Alkylated Using Grignard Reagents or Olefins with Lewis Acid Catalysts", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2003 American Chemical Society. \n\nReceived: October 22, 2002. Publication Date (Web): May 20, 2003. \n\nWe acknowledge the National Science Foundation, Grant CHE-0213589, for support of this work and for providing a graduate research fellowship to L.J.W.", "abstract": "Four methods were used to functionalize crystalline Si(111) surfaces with alkyl groups (C_nH_(2n+1), n = 1, 2, 6, 8):\u2009 chlorination with PCl_5 followed by alkylation with C_nH_(2n+1)MgX (X = Cl, Br), chlorination with Cl_2(g) followed by alkylation with C_nH_(2n+1)MgX, Lewis acid-mediated reduction of a terminal alkene, and anodization in diethyl ether containing 3.0 M CH_3MgI. The chemical properties of each surface were characterized as a function of time exposed to air using X-ray photoelectron spectroscopy, and the electrical properties of the various surfaces were probed using time-resolved radio frequency (rf) photoconductivity decay methods. Both chlorination/alkylation routes produced alkylated Si surfaces that displayed low (<200 cm s^(-1)) initial charge carrier surface recombination velocities (S); furthermore, the recombination velocities of these functionalized surfaces were stable during >600 h of exposure to air. Surfaces functionalized through this route also displayed a significantly lower rate of oxidation than did unalkylated, H-terminated or Cl-terminated Si(111) surfaces. In contrast, surfaces modified by the Lewis acid-catalyzed reduction of 1-hexene and 1-octene exhibited high S values (S > 400 cm s^(-1)) when initially exposed to air and oxidized as rapidly as H-terminated Si(111) surfaces. Methyl-terminated Si(111) surfaces functionalized by anodization in a solution of CH_3MgI in ether exhibited stable, albeit high, S values (460 cm s^(-1)), indicating that the surface had been partially modified by the anodization process. The fractional monolayer coverage of oxide on the alkylated surface after exposure to air was determined for each functionalization technique. Although all four of the functionalization routes studied in this work introduced alkyl groups onto the Si surface, subtle changes in the extent and quality of the alkyl termination are significant factors in determining the magnitude and degree of chemical and electrical passivation of the resulting functionalized Si surfaces.", "date": "2003-06-12", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "107", "number": "23", "publisher": "American Chemical Society", "pagerange": "5404-5412", "id_number": "CaltechAUTHORS:20170607-110132486", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170607-110132486", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-0213589" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1021/jp0222752", "resource_type": "article", "pub_year": "2003", "author_list": "Webb, Lauren J. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ej386-scp13", "eprint_id": 120609, "eprint_status": "archive", "datestamp": "2023-08-22 00:35:59", "lastmod": "2023-10-23 16:04:21", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Smalley-John-F", "name": { "family": "Smalley", "given": "John F." } }, { "id": "Geng-Lin", "name": { "family": "Geng", "given": "Lin" } }, { "id": "Chen-Amy", "name": { "family": "Chen", "given": "Amy" } }, { "id": "Feldberg-Stephen-W", "name": { "family": "Feldberg", "given": "Stephen W." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Cali-George", "name": { "family": "Cali", "given": "George" } } ] }, "title": "An indirect laser-induced temperature jump study of the influence of redox couple adsorption on heterogeneous electron transfer kinetics", "ispublished": "pub", "full_text_status": "public", "keywords": "Electrochemistry; General Chemical Engineering; Analytical Chemistry", "note": "Work at Brookhaven National Laboratory was supported by the US Department of Energy, contract no. DE-AC02-98CH10886. Work at the California Institute of Technology was also supported by the US Department of Energy, Office of Basic Energy Sciences, Fundamental Interactions Branch.", "abstract": "The indirect laser-induced temperature jump technique is used to study the heterogeneous electron transfer kinetics of Fe(CN)\u2086^(3\u2212/4\u2212), Ru(NH\u2083)\u2086^(3+/2+) (both in aqueous 1 M KF) and dimethylferrocene/dimethylferrocenium (Me\u2082Fc, in 1 M LiClO\u2084 in CH\u2083OH) on Au electrodes. Evidence is obtained demonstrating not only that all three of these redox couples adsorb on Au but also that the behavior of the measured electron transfer kinetics for these couples is significantly perturbed from that expected for simple heterogeneous electron transfer reactions. The interpretation of the results of these measurements is, therefore, made much more complex and uncertain. Such complexity and uncertainty is greatly reduced by irreversibly attaching the redox moiety to the electrode surface as a part of a stable, organized structure (e.g. a self-assembled monolayer).", "date": "2003-06-05", "date_type": "published", "publication": "Journal of Electroanalytical Chemistry", "volume": "549", "publisher": "Elsevier", "pagerange": "13-24", "id_number": "CaltechAUTHORS:20230329-853433000.2", "issn": "1572-6657", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-853433000.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-98CH10886" } ] }, "doi": "10.1016/s0022-0728(03)00284-5", "resource_type": "article", "pub_year": "2003", "author_list": "Smalley, John F.; Geng, Lin; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mv29s-shk45", "eprint_id": 77609, "eprint_status": "archive", "datestamp": "2023-08-19 11:26:16", "lastmod": "2023-10-25 23:17:49", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kils\u00e5-K", "name": { "family": "Kils\u00e5", "given": "Kristine" } }, { "id": "Mayo-E-I", "name": { "family": "Mayo", "given": "Elizabeth I." } }, { "id": "Kuciauskas-D", "name": { "family": "Kuciauskas", "given": "Darius" }, "orcid": "0000-0001-8091-5718" }, { "id": "Villahermosa-R-M", "name": { "family": "Villahermosa", "given": "Randy" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Effects of Bridging Ligands on the Current\u2212Potential Behavior and Interfacial Kinetics of Ruthenium-Sensitized Nanocrystalline TiO_2 Photoelectrodes", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2003 American Chemical Society. \n\nReceived 21 August 2002. Published online 11 April 2003. Published in print 1 May 2003. \n\nK.K. thanks the Carlsberg Foundation, Denmark, for a postdoctoral fellowship, and R.V. acknowledges the Link Foundation for funding. This work is supported through NREL subcontract (ACQ-1-30619-09) under DOE contract (DE-AC36-99-G010337). Work on the synthesis and characterization of the Rux complexes was supported by the NSF (H.B.G. and J.R.W.) and by the Arnold and Mabel Beckman Foundation.", "abstract": "We have shown that Ru^(II)(bpy)_2(bpy-4-(xylyl)_x-\u2261-phenyl-COOH)(PF_6)_2 (abbreviated Rux, where x = 0, 1 or 2 xylyl groups; bpy = 2,2'-bipyridine) dyes can act as sensitizers for nanocrystalline TiO_2 in functional photoelectrochemical cells under simulated solar illumination, albeit with low efficiencies. Both the short-circuit photocurrent density and the open-circuit voltage decreased as x was increased. Electron injection (10^6\u221210^8 s^(-1)) was slightly faster for the x = 0 dye, but both recombination (10^(-15)\u221210^(-13) cm^3 s^(-1)) and regeneration (10^4\u221210^6 s^(-1) for 10 mM I^-) were slightly faster for the x = 2 dye. We suggest that the lack of distance dependence is due to the flexible one-carboxyl attachment to the surface resulting in the Ru\u2212TiO_2 electron-tunneling distance being very similar for x = 0, 1, and 2. For all of the Rux sensitizers, a relatively small potential was needed for generation of current in the dark, indicating that the reaction between electrons in TiO_2 and the I_3^-/I^- electrolyte solution is as favorable for the Rux sensitizers as for unmodified TiO_2 electrodes.", "date": "2003-05-08", "date_type": "published", "publication": "Journal of Physical Chemistry A", "volume": "107", "number": "18", "publisher": "American Chemical Society", "pagerange": "3379-3383", "id_number": "CaltechAUTHORS:20170519-142727736", "issn": "1089-5639", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170519-142727736", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Carlsberg Foundation" }, { "agency": "Link Foundation" }, { "agency": "National Renewable Energy Laboratory", "grant_number": "ACQ-1-30619-09" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC36-99-G010337" }, { "agency": "NSF" }, { "agency": "Arnold and Mabel Beckman Foundation" } ] }, "doi": "10.1021/jp021921u", "resource_type": "article", "pub_year": "2003", "author_list": "Kils\u00e5, Kristine; Mayo, Elizabeth I.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5ymer-a5a13", "eprint_id": 69721, "eprint_status": "archive", "datestamp": "2023-08-19 11:16:57", "lastmod": "2023-10-20 20:31:46", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tillman-E-S", "name": { "family": "Tillman", "given": "Eric S." } }, { "id": "Koscho-M-E", "name": { "family": "Koscho", "given": "Michael E." } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Enhanced Sensitivity to and Classification of Volatile Carboxylic Acids Using Arrays of Linear Poly(ethylenimine)\u2212Carbon Black Composite Vapor Detectors", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2003 American Chemical Society. \n\nReceived 24 June 2002; accepted 6 November 2002; published online 1 March 2003; published in print 1 April 2003. \n\nWe acknowledge the NIH and an ARO MURI for support of this work.", "abstract": "Vapor detectors formed from composites of conductors and insulating organic polymers have been tailored to produce increased sensitivity toward specific classes of analyte vapors. Upon exposure to acetic acid at 1% of its vapor pressure, detectors consisting of linear poly(ethylenimine) (l-PEI)\u2212carbon black composites showed an \u223c10^3 increase in signal/noise relative to the performance of typical insulating organic polymer\u2212carbon black composite vapor detectors. Compositional diversity in an array of such vapor detectors was obtained by varying the degree of plasticization of the l-PEI films. The resulting vapor detector array produced sensitive detection of, and robust discrimination between, various volatile organic acids and relatively little response from nonacidic organic vapors or from water vapor. Measurements of the mass uptake, thickness change, and electrical conductivity of such composites indicate that swelling of the polymer film, and thus its normalized resistance response, is beyond that expected by mass uptake alone upon exposure to acetic acid vapor. This additional thickness increase is attributed to charge-induced polymer swelling occurring from polymer\u2212analyte interactions. Electrical percolation also plays a significant role in producing the large increase in normalized resistance response of these composites upon exposure to acetic acid vapor.", "date": "2003-04-01", "date_type": "published", "publication": "Analytical Chemistry", "volume": "75", "number": "7", "publisher": "American Chemical Society", "pagerange": "1748-1753", "id_number": "CaltechAUTHORS:20160817-142702206", "issn": "0003-2700", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160817-142702206", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NIH" }, { "agency": "Army Research Office (ARO)" } ] }, "doi": "10.1021/ac020412l", "resource_type": "article", "pub_year": "2003", "author_list": "Tillman, Eric S.; Koscho, Michael E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/aj8c9-y7j71", "eprint_id": 27525, "eprint_status": "archive", "datestamp": "2023-08-19 10:20:27", "lastmod": "2023-10-24 17:13:17", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A VLSI compatible conducting polymer composite based \"electronic nose\" chip", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2002 IEEE.\nDate of Current Version: 06 February 2003.\n\nPublished - LEWiedm02.pdf
", "abstract": "The focus of this work would be to exploit the vapor detection technology developed recently at Caltech that forms the basis for a low power, simple \"electronic nose\". In this work we have integrated the sensors, signal preprocessing, signal processing, and data analysis functions into a single, low power, low cost, \"nose chip\". Such a device could be implantable covertly or overtly onto suspect sites, deployable through remote delivery methods, worn by soldiers for CW alerts and in principle for IFF or military/nonmilitary identification purposes, and for other areas of national security where low power, lightweight, small, chemical sensing is of importance.", "date": "2002-12", "date_type": "published", "publisher": "IEEE", "id_number": "CaltechAUTHORS:20111031-134322298", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111031-134322298", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "7509331", "name": "INSPEC Accession Number" } ] }, "doi": "10.1109/IEDM.2002.1175885", "primary_object": { "basename": "LEWiedm02.pdf", "url": "https://authors.library.caltech.edu/records/aj8c9-y7j71/files/LEWiedm02.pdf" }, "resource_type": "book_section", "pub_year": "2002", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/k7fqv-0h019", "eprint_id": 120602, "eprint_status": "archive", "datestamp": "2023-08-21 23:52:28", "lastmod": "2023-10-23 15:59:41", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Burl-Michael-C", "name": { "family": "Burl", "given": "Michael C." }, "orcid": "0000-0003-2961-3241" }, { "id": "Sisk-Brian-C", "name": { "family": "Sisk", "given": "Brian C." }, "orcid": "0000-0003-3156-9673" }, { "id": "Vaid-Thomas-P", "name": { "family": "Vaid", "given": "Thomas P." }, "orcid": "0000-0003-4597-0847" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Classification performance of carbon black-polymer composite vapor detector arrays as a function of array size and detector composition", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Electrical and Electronic Engineering; Metals and Alloys; Surfaces, Coatings and Films; Condensed Matter Physics; Instrumentation; Electronic, Optical and Magnetic Materials", "note": "We acknowledge the NIH and an Army MURI for their generous support of this work.", "abstract": "The vapor classification performance of arrays of conducting polymer composite vapor detectors has been evaluated as a function of the number and type of detectors in an array. Quantitative performance comparisons were facilitated by challenging a collection of detector arrays with vapor discrimination tasks that were sufficiently difficult that at least some of the arrays did not exhibit perfect classification ability for all of the tasks of interest. Specific discrimination tasks involved differentiating between low concentration (<1% of the vapor pressure) exposures to 1-propanol versus 2-propanol, low concentration exposures to n-hexane versus n-heptane, and differentiating between compositionally similar mixtures of closely related analytes, such as 9.37 ppm m-xylene with 10.2 ppm p-xylene versus 7.67 ppm m-xylene with 12.4 ppm p-xylene. A decision boundary was developed using a cross-validated Fisher linear discriminant algorithm on a training set of analyte presentations and the resulting chemometric model was then used to classify a subsequent collection of test analyte presentations to the array being evaluated. In other cases, classification performance was evaluated using the Fisher linear discriminant and a leave-one-out (LOO) cross-validation procedure. For nearly all of the discrimination tasks investigated in this work, classification performance either increased or did not significantly decrease as the number of chemically different detectors in the array increased. Any given subset of the full array of detectors, selected because it yielded the best classification performance at a given array size for one particular task, was invariably outperformed by a different subset of detectors, and by the entire array of 20 chemically diverse detectors when used in at least one other vapor discrimination task. Arrays of detectors were nevertheless identified that yielded robust discrimination performance between compositionally close mixtures of 1-propanol and 2-propanol, n-hexane and n-heptane, and m-xylene and p-xylene, attesting to the excellent analyte classification performance that can be obtained through the use of such semi-selective vapor detector arrays.", "date": "2002-11-15", "date_type": "published", "publication": "Sensors and Actuators B: Chemical", "volume": "87", "number": "1", "publisher": "Elsevier", "pagerange": "130-149", "id_number": "CaltechAUTHORS:20230329-825405000.1", "issn": "0925-4005", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-825405000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NIH" }, { "agency": "Army Research Office (ARO)" } ] }, "doi": "10.1016/s0925-4005(02)00229-0", "resource_type": "article", "pub_year": "2002", "author_list": "Burl, Michael C.; Sisk, Brian C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2hnd5-7na22", "eprint_id": 85821, "eprint_status": "archive", "datestamp": "2023-08-21 23:49:10", "lastmod": "2023-10-18 18:50:13", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Anz-S-J", "name": { "family": "Anz", "given": "Samir J." } }, { "id": "Fajardo-A-M", "name": { "family": "Fajardo", "given": "Arnel M." } }, { "id": "Royea-W-J", "name": { "family": "Royea", "given": "William J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Morris-A-J", "name": { "family": "Morris", "given": "Amanda J." } } ] }, "title": "Semiconductor Photoelectrochemistry", "ispublished": "unpub", "full_text_status": "public", "keywords": "photoconductivity; intensity modulated photocurrent and photovoltage spectroscopy; time\u2010resolved microwave conductivity; semiconductor\u2010liquid junctions; laser spot scanning; charge transfer; band gap; electrochemistry", "note": "\u00a9 2003 John Wiley & Sons, Inc. \n\nFirst published: 15 October 2002; Published Online: 12 October 2012.", "abstract": "This article discusses methods and experimental protocols in semiconductor electrochemistry. We first discuss the basic principles that govern the energetics and kinetics of charge flow at a semiconductor\u2010liquid contact. The principal electrochemical techniques of photocurrent and photovoltage measurements used to obtain important interfacial energetic and kinetic quantities of such contacts are then described in detail. After this basic description of concepts and methods in semiconductor electrochemistry, we describe methods for characterizing the optical, electrical, and chemical properties of semiconductors through use of the electrochemical properties of semiconductor\u2010liquid interfaces.", "date": "2002-10-15", "date_type": "published", "publisher": "Wiley", "place_of_pub": "Hoboken, NJ", "id_number": "CaltechAUTHORS:20180413-100118785", "isbn": "9780471268826", "book_title": "Characterization of Materials", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180413-100118785", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Kaufmann-E-N", "name": { "family": "Kaufmann", "given": "Elton N." } } ] }, "doi": "10.1002/0471266965.com052.pub2", "resource_type": "book_section", "pub_year": "2002", "author_list": "Anz, Samir J.; Fajardo, Arnel M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/p5k3p-6kh88", "eprint_id": 77464, "eprint_status": "archive", "datestamp": "2023-08-19 10:02:42", "lastmod": "2023-10-25 23:04:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kuciauskas-D", "name": { "family": "Kuciauskas", "given": "Darius" }, "orcid": "0000-0001-8091-5718" }, { "id": "Monat-J-E", "name": { "family": "Monat", "given": "Jeremy E." } }, { "id": "Villahermosa-R-M", "name": { "family": "Villahermosa", "given": "Randy" } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "McCusker-J-K", "name": { "family": "McCusker", "given": "James K." } } ] }, "title": "Transient Absorption Spectroscopy of Ruthenium and Osmium Polypyridyl Complexes Adsorbed onto Nanocrystalline TiO_2 Photoelectrodes", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2002 American Chemical Society. \n\nReceived: December 18, 2001; In Final Form: April 8, 2002; Publication Date (Web): August 17, 2002. \n\nThis work was supported by the Department of Energy, Office of Basic Energy Sciences, Grants DE-FG03-88ER13932 (D.K., N.S.L.) and DE-FG03-96ER14665 (JKM); by the NSF (H.B.G.); by the University of California Energy Institute (JKM); by the Petroleum Research Fund administered by the American Chemical Society, grant 36108-AC6 (JKM); and by the Alfred P. Sloan Foundation (JKM). We also acknowledge a generous gift in support of work on TiO_2 photoelectrochemistry to Caltech by the DuPont Company.", "abstract": "Transient absorption spectroscopy has been used to probe the electron injection dynamics of transition metal polypyridyl complexes adsorbed onto nanocrystalline TiO_2 photoelectrodes. Experiments were performed on photoelectrodes coated with Ru(H_2L')_2(CN)_2, Os(H_2L')_2(CN)_2, Ru(H_2L')_2(NCS)_2, or Os(H_2L')_2(NCS)_2, where H_2L' is 4,4'-dicarboxylic acid-2,2'-bipyridine, to study how the excited-state energetics and the nature of the metal center affect the injection kinetics. All of these complexes exhibited electron injection dynamics on both the femtosecond and picosecond time scales. The femtosecond components were instrument-limited (<200 fs), whereas the picosecond components ranged from 3.3 \u00b1 0.3 ps to 14 \u00b1 4 ps (electron injection rate constants k_2' = (7.1\u221230) \u00d7 10^(10) s^(-1)). The picosecond decay component became more rapid as the formal excited-state reduction potential of the complex became more negative. Variable excitation wavelength studies suggest that femtosecond injection is characteristic of the nonthermalized singlet metal-to-ligand charge-transfer (^1MLCT) excited state, whereas picosecond injection originates from the lowest-energy ^3MLCT excited state. On the basis of these assignments, the smaller relative amplitude of the picosecond component for the Ru sensitizers suggests that electron injection from nonthermalized excited states competes more effectively with ^1MLCT \u2192 ^3MLCT conversion for the Ru sensitizers than for the Os sensitizers.", "date": "2002-09-12", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "106", "number": "36", "publisher": "American Chemical Society", "pagerange": "9347-9358", "id_number": "CaltechAUTHORS:20170515-143505122", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170515-143505122", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG03-88ER13932" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG03-96ER14665" }, { "agency": "NSF" }, { "agency": "University of California Energy Institute" }, { "agency": "American Chemical Society Petroleum Research Fund", "grant_number": "36108-AC6" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "DuPont" } ] }, "doi": "10.1021/jp014589f", "resource_type": "article", "pub_year": "2002", "author_list": "Kuciauskas, Darius; Monat, Jeremy E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zr2bb-1y573", "eprint_id": 88131, "eprint_status": "archive", "datestamp": "2023-08-19 09:55:24", "lastmod": "2024-01-14 20:29:06", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Burl-Michael-C", "name": { "family": "Burl", "given": "Michael C." }, "orcid": "0000-0003-2961-3241" }, { "id": "Sisk-Brian-C", "name": { "family": "Sisk", "given": "Brian C." }, "orcid": "0000-0003-3156-9673" }, { "id": "Vaid-Thomas-P", "name": { "family": "Vaid", "given": "Thomas P." }, "orcid": "0000-0003-4597-0847" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Classification performance of carbon black-polymer composite vapor detector arrays as a function of array size and detector composition", "ispublished": "unpub", "full_text_status": "public", "keywords": "vapor detectors, detector array size", "note": "\u00a9 2002 Society of Photo-Optical Instrumentation Engineers (SPIE). \n\nWe acknowledge the NIH and an Army MURI for their generous support of this work.\n\nPublished - 520.pdf
", "abstract": "The vapor classification performance of arrays of conducting polymer composite vapor detectors has been evaluated as a function of the number and type of detectors in an array. Quantitative performance comparisons were facilitated by challenging a collection of detector arrays with vapor discrimination tasks that were sufficiently difficult that at least some of the arrays did not exhibit perfect classification ability for all of the tasks of interest. For nearly all of the discrimination tasks investigated in this work, classification performance either increased or did not significantly decrease as the number of chemically different detectors in the array increased. Any given subset of the full array of detectors, selected because it yielded the best classification performance at a given array size for one particular task, was invariably outperformed by a different subset of detectors, and by the entire array, when used in at least one other vapor discrimination task. Arrays of detectors were nevertheless identified that yielded robust discrimination performance between compositionally close mixtures of 1-propanol and 2-propanol, n-hexane and n-heptane, and meta-xylene and para-xylene, attesting to the excellent analyte classification performance that can be obtained through the use of such semi-selective vapor detector arrays.", "date": "2002-08-13", "date_type": "published", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_pub": "Bellingham, WA", "pagerange": "520-531", "id_number": "CaltechAUTHORS:20180723-114137961", "isbn": "0819444928", "book_title": "Detection and Remediation Technologies for Mines and Minelike Targets VII", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180723-114137961", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NIH" }, { "agency": "Army Research Office (ARO)" } ] }, "contributors": { "items": [ { "id": "Broach-J-Thomas", "name": { "family": "Broach", "given": "J. Thomas" } }, { "id": "Harmon-Russell-S", "name": { "family": "Harmon", "given": "Russell S." } }, { "id": "Dobeck-Gerald-J", "name": { "family": "Dobeck", "given": "Gerald J." } } ] }, "doi": "10.1117/12.479125", "primary_object": { "basename": "520.pdf", "url": "https://authors.library.caltech.edu/records/zr2bb-1y573/files/520.pdf" }, "resource_type": "book_section", "pub_year": "2002", "author_list": "Burl, Michael C.; Sisk, Brian C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/54jn0-r0g26", "eprint_id": 88130, "eprint_status": "archive", "datestamp": "2023-08-19 09:41:49", "lastmod": "2024-01-14 20:29:04", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hopkins-A-R", "name": { "family": "Hopkins", "given": "Alan R." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Detection and classification characteristics of arrays of carbon black/organic polymer composite chemiresistive vapor detectors for the nerve agent simulants Dimethylmethylphosphonate and Diisopropylmethylphosponate", "ispublished": "unpub", "full_text_status": "public", "keywords": "Nerve agent simulants, vapor detectors, chemiresistors", "note": "\u00a9 2002 Society of Photo-Optical Instrumentation Engineers (SPIE). \n\nWe acknowledge the Department of Energy (DE-FG03-98NV13367), and the Army Research Office through a MURI (DAAG55-98-1-0266) and DARPA (DAAK-60-97-K9503) for support of this work. We also acknowledge helpful discussions with V. George of the Army Night Vision Laboratory regarding detection limits and background ambients of interest.\n\nPublished - 86.pdf
", "abstract": "Arrays of conducting polymer composite vapor detectors have been evaluated for performance in the presence of the nerve agent simulants dimethylmethylphosphonate (DMMP) and diisopropylmethylphosponate (DIMP). Limits of detection for DMMP on unoptimized carbon black-organic polymer composite vapor detectors in laboratory air were estimated to be 0.047-0.24 mg m^(-3). These values are lower than the EC50 value for the nerve agents sarin (methylphosphonofluoridic acid, (1-methylethyl) ester) and soman, which have been established as equals 0.8 mg m^(-3). Arrays of these vapor detectors were easily able to resolve signatures due to exposures to DMMP from those due to DIMP or due to a variety of other test analytes in a laboratory air background. In addition, DMMP at 27 mg m^(-3) could be detected and differentiated from the signatures of the other test analytes in the presence of backgrounds of potential interferents in the background ambient, including water, methanol, benzene, toluene, diesel fuel, lighter fluid, vinegar and tetrahydrofuran, even when these interferents were present in much higher concentrations than that of the DMMP or DIMP being detected.", "date": "2002-06-24", "date_type": "published", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_pub": "Bellingham, WA", "pagerange": "86-97", "id_number": "CaltechAUTHORS:20180723-113318174", "isbn": "0819444723", "book_title": "Chemical and Biological Sensing III", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180723-113318174", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG03-98NV13367" }, { "agency": "Army Research Office (ARO)", "grant_number": "DAAG55-98-1-0266" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "DAAK-60-97-K9503" } ] }, "contributors": { "items": [ { "name": { "family": "Gardner", "given": "Patrick J." } } ] }, "doi": "10.1117/12.472252", "primary_object": { "basename": "86.pdf", "url": "https://authors.library.caltech.edu/records/54jn0-r0g26/files/86.pdf" }, "resource_type": "book_section", "pub_year": "2002", "author_list": "Hopkins, Alan R. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fxvnm-2en56", "eprint_id": 2425, "eprint_status": "archive", "datestamp": "2023-08-21 23:26:18", "lastmod": "2023-10-13 23:23:21", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Use of near-surface channel conductance and differential capacitance versus potential measurements to correlate inversion layer formation with low effective surface recombination velocities at n-Si/liquid contacts", "ispublished": "pub", "full_text_status": "public", "keywords": "silicon; elemental semiconductors; semiconductor-electrolyte boundaries; surface conductivity; capacitance; inversion layers; surface recombination; organic compounds", "note": "\u00a9 2002 American Institute of Physics. \n\n(Received 20 December 2001; accepted 20 March 2002) \n\nThe authors acknowledge the National Science Foundation, Grant No. CHE-9974562, for support of this work.\n\nPublished - MICapl02.pdf
", "abstract": "Near-surface channel conductance measurements, differential capacitance versus potential measurements, and surface recombination velocity measurements have been performed on (111)- and (100)-oriented n-type Si samples in contact with nitrogen and/or liquid electrolyte solutions containing I2, I2/I\u2013, ferrocene+/0, or decamethylferrocene+/0 in either methanol or tetrahydrofuran. Si/liquid contacts that displayed a low effective surface recombination velocity S corresponded to those that formed an inversion layer at the solid/liquid contact as indicated by channel conductance measurements or by differential capacitance versus potential measurements. Contacts that did not produce an inversion layer at the Si surface did not produce low effective S values. The observed behavior is consistent with the known energetics of Si/liquid contacts and provides an explanation for the low effective S values observed in these systems.", "date": "2002-06-10", "date_type": "published", "publication": "Applied Physics Letters", "volume": "80", "number": "23", "publisher": "American Institute of Physics", "pagerange": "4458-4460", "id_number": "CaltechAUTHORS:MICapl02", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:MICapl02", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9974562" } ] }, "doi": "10.1063/1.1479456", "primary_object": { "basename": "MICapl02.pdf", "url": "https://authors.library.caltech.edu/records/fxvnm-2en56/files/MICapl02.pdf" }, "resource_type": "article", "pub_year": "2002", "author_list": "Michalak, David J. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kzj1a-1f079", "eprint_id": 27578, "eprint_status": "archive", "datestamp": "2023-08-19 09:33:26", "lastmod": "2023-10-24 17:15:30", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Briglin-S-M", "name": { "family": "Briglin", "given": "Shawn M." } }, { "id": "Freund-M-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Sisk-B-C", "name": { "family": "Sisk", "given": "Brian C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Vapor Detection, Classification, and Quantification Performance Using Arrays of Conducting Polymer Composite Chemically Sensitive Resistors", "ispublished": "unpub", "full_text_status": "public", "keywords": "electronic nose, gas sensor, conducting polymer", "note": "\u00a9 2002 IEEE. \n\nDate of Current Version: 07 November 2002. \n\nThis work was supported by the U.S. Army Research Office contracts DAAH04-96-1-0048 Modification 1 and DAAG55-97-1-0187, DARPA, and NASA.\n\nPublished - BRIsens02.pdf
", "abstract": "We describe a method for generating a variety of chemically diverse, broadly responsive, low power vapor sensors. A key to our ability to fabricate chemically diverse sensing elements is the preparation of processable, air stable films of electrically conducting organic polymers. An array of such sensing elements produces a chemically reversible, diagnostic pattern of electrical resistance changes upon exposure to different odorants. Such conducting polymer elements are simply prepared and are readily modified chemically to respond to a broad range of analytes. In addition, these sensors yield a fairly rapid, low power, de electrical signal in response to the vapor of interest, and their signals are readily integrated with software or hardware-based neural networks for purposes of analyte identification. Principle component analysis has demonstrated that such sensors can identify and quantify different airborne organic solvents, and can yield information on the components of gas mixtures.", "date": "2002-06", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, N.J.", "pagerange": "727-731", "id_number": "CaltechAUTHORS:20111102-092856572", "isbn": "0-7803-7454-1", "book_title": "IEEE Sensors 2002", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111102-092856572", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)", "grant_number": "DAAH04-96-1-0048" }, { "agency": "Army Research Office (ARO)", "grant_number": "DAAG55-97-1-0187" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "NASA" } ] }, "doi": "10.1109/ICSENS.2002.1037193", "primary_object": { "basename": "BRIsens02.pdf", "url": "https://authors.library.caltech.edu/records/kzj1a-1f079/files/BRIsens02.pdf" }, "resource_type": "book_section", "pub_year": "2002", "author_list": "Briglin, Shawn M.; Freund, Michael S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4trep-9qe72", "eprint_id": 78001, "eprint_status": "archive", "datestamp": "2023-08-19 09:20:23", "lastmod": "2023-10-25 23:39:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Haber-Joel-A", "name": { "family": "Haber", "given": "Joel A." }, "orcid": "0000-0001-7847-5506" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Infrared and X-ray Photoelectron Spectroscopic Studies of the Reactions of Hydrogen-Terminated Crystalline Si(111) and Si(100) Surfaces with Br\u2082, I\u2082, and Ferrocenium in Alcohol Solvents", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2002 American Chemical Society. \n\nReceived: January 24, 2001; In Final Form: January 3, 2002.\nPublication Date (Web): March 15, 2002. \n\nWe acknowledge the NSF, Grant CHE-9974562, for support of this work.\n\nSupplemental Material - jp0102872_s.pdf
", "abstract": "The reaction chemistry of H-terminated crystalline Si(111) and Si(100) surfaces in CH\u2083OH, CD\u2083OD, CF\u2083(CH\u2082)\u2083OH, C\u2084H\u2089OH, and C\u2084D\u2089OD solutions containing ferrocenium (Fc\u207a)\u2212BF\u2084, I\u2082, or Br\u2082 was monitored using X-ray photoelectron (XP) spectroscopy and infrared (IR) spectroscopy. Addition of the one-electron oxidant Fc\u207a, or addition of the oxidizing species I\u2082 or Br\u2082, produced diagnostic changes in the IR spectra that clearly indicated formation of surficial Si\u2212OR groups. XPS data confirmed the conclusions of the IR studies. Under our reaction conditions, no detectable reaction occurred without the presence of the oxidant. The data are consistent with oxidative activation of the surficial Si\u2212H bonds toward nucleophilic attack by the alcohols. The reaction chemistry was generally similar on (111)- and (100)-oriented Si surfaces, although some differences were observed in the ratio of reaction products on the two different surface orientations. Alkoxylated surfaces were also prepared by a two-step process in which the surface was first chlorinated and then reacted with LiOCH\u2083, LiOCD\u2083, or LiO(CH\u2082)\u2083CF\u2083. The data indicate that formation of silicon\u2212halogen bonding alone is not sufficient to provide a robust correlation between the electronic and chemical properties of such crystalline Si surfaces and that formation of silicon\u2212alkoxyl bonds is a common motif for surfaces often used in electronic and electrochemical studies of Si.", "date": "2002-04-11", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "106", "number": "14", "publisher": "American Chemical Society", "pagerange": "3639-3656", "id_number": "CaltechAUTHORS:20170607-104931347", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170607-104931347", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9974562" } ] }, "doi": "10.1021/jp0102872", "primary_object": { "basename": "jp0102872_s.pdf", "url": "https://authors.library.caltech.edu/records/4trep-9qe72/files/jp0102872_s.pdf" }, "resource_type": "article", "pub_year": "2002", "author_list": "Haber, Joel A. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/42kg6-c0469", "eprint_id": 77594, "eprint_status": "archive", "datestamp": "2023-08-19 09:14:36", "lastmod": "2023-10-25 23:16:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gstrein-F", "name": { "family": "Gstrein", "given": "Florian" } }, { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Royea-W-J", "name": { "family": "Royea", "given": "William J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Effects of Interfacial Energetics on the Effective Surface Recombination Velocity of Si/Liquid Contacts", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2002 American Chemical Society. \n\nReceived 2 August 2001. Published online 22 February 2002. Published in print 1 March 2002. \n\nWe acknowledge the National Science Foundation, grant CHE-9974562, for support of this research. We also are grateful to Reiner N\u00fcrnberg (Weierstrass-Institut, Berlin) and Adrian Lew (Caltech) for helpful discussions relating to the digital simulations.\n\nSupplemental Material - jp012997d_s.pdf
", "abstract": "Photoconductivity decay data have been obtained for NH_4F_((aq))-etched Si(111) and for air-oxidized Si(111) surfaces in contact with solutions of methanol, tetrahydrofuran (THF), or acetonitrile containing either ferrocene^(+/0) (Fc^(+/0)), [bis(pentamethylcyclopentadienyl)iron]^(+/0) (Me_(10)Fc^(+/0)), iodine (I_2), or cobaltocene^(+/0) (CoCp_2^(+/0)). Carrier decay measurements were made under both low-level and high-level injection conditions using a contactless rf photoconductivity decay apparatus. When in contact with electrolyte solutions having either very positive (Fc^(+/0), I_2/I^-) or relatively negative (CoCp_2^(+/0)) Nernstian redox potentials with respect to the conduction-band edge of Si, Si surfaces exhibited low effective surface recombination velocities. In contrast, surfaces that were exposed only to N_2(g) ambients or to electrolyte solutions that contained a mild oxidant (such as Me_(10)Fc^(+/0)) showed differing rf photoconductivity decay behavior depending on their different surface chemistry. Specifically, surfaces that possessed Si\u2212OCH_3 bonds, produced by reaction of H-terminated Si with CH_3OH\u2212Fc^(+/0), showed lower surface recombination velocities in contact with N_(2(g)) or in contact with CH_3OH\u2212Me_(10)Fc^(+/0) solutions than did NH_4F_((aq))-etched, air-exposed H-terminated Si(111) surfaces in contact with the same ambients. Furthermore, the CH_3OH\u2212Fc^(+/0)-treated surfaces showed lower surface recombination velocities than surfaces containing Si\u2212I bonds, which were formed by the reaction of H-terminated Si surfaces with CH_3OH\u2212I_2 or THF\u2212I_2 solutions. These results can all be consistently explained through reference to the electrochemistry of Si/liquid contacts. In conjunction with prior measurements of the near-surface channel conductance for p^+\u2212n\u2212p^+ Si structures in contact with CH_3OH\u2212Fc^(+/0) solutions, the data reveal that formation of an inversion layer (i.e., an accumulation of holes at the surface) on n-type Si, and not a reduced density of surface electrical trap sites, is primarily responsible for the long charge carrier lifetimes observed for Si surfaces in contact with CH_3OH or THF electrolytes containing I_2 or Fc^(+/0). Similarly, formation of an accumulation layer (i.e., an accumulation of electrons at the surface) consistently explains the low effective surface recombination velocity observed for the Si/CH_3OH\u2212CoCp_2 and Si/CH_3CN\u2212CoCp_2 contacts. Detailed digital simulations of the photoconductivity decay dynamics for semiconductors that are in conditions of inversion or depletion while in contact with redox-active electrolytes support these conclusions.", "date": "2002-03-21", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "106", "number": "11", "publisher": "American Chemical Society", "pagerange": "2950-2961", "id_number": "CaltechAUTHORS:20170519-064910131", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170519-064910131", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9974562" } ] }, "doi": "10.1021/jp012997d", "primary_object": { "basename": "jp012997d_s.pdf", "url": "https://authors.library.caltech.edu/records/42kg6-c0469/files/jp012997d_s.pdf" }, "resource_type": "article", "pub_year": "2002", "author_list": "Gstrein, Florian; Michalak, David J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/v6aw2-pd679", "eprint_id": 69425, "eprint_status": "archive", "datestamp": "2023-08-19 09:13:06", "lastmod": "2023-10-20 16:54:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Koscho-M-E", "name": { "family": "Koscho", "given": "Michael E." } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Properties of Vapor Detector Arrays Formed through Plasticization of Carbon Black\u2212Organic Polymer Composites", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2002 American Chemical Society. \n\nReceived 2 October 2001; accepted 6 December 2001; published online 14 February 2002; published in print 15 March 2002. \n\nWe acknowledge the ARO, DOE, and NIH for support of this research.\n\nSupplemental Material - ac011054_2B_s.pdf
", "abstract": "Arrays of vapor detectors have been formed through addition of varying mass fractions of the plasticizer diethylene glycol dibenzoate to carbon black-polymer composites of poly(vinyl acetate) (PVAc) or of poly(N-vinylpyrrolidone). Addition of plasticizer in 5% mass fraction increments produced 20 compositionally different detectors from each polymer composite. Differences in vapor sorption and permeability that effected changes in the dc electrical resistance response of these compositionally different detectors allowed identification and classification of various test analytes using standard chemometric methods. Glass transition temperatures, T_g, were measured using differential scanning calorimetry for plasticized polymers having a mass fraction of 0, 0.10, 0.20, 0.30, 0.40, or 0.50 of plasticizer in the composite. The plasticized PVAc composites with T_g < 25 \u00b0C showed rapid responses at room temperature to all of the test analyte vapors studied in this work, whereas composites with T_g > 25 \u00b0C showed response times that were highly dependent on the polymer/analyte combination. These composites showed a discontinuity in the temperature dependence of their resistance, and this discontinuity provided a simple method for determining the T_g of the composite and for determining the temperature or plasticizer mass fraction above which rapid resistance responses could be obtained for all members of the test set of analyte vapors. The plasticization approach provides a method for achieving rapid detector response times as well as for producing a large number of chemically different vapor detectors from a limited number of initial chemical feedstocks.", "date": "2002-03-15", "date_type": "published", "publication": "Analytical Chemistry", "volume": "74", "number": "6", "publisher": "American Chemical Society", "pagerange": "1307-1315", "id_number": "CaltechAUTHORS:20160803-170009867", "issn": "0003-2700", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160803-170009867", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NIH" } ] }, "doi": "10.1021/ac011054+", "primary_object": { "basename": "ac011054_2B_s.pdf", "url": "https://authors.library.caltech.edu/records/v6aw2-pd679/files/ac011054_2B_s.pdf" }, "resource_type": "article", "pub_year": "2002", "author_list": "Koscho, Michael E.; Grubbs, Robert H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ntwk5-h4h71", "eprint_id": 120601, "eprint_status": "archive", "datestamp": "2023-08-21 23:02:18", "lastmod": "2023-10-23 15:54:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Briglin-Shawn-M", "name": { "family": "Briglin", "given": "Shawn M." } }, { "id": "Freund-Michael-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Tokumaru-Phillip", "name": { "family": "Tokumaru", "given": "Phil" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Exploitation of spatiotemporal information and geometric optimization of signal/noise performance using arrays of carbon black-polymer composite vapor detectors", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Electrical and Electronic Engineering; Metals and Alloys; Surfaces, Coatings and Films; Condensed Matter Physics; Instrumentation; Electronic, Optical and Magnetic Materials", "note": "We acknowledge NASA, DOE, the NIH, and an Army MURI for their generous support of this work.", "abstract": "We have investigated various aspects of the geometric and spatiotemporal response properties of an array of sorption-based vapor detectors. The detectors of specific interest are composites of insulating organic polymers filled with electrical conductors, wherein the detector film provides a reversible dc electrical resistance change upon the sorption of an analyte vapor. An analytical expression derived for the signal/noise performance as a function of detector volume implies that there is an optimum detector film volume which will produce the highest signal/noise ratio for a given carbon black-polymer composite when exposed to a fixed volume of sampled analyte. This prediction has been verified experimentally by exploring the response behavior of detectors having a variety of different geometric form factors. We also demonstrate that useful information can be obtained from the spatiotemporal response profile of an analyte moving at a controlled flow velocity across an array of chemically identical, but spatially nonequivalent, detectors. Finally, we demonstrate the use of these design principles, incorporated with an analysis of the changes in detector signals in response to variations in analyte flow rate, to obtain useful information on the composition of analytes and analyte mixtures.", "date": "2002-02-01", "date_type": "published", "publication": "Sensors and Actuators B: Chemical", "volume": "82", "number": "1", "publisher": "Elsevier", "pagerange": "54-74", "id_number": "CaltechAUTHORS:20230329-941459000.2", "issn": "0925-4005", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-941459000.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NIH" }, { "agency": "Army Research Office (ARO)" } ] }, "doi": "10.1016/s0925-4005(01)00991-1", "resource_type": "article", "pub_year": "2002", "author_list": "Briglin, Shawn M.; Freund, Michael S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/n54ss-vmj13", "eprint_id": 77553, "eprint_status": "archive", "datestamp": "2023-08-19 08:41:40", "lastmod": "2023-10-25 23:15:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Rossi-R-C", "name": { "family": "Rossi", "given": "Robert C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Investigation of the Size-Scaling Behavior of Spatially Nonuniform Barrier Height Contacts to Semiconductor Surfaces Using Ordered Nanometer-Scale Nickel Arrays on Silicon Electrodes", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2001 American Chemical Society. \n\nReceived 15 May 2001. Published online 16 November 2001. Published in print 1 December 2001. \n\nThe National Science Foundation is acknowledged for supporting this work through grant CHE-9974562 and for providing R. Rossi with a Graduate Research Fellowship. We also thank Prof. R. P. Van Duyne and J. C. Hulteen of Northwestern University for discussions regarding nanosphere lithography, G. Kumaraswamy of Caltech for guidance with TMAFM, and Prof. K. Kavanagh and Dr. B. A. Morgan of University of California, San Diego, for helpful discussions regarding BEEM and SC/M contact stability.", "abstract": "Nanosphere lithography has been used to prepare a series of ordered, periodic arrays of low barrier height nanometer-scale n-Si/Ni contacts interspersed among high barrier height n-Si/liquid contacts. To form the arrays, ordered bilayers of close-packed polystyrene spheres were deposited onto (100)-oriented n-type single crystal Si surfaces. The spheres formed a physical mask through which Ni was evaporated to produce regularly spaced and regularly sized Si/Ni contacts. By varying the diameter of the latex spheres from 174 to 1530 nm, geometrically self-similar Si/Ni structures were produced having triangular Si/Ni regions with edge dimensions of 100\u2212800 nm. The resulting Si surfaces were used as electrodes in contact with a methanolic solution of LiClO_4 and 1,1'-dimethylferrocene^(+/0). The current\u2212voltage and photoresponse properties of these mixed barrier height contacts were strongly dependent on the size of the Ni regions, even though the fraction of the Si surface covered by Ni remained constant. Electrodes formed from large-dimension Si/Ni and Si/electrolyte contacts behaved as expected for two area-weighted Schottky diodes operating independently and in parallel, whereas electrodes having nanoscale Si/Ni regions surrounded by Si/liquid contacts behaved in accord with effective barrier height theories that predict a \"pinch-off\" effect for mixed barrier height systems of sufficiently small physical dimensions.", "date": "2001-12-13", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "105", "number": "49", "publisher": "American Chemical Society", "pagerange": "12303-12318", "id_number": "CaltechAUTHORS:20170518-084552546", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170518-084552546", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9974562" } ] }, "doi": "10.1021/jp011861c", "resource_type": "article", "pub_year": "2001", "author_list": "Rossi, Robert C. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7nq5q-sah08", "eprint_id": 56189, "eprint_status": "archive", "datestamp": "2023-08-19 08:40:47", "lastmod": "2023-10-23 15:08:19", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Light work with water", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2001 Macmillan Magazines Ltd.", "abstract": "Sunlight can be harnessed by semiconductors to generate a fuel, hydrogen gas, from water. This approach will be impracticable until certain materials-related constraints are overcome: photochemists are on the case.", "date": "2001-12-06", "date_type": "published", "publication": "Nature", "volume": "414", "number": "6864", "publisher": "Nature Publishing Group", "pagerange": "589-590", "id_number": "CaltechAUTHORS:20150327-132610873", "issn": "0028-0836", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150327-132610873", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1038/414589a", "resource_type": "article", "pub_year": "2001", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/k3s56-v8h81", "eprint_id": 77463, "eprint_status": "archive", "datestamp": "2023-08-19 08:26:34", "lastmod": "2023-10-25 23:04:32", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bansal-A", "name": { "family": "Bansal", "given": "Ashish" } }, { "id": "Li-Xiuling", "name": { "family": "Li", "given": "Xiuling" } }, { "id": "Yi-Sang-I", "name": { "family": "Yi", "given": "Sang I." } }, { "id": "Weinberg-W-H", "name": { "family": "Weinberg", "given": "W. H." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Spectroscopic Studies of the Modification of Crystalline Si(111) Surfaces with Covalently-Attached Alkyl Chains Using a Chlorination/Alkylation Method", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2001 American Chemical Society. \n\nReceived: January 24, 2001; In Final Form: May 23, 2001; Publication Date (Web): October 3, 2001. \n\nWe acknowledge the NSF, Grant No. CHE-997456, for support of this work. Si wafers polished on both sides were generously provided by Mr. Daniel L. McDonald of Wacker Siltronic Corp. We also acknowledge Dr. Steve Doig for constructing the surface IR apparatus and Dr. Alan Rice for assistance with, and technical support of, the UHV equipment.\n\nSupplemental Material - jp010284p_s.pdf
", "abstract": "A two-step procedure, involving radical-initiated chlorination of the Si surface with PCl_5 followed by reaction of the chlorinated surface with alkyl-Grignard or alkyl-lithium reagents, has been developed to functionalize crystalline (111)-oriented H-terminated Si surfaces. The surface chemistry that accompanies these reaction steps has been investigated using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), temperature programmed desorption spectroscopy (TPDS), high-resolution electron energy loss spectroscopy (HREELS), infrared (IR) spectroscopy in both glancing transmission (TIR) and attenuated total multiple internal reflection (ATR) modes, ellipsometry, and contact angle goniometry. The XPS data show the appearance of the Cl signal after exposure to PCl_5 and show its removal, and concomitant appearance of a C 1s signal, after the alkylation step. Auger electron spectra, in combination with TPD spectroscopy, demonstrate the presence of Cl after the chlorination process and its subsequent loss after thermal desorption of Si\u2212Cl fragments due to heating the Si surface to 1200 K. High-resolution XP spectra of the Si 2p region show a peak corresponding to Si\u2212Cl bond formation after the chlorination step, and show the subsequent disappearance of this peak after the alkylation step. IR spectra show the loss of the perpendicularly polarized silicon monohydride (Si\u2212H) vibration at 2083 cm^(-1) after the chlorination step, whereas HREELS data show the appearance of vibrations due to Si\u2212Cl stretches upon chlorination of the Si surface. The HREELS data furthermore show the disappearance of the Si\u2212Cl stretch and the appearance of a Si\u2212C vibration at 650 cm^(-1) after alkylation of the Si surface. Ellipsometric measurements indicate that the thickness of the alkyl overlayer varies monotonically with the length of the alkyl group used in the reactant. Contact angle and IR measurements indicate that the packing of alkyl groups in the monolayers produced by this method is less dense than that found in alkylthiol monolayers on Au. As determined by XPS, the alkylated surfaces show enhanced resistance to oxidation by various wet chemical treatments, compared to the H-terminated Si surface. The two-step reaction sequence thus provides a simple approach to functionalization of (111)-oriented, H-terminated silicon surfaces using wet chemical methods.", "date": "2001-10-25", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "105", "number": "42", "publisher": "American Chemical Society", "pagerange": "10266-10277", "id_number": "CaltechAUTHORS:20170515-141841951", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170515-141841951", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9974562" } ] }, "doi": "10.1021/jp010284p", "primary_object": { "basename": "jp010284p_s.pdf", "url": "https://authors.library.caltech.edu/records/k3s56-v8h81/files/jp010284p_s.pdf" }, "resource_type": "article", "pub_year": "2001", "author_list": "Bansal, Ashish; Li, Xiuling; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/297rk-qfg30", "eprint_id": 88129, "eprint_status": "archive", "datestamp": "2023-08-19 08:25:31", "lastmod": "2024-01-14 20:29:01", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Briglin-S-M", "name": { "family": "Briglin", "given": "Shawn M." } }, { "id": "Freund-M-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Sisk-B-C", "name": { "family": "Sisk", "given": "Brian C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Array-based carbon black-polymer composite vapor detectors for detection of DNT in environments containing complex analyte mixtures", "ispublished": "unpub", "full_text_status": "public", "keywords": "Land mine signatures, vapor detectors, 2,4-dinitrotoluene, carbon black", "note": "\u00a9 2001 Society of Photo-Optical Instrumentation Engineers (SPIE). \n\nWe acknowledge an OSD ARO MURI for demining, DOE, and an ARO olfactory research MURI for support of this work.\n\nPublished - 912.pdf
", "abstract": "Thin films of carbon black-organic polymer composites have been deposited across two metallic leads, with sorption of vapors producing swelling-induced resistance changes of the detector films. To identify and classify vapors, arrays of such vapor sensing elements have been constructed in which each element of the array contains a different polymer as the insulating phase and a common conductor, carbon black, as the conducting phase. The differing gas-solid partition coefficients for the various polymers of the detector array produce a pattern of differential resistance changes that is used to classify vapors and vapor mixtures. The performance of this detector array system towards 2,4-dinitrotoluene, the predominant signature in the vapor phase above land mines, in the presence high concentrations of water or of acetone has been evaluated.", "date": "2001-10-18", "date_type": "published", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_pub": "Bellingham, WA", "pagerange": "912-921", "id_number": "CaltechAUTHORS:20180723-112800453", "isbn": "0819440892", "book_title": "Detection and Remediation Technologies for Mines and Minelike Targets VI", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180723-112800453", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)" }, { "agency": "Department of Energy (DOE)" } ] }, "contributors": { "items": [ { "id": "Dubey-A-C", "name": { "family": "Dubey", "given": "Abinash C." } }, { "id": "Harvey-J-F", "name": { "family": "Harvey", "given": "James F." } }, { "id": "Broach-J-T", "name": { "family": "Broach", "given": "J. Thomas" } }, { "id": "George-V", "name": { "family": "George", "given": "Vivian" } } ] }, "doi": "10.1117/12.445419", "primary_object": { "basename": "912.pdf", "url": "https://authors.library.caltech.edu/records/297rk-qfg30/files/912.pdf" }, "resource_type": "book_section", "pub_year": "2001", "author_list": "Briglin, Shawn M.; Freund, Michael S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5997z-z3611", "eprint_id": 120596, "eprint_status": "archive", "datestamp": "2023-08-21 22:27:30", "lastmod": "2023-10-23 15:52:15", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Frontiers of research in photoelectrochemical solar energy conversion", "ispublished": "pub", "full_text_status": "public", "keywords": "Electrochemistry; General Chemical Engineering; Analytical Chemistry", "note": "The author is grateful to the National Science Foundation, grant CHE-9974562, and to the Department of Energy, Office of Basic Energy Sciences, for generously providing sustained support for photoelectrochemistry at Caltech. The author also acknowledges a very talented group of co-workers and colleagues, only some of whom are mentioned by name in this article, who have engaged in numerous collegial discussions and who have framed many of the important issues and problems in photoelectrochemistry, as they have evolved with time, that are described in this article.", "abstract": "The purpose of this article is to provide an outlook for future research in semiconductor electrochemistry. A historical perspective is first presented to frame the recent scientific and technological progress that has been made in the field. The remainder of the article provides an overview of two selected research projects at the frontier of photoelectrochemistry. The first example discusses how exploitation of a deliberately nanostructured interface can provide useful enhancements to the kinetics of interfacial charge transfer events and can allow the use of catalysts without suffering concomitant efficiency losses. The second example discusses a model system that is useful for elucidating the interconnections between the chemical modification, electrical properties, and electrochemical behavior of photoelectrode surfaces.", "date": "2001-07-27", "date_type": "published", "publication": "Journal of Electroanalytical Chemistry", "volume": "508", "number": "1-2", "publisher": "Elsevier", "pagerange": "1-10", "id_number": "CaltechAUTHORS:20230329-796813000.1", "issn": "1572-6657", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-796813000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9974562" }, { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1016/s0022-0728(01)00399-0", "resource_type": "article", "pub_year": "2001", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dyr2g-njv11", "eprint_id": 117436, "eprint_status": "archive", "datestamp": "2023-08-21 22:05:44", "lastmod": "2024-01-15 21:28:07", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Briglin-Shawn-M", "name": { "family": "Briglin", "given": "Shawn M." } }, { "id": "Freund-Michael-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Sisk-Brian-C", "name": { "family": "Sisk", "given": "Brian C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Array Based Carbon Black-Polymer Composite Vapor Detectors for Detection of DNT in Environments Containing Complex Analyte Mixtures", "ispublished": "unpub", "full_text_status": "public", "keywords": "General Medicine", "abstract": "Thin films of carbon black-organic polymer composites have been deposited across two metallic leads, with sorption of vapors producing swelling-induced resistance changes of the detector films. To identify and classify vapors, arrays of such vapor sensing elements have been constructed in which each element of the array contains a different polymer as the insulating phase and a common conductor, carbon black, as the conducting phase. The differing gas-solid partition coefficients for the various polymers of the detector array produce a pattern of differential resistance changes that is used to classify vapors and vapor mixtures. The performance of this detector array system towards 2,4-dinitrotoluene, the predominant signature in the vapor phase above land mines, in the presence high concentrations of water or of acetone (as a selected volatile organic carbon vapor), has been evaluated.", "date": "2001-03-17", "date_type": "published", "publisher": "Materials Research Society", "pagerange": "Art. No. 41", "id_number": "CaltechAUTHORS:20221017-809168200.2", "isbn": "978-1558996366", "book_title": "Combinatorial and Artificial Intelligence Methods in Materials Science", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221017-809168200.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Takeuchi-I", "name": { "family": "Takeuchi", "given": "I." } }, { "id": "Buelens-C", "name": { "family": "Buelens", "given": "C." } }, { "id": "Koinuma-H", "name": { "family": "Koinuma", "given": "H." } }, { "id": "Amis-E-J", "name": { "family": "Amis", "given": "E. J." } }, { "id": "Newsam-J-M", "name": { "family": "Newsam", "given": "J. M." } }, { "id": "Wille-L-T", "name": { "family": "Wille", "given": "L. T." } } ] }, "doi": "10.1557/proc-700-s4.1", "resource_type": "book_section", "pub_year": "2001", "author_list": "Briglin, Shawn M.; Freund, Michael S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1rvz9-96m19", "eprint_id": 77000, "eprint_status": "archive", "datestamp": "2023-08-19 07:26:15", "lastmod": "2023-10-25 17:04:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Juang-A", "name": { "family": "Juang", "given": "Agnes" } }, { "id": "Scherman-O-A", "name": { "family": "Scherman", "given": "Oren A." } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Formation of Covalently Attached Polymer Overlayers on Si(111) Surfaces Using Ring-Opening Metathesis Polymerization Methods", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2001 American Chemical Society. \n\nReceived 11 September 2000. Published online 2 February 2001. Published in print 1 March 2001. \n\nThis work was supported by the National Science Foundation, CHE-9974562 (N.S.L.), and by the Air Force Office of Scientific Research, Grant F49620-96-1-0035 (R.H.G.). O.A.S. gratefully acknowledges the National Science Foundation for a predoctoral fellowship.", "abstract": "We describe a method for growing uniform, covalently attached polymer onto crystalline Si(111) surfaces. H-Terminated Si was first chlorinated, and the surface-bound chlorine was then replaced by a terminal olefin using a Grignard reaction. A ruthenium ring-opening metathesis polymerization catalyst was then crossed onto the terminal olefin, and the resulting surface was subsequently immersed into a solution of monomer to produce the desired surface-attached polymer. The method provides a direct linkage between the polymer and the Si without the presence of an electrically defective oxide layer. Growth of the polymeric layer could be controlled by varying the concentration of monomer in solution, and polynorbornene films between 0.9 and 5500 nm in thickness were produced through the use of 0.01\u22122.44 M solutions of norbornene.", "date": "2001-03-06", "date_type": "published", "publication": "Langmuir", "volume": "17", "number": "5", "publisher": "American Chemical Society", "pagerange": "1321-1323", "id_number": "CaltechAUTHORS:20170427-104435056", "issn": "0743-7463", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170427-104435056", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9974562" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "F49620-96-1-0035" }, { "agency": "NSF Predoctoral Fellowship" } ] }, "doi": "10.1021/la0012945", "resource_type": "article", "pub_year": "2001", "author_list": "Juang, Agnes; Scherman, Oren A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/w406z-6qx89", "eprint_id": 69241, "eprint_status": "archive", "datestamp": "2023-08-19 07:25:26", "lastmod": "2023-10-20 16:42:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hopkins-A-R", "name": { "family": "Hopkins", "given": "Alan R." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Detection and Classification Characteristics of Arrays of Carbon Black/Organic Polymer Composite Chemiresistive Vapor Detectors for the Nerve Agent Simulants Dimethylmethylphosphonate and Diisopropylmethylphosponate", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2001 American Chemical Society. \n\nPublished on Web 02/28/2001; Received for review July 26, 2000; Accepted December 8, 2000. \n\nWe acknowledge the Department of Energy (DE-FG03-98NV13367), the Army Research Office through a MURI (DAAG55-98-1-0266), and DARPA (DAAK-60-97-K9503) for support of this work. We also acknowledge helpful discussions with V. George of the Army Night Vision Laboratory regarding detection limits and background ambients of interest.", "abstract": "Arrays of conducting polymer composite vapor detectors have been evaluated for performance in the presence of the nerve agent simulants dimethylmethylphosphonate (DMMP) and diisopropylmethylphosponate (DIMP). Limits of detection for DMMP on unoptimized carbon black/organic polymer composite vapor detectors in laboratory air were estimated to be 0.047\u22120.24 mg m^(-3). These values are lower than the EC_50 value (where EC_50 is the airborne concentration sufficient to induce severe effects in 50% of those exposed for 30 min) for the nerve agents sarin (methylphosphonofluoridic acid, 1-methylethyl ester) and soman (methylphosphonofluoridic acid, 1,2,2-trimethylpropyl ester), which has been established as \u223c0.8 mg m^(-3). Arrays of these vapor detectors were easily able to resolve signatures due to exposures to DMMP from those due to DIMP or due to a variety of other test analytes (including water, methanol, benzene, toluene, diesel fuel, lighter fluid, vinegar, and tetrahydrofuran) in a laboratory air background. In addition, DMMP at 27 mg m^(-3) could be detected and differentiated from the signatures of the other test analytes in the presence of backgrounds of potential interferences, including water, methanol, benzene, toluene, diesel fuel, lighter fluid, vinegar, and tetrahydrofuran, even when these interferents were present in much higher concentrations than that of the DMMP or DIMP being detected.", "date": "2001-03-01", "date_type": "published", "publication": "Analytical Chemistry", "volume": "73", "number": "5", "publisher": "American Chemical Society", "pagerange": "884-892", "id_number": "CaltechAUTHORS:20160727-095127275", "issn": "0003-2700", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160727-095127275", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG03- 98NV13367" }, { "agency": "Army Research Office (ARO)", "grant_number": "DAAG55-98-1-0266" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)", "grant_number": "DAAK-60-97-K9503" } ] }, "doi": "10.1021/ac0008439", "resource_type": "article", "pub_year": "2001", "author_list": "Hopkins, Alan R. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5gvgy-51s65", "eprint_id": 120592, "eprint_status": "archive", "datestamp": "2023-08-21 21:57:48", "lastmod": "2023-10-23 16:06:00", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Burl-Michael-C", "name": { "family": "Burl", "given": "Michael C." }, "orcid": "0000-0003-2961-3241" }, { "id": "Doleman-Brett-J", "name": { "family": "Doleman", "given": "Brett J." } }, { "id": "Schaffer-Amanda", "name": { "family": "Schaffer", "given": "Amanda" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Assessing the ability to predict human percepts of odor quality from the detector responses of a conducting polymer composite-based electronic nose", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Electrical and Electronic Engineering; Metals and Alloys; Surfaces, Coatings and Films; Condensed Matter Physics; Instrumentation; Electronic, Optical and Magnetic Materials", "note": "We acknowledge a MURI supported through the Army Research Office for support of this work, and thank W. Cain of UCSD and D. DeCoste for numerous helpful discussions.", "abstract": "The responses of a conducting polymer composite \"electronic nose\" detector array were used to predict human perceptual descriptors of odor quality for a selected test set of analytes. The single-component odorants investigated in this work included molecules that are chemically quite distinct from each other, as well as molecules that are chemically similar to each other but which are perceived as having distinct odor qualities by humans. Each analyte produced a different, characteristic response pattern on the electronic nose array, with the signal strength on each detector reflecting the relative binding of the odorant into the various conducting polymer composites of the detector array. A \"human perceptual space\" was defined by reference to English language descriptors that are frequently used to describe odors. Data analysis techniques, including standard regression, nearest-neighbor prediction, principal components regression, partial least squares regression, and feature subset selection, were then used to determine mappings from electronic nose measurements to this human perceptual space. The effectiveness of the derived mappings was evaluated by comparison with average human perceptual data published by Dravnieks. For specific descriptors, some models provided cross-validated predictions that correlated well with the human data (above the 0.60 level), but none of the models could accurately predict the human values for more than a few descriptors.", "date": "2001-01-25", "date_type": "published", "publication": "Sensors and Actuators B: Chemical", "volume": "72", "number": "2", "publisher": "Elsevier", "pagerange": "149-159", "id_number": "CaltechAUTHORS:20230329-691866000.1", "issn": "0925-4005", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-691866000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)" } ] }, "doi": "10.1016/s0925-4005(00)00645-6", "resource_type": "article", "pub_year": "2001", "author_list": "Burl, Michael C.; Doleman, Brett J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/tjntn-a6292", "eprint_id": 75156, "eprint_status": "archive", "datestamp": "2023-08-19 07:14:08", "lastmod": "2023-10-25 14:47:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kuciauskas-D", "name": { "family": "Kuciauskas", "given": "Darius" }, "orcid": "0000-0001-8091-5718" }, { "id": "Freund-M-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Winkler-J-R", "name": { "family": "Winkler", "given": "Jay R." }, "orcid": "0000-0002-4453-9716" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electron Transfer Dynamics in Nanocrystalline Titanium Dioxide Solar Cells Sensitized with Ruthenium or Osmium Polypyridyl Complexes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2001 American Chemical Society. \n\nReceived: July 18, 2000; In Final Form: September 20, 2000. Publication Date (Web): December 19, 2000. \n\nWe acknowledge Dr. George Coia of Caltech for useful discussions. This work was supported by the Department of Energy, Office of Basic Energy Sciences (D.K., M.S.F., N.S.L.), and by the NSF (H.B.G., J.R.W.). We also acknowledge a generous gift in support of work on TiO2 photoelectrochemistry to Caltech by the DuPont Company.\n\nSupplemental Material - jp002545l_s.pdf
", "abstract": "The electron transfer dynamics in solar cells that utilize sensitized nanocrystalline titanium dioxide photoelectrodes and the iodide/triiodide redox couple have been studied on a nanosecond time scale. The ruthenium and osmium bipyridyl complexes Ru(H_2L')_2(CN)_2, Os(H_2L')_2(CN)_2, Ru(H_2L')_2(NCS)_2, and Os(H_2L')_2(NCS)_2, where H_2L' is 4,4'-dicarboxylic acid 2,2'-bipyridine, inject electrons into the semiconductor with a rate constant >10^8 s^(-1). The effects of excitation intensity, temperature, and applied potential on the recombination reaction were analyzed using a second-order kinetics model. The rates of charge recombination decrease with increasing driving force to the oxidized sensitizer, indicating that charge recombination occurs in the Marcus inverted region. The electronic coupling factors between the oxidized sensitizer and the injected electrons in TiO_2 and the reorganization energies for the recombination reaction vary significantly for the different metal complexes. The charge recombination rates are well described by semiclassical electron transfer theory with reorganization energies of 0.55\u22121.18 eV. Solar cells sensitized with Ru(H_2L')_2(CN)_2, Os(H_2L')_2(CN)_2, and Ru(H_2L')_2(NCS)_2 have favorable photoelectrochemical characteristics, and iodide is oxidized efficiently. In contrast, iodide oxidation limits the efficiency of cells based on sensitization of TiO_2 with Os(H_2L')_2(NCS)_2. The observation that charge recombination occurs in the Marcus inverted region has important implications for the design of molecular sensitizers in nanocrystalline solar cells operated under our experimental conditions.", "date": "2001-01-18", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "105", "number": "2", "publisher": "American Chemical Society", "pagerange": "392-403", "id_number": "CaltechAUTHORS:20170315-151836987", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170315-151836987", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "NSF" }, { "agency": "DuPont Company" } ] }, "doi": "10.1021/jp002545l", "primary_object": { "basename": "jp002545l_s.pdf", "url": "https://authors.library.caltech.edu/records/tjntn-a6292/files/jp002545l_s.pdf" }, "resource_type": "article", "pub_year": "2001", "author_list": "Kuciauskas, Darius; Freund, Michael S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/stvxj-7sa53", "eprint_id": 69409, "eprint_status": "archive", "datestamp": "2023-08-19 07:13:31", "lastmod": "2023-10-20 16:53:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Vaid-T-P", "name": { "family": "Vaid", "given": "Thomas P." } }, { "id": "Burl-M-C", "name": { "family": "Burl", "given": "Michael C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparison of the Performance of Different Discriminant Algorithms in Analyte Discrimination Tasks Using an Array of Carbon Black\u2212Polymer Composite Vapor Detectors", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2001 American Chemical Society. \n\nReceived 10 July 2000; accepted 5 October 2000; published online 15 December 2000; published in print 15 January 2001. \n\nWe acknowledge DARPA, the Army Research Office through a MURI grant, the Department of Energy, and NASA for support of this work.", "abstract": "An array of 20 compositionally different carbon black\u2212polymer composite chemiresistor vapor detectors was challenged under laboratory conditions to discriminate between a pair of extremely similar pure analytes (H_(2)O and D_(2)O), compositionally similar mixtures of pairs of compounds, and low concentrations of vapors of similar chemicals. Several discriminant algorithms were utilized, including k nearest neighbors (kNN, with k = 1), linear discriminant analysis (LDA, or Fisher's linear discriminant), quadratic discriminant analysis (QDA), regularized discriminant analysis (RDA, a hybrid of LDA and QDA), partial least squares, and soft independent modeling of class analogy (SIMCA). H_(2)O and D_(2)O were perfectly classified by most of the discriminants when a separate training and test set was used. As expected, discrimination performance decreased as the analyte concentration decreased, and performance decreased as the composition of the analyte mixtures became more similar. RDA was the overall best-performing discriminant, and LDA was the best-performing discriminant that did not require several cross-validations for optimization.", "date": "2001-01-15", "date_type": "published", "publication": "Analytical Chemistry", "volume": "73", "number": "2", "publisher": "American Chemical Society", "pagerange": "321-331", "id_number": "CaltechAUTHORS:20160803-110835979", "issn": "0003-2700", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160803-110835979", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Army Research Office (ARO)" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NASA" } ] }, "doi": "10.1021/ac000792f", "resource_type": "article", "pub_year": "2001", "author_list": "Vaid, Thomas P.; Burl, Michael C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0qe44-z0n45", "eprint_id": 120593, "eprint_status": "archive", "datestamp": "2023-08-21 21:56:18", "lastmod": "2023-10-23 16:05:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Doleman-Brett-J", "name": { "family": "Doleman", "given": "Brett J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Comparison of odor detection thresholds and odor discriminablities of a conducting polymer composite electronic nose versus mammalian olfaction", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Electrical and Electronic Engineering; Metals and Alloys; Surfaces, Coatings and Films; Condensed Matter Physics; Instrumentation; Electronic, Optical and Magnetic Materials", "note": "We sincerely thank Dr. Matthias Laska and his co-workers from the Department of Medical Psychology at the University of Munich Medical School for providing us with their data on the odorant discriminating ability of humans and monkeys. We thank NASA, the Army Research Office and DARPA for their support of this work, with primary support under a MURI grant from the Army Research Office. B.J.D. acknowledges the Government of Canada for an NSERC 1967 Centennial Graduate Fellowship.", "abstract": "Response data from an array of conducting polymer composite vapor detectors that form an electronic nose were collected for the purpose of comparing selected, quantitatively measurable, phenomena in odor detection and classification to the olfactory characteristics of monkeys and humans. Odor detection thresholds and discriminability between structurally similar pairs of odorants were the two primary quantities evaluated for this comparison. Comparisons were only made for volatile organic vapors as opposed to aroma active odorant vapors. Electronic nose detection thresholds for a homologous series of n-alkane and 1-alcohol odorants were determined and the results were compared to literature values for the mean olfactory detection thresholds observed in psychophysical experiments on humans exposed to these same vapors. The trends in odor detection thresholds of the electronic nose towards the tested analytes were very similar to those exhibited by humans. The discrimination performance of the electronic nose for distinguishing between pairs of odorants within incrementally varying series of esters, carboxylic acids and alcohols were also compared to the published data of Laska and co-workers on the psychophysical performance of humans and monkeys for these same odorant pairs. Similar trends were generally observed between the humans, monkeys, and the electronic nose in that discrimination performance increased as the compounds of an odorant pair became more structurally dissimilar. With use of the Fisher linear discriminant algorithm for classification of these test pairs of odorants, the electronic nose exhibited significantly better discriminability than humans or monkeys for the odorant pairs evaluated in this work under the test conditions for which the discriminability was evaluated.", "date": "2001-01-05", "date_type": "published", "publication": "Sensors and Actuators B: Chemical", "volume": "72", "number": "1", "publisher": "Elsevier", "pagerange": "41-50", "id_number": "CaltechAUTHORS:20230329-643908000.2", "issn": "0925-4005", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-643908000.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Army Research Office (ARO)" }, { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" } ] }, "doi": "10.1016/s0925-4005(00)00635-3", "resource_type": "article", "pub_year": "2001", "author_list": "Doleman, Brett J. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0extx-s5h59", "eprint_id": 120597, "eprint_status": "archive", "datestamp": "2023-08-19 07:06:57", "lastmod": "2023-10-18 17:55:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ryan-M-A", "name": { "family": "Ryan", "given": "M. A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Low power, lightweight vapor sensing using arrays of conducting polymer composite chemically-sensitive resistors", "ispublished": "pub", "full_text_status": "public", "abstract": "Arrays of broadly responsive vapor detectors can be used to detect, identify, and quantify vapors and vapor mixtures. One implementation of this strategy involves the use of arrays of chemically-sensitive resistors made from conducting polymer composites. Sorption of an analyte into the polymer composite detector leads to swelling of the film material. The swelling is in turn transduced into a change in electrical resistance because the detector films consist of polymers filled with conducting particles such as carbon black. The differential sorption, and thus differential swelling, of an analyte into each polymer composite in the array produces a unique pattern for each different analyte of interest, Pattern recognition algorithms are then used to analyze the multivariate data arising from the responses of such a detector array. Chiral detector films can provide differential detection of the presence of certain chiral organic vapor analytes. Aspects of the spaceflight qualification and deployment of such a detector array, along with its performance for certain analytes of interest in manned life support applications, are reviewed and summarized in this article.", "date": "2001", "date_type": "published", "publication": "Enantiomer", "volume": "6", "number": "2-3", "publisher": "Enantiomer", "pagerange": "159-170", "id_number": "CaltechAUTHORS:20230329-173640484", "issn": "1024-2430", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-173640484", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "article", "pub_year": "2001", "author_list": "Ryan, M. A. and Lewis, N. S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ekztg-9bq73", "eprint_id": 71397, "eprint_status": "archive", "datestamp": "2023-08-19 06:30:54", "lastmod": "2023-10-23 15:42:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Haber-J-A", "name": { "family": "Haber", "given": "Joel A." }, "orcid": "0000-0001-7847-5506" }, { "id": "Lauermann-I", "name": { "family": "Lauermann", "given": "Iver" }, "orcid": "0000-0002-9119-3770" }, { "id": "Michalak-D-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Vaid-T-P", "name": { "family": "Vaid", "given": "Thomas P." }, "orcid": "0000-0003-4597-0847" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electrochemical and Electrical Behavior of (111)-Oriented Si Surfaces Alkoxylated through Oxidative Activation of Si\u2212H Bonds", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2000 American Chemical Society. \n\nReceived: May 15, 2000; In Final Form: June 26, 2000. Publication Date (Web): October 11, 2000. \n\nWe acknowledge the National Science Foundation, grant CHE-9974562, for support of this work.", "abstract": "The reaction chemistry of H-terminated (111)-oriented Si surfaces has been explored in the presence of one-electron oxidants in alcohol solvents. Similar chemistry was observed for Si surfaces exposed to methanolic solutions of ferrocenium tetrafluoroborate or to methanolic solutions of I_2, as well as for Si electrodes that were subjected to anodic electrochemical oxidation processes in methanol. Oxidation in alcohols activates the surficial Si\u2212H bond toward nucleophilic attack, producing alkoxylated surfaces. This mechanism for Si\u2212H activation is supported by infrared spectroscopy, temperature-programmed desorption spectroscopy, and by X-ray photoelectron spectroscopic studies of this system. These data explain a variety of observations regarding the surface chemistry and electrochemistry of Si electrodes and surfaces.", "date": "2000-11-02", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "104", "number": "43", "publisher": "American Chemical Society", "pagerange": "9947-9950", "id_number": "CaltechAUTHORS:20161024-135059333", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161024-135059333", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9974562" } ] }, "doi": "10.1021/jp001791u", "resource_type": "article", "pub_year": "2000", "author_list": "Haber, Joel A.; Lauermann, Iver; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2qyea-gz741", "eprint_id": 120588, "eprint_status": "archive", "datestamp": "2023-08-21 21:39:50", "lastmod": "2023-10-18 17:55:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Rossi-Robert-C", "name": { "family": "Rossi", "given": "Robert C." } }, { "id": "Tan-Ming-X", "name": { "family": "Tan", "given": "Ming X." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Size-dependent electrical behavior of spatially inhomogeneous barrier height regions on silicon", "ispublished": "pub", "full_text_status": "public", "keywords": "Physics and Astronomy (miscellaneous)", "note": "\u00a9 2000 American Institute of Physics. \n\nThe authors acknowledge the National Science Foundation, Grant No. CHE-9974562, for support of this research, and R.R. thanks the NSF for a graduate fellowship.\n\nPublished - 1.1319534.pdf
", "abstract": "A series of ordered, periodic arrays of low barrier height n-Si/Ni nanometer-scale contacts interspersed among high barrier height n-Si/liquid contacts were prepared by evaporating Ni through bilayers of close-packed latex spheres deposited on n-Si. By varying the diameter of the spheres from 174 to 1530 nm, geometrically self-similar Si/Ni structures were produced having triangular Si/Ni features ranging from approximately 100 to 800 nm on a side. The resulting Si surfaces were used as electrodes in methanolic electrochemical cells containing LiClO\u2084 and 1,1\u2032-dimethylferrocene^(+/0). The dark current density\u2013voltage properties of the resulting mixed barrier height contacts were strongly dependent on the size of the low barrier height contact regions even though the fraction of the Si surface covered by Ni remained constant.", "date": "2000-10-23", "date_type": "published", "publication": "Applied Physics Letters", "volume": "77", "number": "17", "publisher": "American Institute of Physics", "pagerange": "2698-2700", "id_number": "CaltechAUTHORS:20230329-985098000.2", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-985098000.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9974562" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1063/1.1319534", "primary_object": { "basename": "1.1319534.pdf", "url": "https://authors.library.caltech.edu/records/2qyea-gz741/files/1.1319534.pdf" }, "resource_type": "article", "pub_year": "2000", "author_list": "Rossi, Robert C.; Tan, Ming X.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qw2fk-qfb56", "eprint_id": 120589, "eprint_status": "archive", "datestamp": "2023-08-21 21:39:26", "lastmod": "2023-10-18 17:55:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Royea-William-J", "name": { "family": "Royea", "given": "William J." } }, { "id": "Michalak-David-J", "name": { "family": "Michalak", "given": "David J." }, "orcid": "0000-0002-1226-608X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Role of inversion layer formation in producing low effective surface recombination velocities at Si/liquid contacts", "ispublished": "pub", "full_text_status": "public", "keywords": "Physics and Astronomy (miscellaneous)", "note": "\u00a9 2000 American Institute of Physics. \n\nThe authors acknowledge the National Science Foundation, Grant No. CHE-9974562, for support of this work.\n\nPublished - 1.1318935.pdf
", "abstract": "Photoconductivity decay lifetimes have been obtained for NH\u2084F_(aq)-etched Si(111) and for air-oxidized Si(111) surfaces in contact with solutions of CH\u2083OH or tetrahydrofuran (THF) containing either ferrocene^(+/0) (Fc^(+/0)), bis(pentamethylcyclopentadienyl) Fe^(+/0), or I\u2082. Si surfaces in contact with electrolytes having Nernstian redox potentials >0 V versus the standard calomel electrode exhibited low effective surface recombination velocities regardless of the different surface chemistries, whereas those exposed only to N\u2082(g) ambients or to electrolytes containing mild oxidants showed differing rf photoconductivity decay behavior depending on their different surface chemistry. The data reveal that formation of an inversion layer, and not a reduced density of electrical trap sites on the surface, is primarily responsible for the long charge-carrier lifetimes observed for Si surfaces in contact with CH\u2083OH or THF electrolytes containing I\u2082 or Fc^(+/0).", "date": "2000-10-16", "date_type": "published", "publication": "Applied Physics Letters", "volume": "77", "number": "16", "publisher": "American Institute of Physics", "pagerange": "2566-2568", "id_number": "CaltechAUTHORS:20230329-785534000.2", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-785534000.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9974562" } ] }, "doi": "10.1063/1.1318935", "primary_object": { "basename": "1.1318935.pdf", "url": "https://authors.library.caltech.edu/records/qw2fk-qfb56/files/1.1318935.pdf" }, "resource_type": "article", "pub_year": "2000", "author_list": "Royea, William J.; Michalak, David J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/evzfh-et456", "eprint_id": 2453, "eprint_status": "archive", "datestamp": "2023-08-21 21:35:49", "lastmod": "2023-10-13 23:24:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Royea-W-J", "name": { "family": "Royea", "given": "William J." } }, { "id": "Juang-A", "name": { "family": "Juang", "given": "Agnes" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Preparation of air-stable, low recombination velocity Si(111) surfaces through alkyl termination", "ispublished": "pub", "full_text_status": "public", "keywords": "silicon; elemental semiconductors; surface recombination; surface treatment; surface states; electron traps", "note": "\u00a92000 American Institute of Physics. \n\n(Received 8 May 2000; accepted 27 July 2000) \n\nThe authors acknowledge the National Science Foundation, Grant No. CHE-9974562, for support of this work.", "abstract": "A two-step, chlorination/alkylation procedure has been used to convert the surface Si\u2013H bonds on NH4F(aq)-etched (111)-oriented Si wafers into Si\u2013alkyl bonds of the form Si\u2013CnH2n + 1 (n>=1). The electrical properties of such functionalized surfaces were investigated under high-level and low-level injection conditions using a contactless rf apparatus. The charge carrier recombination velocities of the alkylated surfaces were <25 cm s^\u20131 under high-level and low-level injection conditions, implying residual surface trap densities of <3\u00d710^9 cm\u20132. Although the carrier recombination velocity of hydrogen-terminated Si(111) surfaces in contact with aqueous acids is <20 cm s^\u20131, this surface deteriorates within 30 min in an air ambient, yielding a high surface recombination velocity. In contrast, methylated Si(111) surfaces exhibit low surface recombination velocities in air for more than 4 weeks. Low surface recombination velocities were also observed for Si surfaces that had been modified with longer alkyl chains.", "date": "2000-09-25", "date_type": "published", "publication": "Applied Physics Letters", "volume": "77", "number": "13", "publisher": "Applied Physics Letters", "pagerange": "1988-1990", "id_number": "CaltechAUTHORS:ROYapl00", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:ROYapl00", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1063/1.1312203", "primary_object": { "basename": "ROYapl00.pdf", "url": "https://authors.library.caltech.edu/records/evzfh-et456/files/ROYapl00.pdf" }, "resource_type": "article", "pub_year": "2000", "author_list": "Royea, William J.; Juang, Agnes; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/vg7hq-3dd65", "eprint_id": 88107, "eprint_status": "archive", "datestamp": "2023-08-19 06:13:16", "lastmod": "2024-01-14 20:28:58", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Briglin-S-M", "name": { "family": "Briglin", "given": "Shawn M." } }, { "id": "Burl-M-C", "name": { "family": "Burl", "given": "Michael C." } }, { "id": "Freund-M-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Matzger-A-J", "name": { "family": "Matzger", "given": "Adam" } }, { "id": "Ortiz-D-N", "name": { "family": "Ortiz", "given": "D. Nelson" } }, { "id": "Tokumaru-P-T", "name": { "family": "Tokumaru", "given": "Phil" } } ] }, "title": "Progress in use of carbon-black-polymer composite vapor detector arrays for land mine detection", "ispublished": "unpub", "full_text_status": "public", "keywords": "Land mine, vapor sensors, DNT, carbon black", "note": "\u00a9 2000 Society of Photo-Optical Instrumentation Engineers (SPIE). \n\nWe acknowledge an OSD ARO MURI for demining, and DARPA, for support of this work.\n\nPublished - 530.pdf
", "abstract": "Thin films of carbon black-organic polymer composites have been deposited across two metallic leads, with swelling- induced resistance changes of the films signaling the presence of vapors. To identify and classify vapors, arrays of such vapor sensing elements have been constructed. Each element contained a different organic polymer as the insulating phase. The differing gas-solid partition coefficients for the various polymers of the detector array produced a pattern of resistance changes that was used to classify vapors and vapor mixtures. The performance of this system towards DNT, the predominant signature in the vapor phase above land miens, has been evaluated in detail, with robust detection demonstrated in the laboratory in less than 5 s in air at DNT levels in the low ppb range.", "date": "2000-08-22", "date_type": "published", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_pub": "Bellingham, WA", "pagerange": "530-538", "id_number": "CaltechAUTHORS:20180720-162850664", "isbn": "081943664X", "book_title": "Detection and Remediation Technologies for Mines and Minelike Targets V", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180720-162850664", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" } ] }, "contributors": { "items": [ { "id": "Dubey-A-C", "name": { "family": "Dubey", "given": "Abinash C." } }, { "id": "Harvey-J-F", "name": { "family": "Harvey", "given": "James F." } }, { "id": "Broach-J-T", "name": { "family": "Broach", "given": "J. Thomas" } }, { "id": "Dugan-R-E", "name": { "family": "Dugan", "given": "Regina E." } } ] }, "doi": "10.1117/12.396281", "primary_object": { "basename": "530.pdf", "url": "https://authors.library.caltech.edu/records/vg7hq-3dd65/files/530.pdf" }, "resource_type": "book_section", "pub_year": "2000", "author_list": "Briglin, Shawn M.; Burl, Michael C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ge967-a3857", "eprint_id": 75693, "eprint_status": "archive", "datestamp": "2023-08-19 06:07:50", "lastmod": "2023-10-25 15:13:08", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sauv\u00e9-G", "name": { "family": "Sauv\u00e9", "given": "Genevi\u00e8ve" } }, { "id": "Cass-M-E", "name": { "family": "Cass", "given": "Marion E." } }, { "id": "Coia-G", "name": { "family": "Coia", "given": "George" } }, { "id": "Doig-S-J", "name": { "family": "Doig", "given": "Stephen J." } }, { "id": "Lauermann-I", "name": { "family": "Lauermann", "given": "Iver" } }, { "id": "Pomykal-K-E", "name": { "family": "Pomykal", "given": "Katherine E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Dye Sensitization of Nanocrystalline Titanium Dioxide with Osmium and Ruthenium Polypyridyl Complexes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2000 American Chemical Society. \n\nReceived: January 14, 2000; In Final Form: April 6, 2000. Publication Date (Web): June 30, 2000. \n\nSupport for this project was provided by the U.S. Department of Energy, DE-FG07-96ER14725. M. Cass thanks Prof. John Burmeister of the University of Maryland for useful discussions on linkage isomerism in metal thiocyanate and metal isothiocyanate complexes, and Profs. H. Gray and J. Bercaw of Caltech are acknowledged for numerous helpful discussions. We are grateful to Dr. Andy Maverick at Louisiana State University for measuring the emission spectra of Os(H_2L')_2(NCS)_2. Genevi\u00e8ve Sauv\u00e9 thanks FCAR (Fonds pour la Formation de Chercheurs et l'Aide \u00e0 la Recherche, Qu\u00e9bec, Canada) for a scholarship, and S.D. acknowledges the U.S. Global Change Fellowship Program for a postdoctoral fellowship. We also thank Kodak for a generous gift in support of studies of photoelectrochemistry at Caltech.\n\nSupplemental Material - jp0002143_s.pdf
", "abstract": "A series of osmium polypyridyl complexes having various ground-state reduction potentials has been synthesized and used to sensitize nanoporous titanium dioxide electrodes to solar illumination. The spectral response and current vs potential properties of electrodes modified with these dyes have been compared with the behavior of their ruthenium analogues. The trends can be explained by the differences in absorption spectra and ground-state redox potentials. The osmium complexes appear to be promising candidates for further optimization in operating photoelectrochemical cells for solar energy conversion applications. Of the materials studied, all complexes having ground-state redox potentials in methanol more positive than \u223c0.4 V vs aqueous SCE were able to sustain oxidation of I-/I_3- with a high steady-state quantum yield. For electrodes with very low dye coverages, the open-circuit voltage was mainly determined by the rate of reduction of I_2, whereas for high dye coverages, the open-circuit voltage depended on the nature of the complex and on the dye loading level.", "date": "2000-07-27", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "104", "number": "29", "publisher": "American Chemical Society", "pagerange": "6821-6836", "id_number": "CaltechAUTHORS:20170404-105006672", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170404-105006672", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG07-96ER14725" }, { "agency": "Fonds pour la Formation de Chercheurs et l'Aide \u00e0 la Recherche" }, { "agency": "U. S. Global Change Fellowship" }, { "agency": "Kodak" } ] }, "doi": "10.1021/jp0002143", "primary_object": { "basename": "jp0002143_s.pdf", "url": "https://authors.library.caltech.edu/records/ge967-a3857/files/jp0002143_s.pdf" }, "resource_type": "article", "pub_year": "2000", "author_list": "Sauv\u00e9, Genevi\u00e8ve; Cass, Marion E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mtrg6-c3a79", "eprint_id": 73689, "eprint_status": "archive", "datestamp": "2023-08-19 06:06:08", "lastmod": "2023-10-24 15:36:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sotzing-G-A", "name": { "family": "Sotzing", "given": "Gregory A." } }, { "id": "Briglin-S-M", "name": { "family": "Briglin", "given": "Shawn M." } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Preparation and Properties of Vapor Detector Arrays Formed from Poly(3,4-ethylenedioxy)thiophene\u2212Poly(styrene sulfonate)/Insulating Polymer Composites", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2000 American Chemical Society. \n\nReceived 20 September 1999. Published online 9 June 2000. Published in print 1 July 2000. \n\nThe authors thank NASA, DARPA, and an Army MURI for financial support.\n\nSupplemental Material - ac991079x_s.pdf
", "abstract": "Poly(3,4-ethylenedioxy)thiophene\u2212poly(styrene sulfonate) (PEDOT\u2212PSS) was used as the conductive component in a matrix of chemically different insulating polymers to form an array of vapor detectors. Such composites produced larger relative differential resistance responses when exposed to polar analytes than did the corresponding carbon black filled polymer composite detectors. However, the PEDOT\u2212PSS composites produced smaller responses than carbon black composites when exposed to nonpolar analytes. The resolving power of a PEDOT\u2212PSS detector array was compared to that of a carbon black composite array for a broadly construed set of organic vapors. The PEDOT\u2212PSS array exhibited better, on average, discrimination between pairs of polar analytes and polar/nonpolar analytes than did the carbon black composite array. The carbon black composite array outperformed the PEDOT\u2212PSS array in discriminating between nonpolar compounds. The addition of PEDOT\u2212PSS composites to an array of carbon black composite detectors therefore can produce improved overall discrimination in a vapor sensor system when used in tasks to differentiate between of a broad set of analyte vapors.", "date": "2000-07-15", "date_type": "published", "publication": "Analytical Chemistry", "volume": "72", "number": "14", "publisher": "American Chemical Society", "pagerange": "3181-3190", "id_number": "CaltechAUTHORS:20170125-071215326", "issn": "0003-2700", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170125-071215326", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Army Research Office (ARO)" } ] }, "doi": "10.1021/ac991079x", "primary_object": { "basename": "ac991079x_s.pdf", "url": "https://authors.library.caltech.edu/records/mtrg6-c3a79/files/ac991079x_s.pdf" }, "resource_type": "article", "pub_year": "2000", "author_list": "Sotzing, Gregory A.; Briglin, Shawn M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dnfwx-hh840", "eprint_id": 73940, "eprint_status": "archive", "datestamp": "2023-08-19 06:01:08", "lastmod": "2023-10-24 21:07:53", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Matzger-A-J", "name": { "family": "Matzger", "given": "Adam J." } }, { "id": "Lawrence-C-E", "name": { "family": "Lawrence", "given": "Carolyn E." } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Combinatorial Approaches to the Synthesis of Vapor Detector Arrays for Use in an Electronic Nose", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2000 American Chemical Society. \n\nReceived 4 October 1999. Published online 29 April 2000. Published in print 1 July 2000. \n\nThis work was supported by DARPA, the Army Research Office, the Department of Energy, and NASA.\n\nSupplemental Material - cc990056t_s.pdf
", "abstract": "Synthesis of block copolymers for sorption studies. The first monomer formed the polar block, while the silyl-containing second monomer formed the nonpolar block of the material.", "date": "2000-07", "date_type": "published", "publication": "Journal of Combinatorial Chemistry", "volume": "2", "number": "4", "publisher": "American Chemical Society", "pagerange": "301-304", "id_number": "CaltechAUTHORS:20170201-134515011", "issn": "1520-4766", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170201-134515011", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Army Research Office (ARO)" }, { "agency": "Department of Energy (DOE)" }, { "agency": "NASA" } ] }, "doi": "10.1021/cc990056t", "primary_object": { "basename": "cc990056t_s.pdf", "url": "https://authors.library.caltech.edu/records/dnfwx-hh840/files/cc990056t_s.pdf" }, "resource_type": "article", "pub_year": "2000", "author_list": "Matzger, Adam J.; Lawrence, Carolyn E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4w6tc-y7f51", "eprint_id": 74036, "eprint_status": "archive", "datestamp": "2023-08-19 06:01:16", "lastmod": "2023-10-24 22:01:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Albert-K-J", "name": { "family": "Albert", "given": "Keith J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Schauer-C-L", "name": { "family": "Schauer", "given": "Caroline L." } }, { "id": "Sotzing-G-A", "name": { "family": "Sotzing", "given": "Gregory A." } }, { "id": "Stitzel-S-E", "name": { "family": "Stitzel", "given": "Shannon E." } }, { "id": "Vaid-T-P", "name": { "family": "Vaid", "given": "Thomas P." } }, { "id": "Walt-D-R", "name": { "family": "Walt", "given": "David R." } } ] }, "title": "Cross-Reactive Chemical Sensor Arrays", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2000 American Chemical Society. \n\nReceived 17 August 1999. Published online 24 June 2000. Published in print 1 July 2000. \n\nWe acknowledge the Army Research Office, NASA, and DARPA for support of sensor array work at Caltech and acknowledge DARPA, the Office of Naval Research, the National Institutes of Health, and the Department of Energy for support at Tufts that made preparation of this review, along with some of the examples discussed herein, possible.", "abstract": "Conventional approaches to chemical sensors have\ntraditionally made use of a \"lock-and-key\" design,\nwherein a specific receptor is synthesized in order to\nstrongly and highly selectively bind the analyte of\ninterest.1-6 A related approach involves exploiting a\ngeneral physicochemical effect selectively toward a\nsingle analyte, such as the use of the ionic effect in\nthe construction of a pH electrode. In the first\napproach, selectivity is achieved through recognition\nof the analyte at the receptor site, and in the second,\nselectivity is achieved through the transduction\nprocess in which the method of detection dictates\nwhich species are sensed. Such approaches are appropriate\nwhen a specific target compound is to be\nidentified in the presence of controlled backgrounds\nand interferences. However, this type of approach\nrequires the synthesis of a separate, highly selective\nsensor for each analyte to be detected. In addition,\nthis type of approach is not particularly useful for\nanalyzing, classifying, or assigning human value\njudgments to the composition of complex vapor\nmixtures such as perfumes, beers, foods, mixtures of\nsolvents, etc.", "date": "2000-07", "date_type": "published", "publication": "Chemical Reviews", "volume": "100", "number": "7", "publisher": "American Chemical Society", "pagerange": "2595-2626", "id_number": "CaltechAUTHORS:20170203-135415951", "issn": "0009-2665", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170203-135415951", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)" }, { "agency": "NASA" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Office of Naval Research (ONR)" }, { "agency": "NIH" }, { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1021/cr980102w", "resource_type": "article", "pub_year": "2000", "author_list": "Albert, Keith J.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6yqtn-4kz27", "eprint_id": 78906, "eprint_status": "archive", "datestamp": "2023-08-19 05:56:37", "lastmod": "2023-10-26 14:27:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Casagrande-Louis-G", "name": { "family": "Casagrande", "given": "Louis G." } }, { "id": "Juang-Agnes", "name": { "family": "Juang", "given": "Agnes" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoelectrochemical Behavior of n-GaAs and n-Al\u2093Ga_(1-x)As in CH\u2083CN", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2000 American Chemical Society. \n\nReceived: November 18, 1999; In Final Form: February 24, 2000. Publication Date (Web): May 19, 2000. \n\nWe acknowledge the U.S. Department of Energy, Office of Basic Energy Sciences, for support of this work. We also gratefully acknowledge the Eastman Kodak Company for a gift to Caltech in support of photoelectrochemistry.", "abstract": "Current density vs potential, open-circuit voltage vs temperature, and differential capacitance vs potential measurements have been used to show that n-GaAs and n-Al\u2093Ga_(1-x)As electrodes exhibit partial Fermi level pinning in contact with CH\u2083CN over a wide range of redox potentials. Despite a change of over 1.2 V in redox potential of the solution, the open-circuit voltage only changed by \u223c300 mV. The slope of the open-circuit voltage vs redox potential of the solution was typically 0.33\u22120.44. Differential capacitance vs potential data also yielded a barrier height change of less than 300 mV for over 1.2 V change in the redox potential of the solution. The dependence of the current density vs potential behavior of n-GaAs/CH\u2083CN\u2212ferricenium\u2212ferrocene^(+/0) on variables such as the illumination intensity, dopant density of the semiconductor, concentration of redox acceptor in the solution, crystal face, electrolyte, and cell temperature was evaluated. The resultant kinetic data indicate that surface-state recombination is the dominant recombination mechanism at these interfaces, which are capable of producing an open-circuit voltage of 0.83 V at a short-circuit current density of 20 mA cm\u207b\u00b2, as well as energy conversion efficiencies of > 10%. X-ray photoelectron spectroscopy investigation of n-GaAs confirmed surface changes were induced by electrochemical operation of n-GaAs electrodes in CH_\u2083CN\u2212cobaltocenium\u2212cobaltocene^(+/)0 electrolyte. The presence of Fermi level pinning and the existence of changes in n-GaAs and n-Al_\u2093a_(1-x)As electrode surfaces when these electrodes are in contact with CH\u2083CN\u2212cobaltocenium\u2212cobaltocene^(+/0) electrolyte complicates the extraction of k\u2091\u209c values from the steady-state current density vs potential behavior of n-GaAs or n-Al\u2093Ga_(1-x)As/CH\u2083CN contacts.", "date": "2000-06-15", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "104", "number": "23", "publisher": "American Chemical Society", "pagerange": "5436-5447", "id_number": "CaltechAUTHORS:20170710-143049120", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170710-143049120", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Eastman Kodak Company" } ] }, "doi": "10.1021/jp9941155", "resource_type": "article", "pub_year": "2000", "author_list": "Casagrande, Louis G.; Juang, Agnes; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/tb6b1-36346", "eprint_id": 73688, "eprint_status": "archive", "datestamp": "2023-08-19 05:45:16", "lastmod": "2023-10-24 15:36:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Severin-Erik-J", "name": { "family": "Severin", "given": "Erik J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Relationships among Resonant Frequency Changes on a Coated Quartz Crystal Microbalance, Thickness Changes, and Resistance Responses of Polymer\u2212Carbon Black Composite Chemiresistors", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2000 American Chemical Society. \n\nReceived 7 September 1999. Published online 1 April 2000. Published in print 1 May 2000. \n\nThis work was supported by the National Aeronautics and Space Administration, the Army Research Office, and the Defense Advanced Research Projects Agency.", "abstract": "The relationships among frequency changes on a film-coated quartz crystal microbalance, thickness changes, and dc resistance changes have been investigated for carbon black\u2212insulating polymer composite vapor detectors. Quartz crystal microbalance (QCM) measurements and ellipsometry measurements have been performed simultaneously on polymer films that do not contain carbon black filler to relate the QCM frequency change and the ellipsometrically determined thickness change to the analyte concentration in the vapor phase. In addition, quartz crystal microbalance measurements and dc resistance measurements on carbon black composites of these same polymers have been performed simultaneously to relate the QCM frequency change and dc electrical resistance response to the analyte concentration in the vapor phase. The data indicate that the dc resistance change is directly relatable to the thickness change of the polymers and that a variety of analytes that produce a given thickness change produce a constant resistance change for each member of the test set of polymers investigated in this work.", "date": "2000-05-01", "date_type": "published", "publication": "Analytical Chemistry", "volume": "72", "number": "9", "publisher": "American Chemical Society", "pagerange": "2008-2015", "id_number": "CaltechAUTHORS:20170125-070259952", "issn": "0003-2700", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170125-070259952", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" }, { "agency": "Army Research Office (ARO)" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" } ] }, "doi": "10.1021/ac991026f", "resource_type": "article", "pub_year": "2000", "author_list": "Severin, Erik J. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/81wrb-0wc03", "eprint_id": 79214, "eprint_status": "archive", "datestamp": "2023-08-19 05:40:10", "lastmod": "2023-10-26 14:42:04", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sauv\u00e9-G", "name": { "family": "Sauv\u00e9", "given": "Genevi\u00e8ve" } }, { "id": "Cass-M-E", "name": { "family": "Cass", "given": "Marion E." } }, { "id": "Doig-S-J", "name": { "family": "Doig", "given": "Stephen J." } }, { "id": "Lauermann-I", "name": { "family": "Lauermann", "given": "Iver" } }, { "id": "Pomykal-K-E", "name": { "family": "Pomykal", "given": "Katherine E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "High Quantum Yield Sensitization of Nanocrystalline Titanium Dioxide Photoelectrodes withcis-Dicyanobis(4,4'-dicarboxy-2,2'-bipyridine)osmium(II) or Tris(4,4'-dicarboxy-2,2'-bipyridine)osmium(II) Complexes", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2000 American Chemical Society. \n\nReceived 30 April 1999. Published online 24 March 2000. Published in print 1 April 2000. \n\nSupport for this project was provided by the U.S. Department of Energy, DE-FG07-96ER14725. We thank Kodak for a generous gift in support of photoelectrochemistry at Caltech. We are grateful to Dr. G. Coia of Caltech for assistance with the instruments used to perform the emission measurements and to Dr. G. W. Walker of Caltech for useful discussions. G.S. thanks FCAR (Fonds pour la Formation de Chercheurs et l'Aide \u00e0 la Recherche, Qu\u00e9bec, Canada) for a doctoral scholarship.", "abstract": "Osmium polypyridyl complexes were used as sensitizers in solar cells that utilize nanocrystalline titanium dioxide photoelectrodes. Exposure of TiO_2 electrodes to sources of Os^(II)(H_2L')_2(CN)_2 (where L' is 4,4'-dicarboxylato-2,2'-bipyridine) or Os^(II)(H_2L')_3^(2+) extended the light absorption and spectral response of the cell to longer wavelengths than did exposure of TiO_2 to Ru(H_2L')_2(NCS)_2. The Os complexes also provided very high external quantum yields for photocurrent flow and produced open-circuit voltages similar to those of the Ru complex. The Os-based systems therefore offer promise in developing efficient dye-sensitized nanocrystalline TiO_2-based photoelectrochemical cells.", "date": "2000-04-20", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "104", "number": "15", "publisher": "American Chemical Society", "pagerange": "3488-3491", "id_number": "CaltechAUTHORS:20170719-150532586", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170719-150532586", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG07-96ER14725" }, { "agency": "Fonds pour la Formation de Chercheurs et l'Aide \u00e0 la Recherche" } ] }, "doi": "10.1021/jp994033g", "resource_type": "article", "pub_year": "2000", "author_list": "Sauv\u00e9, Genevi\u00e8ve; Cass, Marion E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/v41yk-9we98", "eprint_id": 74021, "eprint_status": "archive", "datestamp": "2023-08-19 05:27:01", "lastmod": "2023-10-24 22:00:52", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sotzing-G-A", "name": { "family": "Sotzing", "given": "Gregory A." } }, { "id": "Phend-J-N", "name": { "family": "Phend", "given": "Jennifer N." } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Highly Sensitive Detection and Discrimination of Biogenic Amines Utilizing Arrays of Polyaniline/Carbon Black Composite Vapor Detectors", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2000 American Chemical Society. \n\nReceived 1 November 1999. Published online 29 February 2000. \nPublished in print 1 March 2000. \n\nWe acknowledge support from the Army Research Office (under a MURI grant program) and DARPA and thank Dr. C. R. Lewis for insightful discussions and suggestions during the conception and execution of this work.\n\nSupplemental Material - cm990694e_s.pdf
", "abstract": "Chemically-sensitive resistors have been developed that allow rapid detection of an important class of compounds, biogenic amines, at levels of 1\u221210 parts per trillion in ambient air. The materials are composites of a conducting organic polymer, the emeraldine salt of polyaniline, with particles of another conducting phase, carbon black. The resistance response of an EM\u2212DBSA(1:0.5)/CB (80:20) detector exposed to water (a), acetone (b), methanol (c), ethyl acetate (d), and butanol (e) is approximately a factor of a million smaller than that to butylamine (f).", "date": "2000-03", "date_type": "published", "publication": "Chemistry of Materials", "volume": "12", "number": "3", "publisher": "American Chemical Society", "pagerange": "593-595", "id_number": "CaltechAUTHORS:20170203-100738867", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170203-100738867", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" } ] }, "doi": "10.1021/cm990694e", "primary_object": { "basename": "cm990694e_s.pdf", "url": "https://authors.library.caltech.edu/records/v41yk-9we98/files/cm990694e_s.pdf" }, "resource_type": "article", "pub_year": "2000", "author_list": "Sotzing, Gregory A.; Phend, Jennifer N.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/d0shx-vqf63", "eprint_id": 73679, "eprint_status": "archive", "datestamp": "2023-08-19 05:24:38", "lastmod": "2023-10-24 15:35:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Severin-E-J", "name": { "family": "Severin", "given": "Erik J." } }, { "id": "Doleman-B-J", "name": { "family": "Doleman", "given": "Brett J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "An Investigation of the Concentration Dependence and Response to Analyte Mixtures of Carbon Black/Insulating Organic Polymer Composite Vapor Detectors", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2000 American Chemical Society. \n\nReceived 7 September 1999. Published online 21 January 2000. Published in print 1 February 2000. \n\nThis work was supported by the National Aeronautics and\nSpace Administration, the Army Research Office, the Defense\nAdvanced Research Projects Agency, and the Department of\nEnergy, B.J.D. acknowledges the Government of Canada for an\nNSERC 1967 Centennial Graduate Fellowship.\n\nSupplemental Material - ac9910278_s.pdf
", "abstract": "The responses relative to an air background of carbon black/polymer composite vapor detectors have been determined as a function of the concentration of a homologous series of alcohols (n-C_nH_(2n+1)OH, 1 \u2264 n \u2264 8), a homologous series of alkanes (n-C_nH_(2n+2), 5 \u2264 n \u2264 10 and n = 12, 14), and a set of diverse solvent vapors. In all cases, the steady-state relative differential resistance responses, \u0394R/R_b, of the carbon black/polymer composite vapor detectors were well-described by a linear relationship with respect to the analyte partial pressure, at least over the tested concentration range (P/P\u00b0 = 0.005\u22120.03, where P\u00b0 is the vapor pressure of the analyte). When two vapors in air were simultaneously presented to the detectors, the \u0394R/R_b response, relative to an air background, was the sum of the \u0394R/R_b values obtained when each analyte was exposed separately to the carbon black/polymer composite detectors under study. Similarly, when an analyte was exposed to the detectors on top of a background level of another analyte, the \u0394R/R_b values of the array of detectors were very close to those obtained when the test analyte was exposed to the detectors only in the presence of background air. The initial training requirements from the array response output data of such detectors are minimized because the \u0394R/R_b response pattern produced by the analyte of concern can be associated uniquely with that odor, under the conditions explored in this work.", "date": "2000-02-15", "date_type": "published", "publication": "Analytical Chemistry", "volume": "72", "number": "4", "publisher": "American Chemical Society", "pagerange": "658-668", "id_number": "CaltechAUTHORS:20170124-153339196", "issn": "0003-2700", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170124-153339196", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" }, { "agency": "Army Research Office (ARO)" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Department of Energy (DOE)" }, { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" } ] }, "doi": "10.1021/ac9910278", "primary_object": { "basename": "ac9910278_s.pdf", "url": "https://authors.library.caltech.edu/records/d0shx-vqf63/files/ac9910278_s.pdf" }, "resource_type": "article", "pub_year": "2000", "author_list": "Severin, Erik J.; Doleman, Brett J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jnsnf-w9g52", "eprint_id": 88081, "eprint_status": "archive", "datestamp": "2023-08-19 04:59:42", "lastmod": "2023-10-18 21:44:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sturzenegger-Marcel", "name": { "family": "Sturzenegger", "given": "Marcel" } }, { "id": "Prokopuk-Nicholas", "name": { "family": "Prokopuk", "given": "Nicholas" } }, { "id": "Kenyon-C-N", "name": { "family": "Kenyon", "given": "C. N." } }, { "id": "Royea-William-J", "name": { "family": "Royea", "given": "William J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Reactions of Etched, Single Crystal (111)B-Oriented InP To Produce Functionalized Surfaces with Low Electrical Defect Densities", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1999 American Chemical Society. \n\nReceived: July 8, 1999. \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, for support of this work. M.S. acknowledges the Swiss National Science Foundation for a postdoctoral fellowship, and we thank A. Rice for technical assistance with the XPS measurements.", "abstract": "Synthetic routes have been developed that allow attachment of a variety of functional groups to etched, single-crystal InP surfaces. Benzyl halides, alkyl halides, silyl halides, and esters reacted readily with InP to yield covalently attached overlayers on the semiconductor surface. High-resolution X-ray photoelectron spectroscopy (XPS) revealed that the functionalization chemistry was consistent with the reactivity of surficial hydroxyl groups. Analysis of the XP spectra of the (111)B-oriented (P-rich) face in ultrahigh vacuum revealed signals ascribable to a monolayer of oxidized P atoms on the etched (111)B InP surface. The lack of reactivity of the (111)A-oriented (In-rich) face with these same functionalization reagents is therefore attributed to the difference in the nucleophilicity and acidity of the In and P oxides that are present on the (111)A and (111)B faces, respectively. The coverage of benzylic groups obtained through functionalization of (111)B-oriented InP with benzyl halides was estimated to be 4 \u00d7 10^(14) cm^2. This coverage implies that the functionalization can only proceed at alternate surface P atom sites in this system, which is expected from molecular packing considerations of these particular functional groups. Photoluminescence decay measurements were performed to investigate the electrical properties of the etched and modified InP surfaces, and these data indicated that the surface recombination velocity of the functionalized InP surface was \u224810^2 cm s^(-1). This low surface recombination velocity implies that <1 electrically active defect is present for every 10^5 atoms on the modified InP surface, indicating that high electrical quality can be maintained while introducing a variety of chemical functionalities onto the (111)B surface of InP.", "date": "1999-12-09", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "103", "number": "49", "publisher": "American Chemical Society", "pagerange": "10838-10849", "id_number": "CaltechAUTHORS:20180720-142204547", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180720-142204547", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Swiss National Science Foundation (SNSF)" } ] }, "doi": "10.1021/jp992290f", "resource_type": "article", "pub_year": "1999", "author_list": "Sturzenegger, Marcel; Prokopuk, Nicholas; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0q71g-1ja87", "eprint_id": 120782, "eprint_status": "archive", "datestamp": "2023-08-22 14:08:47", "lastmod": "2023-10-18 17:59:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Claypool-Christopher-L", "name": { "family": "Claypool", "given": "Christopher L." } }, { "id": "Faglioni-Francesco", "name": { "family": "Faglioni", "given": "Francesco" }, "orcid": "0000-0002-3327-8848" }, { "id": "Matzger-Adam-J", "name": { "family": "Matzger", "given": "Adam J." } }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A." }, "orcid": "0000-0003-0097-5716" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Effects of Molecular Geometry on the STM Image Contrast of Methyl- and Bromo-Substituted Alkanes and Alkanols on Graphite", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Surfaces, Coatings and Films; Physical and Theoretical Chemistry", "note": "\u00a9 1999 American Chemical Society. \n\nWe acknowledge the NSF, Grants CHE-9634152 (N.S.L.), CHE-95-22179 (W.A.G.), and ASC-92-17368 (W.A.G.) for partial support of this work.", "abstract": "Scanning tunneling microscopy (STM) images have been collected for a series of substituted alkanes and alkanols that form ordered overlayers at room temperature on highly ordered pyrolytic graphite surfaces. Molecules that have been imaged possess an internal bromide, with or without terminal alcohol groups (HO(CH\u2082)\u2089CHBr(CH\u2082)\u2081\u2080OH and H\u2083C(CH\u2082)\u2081\u2086CHBr(CH\u2082)\u2081\u2086CH\u2083), an internal \u2212OH group (H\u2083C(CH\u2082)\u2081\u2086CHOH(CH\u2082)\u2081\u2086CH\u2083), and an internal methyl group (H\u2083C(CH\u2082)\u2081\u2086CHCH\u2083(CH\u2082)\u2081\u2086CH\u2083). These data allow comparison to the STM image contrast reported previously for molecules in which \u2212OH, \u2212Br, and \u2212CH\u2083 groups were located in terminal positions of alkane chains adsorbed onto graphite surfaces. When the functional groups were in gauche positions relative to the alkyl chain, and thus produced molecular features that protruded toward the tip, the functional groups were observed to produce bright regions in a constant current STM image, regardless of the STM contrast behavior observed for these same functional groups when they were in terminal positions of adsorbed alkyl chains. These observations are in excellent agreement with theoretical predictions of the STM behavior of such systems. Additionally, several interesting packing structures have been observed that have yielded insight into the intermolecular forces that control the packing displayed by these overlayers.", "date": "1999-11-04", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "103", "number": "44", "publisher": "American Chemical Society", "pagerange": "9690-9699", "id_number": "CaltechAUTHORS:20230412-312051000.6", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230412-312051000.6", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9634152" }, { "agency": "NSF", "grant_number": "CHE-9522179" }, { "agency": "NSF", "grant_number": "ASC-9217368" } ] }, "other_numbering_system": { "items": [ { "id": "0423", "name": "WAG" } ] }, "doi": "10.1021/jp992257t", "resource_type": "article", "pub_year": "1999", "author_list": "Claypool, Christopher L.; Faglioni, Francesco; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/xyxgd-z5k98", "eprint_id": 120783, "eprint_status": "archive", "datestamp": "2023-08-22 13:58:07", "lastmod": "2023-10-18 17:59:41", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Claypool-Christopher-L", "name": { "family": "Claypool", "given": "Christopher L." } }, { "id": "Faglioni-Francesco", "name": { "family": "Faglioni", "given": "Francesco" }, "orcid": "0000-0002-3327-8848" }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A., III" }, "orcid": "0000-0003-0097-5716" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Tunneling Mechanism Implications from an STM Study of H\u2083C(CH\u2082)\u2081\u2085HC=C=CH(CH\u2082)\u2081\u2085CH\u2083 on Graphite and C\u2081\u2084H\u2082\u2089OH on MoS\u2082", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Surfaces, Coatings and Films; Physical and Theoretical Chemistry", "note": "\u00a9 1999 American Chemical Society. \n\nWe acknowledge the NSF, Grants CHE-9634152 (N.S.L.), CHE-95-22179 (W.A.G.), and ASC-92-17368 (W.A.G.) for support of this work.", "abstract": "The observations reported herein confirm that the bright spots in high-resolution STM images of adsorbed alkanes and alkanols are predominantly due to the electronic and topographic structure of the molecule, and not predominantly due to the substrate. STM images of a monolayer of 17,18-pentatriacontadiene, H\u2083C(CH\u2082)\u2081\u2085HC=C=CH(CH\u2082)\u2081\u2085CH\u2083, adsorbed on graphite were obtained to evaluate whether changes in the orientation of the exposed methylene hydrogen atoms relative to the STM tip produced changes in the observed pattern of bright spots in a STM image. STM images of this system showed a pattern of bright spots within individual molecules that appears to change on either side of the allene \u2212C=C=C\u2212 functionality. STM images were also obtained for tetradecanol overlayers on graphite and MoS\u2082 surfaces. The angles and distances observed in the images of tetradecanol on MoS\u2082 were nearly identical to those measured previously in our laboratories for alkanol and alkane monolayers on graphite despite that fact that the separation between bright spots in an STM image of graphite is 2.46 \u00c5, while the separation between bright spots in STM images of MoS\u2082 is 3.16 \u00c5.", "date": "1999-08-26", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "103", "number": "34", "publisher": "American Chemical Society", "pagerange": "7077-7080", "id_number": "CaltechAUTHORS:20230412-312058000.7", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230412-312058000.7", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9634152" }, { "agency": "NSF", "grant_number": "CHE-9522179" }, { "agency": "NSF", "grant_number": "ASC-9217368" } ] }, "other_numbering_system": { "items": [ { "id": "0417", "name": "WAG" } ] }, "doi": "10.1021/jp991463y", "resource_type": "article", "pub_year": "1999", "author_list": "Claypool, Christopher L.; Faglioni, Francesco; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jjm1b-ckc70", "eprint_id": 88193, "eprint_status": "archive", "datestamp": "2023-08-19 04:36:53", "lastmod": "2024-01-14 20:29:57", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Matzger-A-J", "name": { "family": "Matzger", "given": "Adam" } }, { "id": "Vaid-T-P", "name": { "family": "Vaid", "given": "Thomas P." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Vapor sensing with arrays of carbon black-polymer composites", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1999 Society of Photo-optical Instrumentation Engineers (SPIE). \n\nWe acknowledge multi-university research initiative in demining from the Army Research Office and DARPA for support of this work.\n\nPublished - 315.pdf
", "abstract": "Thin films of carbon black-organic polymer composites have been deposited across two metallic leads, with swelling- induced resistance changes of the films signaling the presence of vapors. To identify and classify vapors, arrays of such vapor-sensing elements have been constructed, with each element containing a different organic polymer as the insulating phase. The differing gas-solid partition coefficients for the various polymers of the sensor array produce a pattern of resistance changes that can be used to classify vapors and vapor mixtures. This type of sensor array has been shown to resolve all organic vapors that have been analyzed, and can even resolve H_2O from D_2O. Blends of poly(vinyl acetate) and poly(methyl methacrylate) have been used to produce a series of sensor that response to vapors with a change in resistance of a magnitude that is not simply a linear combination of the responses of the pure polymers. These compatible blend composite detectors provided additional analyte discrimination information relative to a reference detector array that only contained composites formed using the pure polymer phases. Vapor signatures from chemicals used in land mine explosives, including TNT, DNT, and DNB, have been detected in air in short sampling time and discriminated from each other using these sensor arrays.", "date": "1999-08-02", "date_type": "published", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_pub": "Bellingham, WA", "pagerange": "315-320", "id_number": "CaltechAUTHORS:20180724-131523822", "isbn": "0819431842", "book_title": "Detection and Remediation Technologies for Mines and Minelike Targets IV", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180724-131523822", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" } ] }, "contributors": { "items": [ { "id": "Dubey-A-C", "name": { "family": "Dubey", "given": "Abinash C." } }, { "id": "Harvey-J-F", "name": { "family": "Harvey", "given": "James F." } }, { "id": "Broach-J-T", "name": { "family": "Broach", "given": "J. Thomas" } }, { "id": "Dugan-R-E", "name": { "family": "Dugan", "given": "Regina E." } } ] }, "doi": "10.1117/12.357053", "primary_object": { "basename": "315.pdf", "url": "https://authors.library.caltech.edu/records/jjm1b-ckc70/files/315.pdf" }, "resource_type": "book_section", "pub_year": "1999", "author_list": "Matzger, Adam; Vaid, Thomas P.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qsqyh-nn852", "eprint_id": 120786, "eprint_status": "archive", "datestamp": "2023-08-22 13:46:58", "lastmod": "2023-10-18 17:59:44", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Anz-Samir-J", "name": { "family": "Anz", "given": "Samir J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Simulations of the Steady-State Current Density vs Potential Characteristics of Semiconducting Electrodes", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Surfaces, Coatings and Films; Physical and Theoretical Chemistry", "note": "\u00a9 1999 American Chemical Society. \n\nWe acknowledge Dr. Olaf Kr\u00fcger for his insightful discussions and Herbert Gajewski and Reiner N\u00fcrnberg from the Institute f\u00fcr Angewandte Analysis und Stochastik in Berlin for their help with ToSCA. We also thank the U.S. Department of Energy, Office of Basic Energy Sciences, DE-FG-03-88ER13932, for their generous support of this work.", "abstract": "A series of digital simulations has been performed to obtain insight into the steady-state current density vs potential behavior of semiconductor/liquid interfaces. The ToSCA program, incorporating all of the key kinetic parameters involved with the generation, transport, and recombination of charge carriers both in the semiconductor and across the semiconductor/liquid interface, has been used for this purpose. The simulations confirmed conclusions obtained previously from a simplified analytical model, which state that for ideal behavior of a nondegenerately doped semiconducting electrode the photovoltage of an n-type semiconductor/liquid interface should not change if the concentration of the reduced form of the redox species, A\u207b, is held constant but the concentration of the oxidized form of the redox species, A, is varied. The simplified analytical model also predicts that the photovoltage will be independent of variation in [A\u207b] if [A] is held constant. In contrast, recent work has asserted that ideal junction behavior implies that the photocurrent should exhibit shifts in potential that are linearly dependent on the concentration of the minority carrier acceptor species in the solution, with a magnitude of 59 mV per decade change in the acceptor concentration at 300 K. In accord with the predictions of the simplified analytical model, such shifts are not apparent in the simulations presented in this work. Finally, ToSCA simulations have been applied to analyze literature data on the steady-state current density vs potential behavior of p-InP/Fe(CN)\u2086^(3-/4-)(aq) contacts. Such simulations have established an upper bound for the interfacial charge-transfer rate constant of k\u2091\u209c \u2248 10\u207b\u00b2\u2070 cm\u2074 s\u207b\u00b9 in this system.", "date": "1999-05-13", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "103", "number": "19", "publisher": "American Chemical Society", "pagerange": "3908-3915", "id_number": "CaltechAUTHORS:20230412-312121000.11", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230412-312121000.11", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG-03-88ER13932" } ] }, "doi": "10.1021/jp9845571", "resource_type": "article", "pub_year": "1999", "author_list": "Anz, Samir J. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/37w85-7tb15", "eprint_id": 88557, "eprint_status": "archive", "datestamp": "2023-08-22 13:32:43", "lastmod": "2023-10-18 22:08:25", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Rate Constants for Electron Transfer Across Semiconductor/Liquid Interfaces: Theory and Experiment", "ispublished": "pub", "full_text_status": "public", "keywords": "electron transfer; electrode kinetics; n-Si/methanol contacts; n-GaAs/CH3CN contacts", "note": "\u00a9 1999 Oldenbourg Wissenschaftsverlag, M\u00fcnchen. \n\nReceived August 26, 1998; accepted December 10, 1998.", "abstract": "Fermi's Golden Rule has previously been used to formulate rate expressions for transfer of delocalized charge carriers in a nondegenerately doped semiconducting electrode to localized, outer-sphere redox acceptors in an electrolyte phase. If the charge-transfer rate constant is known experimentally, these rate expressions allow computation of the value of the electronic coupling matrix element between the semiconducting electrode and the redox species. This treatment also facilitates comparison between charge-transfer kinetic data at metallic and semiconducting electrodes in terms of parameters such as the electronic coupling to the electrode, the attenuation of coupling with distance into the electrolyte, and the reorganization energy of the charge-transfer event. Within this framework, rate constant values expected at representative semiconducting electrodes have been evaluated from experimental data for charge transfer from Au electrodes to various redox acceptors.", "date": "1999-02", "date_type": "published", "publication": "Zeitschrift f\u00fcr Physikalische Chemie", "volume": "212", "number": "2", "publisher": "De Gruyter", "pagerange": "161-172", "id_number": "CaltechAUTHORS:20180803-082518915", "issn": "0942-9352", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180803-082518915", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1524/zpch.1999.212.Part_2.161", "resource_type": "article", "pub_year": "1999", "author_list": "Lewis, N. S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/acsyg-bjk27", "eprint_id": 88558, "eprint_status": "archive", "datestamp": "2023-08-22 13:25:01", "lastmod": "2023-10-18 22:08:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Rate Constants for Electron Transfer Across Semiconductor/Liquid Interfaces: Theory and Experiment", "ispublished": "pub", "full_text_status": "public", "keywords": "electron transfer; electrode kinetics; n-Si/methanol contacts; n-GaAs/CH3CN contacts", "note": "\u00a9 1999 Oldenbourg Wissenschaftsverlag, M\u00fcnchen. \n\nReceived August 26, 1998; accepted December 10, 1998.", "abstract": "Fermi's Golden Rule has previously been used to formulate rate expressions for transfer of delocalized charge carriers in a nondegenerately doped semiconducting electrode to localized, outer-sphere redox acceptors in an electrolyte phase. If the charge-transfer rate constant is known experimentally, these rate expressions allow computation of the value of the electronic coupling matrix element between the semiconducting electrode and the redox species. This treatment also facilitates comparison between charge-transfer kinetic data at metallic and semiconducting electrodes in terms of parameters such as the electronic coupling to the electrode, the attenuation of coupling with distance into the electrolyte, and the reorganization energy of the charge-transfer event. Within this framework, rate constant values expected at representative semiconducting electrodes have been evaluated from experimental data for charge transfer from Au electrodes to various redox acceptors.", "date": "1999", "date_type": "published", "publication": "Zeitschrift f\u00fcr Physikalische Chemie", "volume": "1", "number": "1", "publisher": "De Gruyter", "pagerange": "149-160", "id_number": "CaltechAUTHORS:20180803-083706152", "issn": "0942-9352", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180803-083706152", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1524/zpch.1998.1.1.149", "resource_type": "article", "pub_year": "1999", "author_list": "Lewis, N. S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hjyem-dmk70", "eprint_id": 83019, "eprint_status": "archive", "datestamp": "2023-08-19 03:23:48", "lastmod": "2023-10-17 22:51:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Doleman-B-J", "name": { "family": "Doleman", "given": "Brett J." } }, { "id": "Lonergan-M-C", "name": { "family": "Lonergan", "given": "Mark C." } }, { "id": "Severin-E-J", "name": { "family": "Severin", "given": "Erik J." } }, { "id": "Vaid-T-P", "name": { "family": "Vaid", "given": "Thomas P." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Quantitative Study of the Resolving Power of Arrays of Carbon Black\u2212Polymer Composites in Various Vapor-Sensing Tasks", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1998 American Chemical Society. \n\nReceived for review October 31, 1997. Accepted July 8, 1998. Publication Date (Web): August 26, 1998. \n\nWe acknowledge Dr. Dawei Dong and Prof. Rod Goodman of Caltech for helpful suggestions regarding the manuscript. This work was supported by the National Aeronautics and Space Administration, the Army Research Office, and the Defense Advanced Research Projects Agency. B.J.D. acknowledges the Natural Science and Engineering Research Council of Canada for a 1967 Centennial Fellowship.", "abstract": "A statistical metric, based on the magnitude and standard deviations along linear projections of clustered array response data, was utilized to facilitate an evaluation of the performance of detector arrays in various vapor classification tasks. This approach allowed quantification of the ability of a 14-element array of carbon black\u2212insulating polymer composite chemiresistors to distinguish between members of a set of 19 solvent vapors, some of which vary widely in chemical properties (e.g., methanol and benzene) and others of which are very similar (e.g., n-pentane and n-heptane). The data also facilitated evaluation of questions such as the optimal number of detectors required for a specific task, whether improved performance is obtained by increasing the number of detectors in a detector array, and how to assess statistically the diversity of a collection of detectors in order to understand more fully which properties are underrepresented in a particular set of array elements. In addition, the resolving power of arrays of carbon black\u2212polymer composites was compared to the resolving power of specific collections of bulk conducting organic polymer or tin oxide detector arrays in a common set of vapor classification tasks.", "date": "1998-10-01", "date_type": "published", "publication": "Analytical Chemistry", "volume": "70", "number": "19", "publisher": "American Chemical Society", "pagerange": "4177-4190", "id_number": "CaltechAUTHORS:20171107-082351828", "issn": "0003-2700", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171107-082351828", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" }, { "agency": "Army Research Office (ARO)" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Natural Science and Engineering Research Council of Canada (NSERC)" } ] }, "doi": "10.1021/ac971204+", "resource_type": "article", "pub_year": "1998", "author_list": "Doleman, Brett J.; Lonergan, Mark C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qq5c4-1br36", "eprint_id": 88137, "eprint_status": "archive", "datestamp": "2023-08-19 03:19:11", "lastmod": "2024-01-14 20:29:17", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Doleman-B-J", "name": { "family": "Doleman", "given": "Brett J." } }, { "id": "Severin-E-J", "name": { "family": "Severin", "given": "Erik J." } }, { "id": "Sanner-R-D", "name": { "family": "Sanner", "given": "Robert D." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Progress in the development of an electronic nose using arrays of chemically sensitive carbon black-polymer resistors", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1998 Society of Photo-Optical Instrumentation Engineers (SPIE). \n\nThis work was supported by the U.S. Army Research Office contracts DAAH04-96-1-0048 Modification 1 and DAAG55-97-1-0187, DARPA, and NASA.\n\nPublished - 390.pdf
", "abstract": "Response data were collected for a carbon black-polymer composite electronic nose array during exposure to homologous series of alkanes and alcohols. At a fixed partial pressure of odorant in the vapor phase, the mean response intensity of the electronic nose signals varied significantly for members of each series of odorants. However, the mean response intensity of the electronic nose detectors, and the response intensity of the most strongly-driven set of electronic nose detectors, was essentially constant for members of a chemically homologous odorant series when the concentration of each odorant in the gas phase was maintained at a constant fraction of the odorant's vapor pressure. Because the thermodynamic activity of an odorant at equilibrium in a sorbent phase is equal to the partial pressure of the odorant in the gas phase divided by the vapor pressure of the odorant, and because the activity coefficients are similar within these homologous series of odorants for sorption of the vapors into specific polymer films, the data imply that the trends in detector response can be understood based on the thermodynamic tendency to establish a relatively constant concentration of sorbed odorant into each of the polymeric films of the electronic nose at a constant fraction of the odorant's vapor pressure. This phenomenon provides a natural mechanism for enhanced sensitivity to low vapor pressure compounds, like TNT, in the presence of high vapor pressure analytes, such as diesel fuel. In a related study to evaluate the target recognition properties of the electronic nose, a statistical metric based on the magnitudes and standard deviations along Euclidean projections of clustered array response data, was utilized to facilitate an evaluation of the performance of detector arrays in various vapor classification tasks. This approach allowed quantification of the ability of a fourteen-element array of carbon black-insulating polymer composite chemiresistors to distinguish between members of a set of nineteen solvent vapors, some of which vary widely in chemical properties (e.g. methanol and benzene) and others of which are very similar (e.g. n-pentane and n-heptane). The data also facilitated evaluation of questions such as array performance as a function of the number of detectors in the system.", "date": "1998-09-04", "date_type": "published", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_pub": "Bellingham, WA", "pagerange": "390-400", "id_number": "CaltechAUTHORS:20180723-130456632", "isbn": "0819428418", "book_title": "Detection and Remediation Technologies for Mines and Minelike Targets III", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180723-130456632", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)", "grant_number": "DAAH04-96-1-0048" }, { "agency": "Army Research Office (ARO)", "grant_number": "DAAG55-97-1-0187" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "NASA" } ] }, "contributors": { "items": [ { "id": "Dubey-A-C", "name": { "family": "Dubey", "given": "Abinash C." } }, { "id": "Harvey-J-F", "name": { "family": "Harvey", "given": "James F." } }, { "id": "Broach-J-T", "name": { "family": "Broach", "given": "J. Thomas" } } ] }, "doi": "10.1117/12.324211", "primary_object": { "basename": "390.pdf", "url": "https://authors.library.caltech.edu/records/qq5c4-1br36/files/390.pdf" }, "resource_type": "book_section", "pub_year": "1998", "author_list": "Doleman, Brett J.; Severin, Erik J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4m23k-gmn91", "eprint_id": 120793, "eprint_status": "archive", "datestamp": "2023-08-22 13:00:55", "lastmod": "2023-10-18 17:59:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Anz-Samir-J", "name": { "family": "Anz", "given": "Samir J." } }, { "id": "Kr\u00fcger-Olaf", "name": { "family": "Kr\u00fcger", "given": "Olaf" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Gajewski-Herbert", "name": { "family": "Gajewski", "given": "Herbert" } } ] }, "title": "Conditions Under Which Heterogeneous Charge-Transfer Rate Constants Can Be Extracted from Transient Photoluminescence Decay Data of Semiconductor/Liquid Contacts As Determined by Two-Dimensional Transport Modeling", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Surfaces, Coatings and Films; Physical and Theoretical Chemistry", "note": "\u00a9 1998 American Chemical Society. \n\nWe acknowledge Reiner N\u00fcrnberg of the Weierstrass-Institut for his help with ToSCA and thank the U.S. Department of Energy, Office of Basic Energy Sciences, DE-FG-03-88ER13932, for support of this work. O.K. also acknowledges the Deutsche Forschungsgemeinschaft for a postdoctoral fellowship.", "abstract": "An extensive series of digital simulations of the decay dynamics of photoexcited charge carriers at a semiconductor/liquid interface has been performed using the two-dimensional simulation code ToSCA. ToSCA treats majority and minority carrier capture processes separately and incorporates field-dependent carrier mobility terms. These features produce dramatic differences in the output parameters obtained when fitting experimental data with ToSCA relative to those obtained by fitting such data with prior, less complete, simulations. The simulations revealed that for a typical (n-type in our example) InP electrode in contact with outer-sphere redox reagents dissolved in the liquid phase the photoluminescence decays were generally insensitive to the value of the minority carrier charge-transfer rate constant, k\u2095\u209c. Instead, diffusion and drift-induced separation of photogenerated carriers in the space-charge layer of the semiconductor dominated the time decay of the observed luminescence signal under most experimentally accessible conditions. Values of k\u2095\u209c and of the minority carrier low-level surface recombination velocity, Sp, could be obtained from an analysis of the photoluminescence decays only when the following restricted sets of conditions were satisfied simultaneously:\u2009 10\u00b9 cm s\u207b\u00b9 \u2264 S\u209a \u2264 10\u2075 cm s\u207b\u00b9, 10\u207b\u00b9\u2078 cm\u2074 s\u207b\u00b9 \u2264 k\u2095\u209c \u2264 10\u207b\u00b9\u2075 cm\u2074 s\u207b\u00b9, and the electrode potential, E, was in the region 0 < E < +0.15 V relative to the flat-band potential of the n-type semiconductor/liquid interface. The simulations demonstrated that it was not possible to extract a \"field dependence\" of the charge-transfer rate constant when the semiconductor/liquid contact was maintained in reverse bias (E \u2265 +0.15 V vs the flat-band potential) and was subjected to light pulses that produced low or moderate carrier injection levels. Under such conditions, the photoluminescence decay dynamics were dominated by drift-induced charge separation in the space-charge layer of the semiconductor. Under high-level injection conditions, no \"field dependence\" could be observed because the majority of the photoluminescence decay dynamics occurred near the flat-band condition, so the value of the band bending in the semiconductor under dark, equilibrium conditions had negligible influence on the luminescence transients produced by a high-intensity laser pulse. Additionally, comparison between one-dimensional and two-dimensional simulations showed that use of one-dimensional simulation routines to extract S\u209a and k\u2095\u209c values from experimental data obtained using focused laser beam excitation can lead to severe overestimates of interfacial charge-transfer rates.", "date": "1998-07-16", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "102", "number": "29", "publisher": "American Chemical Society", "pagerange": "5625-5640", "id_number": "CaltechAUTHORS:20230412-312172000.21", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230412-312172000.21", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG-03-88ER13932" }, { "agency": "Deutsche Forschungsgemeinschaft (DFG)" } ] }, "doi": "10.1021/jp980582v", "resource_type": "article", "pub_year": "1998", "author_list": "Anz, Samir J.; Kr\u00fcger, Olaf; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dcadg-ytj88", "eprint_id": 84500, "eprint_status": "archive", "datestamp": "2023-08-19 03:05:50", "lastmod": "2023-10-18 16:17:00", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Doleman-B-J", "name": { "family": "Doleman", "given": "Brett J." } }, { "id": "Sanner-R-D", "name": { "family": "Sanner", "given": "Robert D." } }, { "id": "Severin-E-J", "name": { "family": "Severin", "given": "Erik J." } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Use of Compatible Polymer Blends To Fabricate Arrays of Carbon Black\u2212Polymer Composite Vapor Detectors", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1998 American Chemical Society.\n\nReceived for review November 12, 1997. Accepted March\n19, 1998. Publication Date (Web): May 13, 1998.\n\nWe thank NASA, the Army Research Office (Grants DAAH04-96-1-0048 and DAAG55-97-1-0187), and DARPA for support of this work. B.J.D. acknowledges the NSERC Canada for a graduate fellowship, and R.D.S. acknowledges the University of California Lawrence Livermore National Laboratory for support from its Professional Research and Teaching Leave program while at Caltech.", "abstract": "Compatible blends of poly(vinyl acetate) and poly(methyl methacrylate) have been used to produce a series of electrically conducting carbon black composites whose resistance is sensitive to the nature and concentration of an analyte in the vapor phase. The dc electrical resistance response of the composites was found to be a nonlinear function of the mole fraction of poly(vinyl acetate) in the blend. These compatible blend composite detectors provided additional analyte discrimination information relative to a reference detector array that only contained composites formed using the pure polymer phases. The added discrimination power provided by the compatible blend detectors, and thus the added diversity of the enhanced detector array, was quantified through use of a statistical metric to assess the performance of detector arrays in various vapor classification tasks.", "date": "1998-07-01", "date_type": "published", "publication": "Analytical Chemistry", "volume": "70", "number": "13", "publisher": "American Chemical Society", "pagerange": "2560-2564", "id_number": "CaltechAUTHORS:20180124-100638103", "issn": "0003-2700", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180124-100638103", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)", "grant_number": "AAH04-96-1-0048" }, { "agency": "Army Research Office (ARO)", "grant_number": "DAAG55-97-1-0187" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "Lawrence Livermore National Laboratory" } ] }, "doi": "10.1021/ac971238h", "resource_type": "article", "pub_year": "1998", "author_list": "Doleman, Brett J.; Sanner, Robert D.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cde1t-a2v45", "eprint_id": 88045, "eprint_status": "archive", "datestamp": "2023-08-19 03:02:21", "lastmod": "2023-10-18 21:39:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Progress in Understanding Electron-Transfer Reactions at Semiconductor/Liquid Interfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1998 American Chemical Society. \n\nReceived: December 1, 1997; In Final Form: March 26, 1998. \n\nThe National Science Foundation and the Department of Energy, Office of Basic Energy Sciences, are acknowledged for providing the funding for most of the work from Caltech that is summarized in this article. Acknowledgment is also made to a very talented group of graduate student and postdoctoral co-workers, only some of whom have been acknowledged by name, but all of whom have made essential contributions to developing this work to its current level of understanding. I also wish to acknowledge invaluable discussions with colleagues including F. Anson, A. Bard, C. Chidsey, S. Feldberg, H. Finklea, A. Fujishima, H. Gerischer, S. Gottesfeld, A. Heller, J. Hupp, C. Koval, R. Marcus, R. Memming, B. Miller, C. Miller, R. J. D. Miller, T. Mallouk, A. Nozik, B. Parkinson, H. Tributsch, D. Waldeck, and M. Wrighton, among others, that have immensely contributed to advancing my personal understanding of this interesting field of science.", "abstract": "This article describes theoretical treatments and experimental data focused on the rates of interfacial electron-transfer processes at semiconductor/liquid contacts. These systems are of practical interest because such electron transfers are a critical factor in understanding the behavior of photoelectrochemical cells as energy conversion devices. These processes are of theoretical interest because the description of how a delocalized charge carrier in a semiconducting solid reacts with a localized redox acceptor that is dissolved in the liquid electrolyte is a relatively undeveloped area of electron-transfer theory. The general principles of these processes, a discussion of past and present experimental data, and a comparison between theoretical expectations and experimental observations on a variety of semiconducting electrode systems are the main focus of this article.", "date": "1998-06-18", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "102", "number": "25", "publisher": "American Chemical Society", "pagerange": "4843-4855", "id_number": "CaltechAUTHORS:20180719-164420935", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180719-164420935", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1021/jp9803586", "resource_type": "article", "pub_year": "1998", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/gk227-2mn90", "eprint_id": 120790, "eprint_status": "archive", "datestamp": "2023-08-22 12:56:38", "lastmod": "2023-10-18 17:59:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Santangelo-Patrick-G", "name": { "family": "Santangelo", "given": "Patrick G." } }, { "id": "Lieberman-Marya", "name": { "family": "Lieberman", "given": "Marya" }, "orcid": "0000-0003-3968-8044" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Cyclic Voltammetry of Semiconductor Photoelectrodes III:\u2009 A Comparison of Experiment and Theory for n-Si and p-Si Electrodes", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Surfaces, Coatings and Films; Physical and Theoretical Chemistry", "note": "\u00a9 1998 American Chemical Society. \n\nWe acknowledge the Petroleum Research Foundation and the Department of Energy, Office of Basic Energy Sciences, DE-FG-03-88ER13932LN, for support of this work. M. Lieberman also acknowledges the National Science Foundation, Grant CHE-9403134, for a postdoctoral fellowship. We are also grateful to Dr. S. Feldberg of Brookhaven National Laboratory for numerous discussions regarding simulation procedures and methodology for these systems.", "abstract": "Cyclic voltammograms have been obtained under a variety of conditions using a semiconducting photoelectrode or a circuit containing a diode in series with a metallic electrode. Simulations of the voltammetry of both types of systems were performed using a model circuit in which electrode nonideality, double-layer capacitance, and parallel resistance effects were accounted for quantitatively. The simulated voltammograms were in excellent agreement with the experimental data for a diode/electrode circuit, yielding a reliable description of the shapes of the voltammograms as well as of the voltage dropped across the diode element as a function of the total potential dropped across the circuit. The digital simulations were in good agreement with the voltammetry of p-Si/CH\u2083OH\u2212CoCp\u2082^(+/0) contacts at high light intensities, but could not quantitatively describe the shapes of the voltammograms at low light intensities.", "date": "1998-06-11", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "102", "number": "24", "publisher": "American Chemical Society", "pagerange": "4731-4738", "id_number": "CaltechAUTHORS:20230412-312152000.17", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230412-312152000.17", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Petroleum Research Foundation" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG-03-88ER13932LN" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "CHE-9403134" } ] }, "doi": "10.1021/jp980073t", "resource_type": "article", "pub_year": "1998", "author_list": "Santangelo, Patrick G.; Lieberman, Marya; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/13cyv-fz171", "eprint_id": 52177, "eprint_status": "archive", "datestamp": "2023-08-22 12:50:18", "lastmod": "2023-10-18 19:38:15", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Doleman-B-J", "name": { "family": "Doleman", "given": "Brett J." } }, { "id": "Severin-E-J", "name": { "family": "Severin", "given": "Erik J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Trends in odor intensity for human and electronic noses: Relative roles of odorant vapor pressure vs. molecularly specific odorant binding", "ispublished": "pub", "full_text_status": "public", "keywords": "carbon black composites; olfaction; vapor sensor; odor threshold", "note": "\u00a9 1998 The National Academy of Sciences.\n\nCommunicated by John E. Bercaw, California Institute of Technology, Pasadena, CA, March 2, 1998 (received for review August 22, 1997).\n\nWe acknowledge Prof. J. Bower and C. Chee-Ruiter of Caltech for numerous helpful discussions and for their critical comments on this manuscript. We thank the National Aeronautics and Space Administration, the Army Research Office, and the Defense Advanced Research Projects Agency for their support of this work, and B.D. acknowledges the Government of Canada for a Natural Sciences and Engineering Research Council 1967 Centennial Graduate Fellowship.\n\nThe publication costs of this article were defrayed in part by page charge\npayment. This article must therefore be hereby marked ''advertisement'' in\naccordance with 18 U.S.C. \u00a71734 solely to indicate this fact.\n\nPublished - PNAS-1998-Doleman-5442-7.pdf
", "abstract": "Response data were collected for a carbon black-polymer composite electronic nose array during exposure to homologous series of alkanes and alcohols. The mean response intensity of the electronic nose detectors and the response intensity of the most strongly driven set of electronic nose detectors were essentially constant for members of a chemically homologous odorant series when the concentration of each odorant in the gas phase was maintained at a constant fraction of the odorant's vapor pressure. A similar trend is observed in human odor detection threshold values for these same homologous series of odorants. Because the thermodynamic activity of an odorant at equilibrium in a sorbent phase is equal to the partial pressure of the odorant in the gas phase divided by the vapor pressure of the odorant and because the activity coefficients are similar within these homologous series of odorants for sorption of the vapors into specific polymer films, the data imply that the trends in detector response can be understood based on the thermodynamic tendency to establish a relatively constant concentration of sorbed odorant into each of the polymeric films of the electronic nose at a constant fraction of the odorant's vapor pressure. Similarly, the data are consistent with the hypothesis that the odor detection thresholds observed in human psychophysical experiments for the odorants studied herein are driven predominantly by the similarity in odorant concentrations sorbed into the olfactory epithelium at a constant fraction of the odorant's vapor pressure.", "date": "1998-05-12", "date_type": "published", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "volume": "95", "number": "10", "publisher": "National Academy of Sciences", "pagerange": "5442-5447", "id_number": "CaltechAUTHORS:20141126-100946285", "issn": "0027-8424", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141126-100946285", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" }, { "agency": "Army Research Office (ARO)" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" } ] }, "doi": "10.1073/pnas.95.10.5442", "pmcid": "PMC20396", "primary_object": { "basename": "PNAS-1998-Doleman-5442-7.pdf", "url": "https://authors.library.caltech.edu/records/13cyv-fz171/files/PNAS-1998-Doleman-5442-7.pdf" }, "resource_type": "article", "pub_year": "1998", "author_list": "Doleman, Brett J.; Severin, Erik J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rc2rc-2mw27", "eprint_id": 83023, "eprint_status": "archive", "datestamp": "2023-08-19 02:42:46", "lastmod": "2023-10-17 22:51:30", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Severin-E-J", "name": { "family": "Severin", "given": "Erik J." } }, { "id": "Sanner-R-D", "name": { "family": "Sanner", "given": "Robert D." } }, { "id": "Doleman-B-J", "name": { "family": "Doleman", "given": "Brett J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Differential Detection of Enantiomeric Gaseous Analytes Using Carbon Black\u2212Chiral Polymer Composite, Chemically Sensitive Resistors", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1998 American Chemical Society. \n\nReceived for review July 15, 1997. Accepted January 13, 1998. Publication Date (Web): February 20, 1998. \n\nR.D.S. thanks Lawerence Livermore National Laboratory for a Professional Research and Teaching leave. B.J.D. thanks the Natural Science and Engineering Research Council of Canada for a 1967 Centennial Fellowship. We gratefully acknowledge support for this work by DARPA, NASA, and the Army Research Office.", "abstract": "Carbon black\u2212chiral polymer composites were used to provide diagnostic differential resistance responses in the presence of enantiomers of chiral gaseous analytes. Vapors of (+)-2-butanol and (\u2212)-2-butanol, (+)-\u03b1-pinene and (\u2212)-\u03b1-pinene, (+)-epichlorohydrin and (\u2212)-epichlorohydrin, and methyl (+)-2-chloropropionate and methyl (\u2212)-2-chloropropionate were generated and passed over a chemically sensitive carbon black\u2212poly((R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate) (77% butyrate) composite resistor. Each enantiomer of a pair produced a distinct relative differential resistance change on the chiral detector, whereas both enantiomers of a set produced identical signals on achiral carbon black\u2212poly(ethylene-co-vinyl acetate) (82% ethylene) detectors.", "date": "1998-04-01", "date_type": "published", "publication": "Analytical Chemistry", "volume": "70", "number": "7", "publisher": "American Chemical Society", "pagerange": "1440-1443", "id_number": "CaltechAUTHORS:20171107-093619671", "issn": "0003-2700", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171107-093619671", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Lawerence Livermore National Laboratory" }, { "agency": "Natural Science and Engineering Research Council of Canada (NSERC)" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "NASA" }, { "agency": "Army Research Office (ARO)" } ] }, "doi": "10.1021/ac970757h", "resource_type": "article", "pub_year": "1998", "author_list": "Severin, Erik J.; Sanner, Robert D.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2j57t-qw163", "eprint_id": 120792, "eprint_status": "archive", "datestamp": "2023-08-22 12:38:10", "lastmod": "2023-10-18 17:59:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bansal-Ashish", "name": { "family": "Bansal", "given": "Ashish" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electrochemical Properties of (111)-Oriented n-Si Surfaces Derivatized with Covalently- Attached Alkyl Chains", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Surfaces, Coatings and Films; Physical and Theoretical Chemistry", "note": "\u00a9 1998 American Chemical Society. \n\nWe acknowledge the National Science Foundation, Grant CHE-9634152, for support of this work, as well as a gift to Caltech in support of photoelectrochemistry from the Eastman Kodak Company.", "abstract": "The electrochemical properties of alkyl-terminated, (111)-oriented, n-type Si surfaces, prepared via a two-step halogenation/alkylation procedure, were analyzed in contact with CH\u2083OH\u22121,1'-dimethylferrocene^(+/0) (Me\u2082Fc^(+/0)) solutions. Current density\u2212potential and differential capacitance\u2212potential measurements of these surfaces in contact with CH\u2083OH\u2212Me\u2082Fc^(+/0) indicated that the electrochemical properties of the alkyl-terminated surfaces were very similar to those of the H-terminated Si surface. The alkyl overlayers did not shift the Si band edges or induce significant surface recombination, but they did provide an additional electrical series resistance to charge transfer across the Si/liquid interface. The efficacy of alkyl overlayers in preventing photooxidation and photocorrosion of n-silicon surfaces was measured in contact with CH\u2083OH\u2212Me\u2082Fc^(+/0) solutions to which a known amount of water had been added. Under these conditions, the alkyl-terminated surfaces consistently showed excellent current density\u2212potential characteristics and displayed lower oxidation rates than the H-terminated surface, indicating that stability toward oxidation had been achieved without any significant compromise in the electrochemical qualities of the silicon surface.", "date": "1998-02-12", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "102", "number": "7", "publisher": "American Chemical Society", "pagerange": "1067-1070", "id_number": "CaltechAUTHORS:20230412-312166000.20", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230412-312166000.20", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9634152" }, { "agency": "Eastman Kodak Company" } ] }, "doi": "10.1021/jp973118j", "resource_type": "article", "pub_year": "1998", "author_list": "Bansal, Ashish and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zw5gf-0kp18", "eprint_id": 120636, "eprint_status": "archive", "datestamp": "2023-08-22 12:24:04", "lastmod": "2023-10-23 17:49:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Royea-William-J", "name": { "family": "Royea", "given": "William J." } }, { "id": "Fajardo-Arnel-M", "name": { "family": "Fajardo", "given": "Arnel M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Fermi Golden Rule Approach to Evaluating Outer-Sphere Electron-Transfer Rate Constants at Semiconductor/Liquid Interfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Surfaces, Coatings and Films; Physical and Theoretical Chemistry", "note": "We acknowledge the Department of Energy, Office of Basic Energy Sciences, Fundamental Interactions Branch, for their generous support of this work. We also thank Prof. C. J. Miller of the University of Maryland for invaluable discussions that stimulated the development of this work and Dr. M. D. Newton of Brookhaven National Laboratories for very helpful comments and feedback.\n\nFermi Golden Rule Approach to Evaluating Outer-Sphere Electron-Transfer Rate Constants at Semiconductor/Liquid Interfaces\nWilliam J. Royea, Arnel M. Fajardo, and Nathan S. Lewis\nThe Journal of Physical Chemistry B 1998 102 (18), 3653-3653\nDOI: 10.1021/jp9813342", "abstract": "Fermi's golden rule is used to formulate rate expressions for charge transfer of delocalized carriers in a nondegenerately doped semiconducting electrode to localized, outer-sphere redox acceptors in an electrolyte phase. If the charge-transfer rate constant is known experimentally, these rate expressions allow computation of the value of the electronic coupling matrix element between the semiconducting electrode and the redox species. This treatment also facilitates comparison between charge-transfer kinetic data at metallic and semiconducting electrodes in terms of parameters such as the electronic coupling to the electrode, the attenuation of coupling with distance into the electrolyte, and the reorganization energy of the charge-transfer event. Within this framework, rate constant values expected at representative semiconducting electrodes have been evaluated from experimental data for charge transfer from Au electrodes to ferrocene-terminated thiols, to Ru(NH\u2083)\u2085^(3+/2+)-terminated thiols, and through blocking layers to dissolved [Fe(2,2'-bipyridine)\u2082(CN)\u2082]^(+/0). Based on the experimental parameters determined for these systems, the maximum rate constant (i.e. at optimal exoergicity) for outer-sphere processes at semiconducting electrodes is computed to be in the range 10\u207b\u00b9\u2077\u221210\u207b\u00b9\u2076 cm\u2074 s\u207b\u00b9. These values are in excellent agreement with prior theoretical models and experimental results for charge-transfer kinetics at semiconductor/liquid interfaces and thus serve to unify the theoretical and experimental descriptions of electrochemical processes at semiconducting and metallic electrodes.", "date": "1997-12-18", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "101", "number": "51", "publisher": "American Chemical Society", "pagerange": "11152-11159", "id_number": "CaltechAUTHORS:20230330-523253000.1", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230330-523253000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1021/jp972222y", "resource_type": "article", "pub_year": "1997", "author_list": "Royea, William J.; Fajardo, Arnel M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/be9yh-3xh66", "eprint_id": 120969, "eprint_status": "archive", "datestamp": "2023-08-22 12:24:07", "lastmod": "2023-10-18 18:05:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Fajardo-Arnel-M", "name": { "family": "Fajardo", "given": "Arnel M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Free-Energy Dependence of Electron-Transfer Rate Constants at Si/Liquid Interfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Surfaces, Coatings and Films; Physical and Theoretical Chemistry", "note": "\u00a9 1997 American Chemical Society. \n\nWe thank M. C. Lonergan for obtaining the \u00b9H NMR spectra of compounds I, II, III, VI, and VII. This research was supported by the National Science Foundation, Grant CHE-9634152. We also acknowledge a generous gift in support of photoelectrochemistry to Caltech from the Eastman Kodak Company.", "abstract": "Differential capacitance vs potential and current density vs potential measurements have been used to characterize the interfacial energetics and kinetics, respectively, of n-type Si electrodes in contact with a series of one-electron, outer-sphere redox couples. The differential capacitance data yielded values for the electron concentration at the surface of the semiconductor as well as values for the driving force of the interfacial electron-transfer event at Si/CH\u2083OH\u2212viologen^(2+/+) junctions. The differential capacitance vs potential measurements were essentially independent of the ac frequency imposed on the interface, with linear Bode plots (log|impedance| vs log frequency, at a fixed potential) between \u224810\u00b3 and \u224810\u2075 Hz, with slopes typically between \u22120.99 and \u22121.00. The slopes of C\u00b2\u2212E (Mott\u2212Schottky) plots were in excellent agreement with theory, and little frequency dispersion was observed in the x-intercepts of such plots. The conduction band edge of the n-type Si anodes was invariant to within \u00b140 mV in response to a variation in the redox potential of the solution of greater than 400 mV, indicating \"ideal\" interfacial energetic behavior of this system with no evidence for Fermi level pinning. From these measurements, the surface-state density of the Si/CH\u2083OH contact can be estimated as <10\u00b9\u00b9 cm\u00b2, i.e., less than 1 defect for 10\u2074 surface atoms. The current density vs potential plots exhibited a first-order kinetic dependence on the concentration of electrons at the semiconductor surface and a first-order kinetic dependence on the concentration of acceptors in the solution. Rate constants for transfer of charge from the semiconductor to the acceptor were determined as a function of the driving force for the interfacial charge-transfer event. The rate constants varied from 4 \u00d7 10\u207b\u00b9\u2078 cm\u2074 s\u207b\u00b9 to 6 \u00d7 10\u207b\u00b9\u2077 cm\u2074 s\u207b\u00b9 and were well fit to Marcus-type behavior, with a reorganization energy of 0.7 eV and a maximum rate constant at optimal exoergicity of 6 \u00d7 10\u207b\u00b9\u2077 cm\u2074 s\u207b\u00b9. This maximum rate constant value is in excellent agreement with theoretical expectations for transfer of charge from a delocalized carrier in a semiconductor to a one-electron, outer-sphere redox acceptor dissolved in the electrolyte solution.", "date": "1997-12-18", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "101", "number": "51", "publisher": "American Chemical Society", "pagerange": "11136-11151", "id_number": "CaltechAUTHORS:20230418-318337000.3", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230418-318337000.3", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9634152" }, { "agency": "Eastman Kodak Company" } ] }, "doi": "10.1021/jp972087p", "resource_type": "article", "pub_year": "1997", "author_list": "Fajardo, Arnel M. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ysx3d-4t656", "eprint_id": 121138, "eprint_status": "archive", "datestamp": "2023-09-15 07:50:17", "lastmod": "2023-10-23 21:39:19", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Royea-William-J", "name": { "family": "Royea", "given": "William J." } }, { "id": "Kr\u00fcger-Olaf", "name": { "family": "Kr\u00fcger", "given": "Olaf" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Frumkin corrections for heterogeneous rate constants at semiconducting electrodes", "ispublished": "pub", "full_text_status": "public", "keywords": "Electrochemistry; General Chemical Engineering; Analytical Chemistry", "note": "\u00a9 1997 Published by Elsevier. \n\nThis paper was presented at the International Symposium on Electron Transfer in Protein and Supramolecular Assemblies at Interfaces held in Shonan Village, Kanagawa, Japan on 17 to 20 March 1996.\n\nWe acknowledge the National Science Foundation, grant CHE-9634152, and Kodak Corp. for support of this work, and O.K. acknowledges the DFG for a postdoctoral fellowship.", "abstract": "Frumkin corrections for semiconductor electrodes have been evaluated in both depletion and accumulation conditions. In conjunction with the Gouy-Chapman-Stern model, a finite difference approach was used to calculate the potential drop in a depleted semiconductor and in the compact and diffuse layers of the contacting solution as a function of the potential applied to the solid/liquid interface. At potentials greater than 30 mV positive of the flat-band potential E_(fb) the potential drop across the solution accounts for less than 3% of the total potential drop across an n-type semiconductor of dopant density 1 \u00d7 10\u00b9\u2075 cm\u207b\u00b3 in a methanolic solution of 1.0 M LiCl. Under these conditions, the concentration of a non-adsorbing, dipositively-charged redox species at the outer Helmholtz plane does not vary from its concentration in the bulk of the solution by more than 2%. This relatively small concentration gradient and potential drop across the Helmholtz layer combine to produce negligible Frumkin correction terms for kinetic data at depleted semiconductor electrodes compared to those for metallic electrodes at the same applied potential relative to the potential of zero charge. Under accumulation conditions, the potential drop across the solution is more significant, and the concentration of redox species at the surface can be as much as twice as great as that in the bulk of the solution. However, these conditions require an applied potential of \u22121 V relative to E_(fb). Additionally, under all conditions that were simulated, the correction to the driving force used to evaluate the heterogeneous rate constant does not exceed 2% of the uncorrected heterogeneous rate constant.", "date": "1997-11-25", "date_type": "published", "publication": "Journal of Electroanalytical Chemistry", "volume": "438", "number": "1-2", "publisher": "Elsevier", "pagerange": "191-197", "id_number": "CaltechAUTHORS:20230425-58294000.1", "issn": "1572-6657", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230425-58294000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9634152" }, { "agency": "Kodak" }, { "agency": "Deutsche Forschungsgemeinschaft (DFG)" } ] }, "doi": "10.1016/s0022-0728(96)05074-7", "resource_type": "article", "pub_year": "1997", "author_list": "Royea, William J.; Kr\u00fcger, Olaf; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ptah0-rv739", "eprint_id": 59517, "eprint_status": "archive", "datestamp": "2023-08-19 01:39:28", "lastmod": "2023-10-23 20:40:40", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kesselman-Janet-M", "name": { "family": "Kesselman", "given": "Janet M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Hoffmann-M-R", "name": { "family": "Hoffmann", "given": "Michael R." }, "orcid": "0000-0001-6495-1946" } ] }, "title": "Photoelectrochemical Degradation of 4-Chlorocatechol at TiO\u2082 Electrodes: Comparison between Sorption and Photoreactivity", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1997 American Chemical Society. \n\nReceived for review October 14, 1996. Revised manuscript received April 10, 1997. Accepted April 21, 1997. Publication Date (Web): July 30, 1997. \n\nWe are grateful to ARPA and ONR (NAV 5 HFMN N0001492J1901) for financial support. J.M.K. acknowledges NSF for a predoctoral fellowship. We would also like to acknowledge our earlier collaboration with Dr. Scot T. Martin.", "abstract": "The TiO\u2082-catalyzed photodegradation of a strongly adsorbing substrate, 4-chlorocatechol, has been investigated as a function of solution concentration and pH at illuminated polycrystalline TiO\u2082 electrodes operated at a constant current density. The results are compared to the previously determined sorption behavior of 4-chlorocatechol. The initial rates of 4-chlorocatechol photodegradation measured at pH 3, 5, and 8 and solution concentrations of 20, 50, and 200 \u03bcM show a linear correlation with the concentration of the sorbed substrate.", "date": "1997-08", "date_type": "published", "publication": "Environmental Science and Technology", "volume": "31", "number": "8", "publisher": "American Chemical Society", "pagerange": "2298-2302", "id_number": "CaltechAUTHORS:20150814-081851276", "issn": "0013-936X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150814-081851276", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Advanced Research Projects Agency (ARPA)" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "NAV 5 HFMN N0001492J1901" }, { "agency": "NSF Predoctoral Fellowship" } ] }, "doi": "10.1021/es960888k", "resource_type": "article", "pub_year": "1997", "author_list": "Kesselman, Janet M.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6vfct-4mr44", "eprint_id": 56855, "eprint_status": "archive", "datestamp": "2023-08-19 01:37:45", "lastmod": "2023-10-23 16:02:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Claypool-C-L", "name": { "family": "Claypool", "given": "Christopher L." } }, { "id": "Faglioni-F", "name": { "family": "Faglioni", "given": "Francesco" }, "orcid": "0000-0002-3327-8848" }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A., III" }, "orcid": "0000-0003-0097-5716" }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Marcus-R-A", "name": { "family": "Marcus", "given": "R. A." }, "orcid": "0000-0001-6547-1469" } ] }, "title": "Source of Image Contrast in STM Images of Functionalized Alkanes on Graphite:\u2009 A Systematic Functional Group Approach", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1997 American Chemical Society.\n\nReceived: January 7, 1997; In Final Form: April 16, 1997.\n\nWe acknowledge the NSF, grants CHE-9634152 (N.S.L.), CHE-9522179 (W.A.G.), CHE-9610164 (H.B.G.), and ASC-9217368 (W.A.G.), for partial support of this work. C.C. acknowledges the NIH for a training grant, and we also acknowledge helpful discussions with Dr. J. Miller of Argonne National Laboratory regarding orbital coupling issues.", "abstract": "A series of functionalized alkanes and/or alkyl alcohols have been prepared and imaged by scanning tunneling microscopy (STM) methods on graphite surfaces. The stability of these ordered overlayers has facilitated reproducible collection of STM images at room temperature with submolecular resolution, in most cases allowing identification of individual hydrogen atoms in the alkane chains, but in all cases allowing identification of molecular length features and other aspects of the image that can be unequivocally related to the presence of functional groups in the various molecules of concern. Functional groups imaged in this study include halides (X = F, Cl, Br, I), amines, alcohols, nitriles, alkenes, alkynes, ethers, thioethers, and disulfides. Except for \u2212Cl and \u2212OH, all of the other functional groups could be distinguished from each other and from \u2212Cl or \u2212OH through an analysis of their STM metrics and image contrast behavior. The dominance of molecular topography in producing the STM images of alkanes and alkanols was established experimentally and also was consistent with quantum chemistry calculations. Unlike the contrast of the methylene regions of the alkyl chains, the STM contrast produced by the various functional groups was not dominated by topographic effects, indicating that variations in local electronic coupling were important in producing the observed STM images of these regions of the molecules. For molecules in which electronic effects overwhelmed topographic effects in determining the image contrast, a simple model is presented to explain the variation in the electronic coupling component that produces the contrast between the various functional groups observed in the STM images. Additionally, the bias dependence of these STM images has been investigated and the contrast vs bias behavior is related to factors involving electron transfer and hole transfer that have been identified as potentially being important in dominating the electronic coupling in molecular electron transfer processes.", "date": "1997-07-31", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "101", "number": "31", "publisher": "American Chemical Society", "pagerange": "5978-5995", "id_number": "CaltechAUTHORS:20150422-091143996", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150422-091143996", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9634152" }, { "agency": "NSF", "grant_number": "CHE-9522179" }, { "agency": "NSF", "grant_number": "ASC-9217368" }, { "agency": "NIH" } ] }, "doi": "10.1021/jp9701799", "resource_type": "article", "pub_year": "1997", "author_list": "Claypool, Christopher L.; Faglioni, Francesco; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/t0yxy-djh95", "eprint_id": 88079, "eprint_status": "archive", "datestamp": "2023-08-19 01:38:09", "lastmod": "2023-10-18 21:43:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Faglioni-Francesco", "name": { "family": "Faglioni", "given": "Francesco" }, "orcid": "0000-0002-3327-8848" }, { "id": "Claypool-Christopher-L", "name": { "family": "Claypool", "given": "Christopher L." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Goddard-W-A-III", "name": { "family": "Goddard", "given": "William A., III" }, "orcid": "0000-0003-0097-5716" } ] }, "title": "Theoretical Description of the STM Images of Alkanes and Substituted Alkanes Adsorbed on Graphite", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1997 American Chemical Society. \n\nReceived: January 7, 1997; In Final Form: April 16, 1997. \n\nThe research was funded by NSF (CHE 9522179 and ASC 9217368, W.A.G.; and CHE-9634152, N.S.L.). C.C. also acknowledges the NIH for a predoctoral training grant. The facilities of the MSC are also supported by grants from DOE-BCTR, Chevron Petroleum Technology Co., Asahi Chemical, Aramco, Owens-Corning, Asahi Glass, Chevron Research Technology Co., Chevron Chemical Co., Hercules, Avery-Dennison, BP Chemical, and the Beckman Institute.", "abstract": "A theoretical model based on perturbation theory has been developed to predict the scanning tunneling microscopy (STM) images of molecules adsorbed on graphite. The model is applicable to a variety of different molecules with reasonable computational effort and provides images that are in qualitative agreement with experimental results. The model predicts that topographic effects will dominate the STM images of alkanes on graphite surfaces. The computations correlate well with the STM data of functionalized alkanes and allow assessment of the structure and orientation of most of the functionalized alkanes that have been studied experimentally. In addition, the computations suggest that the highly diffuse virtual orbitals of the adsorbed molecules, despite being much farther in energy from the Fermi level of the graphite than the occupied orbitals, may play an important role in determining the STM image contrast of such systems.", "date": "1997-07-31", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "101", "number": "31", "publisher": "American Chemical Society", "pagerange": "5996-6020", "id_number": "CaltechAUTHORS:20180720-141156787", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180720-141156787", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9522179" }, { "agency": "NSF", "grant_number": "ASC-9217368" }, { "agency": "NSF", "grant_number": "CHE-9634152" }, { "agency": "NIH Predoctoral Fellowship" }, { "agency": "Department of Energy (DOE)" }, { "agency": "Chevron Petroleum Technology Co." }, { "agency": "Asahi Chemical" }, { "agency": "Aramco" }, { "agency": "Owens-Corning" }, { "agency": "Asahi Glass" }, { "agency": "Chevron Research and Technology Co." }, { "agency": "Chevron Chemical Co." }, { "agency": "Hercules" }, { "agency": "Avery-Dennison" }, { "agency": "BP Chemical" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/jp9701808", "resource_type": "article", "pub_year": "1997", "author_list": "Faglioni, Francesco; Claypool, Christopher L.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/r37va-r8n44", "eprint_id": 88136, "eprint_status": "archive", "datestamp": "2023-08-19 01:37:15", "lastmod": "2024-01-14 20:29:15", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Lonergan-Mark-C", "name": { "family": "Lonergan", "given": "Mark C." }, "orcid": "0000-0003-4070-5067" }, { "id": "Severin-Erik-J", "name": { "family": "Severin", "given": "Erik J." } }, { "id": "Doleman-Brett-J", "name": { "family": "Doleman", "given": "Brett J." } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" } ] }, "title": "Array-based vapor sensing using chemically sensitive carbon black-polymer resistors", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1997 Society of Photo-Optical Instrumentation Engineers (SPIE). \n\nThis work was supported in part by the Army Research Office MURI grant DAAH04-96-1-0048. Additional supporters include the Caltech Consortium in Chemistry and Chemical Engineering, the E.I. DuPont de Nemours and Company Inc., the Eastman Kodak Company, the National Aeronautics and Space Administration and the National Science Foundation grant CHE-9202583. M.C.L. acknowledges Caltech for an Arthur Amos Noyes Fellowship and B.J.D. acknowledges the Natural Science and Engineering Research Council of Canada for a 1967 Centennial Fellowship and the O'Brien Foundation for financial support.\n\nPublished - 660.pdf
", "abstract": "We describe herein the construction of a simple, low-power, broadly responsive vapor sensor. Carbon black-organic polymer composites have been shown to swell reversibly upon exposure to vapors. Thin films of carbon black-organic polymer composites have been deposited across two metallic leads, with swelling-induced resistance changes of the films signaling the presence of vapors. To identify and classify vapors, arrays of such vapor-sensing elements have been constructed, with each element containing the same carbon black conducting phase but a different organic polymer as the insulating phase. The differing gas-solid partition coefficients for the various polymers of the sensor array produce a pattern of resistance changes that can be sued to classify vapors and vapor mixtures. This type of sensor array has been shown to resolve common organic solvents, including molecules of different classes as well as those within a particular class.", "date": "1997-07-22", "date_type": "published", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_pub": "Bellingham, WA", "pagerange": "660-670", "id_number": "CaltechAUTHORS:20180723-125439537", "isbn": "0819424943", "book_title": "Detection and Remediation Technologies for Mines and Minelike Targets II", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180723-125439537", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)", "grant_number": "DAAH04-96-1-0048" }, { "agency": "Caltech Consortium in Chemistry and Chemical Engineering" }, { "agency": "E. I. DuPont de Nemours and Company, Inc." }, { "agency": "Eastman Kodak Company" }, { "agency": "NASA" }, { "agency": "NSF", "grant_number": "CHE-9202583" }, { "agency": "Arthur A. Noyes Fellowship" }, { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "O'Brien Foundation" } ] }, "contributors": { "items": [ { "id": "Dubey-Abinash-C", "name": { "family": "Dubey", "given": "Abinash C." } }, { "id": "Barnard-Robert-L", "name": { "family": "Barnard", "given": "Robert L." } } ] }, "doi": "10.1117/12.280895", "primary_object": { "basename": "660.pdf", "url": "https://authors.library.caltech.edu/records/r37va-r8n44/files/660.pdf" }, "resource_type": "book_section", "pub_year": "1997", "author_list": "Lewis, Nathan S.; Lonergan, Mark C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4pyn8-87489", "eprint_id": 120971, "eprint_status": "archive", "datestamp": "2023-08-22 11:38:18", "lastmod": "2023-10-18 18:05:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kenyon-C-N", "name": { "family": "Kenyon", "given": "C. N." } }, { "id": "Tan-Ming-X", "name": { "family": "Tan", "given": "Ming X." } }, { "id": "Kr\u00fcger-Olaf", "name": { "family": "Kr\u00fcger", "given": "Olaf" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Behavior of Si Photoelectrodes under High Level Injection Conditions. 3. Transient and Steady-State Measurements of the Quasi-Fermi Levels at Si/CH\u2083OH Contacts", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Surfaces, Coatings and Films; Physical and Theoretical Chemistry", "note": "\u00a9 1997 American Chemical Society. \n\nWe gratefully acknowledge the National Science Foundation, Grant CHE-9634152, for support of this work. M.X.T. is grateful to the Link Energy Foundation and to the W.R. Grace foundation for graduate fellowships, and O.K. gratefully acknowledges the Deutsche Forschungsgemeinschaft for a postdoctoral fellowship. We are grateful to Drs. R. Sinton and R. Swanson of Sunpower, Inc., for helpful discussion and for supplying the samples used in this work.", "abstract": "Real-time measurements of the photovoltage rise and decay at the back of lightly doped, thin, long lifetime Si photoelectrodes were recorded subsequent to a variety of spatial and temporal carrier generation impulses. The functional form of the rising portion of the photovoltage signal is sensitive to charge transport processes, and this signal was used to validate experimentally the hypothesis that charge transport in these samples under high level injection is primarily driven by diffusion, as opposed to drift. The decay of the photovoltage signal back to its equilibrium value yielded information concerning the surface recombination velocity, S_f, of the various Si/CH\u2083OH redox couple contacts. These data validated the relatively high surface quality of the Si/liquid interface in contact with a variety of redox species. Furthermore, the low surface recombination velocities are in agreement with prior theoretical and experimental estimates of interfacial charge-transfer rate constants for semiconductors in contact with nonadsorbing, outer-sphere, redox species. The front surface recombination velocity data also provided a needed boundary condition for modeling the carrier concentration dynamics and allowed quantification of the difference between the quasi-Fermi levels at the back and front surfaces of the samples at all times of experimental interest. Digital simulation and analytical modeling were performed to compute the gradients in the quasi-Fermi levels for samples operated under steady-state, open-circuit, high level injection conditions. In no case was the difference between the quasi-Fermi level value at the back of the sample and its value at the solid/liquid contact greater than 10 meV. These data, combined with those described in parts 1 and 2, comprise a relatively complete picture of the transport and recombination processes that occur at these types of semiconductor/liquid contacts.", "date": "1997-04-10", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "101", "number": "15", "publisher": "American Chemical Society", "pagerange": "2850-2860", "id_number": "CaltechAUTHORS:20230418-318355000.6", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230418-318355000.6", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9634152" }, { "agency": "Link Energy Foundation" }, { "agency": "W. R. Grace & Co." }, { "agency": "Deutsche Forschungsgemeinschaft (DFG)" } ] }, "doi": "10.1021/jp962485c", "resource_type": "article", "pub_year": "1997", "author_list": "Kenyon, C. N.; Tan, Ming X.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6jgpb-gvd84", "eprint_id": 121140, "eprint_status": "archive", "datestamp": "2023-08-22 11:38:05", "lastmod": "2023-10-18 18:09:52", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Tributsch-Helmut", "name": { "family": "Tributsch", "given": "Helmut" } }, { "id": "Nozik-Arthur-J", "name": { "family": "Nozik", "given": "Arthur J." } } ] }, "title": "Biography: Heinz Gerischer", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Surfaces, Coatings and Films; Physical and Theoretical Chemistry", "note": "\u00a9 1997 American Chemical Society.", "abstract": "Heinz Gerischer, born on March 31, 1919, in Wittenberg, Germany, studied Chemistry at the University of Leipzig from 1937 to 1946 (with some interruptions by the war) and received the Dr. rer. nat. degree of this university in 1946; his supervisor was Professor Karl Friedrich Bonhoeffer. From 1946 to 1949 he was Assistant Professor at the Humboldt University of Berlin. In 1949, he joined the Max Planck Institute for Physical Chemistry in G\u00f6ttingen as a Research Associate. He became a Senior Research Fellow of the Max Planck Institute for Metal Research in Stuttgart in 1954 and a Scientific Member of this institute in 1960. In 1956, he was appointed a Lecturer at the Technical University of Stuttgart.", "date": "1997-04-03", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "101", "number": "14", "publisher": "American Chemical Society", "pagerange": "2391-2391", "id_number": "CaltechAUTHORS:20230425-59045000.4", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230425-59045000.4", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1021/jp970544w", "resource_type": "article", "pub_year": "1997", "author_list": "Lewis, Nathan S.; Tributsch, Helmut; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/j8hq0-pqc85", "eprint_id": 59519, "eprint_status": "archive", "datestamp": "2023-08-19 01:14:58", "lastmod": "2023-10-23 20:40:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kesselman-Janet-M", "name": { "family": "Kesselman", "given": "Janet M." } }, { "id": "Weres-Oleh", "name": { "family": "Weres", "given": "Oleh" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Hoffmann-M-R", "name": { "family": "Hoffmann", "given": "Michael R." }, "orcid": "0000-0001-6495-1946" } ] }, "title": "Electrochemical Production of Hydroxyl Radical at Polycrystalline Nb-Doped TiO\u2082 Electrodes and Estimation of the Partitioning between Hydroxyl Radical and Direct Hole Oxidation Pathways", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1997 American Chemical Society. \n\nReceived: August 30, 1996; In Final Form: October 29, 1996. Publication Date (Web): April 3, 1997. \n\nWe are grateful to DARPA and ONR {NAV 5 HFMN N0001492J1901} for financial support. J. Kesselman acknowledges the NSF for a predoctoral fellowship.", "abstract": "The use of TiO\u2082 as a photocatalyst for the destruction of organic chemical pollutants in aqueous systems has been extensively studied. One obstacle to the effective utilization of these systems is the relatively inefficient use of the solar spectrum by the photocatalyst. In addition, light delivery to the photocatalyst can be impeded by UV-absorbing components in mixed effluent streams. We present a novel use of TiO\u2082 as a catalyst for the oxidative degradation of organic compounds in water that uses a potential source instead of light to generate reactive oxidants. Application of an anodic bias of >+2 V vs NHE to titanium electrodes coated with niobium-doped, polycrystalline TiO\u2082 particles electrochemically generates hydroxyl radicals at the TiO\u2082 surface. This process has been demonstrated to efficiently degrade a variety of environmentally important pollutants. In addition, these electrodes offer a unique opportunity to probe mechanistic questions in TiO\u2082 catalysis. By comparing substrate degradation rates with increases in current density upon substrate addition, the extent of degradation due to direct oxidation and \u2022OH oxidation can be quantified. The branching ratio for these two pathways depends on the nature of the organic substrate. Formate is shown to degrade primarily via a hydroxyl radical mechanism at these electrodes, whereas the current increase data for compounds such as 4-chlorocatechol indicate that a higher percentage of their degradation may occur through direct oxidation. In addition, the direct oxidation pathway is shown to be more important for 4-chlorocatechol, a strongly adsorbing substrate, than for 4-chlorophenol, which does not adsorb strongly to TiO\u2082.", "date": "1997-04-03", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "101", "number": "14", "publisher": "American Chemical Society", "pagerange": "2637-2643", "id_number": "CaltechAUTHORS:20150814-081851804", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150814-081851804", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Defense Advanced Research Projects Agency (DARPA)" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "NAV 5 HFMN N0001492J1901" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "collection": "CaltechAUTHORS", "doi": "10.1021/jp962669r", "resource_type": "article", "pub_year": "1997", "author_list": "Kesselman, Janet M.; Weres, Oleh; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pw4q1-7s875", "eprint_id": 121139, "eprint_status": "archive", "datestamp": "2023-08-22 11:38:01", "lastmod": "2023-10-18 18:09:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Pomykal-Katherine-E", "name": { "family": "Pomykal", "given": "Katherine E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Measurement of Interfacial Charge-Transfer Rate Constants at n-Type InP/CH\u2083OH Junctions", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Surfaces, Coatings and Films; Physical and Theoretical Chemistry", "note": "\u00a9 1997 American Chemical Society. \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, Fundamental Interactions Branch, for their generous support of this work. K.E.P. also acknowledges the National Science Foundation for a predoctoral fellowship.", "abstract": "Steady-state current density vs potential methods have been used to measure interfacial electron-transfer rate constants at n-type indium phosphide/liquid junctions. n-InP/CH\u2083OH-1,1'-dimethylferrocene^(+/0), n-InP/CH\u2083OH-ferrocene^(+/0), n-InP/CH\u2083OH-tetrahydrofuran-decamethylferrocene^(+/0), and n-InP/CH\u2083OH-1,1'-diphenyl-4,4'-dipyridinium^(2+/+\u2022) contacts displayed bimolecular kinetic behavior in which the observed current density was first order in the concentration of electrons at the semiconductor surface and in the concentration of acceptors in the solution. Differential capacitance potential measurements were used to determine the energetics for the charge-transfer process as well as to determine the concentration of electrons at the semiconductor surface as a function of applied potential. These measurements indicated that the voltage dropped across the semiconductor space charge region varied linearly with changes in the Nernst potential of the solution, as expected for an ideally behaving semiconductor/liquid junction. The measured charge-transfer rate constants, ket, for these systems were \u224810\u207b\u00b9\u2076 cm\u2074 s\u207b\u00b9, in excellent agreement with previous theoretical predictions.", "date": "1997-04-03", "date_type": "published", "publication": "Journal of Physical Chemistry B", "volume": "101", "number": "14", "publisher": "American Chemical Society", "pagerange": "2476-2484", "id_number": "CaltechAUTHORS:20230425-59040000.3", "issn": "1520-6106", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230425-59040000.3", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "doi": "10.1021/jp962570k", "resource_type": "article", "pub_year": "1997", "author_list": "Pomykal, Katherine E. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/tmhkb-e7852", "eprint_id": 28979, "eprint_status": "archive", "datestamp": "2023-08-19 01:00:22", "lastmod": "2023-10-24 18:17:13", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lonergan-M-C", "name": { "family": "Lonergan", "given": "Mark C." } }, { "id": "Freund-M-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Severin-E-J", "name": { "family": "Severin", "given": "Erik J." } }, { "id": "Doleman-B-J", "name": { "family": "Doleman", "given": "Brett J." } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Array-based vapor sensing using chemically sensitive, polymer composite resistors", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1997 IEEE. \n\nDate of Current Version: 06 August 2002. \n\nThis work was supported in part by the Caltech Consortium in Chemistry and Chemical Engineering, the E.I. DuPont de Nemours and Company, Inc. and the Eastman Kodak Company, and by the National Aeronautics and Space Administration and the National Science Foundation, grant CHE-9202583. M.C.L. acknowledges Caltech for an Arthur Amos Noyes Fellowship and B.J.D. acknowledges the Natural Science and Engineering Research Council of Canada for a 1967 Centennial Fellowship and the O'Brien Foundation for financial support. We thank Profs. J.J. Hopfield and J.M. Bower, and the members of their research groups, for helpful discussions.\n\nPublished - LONaero97.pdf
", "abstract": "We describe herein the construction of simple, low-power, broadly responsive vapor sensors. Insulating polymer-conductor composites have been shown to swell reversibly upon exposure to vapors. Thin films of polymer composites have been deposited across two metallic leads, with swelling-induced resistance changes of the films signaling the presence of vapors. To identify and classify vapors, arrays of such vapor-sensing elements have been constructed, with each element containing either carbon black or poly(pyrrole) as the conducting phase mixed with one of several different organic polymers as the insulating phase. A convenient chemical polymerization of poly(pyrrole) which allows a high degree of processibility is also described. The differing gas-solid partition coefficients for the various polymers of the sensor array produce a pattern of resistance changes that can be used to classify vapors and vapor mixtures. This type of sensor array has been shown to resolve common organic solvents, including molecules of different classes (such as aromatics from alcohols) as well as those within a particular class (such as benzene from toluene and methanol from ethanol). The response of an individual composite to varying concentrations of solvent is shown to be consistent with the predictions of percolation theory. Accordingly, significant increases in the signals of array elements have been observed for carbon black-polymer composites that were operated near their percolation thresholds.", "date": "1997-02", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "583-631", "id_number": "CaltechAUTHORS:20120126-094442947", "isbn": "0-7803-3742-5", "book_title": "1997 IEEE Aerospace Conference proceedings", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120126-094442947", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech Consortium in Chemistry and Chemical Engineering" }, { "agency": "E.I. DuPont de Nemours and Company, Inc." }, { "agency": "Eastman Kodak Company" }, { "agency": "NASA" }, { "agency": "NSF", "grant_number": "CHE-9202583" }, { "agency": "Caltech Arthur Amos Noyes Fellowship" }, { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" }, { "agency": "O'Brien Foundation" } ] }, "doi": "10.1109/AERO.1997.574914", "primary_object": { "basename": "LONaero97.pdf", "url": "https://authors.library.caltech.edu/records/tmhkb-e7852/files/LONaero97.pdf" }, "resource_type": "book_section", "pub_year": "1997", "author_list": "Lonergan, Mark C.; Freund, Michael S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/65edd-0hq10", "eprint_id": 52472, "eprint_status": "archive", "datestamp": "2023-08-19 00:34:02", "lastmod": "2023-10-18 19:54:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Farjardo-Arnel-M", "name": { "family": "Farjardo", "given": "Arnel M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Rate Constants for Charge Transfer Across Semiconductor-Liquid Interfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1996 American Association for the Advancement of Science.\n\nReceived 25 June 1996; accepted 13 September 1996.\n\nSupported by NSF grant CHE-9634152.", "abstract": "Interfacial charge-transfer rate constants have been measured for n-type Si electrodes\nin contact with a series of viologen-based redox couples in methanol through analyses\nof the behavior of these junctions with respect to their current density versus potential\nand differential capacitance versus potential properties. The data allow evaluation of the\nmaximum rate constant (and therefore the electronic coupling) for majority carriers in the\nsolid as well as of the dependence of the rate constant on the driving force for transfer\nof delocalized electrons from the n-Si semiconducting electrode into the localized molecular\nredox species in the solution phase. The data are in good agreement with existing\nmodels of this interfacial electron transfer process and provide insight into the fundamental\nkinetic events underlying the use of semiconducting photoelectrodes in applications\nsuch as solar energy conversion.", "date": "1996-11-08", "date_type": "published", "publication": "Science", "volume": "274", "number": "5289", "publisher": "American Association for the Advancement of Science", "pagerange": "969-972", "id_number": "CaltechAUTHORS:20141208-130032900", "issn": "0036-8075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141208-130032900", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9634152" } ] }, "doi": "10.1126/science.274.5289.969", "resource_type": "article", "pub_year": "1996", "author_list": "Farjardo, Arnel M. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/xzbse-48240", "eprint_id": 85366, "eprint_status": "archive", "datestamp": "2023-08-19 00:19:40", "lastmod": "2023-10-18 18:09:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lonergan-Mark-C", "name": { "family": "Lonergan", "given": "Mark C." }, "orcid": "0000-0003-4070-5067" }, { "id": "Severin-Erik-J", "name": { "family": "Severin", "given": "Erik J." } }, { "id": "Doleman-Brett-J", "name": { "family": "Doleman", "given": "Brett J." } }, { "id": "Beaber-Sara-A", "name": { "family": "Beaber", "given": "Sara A." } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Array-Based Vapor Sensing Using Chemically Sensitive, Carbon Black\u2212Polymer Resistors", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 1996 American Chemical Society. \n\nReceived January 22, 1996. Revised Manuscript Received April 15, 1996. Publication Date (Web): September 12, 1996. \n\nThis work was supported in part by the Caltech Consortium in Chemistry and Chemical Engineering, the E.I. DuPont de Nemours and Co., Inc. and the Eastman Kodak Co., and by the National Aeronautics and Space Administration and the National Science Foundation, Grant CHE-9202583. M.C.L. acknowledges Caltech for an Arthur Amos Noyes Fellowship and B.J.D. acknowledges the Natural Science and Engineering Research Council of Canada for a 1967 Centennial Fellowship and the O'Brien Foundation for financial support.\n\nSupplemental Material - cm2298.pdf
Supplemental Material - cm2298a.pdf
", "abstract": "We describe herein the construction of a simple, low-power, broadly responsive vapor sensor. Carbon black\u2212organic polymer composites have been shown to swell reversibly upon exposure to vapors. Thin films of carbon black\u2212organic polymer composites were deposited across two metallic leads, and swelling-induced resistance changes of the films signaled the presence of vapors. To identify and classify vapors, arrays of such vapor-sensing elements were constructed, with each element containing the same carbon black conducting phase but a different organic polymer as the insulating phase. The differing gas\u2212solid partition coefficients for the various polymers of the sensor array produced a pattern of resistance changes that can be used to classify vapors and vapor mixtures. This type of sensor array resolved common organic solvents, including molecules of different classes (such as aromatics from alcohols) as well as those within a particular class (such as benzene from toluene and methanol from ethanol). The response of an individual composite to varying concentrations of solvent was consistent with the predictions of percolation theory. Accordingly, significant increases in the signals from array elements were observed for carbon black\u2212polymer composites that were operated near their percolation thresholds.", "date": "1996-09-12", "date_type": "published", "publication": "Chemistry of Materials", "volume": "8", "number": "9", "publisher": "American Chemical Society", "pagerange": "2298-2312", "id_number": "CaltechAUTHORS:20180319-153251654", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180319-153251654", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech Consortium in Chemistry and Chemical Engineering" }, { "agency": "E.I. DuPont de Nemours and Company, Inc." }, { "agency": "Eastman Kodak Company" }, { "agency": "NASA" }, { "agency": "NSF", "grant_number": "CHE-9202583" }, { "agency": "Caltech Arthur Amos Noyes Fellowship" }, { "agency": "Natural Science and Engineering Research Council of Canada (NSERC)" }, { "agency": "O'Brien Foundation" } ] }, "other_numbering_system": { "items": [ { "id": "9134", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/cm960036j", "primary_object": { "basename": "cm2298.pdf", "url": "https://authors.library.caltech.edu/records/xzbse-48240/files/cm2298.pdf" }, "related_objects": [ { "basename": "cm2298a.pdf", "url": "https://authors.library.caltech.edu/records/xzbse-48240/files/cm2298a.pdf" } ], "resource_type": "article", "pub_year": "1996", "author_list": "Lonergan, Mark C.; Severin, Erik J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1683h-85419", "eprint_id": 59365, "eprint_status": "archive", "datestamp": "2023-08-19 00:10:35", "lastmod": "2023-10-23 20:29:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Martin-Scot-T", "name": { "family": "Martin", "given": "Scot T." }, "orcid": "0000-0002-8996-7554" }, { "id": "Kesselman-Janet-M", "name": { "family": "Kesselman", "given": "Janet M." } }, { "id": "Park-David-S", "name": { "family": "Park", "given": "David S." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Hoffmann-M-R", "name": { "family": "Hoffmann", "given": "Michael R." }, "orcid": "0000-0001-6495-1946" } ] }, "title": "Surface Structures of 4-Chlorocatechol Adsorbed on Titanium Dioxide", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1996 American Chemical Society. \n\nReceived for review November 21, 1995. Revised manuscript received April 10, 1996. Accepted April 12, 1996. \n\nWe are grateful to ARPA and ONR (NAV 5 HFMN N0001492J1901) for financial support.Drs. Ira Skurnick and Harold Guard provided generous support and encouragement. S.T.M. is supported by a National Defense Science and Engineering Graduate Fellowship. J.M.K. is the recipient of a National Science Foundation Predoctoral Fellowship. D.S.P. is a Summer Undergraduate Research Fellow. Wonyong Choi, Peter Green, and Nicole Peill provided critical analyses and stimulating discussion.", "abstract": "TiO_2 has been extensively studied as a photocatalyst for the complete oxidation of a variety of organic pollutants commonly found in groundwater. In this paper, we investigate the surface structures formed between an organic substrate and TiO_2 in the context of understanding how these specific surface interactions affect photoreactivity. The surface complexes formed by 4-chlorocatechol (CT) sorbed on TiO_2 are investigated as a function of concentration and of pH. Singular-value decomposition of the IR spectra of CT adsorbed on TiO_2 indicates that a single bidentate chemisorbed species is present over the pH range of 2\u221210. The surface-bound species appears to have 40% covalent and 60% ionic bond character. The pH dependence of the adsorption isotherms is modeled using a generalized electric double-layer approach. The data are consistent with the formation of a bidentate binuclear surface group for solution CT concentrations below 50 \u03bcM followed by nonspecific multilayer partitioning at concentrations above 100 \u03bcM.", "date": "1996-08", "date_type": "published", "publication": "Environmental Science and Technology", "volume": "30", "number": "8", "publisher": "American Chemical Society", "pagerange": "2535-2542", "id_number": "CaltechAUTHORS:20150810-152945299", "issn": "0013-936X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150810-152945299", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Advanced Research Projects Agency (ARPA)" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "NAV 5 HFMN N0001492J1901" }, { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Caltech Summer Undergraduate Research Fellowship (SURF)" } ] }, "doi": "10.1021/es950872e", "resource_type": "article", "pub_year": "1996", "author_list": "Martin, Scot T.; Kesselman, Janet M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rxrzq-9w424", "eprint_id": 121051, "eprint_status": "archive", "datestamp": "2023-08-22 11:09:03", "lastmod": "2023-10-18 18:07:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bansal-Ashish", "name": { "family": "Bansal", "given": "Ashish" } }, { "id": "Li-Xiuling", "name": { "family": "Li", "given": "Xiuling" } }, { "id": "Lauermann-Iver", "name": { "family": "Lauermann", "given": "Iver" }, "orcid": "0000-0002-9119-3770" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Yi-Sang-I", "name": { "family": "Yi", "given": "Sang I." } }, { "id": "Weinberg-W-H", "name": { "family": "Weinberg", "given": "W. H." } } ] }, "title": "Alkylation of Si Surfaces Using a Two-Step Halogenation/Grignard Route", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1996 American Chemical Society. \n\nN.S.L. acknowledges the National Science Foundation (grants CHE-9221311 and CHE-9634152) for support of this work and I.L. acknowledges the DAAD for a post-doctoral fellowship. S.I.Y. and W.H.W. gratefully acknowledge support by QUEST, a NSF Science and Technology Center for Quantized Electronic Structures (grant DMR-9120007), the W.M. Keck Foundation, and the National Science Foundation (grant DMR-9504400).", "abstract": "Despite the fact that H-terminated, HF-etched Si crystals are the starting point for construction of most contemporary electronic devices, little is known about the chemical reactions of H-terminated Si surfaces under ambient temperature and pressure. Functionalization of Si without partial oxidation and/or formation of electrical defects is potentially important in fabricating improved electronic devices as well as in measurement of charge transfer rate constants at semiconductor/liquid contacts. One recently described approach involves the reaction of HF-etched Si(111) with olefins and organic diacyl peroxides, in which formation of a self-assembled (near)-monolayer of Si-alkyls was hypothesized. We report here an alternative strategy to functionalize HF-etched Si surfaces involving halogenation and subsequent reaction with alkyl Grignard or alkyl lithium reagents. We report vibrational spectroscopic and temperature programmed desorption data which confirm that the alkyl groups are bonded covalently to the Si surface, and we demonstrate that such overlayer formation can impede the undesirable oxidation of Si in a variety of environments while providing surfaces of high electrical quality.", "date": "1996-07-31", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "118", "number": "30", "publisher": "American Chemical Society", "pagerange": "7225-7226", "id_number": "CaltechAUTHORS:20230420-689896000.10", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230420-689896000.10", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9221311" }, { "agency": "NSF", "grant_number": "CHE-9634152" }, { "agency": "Deutscher Akademischer Austauschdienst (DAAD)" }, { "agency": "NSF", "grant_number": "DMR-9120007" }, { "agency": "W. M. Keck Foundation" }, { "agency": "NSF", "grant_number": "DMR-9504400" } ] }, "doi": "10.1021/ja960348n", "resource_type": "article", "pub_year": "1996", "author_list": "Bansal, Ashish; Li, Xiuling; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8r9dp-qqz48", "eprint_id": 86407, "eprint_status": "archive", "datestamp": "2023-08-20 07:24:30", "lastmod": "2023-10-18 19:33:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sturzenegger-Marcel", "name": { "family": "Sturzenegger", "given": "Marcel" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "An X-Ray Photoelectron Spectroscopic and Chemical Reactivity Study of Routes to Functionalization of Etched InP Surfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1996 American Chemical Society. \n\nReceived November 2, 1995. Publication Date (Web): March 27, 1996. \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, for support of this work. M.S. is grateful to the Swiss National Science Foundation for a postdoctoral fellowship.", "abstract": "Although InP is widely used in optoelectronic applications,\nlittle is known about the surface chemistry of this important semiconductor. Modification of the InP surface is potentially important as a route to introduce functional groups for the stabilization of InP photoelectrodes,4 to control the surface recombination properties of InP-based electrical devices, to study electron transfer from a solid to a redox-active donor at a fixed distance from the solid, to control nucleation and growth of metals on semiconductors, and for use in optically\nlinked chemical-sensing applications. To our knowledge, the only prior investigations of the derivatization of etched InP surfaces are the work of Gu et al., who coated the InP surface with overlayers of thiols through an unidentified binding mode, and that of Spool et al., who observed face-selective reactivity of InP with benzyl bromides and proposed that the reactivity of the P-rich, (111)B face of InP was dominated by the lone pairs of the terminal P surface atoms. We describe herein a new, apparently general strategy for functionalization of InP surfaces. We also present evidence that the reactions of this semiconductor surface are dominated by the reactivity of residual -OH functionalities on the InP surface.", "date": "1996-03-27", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "118", "number": "12", "publisher": "American Chemical Society", "pagerange": "3045-3046", "id_number": "CaltechAUTHORS:20180515-111735903", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180515-111735903", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Swiss National Science Foundation (SNSF)" } ] }, "doi": "10.1021/ja953691l", "resource_type": "article", "pub_year": "1996", "author_list": "Sturzenegger, Marcel and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/j5zwa-tn981", "eprint_id": 88093, "eprint_status": "archive", "datestamp": "2023-08-20 07:19:22", "lastmod": "2023-10-18 21:45:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Pomykal-Katherine-E", "name": { "family": "Pomykal", "given": "Katherine E." } }, { "id": "Fajardo-Arnel-M", "name": { "family": "Fajardo", "given": "Arnel M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Theoretical and Experimental Upper Bounds on Interfacial Charge-Transfer Rate Constants between Semiconducting Solids and Outer-Sphere Redox Couples", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1996 American Chemical Society. \n\nReceived: June 27, 1995; In Final Form: November 8, 1995. \n\nWe acknowledge the National Science Foundation (NSF), Grant CHE-9221311, for support of this work. K.E.P. also acknowledges the NSF for a predoctoral fellowship.", "abstract": "Theoretical expressions for the charge-transfer rate constant at a semiconductor/liquid junction have been modified to include the effects of adiabaticity and the existence of a Helmholtz layer at the solid/liquid interface. These expressions have yielded an estimate of the maximum interfacial charge-transfer rate constant, at optimal exoergicity, for a semiconductor in contact with a random distribution of nonadsorbing, outer-sphere redox species. An experimental upper bound on this interfacial charge-transfer rate constant has been obtained through the determination of key energetic and kinetic properties for stable semiconductor electrodes in contact with outer-sphere redox species. For this purpose, n-Si/CH_3OH\u2212dimethylferrocenium\u2212dimethylferrocene, n-GaAs/CH_3CN\u2212ferrocenium\u2212ferrocene, and p-InP/CH_3CN\u2212cobaltocenium\u2212cobaltocene contacts were investigated using a combination of current density-potential and differential capacitance-potential methods. The upper limits for the interfacial charge-transfer rate constant at these semiconductor/liquid contacts were found to be consistent with the upper limits predicted by theory. The current density-potential behavior of n-InP and p-InP/Fe(CN)_6^(3-/4-)(aq) junctions was also examined in order to assess the validity of prior kinetic measurements on these interfaces.", "date": "1996-02-29", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "100", "number": "9", "publisher": "American Chemical Society", "pagerange": "3652-3664", "id_number": "CaltechAUTHORS:20180720-151949312", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180720-151949312", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9221311" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "other_numbering_system": { "items": [ { "id": "9107", "name": "Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/jp951779f", "resource_type": "article", "pub_year": "1996", "author_list": "Pomykal, Katherine E.; Fajardo, Arnel M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/avzrg-kdd22", "eprint_id": 121016, "eprint_status": "archive", "datestamp": "2023-08-22 10:42:34", "lastmod": "2023-10-18 18:07:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Stanton-Colby-E", "name": { "family": "Stanton", "given": "Colby E." } }, { "id": "Lee-T-Randall", "name": { "family": "Lee", "given": "T. Randall" } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Pudelski-John-K", "name": { "family": "Pudelski", "given": "John K." } }, { "id": "Callstrom-Matthew-R", "name": { "family": "Callstrom", "given": "Matthew R." } }, { "id": "Erickson-Mark-S", "name": { "family": "Erickson", "given": "Mark S." } }, { "id": "McLaughlin-Mark-L", "name": { "family": "McLaughlin", "given": "Mark L." } } ] }, "title": "Routes to Conjugated Polymers with Ferrocenes in Their Backbones: Synthesis and Characterization of Poly(ferrocenylenedivinylene) and Poly(ferrocenylenebutenylene)", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Inorganic Chemistry; Polymers and Plastics; Organic Chemistry", "note": "\u00a9 1995 American Chemical Society. \n\nWe acknowledge the National Science Foundation, grant CHE-9202583, for support of this work. T.R.L. wishes to thank the NIH for a Postdoctoral Fellowship (GM14688-02). We thank Dr. Robert Lee for assistance in obtaining and analyzing the solid state \u00b9\u00b3C NMR spectra, Marc Hillmyer for performing the TGA and DSC measurements, and Dr. Iver Lauermann for obtaining the XPS spectra.", "abstract": "Ring opening metathesis polymerization (ROMP) has been used to prepare conjugated polymers that contain ferrocene moieties as part of their backbones. The conjugated polymer poly-(ferrocenylenedivinylene) (PFDV) and the analogous unconjugated polymer poly(ferrocenylenebutenylene) (PFB) with chain lengths of greater than 10 were found to be insoluble in typical organic solvents. The conductivities of oxidatively doped films of PFDV and PFB were found to be 10\u207b\u2074 and 10\u207b\u2075 \u03a9\u207b\u00b9 cm\u207b\u00b9, respectively. Oxidative doping of the monomer 1,4-(1,1'-ferrocenediyl)-1-butene was found to yield conductivities on the order of 10\u207b\u2075 \u03a9\u207b\u00b9 cm\u207b\u00b9, supporting interchain hopping as the dominant mechanism for charge carrier movement through these films. The ROMP of monomers octamethyl-l,4-(1,1'-ferrocenediyl)-!,3-butadiene and l,4-(l,l'-ferrocenediyl)-l-methoxy-l,3-butadiene was also studied. Although soluble polymer was successfully generated from the latter monomer, no conditions were found under which the octamethyl compound could be polymerized.", "date": "1995-12-18", "date_type": "published", "publication": "Macromolecules", "volume": "28", "number": "26", "publisher": "American Chemical Society", "pagerange": "8713-8721", "id_number": "CaltechAUTHORS:20230419-952789000.1", "issn": "0024-9297", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-952789000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9202583" }, { "agency": "NIH Postdoctoral Fellowship", "grant_number": "GM14688-02" } ] }, "other_numbering_system": { "items": [ { "id": "8967", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/ma00130a002", "resource_type": "article", "pub_year": "1995", "author_list": "Stanton, Colby E.; Lee, T. Randall; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/akqf9-3j567", "eprint_id": 121021, "eprint_status": "archive", "datestamp": "2023-08-22 10:41:10", "lastmod": "2023-10-18 18:07:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Freund-Michael-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Karp-Christopher-D", "name": { "family": "Karp", "given": "Chris" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Growth of thin processable films of poly(pyrrole) using phosphomolybdate clusters", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Inorganic Chemistry; Physical and Theoretical Chemistry", "note": "\u00a9 1995 Published by Elsevier. \n\nThis paper is dedicated to Professor F. Basolo. \n\nThis work was supported by NASA, the National Science Foundation, Grant CHE-9202583 and by the Caltech Consortium in Chemistry and Chemical Engineering: E.I. duPont de Nemours and Company, Inc. and Eastman Kodak Company.", "abstract": "Facile control over the chemical polymerization of pyrrole from solutions of pyrrole-phosphomolybdic acid has allowed processibility of conducting poly(pyrrole). This approach has allowed thin conducting films of poly(pyrrole) to be deposited in a single step, and in contrast to electrochemical polymerization methods, is not limited to electrically conducting substrates. For example, 40\u2013100 nm thick poly(pyrrole) films with conducivities in the range of 15 to 30 S cm\u207b\u00b9 have been spin coated onto insulating glass substrates. Insight into the mechanism of polymerization has been obtained with cyclic voltammetry and UV-Vis spectroscopy.", "date": "1995-12", "date_type": "published", "publication": "Inorganica Chimica Acta", "volume": "240", "number": "1-2", "publisher": "Elsevier", "pagerange": "447-451", "id_number": "CaltechAUTHORS:20230419-953242000.8", "issn": "0020-1693", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953242000.8", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" }, { "agency": "NSF", "grant_number": "CHE-9202583" }, { "agency": "Caltech Consortium in Chemistry and Chemical Engineering" }, { "agency": "E. I. DuPont de Nemours and Company, Inc." }, { "agency": "Eastman Kodak Company" } ] }, "doi": "10.1016/0020-1693(95)04569-4", "resource_type": "article", "pub_year": "1995", "author_list": "Freund, Michael S.; Karp, Chris; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pb0c7-98w12", "eprint_id": 68200, "eprint_status": "archive", "datestamp": "2023-08-20 06:28:56", "lastmod": "2023-10-19 22:10:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Artificial photosynthesis", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 1995 Sigma Xi. \n\nI am indebted to an extremely talented group of students and post doctoral fellows in my research group who have made significant contributions to the field of semiconductor photoelectrochemistry. Discussions with Professors Michael Gr\u00e4tzel, Adam Heller, Rudiger Memming, Helmut Tributsch, Carl Koval, Tom Mallouk, Bruce Parkinson and Arthur Nozik have helped me with this overview of the field. I am grateful for sustained support from the National Science Foundation and from the Department of Energy, Office of Basic Energy Sciences.", "abstract": "[no abstract]", "date": "1995-11", "date_type": "published", "publication": "American Scientist", "volume": "83", "number": "6", "publisher": "Sigma Xi", "pagerange": "534-541", "id_number": "CaltechAUTHORS:20160616-173848341", "issn": "0003-0996", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160616-173848341", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "Department of Energy (DOE)" } ] }, "resource_type": "article", "pub_year": "1995", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qkjcv-yk044", "eprint_id": 80001, "eprint_status": "archive", "datestamp": "2023-08-20 05:54:06", "lastmod": "2023-10-26 17:30:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Pomykal-Katherine-E", "name": { "family": "Pomykal", "given": "Katherine E." } }, { "id": "Fajardo-Arnel-M", "name": { "family": "Fajardo", "given": "Arnel M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Stability of n-Si/CH\u2083OH Contacts as a Function of the Reorganization Energy of the Electron Donor", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1995 American Chemical Society. \n\nReceived: December 1, 1994; In Final Form: February 28, 1995. \n\nWe acknowledge the National Science Foundation (NSF), Grant CHE-9221311, for support of this work. K.E.P. acknowledges the NSF for a predoctoral fellowship, and the authors are grateful to T. Longin for assistance in using the XPS instrument.", "abstract": "Predictions of the Marcus/Gerischer theory for photoelectrode stability have been investigated experimentally for n-Si/CH\u2083OH photoelectrochemical cells. Specifically, a semiconductor electrode is predicted to be more stable if the reorganization energy of the stabilizing agent is decreased (in the normal region of the Marcus\nbehavior), thereby increasing the rate of minority carrier capture by the stabilizer. This prediction was quantified\nexperimentally by monitoring the branching ratio between two competing reactions at a semiconductor/liquid\ninterface: hole transfer from a Si photoanode to the electron donor in solution vs passivation of the Si\nphotoanode through hole transfer to water. Deliberate addition of water to n-Si/CH\u2083OH contacts provided a\nconstant, known passivation pathway that competed with charge transfer to the stabilizing agent. Dimethylferrocene\n(Me\u2082Fc), ruthenium(II) pentaamrnine 4,4'-bipyridine (Ru(NH\u2083)\u2085(4,4'-bpy)\u00b2\u207a, and cobalt(II) tris(2,2'-bipyridine) (Co(2,2'-bpy)\u2083\u00b2\u207a) provided three outer sphere electron donors with very similar standard electrochemical potentials but varying solvent reorganization energies. At constant electron donor concentration, constant driving force for reaction, constant photocurrent density, and constant water concentration in CH\u2083-OH, the stability of n-Si photoelectrodes decreased in the order Me\u2082Fc^(+/0) > Ru(NH\u2083)_5(4,4'-bpy)^(3+/2+) > Co(2,2'-bpy)\u2083^(3+/2+). This observation can be consistently explained through the theoretically predicted influence of the minority carrier acceptor reorganization energy on the interfacial charge transfer rate constant.", "date": "1995-05-18", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "99", "number": "20", "publisher": "American Chemical Society", "pagerange": "8302-8310", "id_number": "CaltechAUTHORS:20170809-092636466", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170809-092636466", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9221311" }, { "agency": "NSF Predoctoral Fellowship" } ] }, "other_numbering_system": { "items": [ { "id": "9007", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/j100020a064", "resource_type": "article", "pub_year": "1995", "author_list": "Pomykal, Katherine E.; Fajardo, Arnel M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ah015-6f950", "eprint_id": 86625, "eprint_status": "archive", "datestamp": "2023-08-20 05:43:42", "lastmod": "2023-10-18 19:48:00", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shreve-Gary-A", "name": { "family": "Shreve", "given": "Gary A." } }, { "id": "Karp-Chris-D", "name": { "family": "Karp", "given": "Chris D." } }, { "id": "Pomykal-Katherine-E", "name": { "family": "Pomykal", "given": "Katherine E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Limits on the Corrosion Rate of Si Surfaces in Contact with CH\u2083OH-Ferrocene^(+/0) and CH\u2083OH-1,1'-Dimethylferrocene^(+/0) Solutions", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1995 American Chemical Society. \n\nReceived: November 2, 1994; In Final Form: January 25, 1995. \n\nWe acknowledge the National Science Foundation, Grant CHE-9221311, for support of this work. K.E.P. acknowledges the NSF for a Graduate Fellowship, and we also thank Professor A. Bard for generously providing us with a copy of ref 12 prior to publication.", "abstract": "Although Si/CH\u2083OH contacts have been extensively investigated and reported to provide highly efficient photoelectrochemical energy conversion devices, a recent study using the scanning electrochemical microscope (SECM) has claimed that, in CH_3OH solutions, Si surfaces in contact with 4.57 mM ferrocenium (Fc\u207a) were etched in the dark at a mass-transport-limited rate. The reported etching rate constant of > 0.37 cm s\u207b\u00b9) at 4.57 mM ferrocenium corresponds to an equivalent corrosion current density of > 240 mA cm\u207b\u00b2 and to a Si etch rate of > 75 nm s\u207b\u00b9. The presence of such severe corrosion was inferred from an unexpectedly large feedback current in an SECM experiment. The present work describes a search for corrosion of Si in contact with CH\u2083OH-ferrocene^+/0) and CH\u2083OH-dimethylferrocene(Me\u2082Fc)^(+/0) solutions through the use of very sensitive electrochemical, chemical, and physical methods. For CH\u2083OH - 1.0 M LiClO\u2084 - 100 mM Me\u2082Fc- 80 mM Me\u2082Fc\u207a solutions, an upper limit on the etch rate of 6.6 x10\u207b\u2076 nm s\u207b\u00b9) has been established through direct experimental measurements; thus, a 400 pm thick Si photoelectrode in contact with the CH\u2083OH-Me\u2082-Fc^(+/0) electrolyte would require over 1500 years to corrode completely at room temperature. An alternative explanation for the SECM data, based on the documented existence of an inversion layer at the Si/liquid contact, is presented and shown to be consistent with the available data.", "date": "1995-04-13", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "99", "number": "15", "publisher": "American Chemical Society", "pagerange": "5575-5580", "id_number": "CaltechAUTHORS:20180525-112848439", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180525-112848439", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9221311" }, { "agency": "NSF Graduate Research Fellowship" } ] }, "other_numbering_system": { "items": [ { "id": "9006", "name": "Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/j100015a047", "resource_type": "article", "pub_year": "1995", "author_list": "Shreve, Gary A.; Karp, Chris D.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/y4ppc-eef38", "eprint_id": 52354, "eprint_status": "archive", "datestamp": "2023-08-22 10:22:43", "lastmod": "2023-10-18 19:47:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Freund-Michael-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A chemically diverse conducting polymer-based \"electronic nose\"", "ispublished": "pub", "full_text_status": "public", "keywords": "sensor arrays; olfaction; principal component analysis; poly(pyrrole); plasticizers", "note": "\u00a9 1995 National Academy of Sciences. \n\nCommunicated by Robert H. Grubbs, California Institute of Technology, Pasadena, CA, November 28, 1994. \n\nWe thank Profs. J. J. Hopfield and J. M. Bower, and the members of their research groups, for helpful discussions. This work was supported in part by the Caltech Consortium in Chemistry and Chemical Engineering; E. I. DuPont de Nemours and Company, Inc., the Eastman Kodak Company, National Aeronautics and Space Administration, and National Science Foundation Grant CHE-9202583. This is contribution no. 8952. \n\nThe publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked \"advertisement\" in accordance with 18 U.S.C. \u00a71734 solely to indicate this fact.\n\nPublished - PNAS-1995-Freund-2652-6.pdf
", "abstract": "We describe a method for generating a variety of chemically diverse broadly responsive low-power vapor sensors. The chemical polymerization of pyrrole in the presence of plasticizers has yielded conducting organic polymer films whose resistivities are sensitive to the identity and concentration of various vapors in air. An array of such sensing elements produced a chemically reversible diagnostic pattern of electrical resistance changes upon exposure to different odorants. Principal component analysis has demonstrated that such sensors can identify and quantify different airborne organic solvents and can yield information on the components of gas mixtures.", "date": "1995-03-28", "date_type": "published", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "volume": "92", "number": "7", "publisher": "National Academy of Sciences", "pagerange": "2652-2656", "id_number": "CaltechAUTHORS:20141203-144657553", "issn": "0027-8424", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141203-144657553", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech Consortium in Chemistry and Chemical Engineering" }, { "agency": "E. I. DuPont de Nemours and Company, Inc." }, { "agency": "Eastman Kodak Corporation" }, { "agency": "NASA" }, { "agency": "NSF", "grant_number": "CHE-9202583" } ] }, "other_numbering_system": { "items": [ { "id": "8952", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1073/pnas.92.7.2652", "pmcid": "PMC42276", "primary_object": { "basename": "PNAS-1995-Freund-2652-6.pdf", "url": "https://authors.library.caltech.edu/records/y4ppc-eef38/files/PNAS-1995-Freund-2652-6.pdf" }, "resource_type": "article", "pub_year": "1995", "author_list": "Freund, Michael S. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/89yhm-f6n72", "eprint_id": 121017, "eprint_status": "archive", "datestamp": "2023-08-22 10:16:56", "lastmod": "2023-10-18 18:07:04", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shreve-Gary-A", "name": { "family": "Shreve", "given": "Gary A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "An Analytical Description of the Consequences of Abandoning the Principles of Detailed Balance and Microscopic Reversibility in Semiconductor Photoelectrochemistry", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Electrochemistry; Surfaces, Coatings and Films; Condensed Matter Physics; Renewable Energy, Sustainability and the Environment; Electronic, Optical and Magnetic Materials", "note": "\u00a9 1995 ECS - The Electrochemical Society. \n\nWe acknowledge the National Science Foundation, Grant CHE-9221311, for support of this work. We are also grateful to R. Blumenthal, W. C. A. Wilisch, and A. Kumar for discussions regarding this manuscript. This Contribution Number 8941 from the Caltech Chemistry Division.\n\nPublished - Shreve_1995_J._Electrochem._Soc._142_112.pdf
", "abstract": "Key differences between the conventional and \"irreversible\" models of semiconductor photoelectrochemistry are identified and discussed within the framework of experimental observations. Conceptual differences between these two models appear to lie in the treatment of interfacial charge\u2010transfer processes for photogenerated charge carriers. The conventional model utilizes detailed balance principles for obtaining rate constant relationships for all interfacial charge\u2010transfer events at semiconductor/liquid contacts and uses the principle of microscopic reversibility to evaluate these rate constants for situations away from equilibrium. In contrast, the irreversible model postulates that local statistical detailed balance does not apply to charge\u2010transfer events in photoelectrolysis, and that such charge\u2010transfer events are highly irreversible, like photoemission into a vacuum. It is shown analytically that the two models predict differences in the behavior of the available free energy produced by a photoelectrochemical cell at a fixed incident light intensity. The conceptual implications of these differences are evaluated analytically and are also compared to experimental results for semiconductor/liquid junctions.", "date": "1995-01-01", "date_type": "published", "publication": "Journal of the Electrochemical Society", "volume": "142", "number": "1", "publisher": "Electrochemical Society", "pagerange": "112-119", "id_number": "CaltechAUTHORS:20230419-953199000.2", "issn": "0013-4651", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953199000.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9221311" } ] }, "other_numbering_system": { "items": [ { "id": "8941", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1149/1.2043848", "primary_object": { "basename": "Shreve_1995_J._Electrochem._Soc._142_112.pdf", "url": "https://authors.library.caltech.edu/records/89yhm-f6n72/files/Shreve_1995_J._Electrochem._Soc._142_112.pdf" }, "resource_type": "article", "pub_year": "1995", "author_list": "Shreve, Gary A. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/k0bbp-bsd82", "eprint_id": 121019, "eprint_status": "archive", "datestamp": "2023-08-22 10:15:07", "lastmod": "2023-10-18 18:07:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Charge transfer rate constants for semiconductor/liquid contacts", "ispublished": "pub", "full_text_status": "public", "keywords": "Surfaces, Coatings and Films; Renewable Energy, Sustainability and the Environment; Electronic, Optical and Magnetic Materials", "note": "\u00a9 1995 Published by Elsevier. \n\nWe gratefully acknowledge support for this research from the US National Science Foundation, grant CHE-9221311, and from the US Department of Energy, Office of Basic Energy Sciences.", "abstract": "The purpose of this discussion is to provide a framework for analyzing interfacial charge transfer rate constants at semiconductor/liquid interfaces. A theoretical approach and preliminary experimental evidence to support this theory will be presented.", "date": "1995", "date_type": "published", "publication": "Solar Energy Materials and Solar Cells", "volume": "38", "number": "1-4", "publisher": "Elsevier", "pagerange": "323-325", "id_number": "CaltechAUTHORS:20230419-953222000.4", "issn": "0927-0248", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953222000.4", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9221311" }, { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1016/0927-0248(95)00006-2", "resource_type": "article", "pub_year": "1995", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hkazy-6b976", "eprint_id": 121018, "eprint_status": "archive", "datestamp": "2023-08-22 10:15:04", "lastmod": "2023-10-18 18:07:07", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Nozik-Arthur-J", "name": { "family": "Nozik", "given": "A. J." }, "orcid": "0000-0001-7176-7645" }, { "id": "Miller-R-J-D", "name": { "family": "Miller", "given": "R. J. D." } }, { "id": "Lindquist-S-F", "name": { "family": "Lindquist", "given": "S.-F." } }, { "id": "Moser-J-E", "name": { "family": "Moser", "given": "J.-E." } }, { "id": "Hagfeldt-A", "name": { "family": "Hagfeldt", "given": "A." } }, { "id": "Uosaki-K", "name": { "family": "Uosaki", "given": "K." } }, { "id": "Schaafsma-T-J", "name": { "family": "Schaafsma", "given": "T. J." } }, { "id": "Licht-Stuart", "name": { "family": "Licht", "given": "S." } }, { "id": "Tributsch-H", "name": { "family": "Tributsch", "given": "H." } }, { "id": "Willig-F", "name": { "family": "Willig", "given": "F." } } ] }, "title": "Comment on photoelectrochemistry", "ispublished": "pub", "full_text_status": "public", "keywords": "Surfaces, Coatings and Films; Renewable Energy, Sustainability and the Environment; Electronic, Optical and Magnetic Materials", "note": "\u00a9 1995 Published by Elsevier Under a Creative Commons license\nAttribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0).\n\nPublished - 1-s2.0-0927024895800239-main.pdf
", "abstract": "Workshop III at the IPS10-meeting was organized by H. Tributsch and F. Willig. The workshop consisted of three sessions, each taking place on a separate day with a duration of 80 minutes. Each session comprised three short key note lectures and a discussion period. The lectures addressed topics of fundamental importance for the understanding and utilization of photo-electrochemical processes at semiconductor electrodes.", "date": "1995", "date_type": "published", "publication": "Solar Energy Materials and Solar Cells", "volume": "38", "number": "1-4", "publisher": "Elsevier", "pagerange": "321-322", "id_number": "CaltechAUTHORS:20230419-953215000.3", "issn": "0927-0248", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953215000.3", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1016/0927-0248(95)80023-9", "primary_object": { "basename": "1-s2.0-0927024895800239-main.pdf", "url": "https://authors.library.caltech.edu/records/hkazy-6b976/files/1-s2.0-0927024895800239-main.pdf" }, "resource_type": "article", "pub_year": "1995", "author_list": "Lewis, N. S.; Nozik, A. J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/p6980-yk634", "eprint_id": 121022, "eprint_status": "archive", "datestamp": "2023-08-22 10:15:11", "lastmod": "2023-10-18 18:07:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Fajardo-Arnel-M", "name": { "family": "Fajardo", "given": "Arnel M." } }, { "id": "Karp-Christoph-D", "name": { "family": "Karp", "given": "Christoph D." } }, { "id": "Kenyon-C-N", "name": { "family": "Kenyon", "given": "C. N." } }, { "id": "Pomykal-Katherine-E", "name": { "family": "Pomykal", "given": "Katherine E." } }, { "id": "Shreve-Gary-A", "name": { "family": "Shreve", "given": "Gary A." } }, { "id": "Tan-Ming-X", "name": { "family": "Tan", "given": "Ming X." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "New approaches to solar energy conversion using Si/liquid junctions", "ispublished": "pub", "full_text_status": "public", "keywords": "Surfaces, Coatings and Films; Renewable Energy, Sustainability and the Environment; Electronic, Optical and Magnetic Materials", "note": "\u00a9 1995 Published by Elsevier. \n\nWe acknowledge the National Science Foundation, grant CHE-922131 for support of this research. KEP acknowledges the National Science Foundation for a graduate fellowship, and MXT is grateful to the Link Energy Foundation and the W.R. Grace Foundation for graduate fellowships. We also thank Prof. A.J. Bard for generously supplying us with a preprint of Ref. [45]. This is the contribution number from the Caltech Division of Chemistry and Chemical Engineering.", "abstract": "New data are presented on efficient Si/liquid junction photoelectrochemical energy conversion devices. Additional information on the interfacial energetics, charge transfer kinetics, and stabilization factors of these interfaces has been obtained using a variety of chemical and electrical methods. Transconductance and Mott-Schottky measurements of the barrier height of n-Si/CH\u2083OH-Me\u2082Fc^(+/0) contacts have demonstrated that the Si is in strong inversion, with a barrier height of 1.0 eV. Qualitative evidence for the validity of Marcus-Gerischer theory was obtained in measurements of the stabilization ratio as a function of the reorganization energy of the stabilizing redox agent. In addition, a new type of photoelectrochemical cell, in which charge carriers are collected primarily using diffusion gradients as opposed to drift, has shown high efficiency and unpinned electrical junction behavior in contact with various redox couples.", "date": "1995", "date_type": "published", "publication": "Solar Energy Materials and Solar Cells", "volume": "38", "number": "1-4", "publisher": "Elsevier", "pagerange": "279-303", "id_number": "CaltechAUTHORS:20230419-953245000.9", "issn": "0927-0248", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953245000.9", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9221311" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Link Energy Foundation" }, { "agency": "W. R. Grace & Co." } ] }, "doi": "10.1016/0927-0248(94)00228-2", "resource_type": "article", "pub_year": "1995", "author_list": "Fajardo, Arnel M.; Karp, Christoph D.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mz82n-6mg66", "eprint_id": 59339, "eprint_status": "archive", "datestamp": "2023-08-20 04:56:58", "lastmod": "2023-10-23 20:28:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kesselman-Janet-M", "name": { "family": "Kesselman", "given": "Janet M." } }, { "id": "Shreve-Gary-A", "name": { "family": "Shreve", "given": "Gary A." } }, { "id": "Hoffmann-M-R", "name": { "family": "Hoffmann", "given": "Michael R." }, "orcid": "0000-0001-6495-1946" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Flux-Matching Conditions at TiO\u2082 Photoelectrodes: Is Interfacial Electron Transfer to O\u2082 Rate-Limiting in the TiO\u2082-Catalyzed Photochemical Degradation of Organics?", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1994 American Chemical Society. \n\nReceived: July 6, 1994; In Final Form: September 16, 1994. \n\nWe gratefully acknowledge ARPA (NAV 5 HFMN N0001 149211901) and the National Science Foundation, Grant CHE-9221311, for support of this work, and J.M.K. acknowledges the National Science Foundation for a predoctoral fellowship. We thank Dr. Com for a preprint of ref 51.", "abstract": "A flux-matching condition has been applied to determine whether O\u2082 reduction is rate-limiting under photocatalytic conditions for the degradation of CHCl\u2083 at rutile TiO\u2082 single-crystal electrodes. In this approach, the potential dependence of the photooxidation current density is compared to the potential dependence of the current density for O\u2082 reduction. The potential at which the oxidation and reduction fluxes are equal determines the operating potential and the steady-state flux that will flow through the crystal under no applied bias. If this flux-matching condition occurs when the cathodic flux equals the flux of photogenerated carriers, then the predicted quantum yield should approach unity; otherwise, recombination should be significant in the TiO\u2082. Our measurements indicate that significant recombination will occur for the oxidation of typical organic molecules in H\u2082O over a range of pH values. The data also indicate that Pt catalysis of O\u2082 reduction should be beneficial for the oxidation of organic molecules, as would the use of alternate electron acceptors such as Fe(CN)\u2086\u00b3\u207b. The O\u2082 reduction data and rotating disk electrode data collected in this work allow a quantitative comparison to theoretical estimates of the electron transfer rate constant for O\u2082 reduction at TiO\u2082. We also present an elucidation of the previously published theoretical treatments of TiO\u2082 charge transfer rate constants in view of the new data collected herein.", "date": "1994-12", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "98", "number": "50", "publisher": "American Chemical Society", "pagerange": "13385-13395", "id_number": "CaltechAUTHORS:20150810-083413352", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150810-083413352", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Advanced Research Projects Agency (ARPA)" }, { "agency": "NSF", "grant_number": "CHE-9221311" }, { "agency": "NSF Predoctoral Fellowship" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "NAV 5 HFMN N0001 149211901" } ] }, "doi": "10.1021/j100101a044", "resource_type": "article", "pub_year": "1994", "author_list": "Kesselman, Janet M.; Shreve, Gary A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cfqhj-yzq56", "eprint_id": 86765, "eprint_status": "archive", "datestamp": "2023-08-20 04:40:57", "lastmod": "2023-10-18 20:33:57", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Laibinis-Paul-E", "name": { "family": "Laibinis", "given": "Paul E." } }, { "id": "Stanton-Colby-E", "name": { "family": "Stanton", "given": "Colby E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Measurement of Barrier Heights of Semiconductor/Liquid Junctions Using a Transconductance Method: Evidence for Inversion at n-Si/CH\u2083OH-1,1'-Dimethylferrocene^(+/0) Junctions", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1994 American Chemical Society. \n\nReceived: March 9, 1994; In Final Form: May 23, 1994. \n\nThis research was supported by the National Science Foundation, Grant CHE-9221311. P.E.L. gratefully acknowledges the National Institutes of Health for a post-doctoral fellowship. We thank Prof. Harry Atwater of Caltech for the use of semiconductor fabrication facilities. This paper is contribution no. 8928 from the Division of Chemistry and Chemical Engineering at Caltech.", "abstract": "Transconductance measurements have been used to characterize the space-charge regions of various n-Si/liquid contacts. To perform these measurements, Si electrodes were photolithographically processed to introduce p^+-contact areas into the surface of an n-type Si electrode. The electrical conductance between these p\u207a regions was then used to probe the minority carrier concentration in the near-surface region of the n-type Si. Unlike conventional differential capacitance or current-voltage measurements, these transconductance measurements can be performed under near-equilibrium conditions and can be performed in the presence of gaseous ambients or when the sample is in contact with ionically conducting electrolyte solutions. In contact with the electrolyte solutions, faradaic and solid-state conduction pathways were distinguished using ac impedance measurements. The impedance spectra provided clear evidence that contact with Me\u2082Fc (1,1'-dimethylferrocene)^(+/0) and Fc^(+/0) redox couples in CH\u2083OH(l)-1.0 M LiClO\u2084 formed an inversion layer in the n-Si, but that CH\u2083OH(l)-1.0 M LiClO\u2084-Me\u2081\u2080Fc^(+/0) solutions did not yield an inversion layer. These observations are consistent with prior current-voltage measurements on these junctions. The barrier heights of the n-Si/CH_3OH-Me\u2082Fc^(+/0) and n-Si/CH\u2083OH-Fc^(+/0) junctions were determined to be 1.01 and 1.02 V, respectively. These measurements provide new insight into the photoelectrochemical behavior of Si/CH\u2083OH contacts and provide an alternate method for characterizing the energetics of semiconductor/liquid contacts.", "date": "1994-09-01", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "98", "number": "35", "publisher": "American Chemical Society", "pagerange": "8765-8774", "id_number": "CaltechAUTHORS:20180601-161216529", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180601-161216529", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9221311" }, { "agency": "NIH Postdoctoral Fellowship" } ] }, "other_numbering_system": { "items": [ { "id": "8928", "name": "Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/j100086a029", "resource_type": "article", "pub_year": "1994", "author_list": "Laibinis, Paul E.; Stanton, Colby E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/34z8x-eb025", "eprint_id": 85343, "eprint_status": "archive", "datestamp": "2023-08-20 04:14:15", "lastmod": "2023-10-18 18:07:53", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tan-Ming-X", "name": { "family": "Tan", "given": "Ming X." } }, { "id": "Kenyon-C-N", "name": { "family": "Kenyon", "given": "C. N." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Experimental Measurement of Quasi-Fermi Levels at an Illuminated Semiconductor/Liquid Contact", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1994 American Chemical Society. \n\nReceived: September 7, 1993; In Final Form: March 12, 1994. \n\nWe thank the National Science Foundation, Grant CHE-9221311, for support of this work. We also thank Drs. R. A. Sinton, R. M. Swanson, and P. J. Verlinden of SunPower Corp. for providing the lithographically patterned Si samples, and M.X.T. gratefully acknowledges the Link Foundation for a Graduate Fellowship.", "abstract": "A novel electrode geometry and contacting procedure has allowed measurement of the quasi-Fermi levels, i.e.,\nthe apparent electrochemical potentials, of electrons and holes at an illuminated semiconductor / liquid contact.\nThe key feature of our experiments is the use of a lithographically patterned, high purity (100-400 \u03a9-km n-type\nfloat zone material), low dopant density Si sample in contact with CH_3OH-dimethylferrocene^(+/o) solutions.\nThe photogenerated carriers can be collected at the back side of the Si sample through a series of diffused n+\nand p^+ points. The lifetime of photogenerated carriers approaches 2 ms in this sample, indicating that electronhole\nrecombination is minimized in the bulk of the semiconductor. Furthermore, surface recombination is\nminimized by use of low saturation current density, ohmic-selective contacts at the back of the sample. The\nsolid/liquid contact also has a low recombination rate. Therefore, the potentials measured at the diffused points\nyield values for the quasi-Fermi levels of electrons and holes under illumination of the semiconductor/ liquid\ncontact. Transient photovoltage measurements have also been performed to confirm quantitatively that the quasi-Fermi levels are flat across the Si samples used in this work.", "date": "1994-05-01", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "98", "number": "19", "publisher": "American Chemical Society", "pagerange": "4959-4962", "id_number": "CaltechAUTHORS:20180315-161240932", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180315-161240932", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-9221311" }, { "agency": "Link Foundation" } ] }, "other_numbering_system": { "items": [ { "id": "8858", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/j100070a002", "resource_type": "article", "pub_year": "1994", "author_list": "Tan, Ming X.; Kenyon, C. N.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/22xb9-kwt16", "eprint_id": 86676, "eprint_status": "archive", "datestamp": "2023-08-20 04:10:05", "lastmod": "2023-10-18 19:52:18", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Freund-Michael-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Irreversible electrocatalytic reduction of V(V) to V(IV) using phosphomolybdic acid", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1994 American Chemical Society. \n\nReceived January 28, 1993. \n\nWe acknowledge ARPA for support of this work and thank Professors F. C. Anson and J. E. Bercaw and Dr. J. Labinger of Caltech for helpful discussions and Dr. D. A. Keire for help with ^(31)P NMR. We also acknowledge Dr. J. Grate for generously supplying a preprint of ref 3d.", "abstract": "Although VO\u2082\u207a(aq) reduction is kinetically slow at glassy carbon and Pt electrodes, phosphomolybdic acid is shown to catalyze the electrochemical reduction of VO\u2082\u207a(aq) to VO\u00b2\u207a(aq) in 1.0 M H\u2082SO\u2084(aq). A second-order rate\nconstant of 33 M\u207b\u00b9 s\u207b\u00b9 was observed for this process. \u00b3\u00b9P NMR spectra demonstrated that PMo\u2081\u2081VO\u2084\u2074\u207b and PMo\u2081\u2080V\u2082O\u2084\u2075\u207b were the dominant P-containing species under electrocatalytic conditions. The incorporation of V\u2c7d into the polyoxoanion led to a shift in potential from E\u2070(VO\u2082\u207a(aq)/VO\u00b2\u207a(aq)) = +0.80 V vs Ag/AgCl for free V\u2c7d/V\u1d35\u2c7d to E\u00b0' = +0.55 V vs Ag/AgCl for V\u2c7d/V\u1d35\u2c7d bound in the heteropolyoxometalate (PM\u2081\u2081VO\u2084\u2080\u207b). This shift in formal potential corresponded to an equilibrium constant of 1.7 X 10\u2074 M\u207b\u00b9 for preferential binding of V\u2c7d over V\u1d35\u2c7d by the heteropolyoxoanion. This negative shift in redox potential, combined with the slow electrochemical kinetics of free VO\u2082\u207a(aq) reduction and with the facile reaction of bound V\u1d35\u2c7d with free V\u2c7d in 1.0 M H\u2082SO\u2084(aq), resulted in the irreversible electrocatalytic reduction of VO\u2082\u207a(aq) to VO\u00b2\u207a(aq).", "date": "1994-04-13", "date_type": "published", "publication": "Inorganic Chemistry", "volume": "33", "number": "8", "publisher": "American Chemical Society", "pagerange": "1638-1643", "id_number": "CaltechAUTHORS:20180529-141900848", "issn": "0020-1669", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180529-141900848", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Advanced Research Projects Agency (ARPA)" } ] }, "other_numbering_system": { "items": [ { "id": "8794", "name": "Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/ic00086a013", "resource_type": "article", "pub_year": "1994", "author_list": "Freund, Michael S. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9mj34-g9564", "eprint_id": 121025, "eprint_status": "archive", "datestamp": "2023-08-22 09:45:46", "lastmod": "2023-10-23 16:56:46", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Freund-Michael-S", "name": { "family": "Freund", "given": "Michael S." }, "orcid": "0000-0003-1104-2292" }, { "id": "Labinger-Jay-A", "name": { "family": "Labinger", "given": "Jay A." }, "orcid": "0000-0002-1942-9232" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Bercaw-J-E", "name": { "family": "Bercaw", "given": "John E." } } ] }, "title": "Electrocatalytic functionalization of alkanes using aqueous platinum salts", "ispublished": "pub", "full_text_status": "public", "keywords": "General Engineering", "note": "\u00a9 1994 Published by Elsevier. \n\nWe acknowledge the Office of Naval Research for funding, and thank Andrew Sykes and Gerrit Luinstra for helpful discussions.", "abstract": "p-Toluenesulfonic acid is electrocatalytically hydroxylated to the alcohol,p-HO\u2083SC\u2086H\u2084CH\u2082OH, by a system consisting of aqueous PtCl\u2084\u00b2\u207b as C-H activation catalyst, phosphomolybdic acid as redox mediator, in an electrochemical cell containing a carbon cloth anode.", "date": "1994-01-19", "date_type": "published", "publication": "Journal of Molecular Catalysis", "volume": "87", "number": "1", "publisher": "Elsevier", "pagerange": "L11-L15", "id_number": "CaltechAUTHORS:20230419-953279000.13", "issn": "0304-5102", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953279000.13", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)" } ] }, "doi": "10.1016/0304-5102(93)e0230-e", "resource_type": "article", "pub_year": "1994", "author_list": "Freund, Michael S.; Labinger, Jay A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nf7g7-0ef86", "eprint_id": 120586, "eprint_status": "archive", "datestamp": "2023-08-20 03:41:04", "lastmod": "2023-10-18 17:55:06", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tan-Ming-X", "name": { "family": "Tan", "given": "Ming X." } }, { "id": "Laibinis-Paul-E", "name": { "family": "Laibinis", "given": "Paul E." } }, { "id": "Nguyen-SonBinh-T", "name": { "family": "Nguyen", "given": "SonBinh T." }, "orcid": "0000-0002-6977-3445" }, { "id": "Kesselman-Janet-M", "name": { "family": "Kesselman", "given": "Janet M." } }, { "id": "Stanton-Colby-E", "name": { "family": "Stanton", "given": "Colby E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Principles and Applications of Semiconductor Photoelectrochemistry", "ispublished": "unpub", "full_text_status": "public", "abstract": "[no abstract]", "date": "1994", "date_type": "published", "publisher": "John Wiley & Sons, Inc.", "place_of_pub": "Hoboken, NJ", "pagerange": "21-144", "id_number": "CaltechAUTHORS:20230329-793467000.1", "isbn": "9780471596998", "book_title": "Progress in Inorganic Chemistry", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230329-793467000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Karlin-Kenneth-D", "name": { "family": "Karlin", "given": "Kenneth D." } } ] }, "doi": "10.1002/9780470166420.ch2", "resource_type": "book_section", "pub_year": "1994", "author_list": "Tan, Ming X.; Laibinis, Paul E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qd86f-h1f44", "eprint_id": 86755, "eprint_status": "archive", "datestamp": "2023-08-20 03:27:47", "lastmod": "2023-10-18 20:32:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ryba-Gail-N", "name": { "family": "Ryba", "given": "Gail N." } }, { "id": "Kenyon-C-N", "name": { "family": "Kenyon", "given": "C. N." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Effects of metal ion chemisorption on gallium arsenide surface recombination: picosecond luminescence decay measurements", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1993 American Chemical Society. \n\nReceived: September 1, 1993. \n\nWe gratefully acknowledge C. L. R. Lewis, H. MacMillan, L. Eng, and A. Yariv for supplying the GaAs samples that were used in this work. We are also grateful to Steve Feldberg for discussions regarding the finite-difference calculations, to J. Winkler of Caltech and J. Perry of JPL for invaluable assistance with the laser experiments, and to A. Heller of the University of Texas, Austin, for helpful discussions. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, through the Fundamental Interactions Branch.", "abstract": "n-GaAs/KOHSe^(-/2-)(aq) contacts have been studied using real time photoluminescence decay techniques. This system is of interest because metal ion chemisorption improves the steady-state current-voltage properties of GaAs/KOH-Se^(-/2-)(aq)/Pt cells, yielding 16% efficiency under simulated 1-sun illumination conditions. In this work, the luminescence decay dynamics of thin epilayer GaAs samples under high level injection conditions were monitored in contact with KOHSe^(-/2-)(aq) solutions. The photoluminescence signals decayed more rapidly after metal ion chemisorption than after a fresh etch, indicating that the metal ion treatment induced a more active recombination and/or charge-transfer process than the etch. A finite-difference simulation was used to model the decays and to extract a minority carrier surface recombination velocity, S_(min), for these systems. For etched GaAs surfaces, S_(min) = 5 X 10\u00b3 cm s\u207b\u00b9, while GaAs surfaces that had been etched and then exposed to 0.010 M Co(NH\u2083)\u2086\u00b3\u207a (pH = 11) solutions displayed S_(min) = 2 X 10\u2075 cm s\u207b\u00b9. Qualitatively similar behavior was observed for Rh-, Ru-, and Os-treated GaAs surfaces as well. These data are fully consistent with prior suggestions that the primary effect of metal ion chemisorption is to increase the rate of hole transfer to the Se^(-/2-)(aq) electrolyte, as opposed to decreasing surface recombination processes at the GaAs/liquid contact.", "date": "1993-12-23", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "97", "number": "51", "publisher": "American Chemical Society", "pagerange": "13814-13819", "id_number": "CaltechAUTHORS:20180601-145807055", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180601-145807055", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "other_numbering_system": { "items": [ { "id": "8853", "name": "Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/j100153a062", "resource_type": "article", "pub_year": "1993", "author_list": "Ryba, Gail N.; Kenyon, C. N.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qq3c3-85n03", "eprint_id": 86753, "eprint_status": "archive", "datestamp": "2023-08-20 03:26:15", "lastmod": "2023-10-18 20:32:39", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kenyon-C-N", "name": { "family": "Kenyon", "given": "C. N." } }, { "id": "Ryba-Gail-N", "name": { "family": "Ryba", "given": "Gail N." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Analysis of time-resolved photocurrent transients at semiconductor/liquid interfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1993 American Chemical Society. \n\nReceived: August 25, 1993. \n\nWe are indebted to Dr. S. Gottesfeld of Los Alamos National Laboratory and Dr. S. Feldberg of Brookhaven National Laboratory for invaluable discussions regarding the equivalent circuit models discussed herein, Dr. J. R. Winkler for his assistance with the data collection and analysis programs, Prof. H. Martel of Caltech for aid in the circuit analysis, and Profs. H. Gerischer and F. Anson for several helpful discussions regarding this work. We also acknowledge the Department of Energy, Office of Basic Energy Sciences, for their generous support of this work.", "abstract": "Small signal photocurrent transients have been measured for n-Si/CH\u2083OH-Me_2Fc^(+/0)/Pt, n-Si/Au/CH\u2083OH-Me\u2082Fc^(+/0)/Pt, n-Si/Pt/NaOH(aq)/Ni(OH)\u2082/Ni, n-TiO\u2082/NaOH(aq)/Ni(OH)\u2082/Ni, and n-TiO\u2082/NaOH(aq)-Fe(CN)\u2086^(3-/4-)/Pt cells. Even though the radio-frequency and microwave conductivity signals for photoexcited n-Si/CH\u2083OH-Me\u2082Fc^(+/0) contacts persist for > 100 \u00b5s, the photocurrent transients for these interfaces decayed in <10 \u00b5s and were limited by the series resistance of the cell in combination with the space-charge capacitance of the semiconductor. An equivalent circuit model is presented and physically justified in order to explain this behavior. The model is also used to elucidate the conditions under which photocurrent transients at semiconductor electrodes can be expected to yield information regarding the faradaic charge-transfer rate across the semiconductor/liquid interface.", "date": "1993-12-09", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "97", "number": "49", "publisher": "American Chemical Society", "pagerange": "12928-12936", "id_number": "CaltechAUTHORS:20180601-144522043", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180601-144522043", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "other_numbering_system": { "items": [ { "id": "8852", "name": "Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/j100151a048", "resource_type": "article", "pub_year": "1993", "author_list": "Kenyon, C. N.; Ryba, Gail N.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/q4nqd-f9x16", "eprint_id": 121029, "eprint_status": "archive", "datestamp": "2023-08-22 09:32:09", "lastmod": "2023-10-18 18:07:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "The Caltech chemistry animation project", "ispublished": "pub", "full_text_status": "public", "keywords": "Education; General Chemistry", "note": "\u00a9 1993 American Chemical Society and Division of Chemical Education, Inc. \n\nMembers of the advisory group are; J. Barton, H. Gray, D. Goodstein, P. Bjorkman, and D. Dougherty. The author is grateful for their insight and valuable contributions. \n\nThe project has received partial support from the National Science Foundation grant DUE-9113694, the Howard Hughes Medical Foundation, the Stauffer Foundation, and the Beckman Institute. Donations of software and hardware by Sony, IBM, Biosym, and Thomson Digital Image are appreciated. The author also thanks JPL for use of their video facilities.", "abstract": "The Caltech Chemistry Animation Project utilizes broadcast quality computer graphics to develop teaching tools for the visualization of chemistry. The impetus for this project is quite simple: visualization is an integral part of the chemistry curriculum. Orbitals, chemical reactions, stereochemistry, atomic shapes, sigma vs. pi bonding, inversion during nucleophilic substitution, chirality, dynamics, the solid state, and a host of other basic concepts are inherently difficult for many students to visualize. Our goal is to use the highest available video and special effects technology to prepare stunning images that can be used as effective teaching tools in a wide variety of classroom settings.", "date": "1993-09", "date_type": "published", "publication": "Journal of Chemical Education", "volume": "70", "number": "9", "publisher": "American Chemical Society, Division of Chemical Education", "pagerange": "739", "id_number": "CaltechAUTHORS:20230419-953316000.19", "issn": "0021-9584", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953316000.19", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DUE-9113694" }, { "agency": "Howard Hughes Medical Institute (HHMI)" }, { "agency": "Stauffer Foundation" }, { "agency": "Caltech Beckman Institute" } ] }, "doi": "10.1021/ed070p739", "resource_type": "article", "pub_year": "1993", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/n6y40-k6p77", "eprint_id": 121033, "eprint_status": "archive", "datestamp": "2023-08-22 09:28:37", "lastmod": "2023-10-18 18:07:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bansal-Ashish", "name": { "family": "Bansal", "given": "Ashish" } }, { "id": "Tan-Ming-X", "name": { "family": "Tan", "given": "Ming X." } }, { "id": "Tufts-Bruce-J", "name": { "family": "Tufts", "given": "Bruce J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Distinguishing between buried semiconductor/metal contacts and hybrid semiconductor/metal/liquid contacts at n-gallium arsenide/potassium hydroxide-selenium (Se^(-/2-))(aq) junctions", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1993 American Chemical Society. \n\nWe thank the Department of Energy, Office of Basic Energy Sciences, for their generous support of this work. We acknowledge stimulating discussions with Prof. R. Memming and thank S. Halsell of Caltech for assistance with the electrode photographs. We also are grateful to Dr. A. J. Nozik of NREL for forwarding a preprint of time-resolved studies of GaAs/liquid contacts.", "abstract": "The current-voltage properties of n-GaAs photoanodes have been evaluated in KOH-Se^(-/2-)(aq), CH3CN-Fc^(+/0), and CH\u2083CN-MV^(2+/+) solutions. Chemisorption of transition-metal ions (Rh\u1d35\u1d35\u1d35, Co\u1d35\u1d35\u1d35, Ru\u1d35\u1d35\u1d35, Os\u1d35\u1d35\u1d35) onto n-GaAs has been shown previously to effect improved photoanode behavior for n-GaAs/KOH-Se^(-/2-)(aq) contacts, but it is not clear whether the chemisorbed metal forms a buried semiconductor/metal junction or results in a hybrid semiconductor/metal/liquid contact. After chemisorption of transition-metal ions, n-GaAs photoanodes displayed different open circuit voltages in contact with each electrolyte solution investigated. The role of the chemisorbed metal in the n-GaAs/M/KOH-Se^(-/2-)(aq) system is, therefore, best described as catalyzing interfacial charge transfer at the semiconductor/liquid interface, as opposed to establishing a semiconductor/metal or semiconductor/insulator/metal contact that is exposed to, but not influenced by, the electrolyte solution.", "date": "1993-07-15", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "97", "number": "28", "publisher": "American Chemical Society", "pagerange": "7309-7315", "id_number": "CaltechAUTHORS:20230419-953364000.24", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953364000.24", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "other_numbering_system": { "items": [ { "id": "8793", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/j100130a031", "resource_type": "article", "pub_year": "1993", "author_list": "Bansal, Ashish; Tan, Ming X.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/gmfef-kv220", "eprint_id": 68145, "eprint_status": "archive", "datestamp": "2023-08-20 02:49:42", "lastmod": "2023-10-19 22:10:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jozefiak-Thomas-H", "name": { "family": "Jozefiak", "given": "Thomas H." } }, { "id": "Ginsburg-Eric-J", "name": { "family": "Ginsburg", "given": "Eric J." } }, { "id": "Gorman-Christopher-B", "name": { "family": "Gorman", "given": "Christopher B." }, "orcid": "0000-0001-7367-2965" }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "R. H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Voltammetric characterization of soluble polyacetylene derivatives obtained from the ring-opening metathesis polymerization (ROMP) of substituted cyclooctatetraenes", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 1993 American Chemical Society. \n\nWe acknowledge the Office of Naval Research (R.H.G.) and the National Science Foundation (N.S.L. Grant CHE-8814694; R.H.G. and N.S.L. joint, Grant CHE-9202583) for support of this work. We also wish to thank the IBM Corp. (E.J.G.), the American Chemical Society Division of Organic Chemistry (C.B.G.), and Smith Kline & French Laboratories (C.B.G.) for research fellowships. We also thank Professor F. C. Anson for helpful discussions and the reviewers for suggestions regarding the possible effects of Fermi level shifts on the absorption spectra of the polyenes.", "abstract": "High molecular weight, amorphous, partially substituted polyacetylenes (poly-RCOT) have been prepared using the ring-opening metathesis polymerization of substituted cyclooctatetraenes. Spin-cast films of these polymers yielded unusually sharp, well-defined, reversible electrochemistry for oxidative and reductive doping processes. As the substituent on the polymer chain was varied (R = alkyl, tert-butoxy, trimethylsilyl, and p-X-phenyl), the potentials for oxidative and reductive doping changed by 0.3 V. In addition, the separation between the oxidative and reductive doping processes varied from 1.66 V to >2.0 V. Coulometry suggested that the reversible doping step represented a transfer of 1 electron for every 13-15 double bonds of the polymer. In contrast, the electrochemistry of predominantlycis poly-RCOT films was irreversible, and indicated the presence of an electrochemical cis-trans isomerization on the first voltammetric sweep through either reductive or oxidative doping. Spectroelectrochemical studies indicated that the electrochemically doped poly-RCOT materials (R = sec-butyl, (CH\u2083)\u2083Si) possessed mid-gap transitions at energies of 0.8-0.9 eV. The redox chemistry of the soluble, poly-RCOT (R = sec-butyl, (CH\u2083)\u2083Si) species in CH\u2082C1\u2082 solution was also investigated. Voltammetric studies showed that both the reductive and oxidative doping processes were chemically irreversible, and indicated that the dissolved polymers were electroactive over a wide range of potentials.", "date": "1993-06-02", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "115", "number": "11", "publisher": "American Chemical Society", "pagerange": "4705-4713", "id_number": "CaltechAUTHORS:20160616-173842676", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160616-173842676", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)" }, { "agency": "NSF", "grant_number": "CHE-8814694" }, { "agency": "NSF", "grant_number": "CHE-9202583" }, { "agency": "IBM" }, { "agency": "American Chemical Society Division of Organic Chemistry" }, { "agency": "Smith Kline & French Laboratories" } ] }, "other_numbering_system": { "items": [ { "id": "8645", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "resource_type": "article", "pub_year": "1993", "author_list": "Jozefiak, Thomas H.; Ginsburg, Eric J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/khe3k-3py29", "eprint_id": 121030, "eprint_status": "archive", "datestamp": "2023-08-22 09:12:02", "lastmod": "2023-10-18 18:07:25", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kumar-Amit", "name": { "family": "Kumar", "given": "Amit" } }, { "id": "Willisch-Wolf-Christian-A", "name": { "family": "Wilisch", "given": "Wolf Christian A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "The electrical properties of semiconductor/metal, semiconductor/liquid, and semiconductor/conducting polymer contacts", "ispublished": "pub", "full_text_status": "public", "keywords": "Electrical and Electronic Engineering; Physical and Theoretical Chemistry; Condensed Matter Physics; General Chemical Engineering; Electronic, Optical and Magnetic Materials", "note": "\u00a9 1993 Informa.", "abstract": "Critical comparisons are drawn between the basic electrical properties of semiconductor/metal, semiconductor/liquid, and semiconductor/conducting polymer junctions. A theoretical model is developed to describe the basic current-voltage properties of semiconductor contacts, with emphasis on the contrasts between ideal and observed behavior. Using the concepts from this model, the characteristics of a variety of semiconductor contacts are evaluated. The discussion focuses on the following semiconductors: Si, GaAs, InP, and II-VI compounds based on the Cd-(chalcogenide) materials.", "date": "1993-01", "date_type": "published", "publication": "Critical Reviews in Solid State and Materials Sciences", "volume": "18", "number": "4", "publisher": "Informa UK Limited", "pagerange": "327-353", "id_number": "CaltechAUTHORS:20230419-953328000.21", "issn": "1040-8436", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953328000.21", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1080/10408439308243731", "resource_type": "article", "pub_year": "1993", "author_list": "Kumar, Amit; Wilisch, Wolf Christian A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/g51f6-qk849", "eprint_id": 117438, "eprint_status": "archive", "datestamp": "2023-08-20 02:13:41", "lastmod": "2024-01-15 21:28:08", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kesselman-J-M", "name": { "family": "Kesselman", "given": "J. M." } }, { "id": "Kumar-A", "name": { "family": "Kumar", "given": "A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Fundamental Photoelectrochemistry of TiO\u2082 and SrTiO\u2083 Applied to Environmental Problems", "ispublished": "unpub", "full_text_status": "public", "abstract": "[no abstract]", "date": "1993", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20221017-164824313", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221017-164824313", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Ollis-D-F", "name": { "family": "Ollis", "given": "D. F." } }, { "id": "Alekabi-H", "name": { "family": "Alekabi", "given": "H." } } ] }, "resource_type": "book_section", "pub_year": "1993", "author_list": "Kesselman, J. M.; Kumar, A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/32kwb-sdv62", "eprint_id": 121032, "eprint_status": "archive", "datestamp": "2023-08-22 08:54:54", "lastmod": "2023-10-23 16:52:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Collman-J-P", "name": { "family": "Collman", "given": "James P." } }, { "id": "Wagenknecht-Paul-S", "name": { "family": "Wagenknecht", "given": "Paul S." }, "orcid": "0000-0001-8698-073X" }, { "id": "Hutchison-James-E", "name": { "family": "Hutchison", "given": "James E." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Lopez-Michel-Angel", "name": { "family": "Lopez", "given": "Michel Angel" } }, { "id": "Guilard-Roger", "name": { "family": "Guilard", "given": "Roger" } }, { "id": "L'Her-Maurice", "name": { "family": "L'Her", "given": "Maurice" } }, { "id": "Bothner-By-Aksel-A", "name": { "family": "Bothner-By", "given": "Aksel A." } }, { "id": "Mishra-P-K", "name": { "family": "Mishra", "given": "P. K." } } ] }, "title": "Dihydrogen complexes of metalloporphyrins: characterization and catalytic hydrogen oxidation activity", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1993 American Chemical Society. \n\nWe thank Dr. Robert Hembre for helpful discussions. We thank the National Science Foundation, National Institutes of Health, and the Gas Research Institute for financial support. The 620-MHz NMR spectra were obtained at the NMR Facility for Biomedical Studies, supported by the National Institutes of Health Grant RR00292. This is contribution No. 8521 from the Division of Chemistry and Chemical Engineering, California Institute of Technology.", "abstract": "A series of monometallic dihydrogen complexes of the type M(OEP)(L)(H\u2082) (M = Ru, Os; L = THF, *Im) was synthesized and characterized by \u00b9H NMR. The H-H bond length was found to increase when Os was replaced by Ru or when *Im was replaced by THF. The bond distances (as determined by T\u2081) range from 0.92 to 1.18 \u00c1. The first example of a bimetallic bridging dihydrogen complex, Ru\u2082(DPB)(*Im)\u2082(H\u2082), was also prepared. The H\u2082 ligand is simultaneously bound to both Ru-metal centers. High-field \u00b9H NMR experiments (620 MHz) revealed a -7.37 Hz dipolar splitting of the H\u2082 ligand for this complex. Analysis of this splitting suggests that the H\u2082 ligand is bound with the H-H axis perpendicular to the Ru-Ru axis. These complexes were examined as possible catalysts for the oxidation of dihydrogen through prior heterolytic activation of H\u2082. Only Ru(OEP)(THF)(H\u2082) can be conveniently deprotonated. Ru(OEP)(THF)(H\u2082) is also implicated in the Ru-\n(OEP)(THF)\u2082 catalyzed isotopic exchange between H\u2082 and D\u2082O in THF solution. Each step for this mechanism has been elucidated. We have also achieved catalytic dihydrogen oxidation using [Ru(OEP)]\u2082 adsorbed onto graphite. Two mechanisms for this ruthenium porphyrin catalyzed dihydrogen oxidation are presented and compared.", "date": "1992-07-02", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "114", "number": "14", "publisher": "American Chemical Society", "pagerange": "5654-5664", "id_number": "CaltechAUTHORS:20230419-953343000.23", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953343000.23", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "NIH", "grant_number": "RR00292" }, { "agency": "Gas Research Institute" } ] }, "other_numbering_system": { "items": [ { "id": "8521", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/ja00040a027", "resource_type": "article", "pub_year": "1992", "author_list": "Collman, James P.; Wagenknecht, Paul S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wehk6-eve56", "eprint_id": 121038, "eprint_status": "archive", "datestamp": "2023-08-22 08:54:50", "lastmod": "2023-10-18 18:07:36", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Collman-J-P", "name": { "family": "Collman", "given": "James P." } }, { "id": "Wagenknecht-Paul-S", "name": { "family": "Wagenknecht", "given": "Paul S." }, "orcid": "0000-0001-8698-073X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Hydride transfer and dihydrogen elimination from osmium and ruthenium metalloporphyrin hydrides: model processes for hydrogenase enzymes and the hydrogen electrode reaction", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1992 American Chemical Society. \n\nWe acknowledge Professor Robert Hembre for first suggesting that we analyze these compounds for hydrogenase enzyme reactivity. We thank Professor Royce Murray, Professor Jack Norton, and Jim Hutchison for helpful suggestions. Dr. Scott Bohle and Cindy Kellen are thanked for their help in the preparation of this paper. We thank the National Science Foundation, the National Institutes of Health, and the Gas Research Institute for financial support. This is contribution No. 8520 from the Division of Chemistry and Chemical Engineering, California Institute of Technology.", "abstract": "A series of metalloporphyrin hydride complexes of the type K[M(Por)(L)(H)] (M = Ru, Os; Por = OEP, TMP; L = THF, *Im, PPh\u2083, pyridine) has been synthesized by stoichiometric protonation of the corresponding K\u2082[M(Por)], followed by addition of L. The addition of excess acids to these hydrides resulted in the elimination of dihydrogen. The kinetics showed no evidence for a bimolecular mechanism for this process and suggest simple protonation of the metal-hydride bond followed by dihydrogen loss. One-electron oxidation of the metal hydrides also resulted in dihydrogen formation. The kinetics of the oxidatively induced hydrogen evolution step from K[Ru(OEP) (THF) (H)] were examined and indicate a bimolecular mechanism in which two metal hydrides reductively eliminate one dihydrogen molecule. The rate constant was determined to be 88 \u00b1 14 M\u207b\u00b9 s\u207b\u00b9. These reaction mechanisms are discussed in the context of designing bimetallic proton reduction catalysts. The\nmetal hydride K[Ru(OEP)(THF)(H)], was also synthesized by heterolytic activation of H\u2082. This hydride is a good one-electron reductant (\u20141.15 V vs FeCp\u2082) and is capable of reducing, by hydride transfer, the NAD\u207a analogue, 1-benzyl-N,N-diethylnicotinamide. This nicotinamide reduction by a hydride formed from heterolytic dihydrogen activation is suggested as the mechanism for hydrogenase enzymes.", "date": "1992-07-01", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "114", "number": "14", "publisher": "American Chemical Society", "pagerange": "5665-5673", "id_number": "CaltechAUTHORS:20230419-953407000.30", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953407000.30", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "NIH" }, { "agency": "Gas Research Institute" } ] }, "other_numbering_system": { "items": [ { "id": "8520", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/ja00040a028", "resource_type": "article", "pub_year": "1992", "author_list": "Collman, James P.; Wagenknecht, Paul S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/n7vzq-4s030", "eprint_id": 121037, "eprint_status": "archive", "datestamp": "2023-08-22 08:43:00", "lastmod": "2023-10-18 18:07:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kumar-Amit", "name": { "family": "Kumar", "given": "Amit" } }, { "id": "Santangelo-Patrick-G", "name": { "family": "Santangelo", "given": "Patrick G." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electrolysis of water at strontium titanate (SrTiO\u2083) photoelectrodes: distinguishing between the statistical and stochastic formalisms for electron-transfer processes in fuel-forming photoelectrochemical systems", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1992 American Chemical Society. \n\nWe thank the National Science Foundation, Grant CHE-8814263, for support of this work. A.K. also is grateful to the U.S. Department of Education for a graduate fellowship.", "abstract": "Conventional photoelectrochemical and photovoltaic theory predicts a light intensity threshold for sustaining the net electrolysis of water using semiconductor electrodes, but a stochastic charge-transfer formalism for photoelectrolysis reactions does not predict such threshold behavior. This work examines the theoretical and experimental aspects of light-assisted water electrolysis using n-type SrTiO\u2083/H\u2082O interfaces. A theoretical framework, based upon simple chemical kinetic considerations, has been formulated to describe the behavior of such photoelectrosynthetic cells. Experiments conducted on the n-SrTiO\u2083/5.0 M NaOH(aq)/Pt photoelectrosynthetic cell have revealed a threshold in the short-circuit electrolysis current at 5 X 10\u207b\u2075 W/cm\u00b2 of 325-nm illumination. Additional theory and experiments have provided insight into relationships between two-electrode regenerative photoelectrochemical cells, two-electrode photoelectrosynthetic cells, and three-electrode potentiostatic cells. These experiments and theory indicate that a conventional chemical kinetic treatment of interfacial electron-transfer rates appears to be sufficient to describe the photoelectrochemical behavior of SrTiO\u2083 and TiO\u2082/aqueous junctions.", "date": "1992-01-23", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "96", "number": "2", "publisher": "American Chemical Society", "pagerange": "834-842", "id_number": "CaltechAUTHORS:20230419-953397000.29", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953397000.29", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-8814263" }, { "agency": "Department of Education" } ] }, "other_numbering_system": { "items": [ { "id": "8471", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/j100181a057", "resource_type": "article", "pub_year": "1992", "author_list": "Kumar, Amit; Santangelo, Patrick G.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/s98my-d8p49", "eprint_id": 2419, "eprint_status": "archive", "datestamp": "2023-08-22 08:35:49", "lastmod": "2023-10-13 23:23:07", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lunt-Sharon-R", "name": { "family": "Lunt", "given": "Sharon R." } }, { "id": "Ryba-Gail-N", "name": { "family": "Ryba", "given": "Gail N." } }, { "id": "Santangelo-Patrick-G", "name": { "family": "Santangelo", "given": "Patrick G." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Chemical studies of the passivation of GaAs surface recombination using sulfides and thiols", "ispublished": "pub", "full_text_status": "public", "keywords": "GALLIUM ARSENIDES; PASSIVATION; RECOMBINATION; SURFACE REACTIONS; THIOLS; PH VALUE; PHOTOELECTRON SPECTROSCOPY; DONORS; SULFUR; ELECTRICAL PROPERTIES; PHOTOLUMINESCENCE", "note": "\u00a9 1991 American Institute of Physics. \n\n(Received 3 April 1991; accepted 3 September 1991) \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, for funding the research. S.R.L. also thanks the Department of Education for a graduate fellowship. We wish to thank Dr. E.-H. Cirlin of Hughes Research Laboratories, and Dr. M. Hecht and Dr. R. Vasquez of Jet Propulsion Laboratories for the use of XPS equipment and for numerous helpful discussions. This paper is Contribution #8420 from the Caltech Division of Chemistry and Chemical Engineering.\n\nPublished - LUNjap91.pdf
", "abstract": "Steady-state photoluminescence, time-resolved photoluminescence, and x-ray photoelectron spectroscopy have been used to study the electrical and chemical properties of GaAs surfaces exposed to inorganic and organic sulfur donors. Despite a wide variation in S\u00b2\u207b(aq) concentration, variation of the pH of aqueous HS\u2013solutions had a small effect on the steady-state n-type GaAs photoluminescence intensity, with surfaces exposed to pH = 8, 0.1-M HS\u207b(aq) solutions displaying comparable luminescence intensity relative to those treated with pH = 14, 1.0-M Na\u2082S\u00b79H\u2082O(aq). Organic thiols (R-SH, where R=\u2013CH\u2082CH\u2082SH or \u2013C\u2086H\u2084Cl) dissolved in nonaqueous solvents were found to effect increases in steady-state luminescence yields and in time-resolved luminescence decay lifetimes of (100)-oriented GaAs. X-ray photoelectron spectroscopy showed that exposure of GaAs surfaces to these organic systems yielded thiols bound to the GaAs surface, but such exposure did not remove excess elemental As and did not form a detectable As\u2082S\u2083 overlayer on the GaAs. These results imply that complete removal of As\u2070 or formation of monolayers of As\u2082S\u2083 is not necessary to effect a reduction in the recombination rate at etched GaAs surfaces. Other compounds that do not contain sulfur but that are strong Lewis bases, such as methoxide ion, also improved the GaAs steady-state photoluminescence intensity. These results demonstrate that a general class of electron-donating reagents can be used to reduce nonradiative recombination at GaAs surfaces, and also imply that prior models focusing on the formation of monolayer coverages of As\u2082S\u2083 and Ga\u2082S\u2083 are not adequate to describe the passivating behavior of this class of reagents. The time-resolved, high level injection experiments clearly demonstrate that a shift in the equilibrium surface Fermi-level energy is not sufficient to explain the luminescence intensity changes, and confirm that HS\u207b and thiol-based reagents induce substantial reductions in the surface recombination velocity through a change in the GaAs surface state recombination rate.", "date": "1991-12-15", "date_type": "published", "publication": "Journal of Applied Physics", "volume": "70", "number": "12", "publisher": "American Institute of Physics", "pagerange": "7449-7467", "id_number": "CaltechAUTHORS:LUNjap91", "issn": "0021-8979", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:LUNjap91", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Department of Education" } ] }, "other_numbering_system": { "items": [ { "id": "8420", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1063/1.349741", "primary_object": { "basename": "LUNjap91.pdf", "url": "https://authors.library.caltech.edu/records/s98my-d8p49/files/LUNjap91.pdf" }, "resource_type": "article", "pub_year": "1991", "author_list": "Lunt, Sharon R.; Ryba, Gail N.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ceawh-6q767", "eprint_id": 117428, "eprint_status": "archive", "datestamp": "2023-08-20 00:40:09", "lastmod": "2024-01-15 21:28:05", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Blumenthal-Rik", "name": { "family": "Blumenthal", "given": "Rik" }, "orcid": "0000-0003-1709-9345" }, { "id": "Penner-Reginald-M", "name": { "family": "Penner", "given": "Reginald M." }, "orcid": "0000-0003-2831-3028" }, { "id": "Heben-Michael-J", "name": { "family": "Heben", "given": "Michael J." }, "orcid": "0000-0002-3788-3471" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Pulse Induced Nanolithography of Graphite in H\u2082O: A Road to Chemical Linkages to the Surface?", "ispublished": "unpub", "full_text_status": "public", "abstract": "The effects of tip\u2010sample bias pulses while within tunneling distances have been investigated for graphite surfaces in contact with dry fluids, fluids containing water, and liquid water. In dry ambients, no surface modifications were observed at pulse voltages in excess of \u00b110 V. In fluids containing water, bias pulses exceeding a threshold voltage produced pits in the graphite surface, but the threshold voltage exhibited daily fluctuations of as much as 5 V. At the threshold for surface modification, a typical pit was found to have a diameter of approximately 30 \u00c5 and was 3 \u00c5 in depth. The diameter and depth of the pits increased with pulse amplitude above the observed threshold. In pure water, a reproducible bias pulse threshold of 4.0\u00b10.2 V was observed, and such pulses yielded dome\u2010like features on the surface. The domed features were found to have a diameter of \u223c7 \u00c5 and were \u223c1.5 \u00c5 high. Bias pulses greater than 4.0 V were found to produce pits of approximately the same diameter as those produced in humid gases. Although little is known at present about the chemical structure of the domed features, their conversion into pits with subsequent bias pulses of only 0.2 V suggests that they are structural intermediates in the pit formation process. This hypothesis implies that the domed features may be vulnerable to chemical attack; consequently, the domes may present a viable route to the localized, designed, chemical functionalization of a graphite surface.", "date": "1991-12-05", "date_type": "published", "publisher": "American Institute of Physics", "place_of_pub": "Melville, NY", "pagerange": "248-252", "id_number": "CaltechAUTHORS:20221017-617232800.1", "isbn": "978-0-88318-816-3", "book_title": "Scanned probe microscopy", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221017-617232800.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "8378", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "contributors": { "items": [ { "id": "Wickramasinghe-H-Kumar", "name": { "family": "Wickramasinghe", "given": "H. Kumar" } } ] }, "doi": "10.1063/1.41418", "resource_type": "book_section", "pub_year": "1991", "author_list": "Blumenthal, Rik; Penner, Reginald M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/n1bwb-qjq78", "eprint_id": 30206, "eprint_status": "archive", "datestamp": "2023-08-20 00:26:22", "lastmod": "2023-10-17 15:33:04", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "An Analysis of Charge Transfer Rate Constants for Semiconductor/Liquid Interfaces", "ispublished": "pub", "full_text_status": "restricted", "keywords": "photoelectrochemistry, semiconductor kinetics, heterogeneous\nelectron transfer", "note": "\u00a9 1991 Annual Reviews. \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, and the National Science Foundation for support for semiconductor electrochemistry during the preparation of this work. We are also indebted to Drs. C. A. Koval, R. L D. Miller, A. B. Ellis, and A. J. Nozik for helpful comments and a critical reading of the manuscript before publication.", "abstract": "Although a variety of heterogeneous rate constant data is now available\nat metal electrodes (1, 2), relatively little kinetic information has been\nobtained at semiconductor electrodes (3). Several recent experiments have\nindicated that the rates of charge transfer at semiconductor/liquid interfaces\ncan vary from picoseconds to milliseconds (4-7); thus, a wide range\nof timescales are apparently important in the dynamics of semiconductor\nphotoelectrochemistry. The experiments that yield long decay times have\noften been interpreted in the same general framework as those that yield\nshort carrier lifetimes; yet, the various types of kinetic experiments actually\ndiffer substantially in their design and kinetic interpretation. This review\npresents a unified treatment of the kinetics of the various charge transfer\nexperiments and presents estimates of the timescales that can be expected\nfor these reactions.", "date": "1991-10", "date_type": "published", "publication": "Annual Review of Physical Chemistry", "volume": "42", "publisher": "Annual Reviews", "pagerange": "543-580", "id_number": "CaltechAUTHORS:20120419-134352971", "issn": "0066-426X", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120419-134352971", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "NSF" } ] }, "doi": "10.1146/annurev.physchem.42.1.543", "resource_type": "article", "pub_year": "1991", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/vjq7z-5qn43", "eprint_id": 121040, "eprint_status": "archive", "datestamp": "2023-08-22 08:24:08", "lastmod": "2023-10-18 18:07:39", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kumar-Amit", "name": { "family": "Kumar", "given": "Amit" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Further mechanistic studies of n-type silicon photoelectrodes: behavior in contact with methanol-dimethylferrocene^(+/0) and in contact with aqueous electrolytes", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1991 American Chemical Society. \n\nWe acknowledge the National Science Foundation, Grant CHE-8814694, for support of this work. A.K. acknowledges the Department of Education for a research fellowship, and the authors are grateful to Prof. H. Tsubomura for helpful discussions and for generously providing a metalized Si sample for use in our work.", "abstract": "Mechanistic studies of n-Si photoelectrodes have been conducted using aqueous and nonaqueous electrolytes. In contact with the CH\u2083OH-dimethylferrocene (Me\u2082Fc)^(+/0) electrolyte, the dark current and open-circuit voltage (V_(oc)) were not dependent on acceptor concentration for [Me\u2082Fc\u207a] < 0.010 M and were only weakly dependent on acceptor concentration for [Me\u2082Fc\u207a] 0.010 M. For [Me\u2082Fc\u207a] between 0.3 mM and 0.050 M, the temperature dependence of V_(oc) indicated that bulk-diffusion/recombination was the rate-limiting recombination process. In all of these experiments, conventional Shockley diode theory provided an excellent description of the solid/liquid junction properties. In a related set of experiments, HF-etched n-Si photoelectrodes ((100)- and (11l)-oriented samples) and n-Si samples that had been metalized by several different methods\nall showed passivation in contact with Fe(CN)\u2086^(3-/4-) (aq) Br\u2082/Br\u207b(aq) electrolytes. For several metalized Si samples, etches that had been reported to produce metal islands on the Si surface instead yielded Si surfaces free of metal. All Si samples that had been metalized by filament evaporation yielded I-V behavior in contact with the CH\u2083OH-Me\u2082Fc^(+/0) redox system that was characteristic of a pinned surface Fermi level, even for coverages of metal as low as 9 \u00c2. This indicates that proposed metal-insulator-semiconductor junctions with anomalously high barrier heights are difficult to obtain by such metalization and etching methods.", "date": "1991-09-05", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "95", "number": "18", "publisher": "American Chemical Society", "pagerange": "7021-7028", "id_number": "CaltechAUTHORS:20230419-953419000.33", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953419000.33", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-8814694" }, { "agency": "Department of Education" } ] }, "other_numbering_system": { "items": [ { "id": "8395", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/j100171a055", "resource_type": "article", "pub_year": "1991", "author_list": "Kumar, Amit and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/59g6h-4c321", "eprint_id": 12053, "eprint_status": "archive", "datestamp": "2023-08-22 08:09:52", "lastmod": "2023-10-17 16:29:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lunt-Sharon-R", "name": { "family": "Lunt", "given": "Sharon R." } }, { "id": "Santangelo-Patrick-G", "name": { "family": "Santangelo", "given": "Patrick G." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Passivation of GaAs surface recombination with organic thiols", "ispublished": "pub", "full_text_status": "public", "keywords": "GALLIUM ARSENIDES, SURFACES, THIOLS, PASSIVATION, RECOMBINATION, PHOTOLUMINESCENCE, PHOTOELECTRON SPECTROSCOPY", "note": "\u00a9 1991 American Vacuum Society. \n\nReceived 30 January 1991; accepted 22 March 1991. \n\nWe thank the Department of Energy, Office of Basic Energy Sciences, for support of this work. We are grateful to C. Sandroff and E. Yablonovitch of Bellcore for several helpful discussions, to H. McMillan of Varian Associates for supplying the GaAs/AlGaAs sample used in this work, and to R.P. Vasquez of JPL and E.-H. Cirlin of Hughes Research Laboratories for use of the XPS instrumentation. This is Contribution No. 8392 from the Caltech Division of Chemistry and Chemical Engineering.\n\nPublished - LUNjvstb91.pdf
", "abstract": "Exposure of GaAs crystals to solutions of organic thiols resulted in substantial reductions in nonradiative GaAs surface recombination rates. This process yielded improvements in steady state photoluminescence signals that were comparable to those obtained after a Na\u2082S\u00b79H\u2082O (aqueous) treatment. Use of a series of thiols indicated that the chemically important surface electrical trap levels behaved as a polarizable, electron deficient center. X-ray photoelectron spectroscopy indicated that the thiols did not remove excess As\u2070 nor form detectable levels of As\u2082S\u2083-like phases, implying that neither of these factors is required for effective surface passivation chemistry.", "date": "1991-07", "date_type": "published", "publication": "Journal of Vacuum Science and Technology B", "volume": "9", "number": "4", "publisher": "American Vacuum Society", "pagerange": "2333-2336", "id_number": "CaltechAUTHORS:LUNjvstb91", "issn": "1071-1023", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:LUNjvstb91", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "other_numbering_system": { "items": [ { "id": "8392", "name": "Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1116/1.585743", "primary_object": { "basename": "LUNjvstb91.pdf", "url": "https://authors.library.caltech.edu/records/59g6h-4c321/files/LUNjvstb91.pdf" }, "resource_type": "article", "pub_year": "1991", "author_list": "Lunt, Sharon R.; Santangelo, Patrick G.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fdyhk-f1v24", "eprint_id": 121041, "eprint_status": "archive", "datestamp": "2023-08-22 08:06:11", "lastmod": "2023-10-23 19:31:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gorman-Christopher-B", "name": { "family": "Gorman", "given": "C. B." } }, { "id": "Ginsburg-Eric-J", "name": { "family": "Ginsburg", "given": "E. J." } }, { "id": "Sailor-Michael-J", "name": { "family": "Sailor", "given": "M. J." }, "orcid": "0000-0002-4809-9826" }, { "id": "Moore-J-S", "name": { "family": "Moore", "given": "J. S." } }, { "id": "Jozefiak-T-H", "name": { "family": "Jozefiak", "given": "T. H." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "R. H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Marder-S-R", "name": { "family": "Marder", "given": "S. R." } }, { "id": "Perry-J-W", "name": { "family": "Perry", "given": "J. W." } } ] }, "title": "Substituted polyacetylenes through the ring-opening metathesis polymerization (ROMP) of substituted cyclooctatetraenes: A route into soluble polyacetylene", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Metals and Alloys; Mechanical Engineering; Mechanics of Materials; Condensed Matter Physics; Electronic, Optical and Magnetic Materials", "note": "\u00a9 1991 Published by Elsevier. \n\nThe research described in this paper was performed in part by the Jet Propulsion Laboratory, California Institute of Technology, as part of its Center for Space Microelectronics Technology which is supported by the Strategic Defense Initiative Organization, Innovative Science and Technology Office through an agreement with the National Aeronautics and Space Administration (NASA). RHG acknowledges financial support from the Office of Naval Research, NSL acknowledges financial support from NSF. SRM thanks the National Research Council and NASA for a Resident Research Associateship at JPL. EJG thanks IBM for a research fellowship. CBG thanks the JPL for a research fellowship. JSM thanks the NSF for a postdoctoral fellowship.", "abstract": "Ring-Opening metathesis polymerization (ROMP) of substituted cyclooctatetraenes (COT) produces polyacetylenes that are substituted, on the average, every eight carbon atoms. In several cases these polymers are soluble and highly conjugated. The effect of the side group on the optical, electrical and materials properties of the polymer will be discussed.", "date": "1991-05-06", "date_type": "published", "publication": "Synthetic Metals", "volume": "41", "number": "3", "publisher": "Elsevier", "pagerange": "1033-1038", "id_number": "CaltechAUTHORS:20230419-953429000.34", "issn": "0379-6779", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953429000.34", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA/JPL/Caltech" }, { "agency": "Strategic Defense Initiative Organization (SDIO)" }, { "agency": "Office of Naval Research (ONR)" }, { "agency": "NSF Postdoctoral Fellowship" }, { "agency": "National Research Council" }, { "agency": "IBM" } ] }, "doi": "10.1016/0379-6779(91)91550-t", "resource_type": "article", "pub_year": "1991", "author_list": "Gorman, C. B.; Ginsburg, E. J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hvnc5-7gf10", "eprint_id": 2422, "eprint_status": "archive", "datestamp": "2023-08-22 08:03:58", "lastmod": "2023-10-13 23:23:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Penner-Reginald-M", "name": { "family": "Penner", "given": "Reginald M." }, "orcid": "0000-0003-2831-3028" }, { "id": "Heben-Michael-J", "name": { "family": "Heben", "given": "Michael J." }, "orcid": "0000-0002-3788-3471" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Quate-Calvin-F", "name": { "family": "Quate", "given": "Calvin F." } } ] }, "title": "Mechanistic investigations of nanometer-scale lithography at liquid-covered graphite surfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "GRAPHITE; SORPTIVE PROPERTIES; LITHOGRAPHY; WATER; THRESHOLD VOLTAGE; AQUEOUS SOLUTIONS; SOLID\u2013FLUID INTERFACES; SCANNING TUNNELING MICROSCOPY", "note": "\u00a9 1991 American Institute of Physics. \n\n(Received 13 September 1990; accepted 2 January 1991) \n\nWe acknowledge the Caltech Consortium in Chemistry and Chemical Engineering; Founding Members: E. I. du Pont de Nemours, Eastman Kodak, 3M, and Shell Development Co. and the Joint Services Electronics Program for support of this work, and Dr. A. Moore of Union Carbide for a generous donation of HOPG. J. Jahanmir at QuanScan Inc. is acknowledged for assistance with Z calibration of the piezo using interferometry. The authors also thank M. Dovek and M. Kirk of Stanford University for valuable conversations regarding experimental results in gaseous ambients. This is contribution No. 8201 from the Division of Chemistry and Chemical Engineering at Caltech.\n\nPublished - PENapl91b.pdf
", "abstract": "Pulse-induced nanometer-scale lithography has been performed on graphite surfaces that were in contact with pure water or other organic liquids. Very reproducible control over the pit diameter was observed in aqueous solutions, and a well-defined voltage threshold (4.0 \u00b1 0.2 V) was also apparent. Near the threshold voltage, 7 \u00c5 diameter \u00d7 2 \u00c5 high protrusions were formed, while larger initial pulse voltages resulted in pits of diameter> ~20 \u00c5.", "date": "1991-04-01", "date_type": "published", "publication": "Applied Physics Letters", "volume": "58", "number": "13", "publisher": "American Institute of Physics", "pagerange": "1389-1391", "id_number": "CaltechAUTHORS:PENapl91b", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:PENapl91b", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech Consortium in Chemistry and Chemical Engineering" } ] }, "other_numbering_system": { "items": [ { "id": "8201", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1063/1.104317", "primary_object": { "basename": "PENapl91b.pdf", "url": "https://authors.library.caltech.edu/records/hvnc5-7gf10/files/PENapl91b.pdf" }, "resource_type": "article", "pub_year": "1991", "author_list": "Penner, Reginald M.; Heben, Michael J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/grf69-63x87", "eprint_id": 88134, "eprint_status": "archive", "datestamp": "2023-08-19 23:48:44", "lastmod": "2024-01-14 20:29:12", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jozefiak-T-H", "name": { "family": "Jozefiak", "given": "Thomas H." } }, { "id": "Sailor-M-J", "name": { "family": "Sailor", "given": "Michael J." } }, { "id": "Ginsburg-E-J", "name": { "family": "Ginsburg", "given": "Eric J." } }, { "id": "Gorman-C-B", "name": { "family": "Gorman", "given": "Christopher B." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" } ] }, "title": "Soluble polyacetylenes derived from the ring-opening metathesis polymerization of substituted cyclooctatetraenes: electrochemical characterization and Schottky barrier devices", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1991 Society of Photo-Optical Instrumentation Engineers (SPIE). \n\nTHJ, EJG, CBG, and RHG acknowledge financial support from the Office of Naval Research. NSL and MJS acknowledge financial support from NSF grant CHE-8814694. EJG thanks IBM for a research fellowship. CBG thanks JPL for a research fellowship.\n\nPublished - 8.pdf
", "abstract": "Recent developments in ring-opening metathesis polymerization (ROMP) have enabled the synthesis of poly-cyclooctatetraene (poly-COT), a material which is isostructural to polyacetylene. This liquid-phase polymerization method allows facile construction of interfaces, films, and devices with polyacetylene-like materials. The ROMP method also allows the preparation of soluble, yet highly conjugated polyacetylene analogs from substituted cyclooctatetraenes (R-COT). The redox characteristics of R-COT polymers were investigated at electrodes modified with thin polymer films. Voltammetric methods were used to characterize the redox response, band gap, electrochemical doping, and cis-trans isomerization properties of these polyenes. We have applied poly-COT technology to the fabrication of Schottky diodes and photoelectrochemical cells, by forming poly-COT films on semiconductor surfaces. The resultant semiconductor/organic-metal interfaces behave more ideally than semiconductor contacts with conventional metals, in that changes in the work function of the conducting polymer exert a large and predictable effect on the electrical properties of the resulting Schottky diodes. Transparent films of the solution-processible polymer poly- trimethylsilyl-cyclooctatetraene (poly-TMS-COT) have been cast onto n-silicon substrates and doped with iodine to form surface barrier solar cells. These devices produce photovoltages that are much larger than can be obtained from n-silicon contacts with conventional metals.", "date": "1991-03-01", "date_type": "published", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_pub": "Bellingham, WA", "pagerange": "8-19", "id_number": "CaltechAUTHORS:20180723-120031113", "isbn": "0819405264", "book_title": "Photochemistry and Photoelectrochemistry of Organic and Inorganic Molecular Thin Films", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180723-120031113", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)" }, { "agency": "NSF", "grant_number": "CHE-8814694" }, { "agency": "IBM" }, { "agency": "JPL" } ] }, "other_numbering_system": { "items": [ { "id": "8376", "name": "Division of Chemistry and Chemical Engineering" } ] }, "contributors": { "items": [ { "id": "Lawrence-M-F", "name": { "family": "Lawrence", "given": "Marcus F." } }, { "id": "Frank-A-J", "name": { "family": "Frank", "given": "Arthur Jesse" } }, { "id": "Ramasesha-S", "name": { "family": "Ramasesha", "given": "S." } }, { "id": "Wamser-C-C", "name": { "family": "Wamser", "given": "Carl C." } } ] }, "doi": "10.1117/12.45109", "primary_object": { "basename": "8.pdf", "url": "https://authors.library.caltech.edu/records/grf69-63x87/files/8.pdf" }, "resource_type": "book_section", "pub_year": "1991", "author_list": "Jozefiak, Thomas H.; Sailor, Michael J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/59te2-e6129", "eprint_id": 57539, "eprint_status": "archive", "datestamp": "2023-08-19 23:44:40", "lastmod": "2023-10-23 17:31:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kumar-A", "name": { "family": "Kumar", "given": "Amit" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan" }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Energy option", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1991 Nature Publishing Group.", "abstract": "AT present, photovoltaic power provides an insignificant fraction of the world's energy supply. Some devoted followers of the field feel that this will change dramatically, but others feel that photovoltaics will never be a significant terrestrial power source.", "date": "1991-02-14", "date_type": "published", "publication": "Nature", "volume": "349", "number": "6310", "publisher": "Nature Publishing Group", "pagerange": "577", "id_number": "CaltechAUTHORS:20150514-143927177", "issn": "0028-0836", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150514-143927177", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1038/349577a0", "resource_type": "article", "pub_year": "1991", "author_list": "Kumar, Amit and Lewis, Nathan" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/xbfjm-89j53", "eprint_id": 121042, "eprint_status": "archive", "datestamp": "2023-08-22 08:00:28", "lastmod": "2023-10-18 18:07:42", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Casagrande-Louis-G", "name": { "family": "Casagrande", "given": "Louis G." } }, { "id": "Tufts-Bruce-J", "name": { "family": "Tufts", "given": "Bruce J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Trends in the open circuit voltage of semiconductor/liquid interfaces: studies of n-Al\u2093Ga\u2081\u208b\u2093As/CH\u2083CN-Ferrocene^(+/0) and n-Al\u2093Ga\u2081\u208b\u2093As/KOH-Se^(~/2~)(aq) Junctions", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1991 American Chemical Society. \n\nWe thank the Department of Energy, Office of Basic Energy Sciences, for support of this work. We are indebted to Dr. C. R. Lewis of Varian Associates for generously providing the n-Al\u2093Ga\u2081\u208b\u2093As alloy samples utilized in this study. We also thank Dr. B. Anspaugh of the Jet Propulsion Laboratory for performing some of the spectral irradiance measurements. N.S.L. acknowledges support as a Dreyfus Teacher-Scholar\n(1985-1990).", "abstract": "Trends in open-circuit voltage (V_(oc)), short-circuit current density (J_(sc)), and energy conversion efficiency have been determined for the n-type Al\u2093Ga\u2081\u208b\u2093As series of photoelectrodes (x = 0.0, 0.09, 0.16, 0.24, 0.31) in contact with CH\u2083CN-Ferrocene^(+/0) and KOH-Se^(~/2~)(aq) electrolytes. V_(oc) increased linearly with increases in bandgap energy (E_g) of the n-Al\u2093Ga\u2081\u208b\u2093As alloy electrodes, with \u0394V_(oc)/\u0394E_g = 0.45 \u00b1 0.04 V eV\u207b\u00b9 in CH\u2083CN and 0.41 \u00b1 0.09 V eV\u207b\u00b9 in KOH-Se^(~/2~)(aq) at a light intensity\nsufficient to provide J_(sc) = 1.0 mA cm\u00b2. J_(sc) values under solar-simulated illumination decreased monotonically with increasing bandgap energy. The relatively low value of \u0394V_(oc)/\u0394E_g implies decreases in optimal energy conversion efficiency as the mole fraction of A1 in the Al\u2093Ga\u2081\u208b\u2093As alloy is increased. This is in contrast to the behavior of the GaAs\u2093P\u2081\u208b\u2093 alloy series in the same electrolytes. The lower value of \u0394V_(oc)/\u0394E_g for n-Al\u2093Ga\u2081\u208b\u2093As also indicates that predictions of the \"common anion rule\" in solid-state barriers do not apply to this family of III\u2014V semiconductor/liquid junctions.", "date": "1991-02-07", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "95", "number": "3", "publisher": "American Chemical Society", "pagerange": "1373-1380", "id_number": "CaltechAUTHORS:20230419-953442000.36", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953442000.36", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Camille and Henry Dreyfus Foundation" } ] }, "other_numbering_system": { "items": [ { "id": "8149", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/j100156a063", "resource_type": "article", "pub_year": "1991", "author_list": "Casagrande, Louis G.; Tufts, Bruce J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/grdas-43308", "eprint_id": 68307, "eprint_status": "archive", "datestamp": "2023-08-19 23:30:59", "lastmod": "2023-10-19 22:10:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Penner-Reginald-M", "name": { "family": "Penner", "given": "R. M." }, "orcid": "0000-0003-2831-3028" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Invisible electrodes with amazing powers", "ispublished": "pub", "full_text_status": "public", "abstract": "[no abstract]", "date": "1991", "date_type": "published", "publication": "Chemistry & Industry", "volume": "65", "number": "21", "publisher": "Wiley", "pagerange": "788-791", "id_number": "CaltechAUTHORS:20160616-173859892", "issn": "2047-6329", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160616-173859892", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "article", "pub_year": "1991", "author_list": "Penner, R. M. and Lewis, N. S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/bmk1e-wx937", "eprint_id": 2423, "eprint_status": "archive", "datestamp": "2023-08-22 07:51:25", "lastmod": "2023-10-13 23:23:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kumar-Amit", "name": { "family": "Kumar", "given": "Amit" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Studies of silicon photoelectrochemical cells under high injection conditions", "ispublished": "pub", "full_text_status": "public", "keywords": "SILICON; THRESHOLD CURRENT; PHOTOCURRENTS; SILICON DIODES; PHOTOELECTROCHEMICAL CELLS; OPERATION; SEMICONDUCTOR\u2013ELECTROLYTIC CONTACTS; PHOTOCONDUCTIVITY", "note": "\u00a9 1990 American Institute of Physics. \n\n(Received 2 July 1990; accepted 21 September 1990) \n\nWe thank the National Science Foundation for support of this work. This is contribution No. 8167 from the Caltech Division of Chemistry and Chemical Engineering. We also thank Ronald A. Sinton and Richard M. Swanson of the Stanford Electronics Laboratory (Stanford, CA) for invaluable discusisons and for supplying the samples used in this study. A. K. acknowledges the Department of Education for a Research Fellowship.\n\nPublished - KUMapl90a.pdf
", "abstract": "The behavior of Si/CH\u2083OH-dimethylferrocene^(+/0) junctions has been investigated under high injection conditions. Open circuit voltages of (626\u00b15) mV were obtained at short circuit photocurrent densities of 20 mA/cm\u00b2 for samples with an n\u207a-diffused back region, point contacts on the back surface, and with a base of thickness 390 \u00b5m and a 1 ms hole lifetime. The diode quality factor and recombination current density were 1.8 \u00b1 0.1 and (2.6 \u00b1 1.5) \u00d7 10\u207b\u2078 A/cm\u00b2, respectively. These data are consistent with recombination dominated by the base and back contact regions, and not at the Si/CH\u2083OH interface.", "date": "1990-12-17", "date_type": "published", "publication": "Applied Physics Letters", "volume": "57", "number": "25", "publisher": "American Institute of Physics", "pagerange": "2730-2732", "id_number": "CaltechAUTHORS:KUMapl90a", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:KUMapl90a", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "other_numbering_system": { "items": [ { "id": "8167", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1063/1.103773", "primary_object": { "basename": "KUMapl90a.pdf", "url": "https://authors.library.caltech.edu/records/bmk1e-wx937/files/KUMapl90a.pdf" }, "resource_type": "article", "pub_year": "1990", "author_list": "Kumar, Amit and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1570x-19p55", "eprint_id": 52360, "eprint_status": "archive", "datestamp": "2023-08-19 23:18:39", "lastmod": "2023-10-18 19:47:49", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Penner-Reginald-M", "name": { "family": "Penner", "given": "Reginald M." }, "orcid": "0000-0003-2831-3028" }, { "id": "Heben-Michael-J", "name": { "family": "Heben", "given": "Michael J." }, "orcid": "0000-0002-3788-3471" }, { "id": "Longin-Teresa-L", "name": { "family": "Longin", "given": "Teresa L." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Fabrication and Use of Nanometer-Sized Electrodes in Electrochemistry", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1990 American Association for the Advancement of Science.\n\n15 August 1990; Accepted 13 September 1990.\n\nWe acknowledge the Office of Naval Research for support of this work and F. C. Anson and M. J. Weaver for helpful discussions. Contribution no. 8153 from the Division of Chemistry and Chemical Engineering at Caltech. We dedicate this report to George McManis, whose promising scientific career was tragically cut short by his untimely death.", "abstract": "Electrodes with electrochemical dimensions as small as 10 angstroms have been fabricated and used for electrochemical studies. These nanometer-scale electrodes have enabled the measurement of electron-transfer rate constants, k_(het), that are two orders of magnitude faster than k_(het) values accessible with any other electrochemical method.", "date": "1990-11-23", "date_type": "published", "publication": "Science", "volume": "250", "number": "4984", "publisher": "American Association for the Advancement of Science", "pagerange": "1118-1121", "id_number": "CaltechAUTHORS:20141203-160128178", "issn": "0036-8075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141203-160128178", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)" } ] }, "other_numbering_system": { "items": [ { "id": "8153", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1126/science.250.4984.1118", "resource_type": "article", "pub_year": "1990", "author_list": "Penner, Reginald M.; Heben, Michael J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/q2ec8-1m914", "eprint_id": 121001, "eprint_status": "archive", "datestamp": "2023-08-22 07:47:34", "lastmod": "2023-10-18 18:06:49", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Collman-James-P", "name": { "family": "Collman", "given": "James P." } }, { "id": "Hutchison-James-E", "name": { "family": "Hutchison", "given": "James E." } }, { "id": "Wagenknecht-Paul-S", "name": { "family": "Wagenknecht", "given": "Paul S." }, "orcid": "0000-0001-8698-073X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Lopez-Michel-Angel", "name": { "family": "Lopez", "given": "Michel Angel" } }, { "id": "Guilard-Roger", "name": { "family": "Guilard", "given": "Roger" } } ] }, "title": "An unprecedented, bridged dihydrogen complex of a cofacial metallodiporphyrin and its relevance to the bimolecular reductive elimination of hydrogen", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1990 American Chemical Society. \n\nJ.E.H. acknowledges support from the Franklin Veatch Memorial Fellowship fund, 1987-1989. P.S.W. acknowledges support as a National Science Foundation Graduate Research Fellow, 1986-1989. Support from the National Science Foundation, the National Institutes of Health, and the Gas Research Institute is acknowledged. Helpful discussions with Professor Jack Norton and Professor Royce Murray are gratefully acknowledged. Contribution No. 8152 from the Division of Chemistry and Chemical Engineering, California Institute of Technology.", "abstract": "Recently, we characterized the first metalloporphyrin dihydrogen complex, Os(OEP)(H\u2082), and proposed that a similar\nruthenium porphyrin dihydrogen complex, Ru(OEP)(H\u2082), is involved as an intermediate in the catalytic H/D isotopic exchange between water and hydrogen. We now report that treatment of a metal-metal-bonded cofacial ruthenium porphyrin dimer with a sterically bulky ligand in the presence of hydrogen gas has yielded the first known complex containing a dihydrogen ligand bound between two metals. Such a bridged dihydrogen complex is proposed as an intermediate in the bimolecular elimination of dihydrogen from two metalloporphyrin hydrides.", "date": "1990-10-24", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "112", "number": "22", "publisher": "American Chemical Society", "pagerange": "8206-8208", "id_number": "CaltechAUTHORS:20230419-898261000.10", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-898261000.10", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Franklin Veatch Memorial Fellowship" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "NIH" }, { "agency": "Gas Research Institute" } ] }, "other_numbering_system": { "items": [ { "id": "8152", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/ja00178a077", "resource_type": "article", "pub_year": "1990", "author_list": "Collman, James P.; Hutchison, James E.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wczfa-43t52", "eprint_id": 2424, "eprint_status": "archive", "datestamp": "2023-08-22 07:45:11", "lastmod": "2023-10-13 23:23:19", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tufts-B-J", "name": { "family": "Tufts", "given": "Bruce J." } }, { "id": "Casagrande-L-G", "name": { "family": "Casagrande", "given": "Louis G." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Grunthaner-F-J", "name": { "family": "Grunthaner", "given": "Frank J." } } ] }, "title": "Correlations between the interfacial chemistry and current-voltage behavior of n-GaAs/liquid junctions", "ispublished": "pub", "full_text_status": "public", "keywords": "GALLIUM ARSENIDES; CHEMICAL PROPERTIES; ELECTROLYTES; SURFACE PROPERTIES; CORRELATIONS; PHOTOCHEMISTRY; ELECTROCHEMISTRY; SCHOTTKY EFFECT; PHOTOCONDUCTIVITY; SURFACE REACTIONS; IV CHARACTERISTIC; SOLID\u2013FLUID INTERFACES; SEMICONDUCTOR\u2013ELECTROLYTIC CONTACTS", "note": "Copyright \u00a9 1990 American Institute of Physics \n\n(Received 16 April 1990; accepted 2 July 1990) \n\nWe thank the Department of Energy, Office of Basic Energy Sciences, for support of this work. We thank Dr. C. L. R. Lewis of Varian Associates, Palo Alto, CA, for a generous supply of GaAs samples and acknowledge R. P. Vasquez and M. H. Hecht of the Jet Propulsion Laboratory, Pasadena, CA, for assistance with the XPS instrument used in this study. N.S.L. also acknowledges support as an A. P. Sloan Fellow and as a Dreyfus Teacher-Scholar. \n\nErratum: Appl. Phys. Lett. 57, 2262 (1990)", "abstract": "Correlations between the surface chemistry of etched, (100) oriented n-GaAs electrodes and their subsequent photoelectrochemical behavior have been probed by high-resolution x-ray photoelectron spectroscopy. GaAs photoanodes were chemically treated to prepare either an oxide-free near stoichiometric surface, a surface enriched in zero-valent arsenic (As0), or a substrate-oxide terminated surface. The current-voltage (I-V) behavior of each surface type was subsequently monitored in contact with several electrolytes.", "date": "1990-09-17", "date_type": "published", "publication": "Applied Physics Letters", "volume": "57", "number": "12", "publisher": "Applied Physics Letters", "pagerange": "1242-1244", "id_number": "CaltechAUTHORS:TUFapl90", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:TUFapl90", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1063/1.103497", "primary_object": { "basename": "TUFapl90.pdf", "url": "https://authors.library.caltech.edu/records/wczfa-43t52/files/TUFapl90.pdf" }, "related_objects": [ { "basename": "TUFapl90corr.pdf", "url": "https://authors.library.caltech.edu/records/wczfa-43t52/files/TUFapl90corr.pdf" } ], "resource_type": "article", "pub_year": "1990", "author_list": "Tufts, Bruce J.; Casagrande, Louis G.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/j0v1n-rff89", "eprint_id": 120996, "eprint_status": "archive", "datestamp": "2023-08-22 07:45:00", "lastmod": "2023-10-18 18:06:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sailor-Michael-J", "name": { "family": "Sailor", "given": "Michael J." }, "orcid": "0000-0002-4809-9826" }, { "id": "Ginsburg-Eric-J", "name": { "family": "Ginsburg", "given": "Eric J." } }, { "id": "Gorman-Christopher-B", "name": { "family": "Gorman", "given": "Christopher B." }, "orcid": "0000-0001-7367-2965" }, { "id": "Kumar-Amit", "name": { "family": "Kumar", "given": "Amit" } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Thin Films of n-Si/Poly-(CH\u2083)\u2083Si-Cyclooctatetraene: Conducting-Polymer Solar Cells and Layered Structures", "ispublished": "pub", "full_text_status": "public", "keywords": "Multidisciplinary", "note": "\u00a9 1990 by the American Association for the Advancement of Science. \n\nSupported by NSF grant CHE-8814694 and ONR grant N00014-88-K-0208. C.B.G. thanks the Jet Propulsion Laboratory, Caltech, for a research fellowship. E.J.G. thanks IBM for a graduate fellowship, ands A.K. thanks the Department of Education for a graduate fellowship. Contribution 8134 from the Arnold and Mabel Beckman Laboratory of Synthesis and the Arthur Amos Noyes Laboratory of Chemical Physics.", "abstract": "The optical and electronic properties of thin films of the solution-processible polymer poly-(CH\u2083)\u2083Si-cyclooctatetraene are presented. This conjugated polymer is based on a polyacetylene backbone with (CH\u2083)3Si side groups. Thin transparent films have been cast onto n-doped silicon (n-Si) substrates and doped with iodine to form surface-barrier solar cells. The devices produce photovoltages that are at the theoretical limit and that are much greater than can be obtained from n-Si contacts with conventional metals. Two methods for forming layered polymeric materials, one involving the spin-coating of preformed polymers and the other comprising the sequential polymerization of different monomers, are also described. An organic polymer analog of a metal/insulator/metal capacitor has been constructed with the latter method.", "date": "1990-09-07", "date_type": "published", "publication": "Science", "volume": "249", "number": "4973", "publisher": "American Association for the Advancement of Science", "pagerange": "1146-1149", "id_number": "CaltechAUTHORS:20230419-898234000.3", "issn": "0036-8075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-898234000.3", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-8814694" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-88-K-0208" }, { "agency": "JPL/Caltech" }, { "agency": "IBM" }, { "agency": "Department of Education" } ] }, "other_numbering_system": { "items": [ { "id": "8134", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1126/science.249.4973.1146", "resource_type": "article", "pub_year": "1990", "author_list": "Sailor, Michael J.; Ginsburg, Eric J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/729nv-xcg23", "eprint_id": 86140, "eprint_status": "archive", "datestamp": "2023-08-19 22:57:06", "lastmod": "2023-10-18 19:17:20", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kumar-Amit", "name": { "family": "Kumar", "given": "Amit" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Short-wavelength spectral response properties of semiconductor/liquid junctions", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1990 American Chemical Society. \n\n(Received: December 11, 1989) \n\nWe thank the Department of Energy, Office of Basic Energy Sciences, for support of this work. We also acknowledge Mary L. Rosenbluth and Pat G. Santangelo for technical assistance with some of the experiments and for helpful discussions.", "abstract": "We report the first measurements of photocurrent quantum yields for semiconductor/liquid junctions in the short-wavelength region of the spectrum (200-600 nm). The key feature of this wavelength region is the short penetration depth for the absorbed photon (less than 100 A), which allows measurement of the majority carrier collection velocity. Spectra have been obtained for semiconductor/liquid, semiconductor/metal, and semiconductor/insulator/metal junctions. For all semiconductors studied (n-Si, p-Si, n-GaAs, n-InP, a-Si:H), the spectral responses of the liquid junctions showed higher quantum yields than the metal junctions, indicating greater majority carrier losses at the metal junctions. This general trend was independent of redox species, solvent, supporting electrolyte, and metal overlayer. The spectral response data can also be used to distinguish Schottky barrier behavior from electrocatalytic behavior of metal overlayers, and this approach has been used to study several semiconductor/metal film junctions in contact with electrolytes.", "date": "1990-07-26", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "94", "number": "15", "publisher": "American Chemical Society", "pagerange": "6002-6009", "id_number": "CaltechAUTHORS:20180430-145302857", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180430-145302857", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" } ] }, "other_numbering_system": { "items": [ { "id": "8085", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/j100378a070", "resource_type": "article", "pub_year": "1990", "author_list": "Kumar, Amit and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/bhh43-q9297", "eprint_id": 56477, "eprint_status": "archive", "datestamp": "2023-08-19 22:56:15", "lastmod": "2023-10-23 15:27:39", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sailor-Michael-J", "name": { "family": "Sailor", "given": "Michael J." }, "orcid": "0000-0002-4809-9826" }, { "id": "Klavetter-Floyd-L", "name": { "family": "Klavetter", "given": "Floyd L." } }, { "id": "Grubbs-R-H", "name": { "family": "Grubbs", "given": "Robert H." }, "orcid": "0000-0002-0057-7817" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Electronic properties of junctions between silicon and organic conducting polymers", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1990 Nature Publishing Group. \n\nReceived 19 March; accepted 18 May 1990. \n\nWe thank J. Toth for discussions. This work was supported by the NSF and The Office of Naval research. This is contribution 8088 from the Division of Chemistry and Chemical Engineering, California Institute of Technology.", "abstract": "Diodes formed from semiconductor/metal interfaces often display non-ideal electronic properties. For instance, silicon/metal (Schottky) diodes made from n-type silicon and a variety of contacting metals exhibit only small differences in their rectification properties, despite theoretical and practical expectations that changes in the metal should effect changes in device properties. Similarly, Schottky diodes formed on p-type silicon generally exhibit ohmic behaviour with poor rectification characteristics. This lack of electrical response to changes in the properties of the contacting metal phase is generally attributed to interfacial reactions that take place during the high-temperature thermal or electron-beam deposition of metals onto silicon. Here we describe the fabrication of diodes using a low-temperature chemical procedure, in which contact to the semiconductor is made by a layer of the conducting organic polymer, polyacetylene. Unlike conventional metals, the electrical properties of polyacetylene can be manipulated through choice of the polymer dopant. The resultant organic/inorganic interfaces behave more ideally than contacts with conventional metals, in that changes in the electrical properties of the conducting polymer exert a large and predictable effect on the electrical properties of the resulting semiconductor/polymer diodes.", "date": "1990-07-12", "date_type": "published", "publication": "Nature", "volume": "346", "number": "6280", "publisher": "Nature Publishing Group", "pagerange": "155-157", "id_number": "CaltechAUTHORS:20150408-101436954", "issn": "0028-0836", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150408-101436954", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "Office of Naval Research (ONR)" } ] }, "other_numbering_system": { "items": [ { "id": "8088", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1038/346155a0", "resource_type": "article", "pub_year": "1990", "author_list": "Sailor, Michael J.; Klavetter, Floyd L.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/26jwf-wgx33", "eprint_id": 83032, "eprint_status": "archive", "datestamp": "2023-08-19 22:49:57", "lastmod": "2023-10-17 22:52:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Mechanistic studies of light-induced charge separation at semiconductor/liquid interfaces", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1990 American Chemical Society. \n\nReceived October 31, 1989; Revised Manuscript Received March 12, 1990. \n\nI have been fortunate to work with a series of talented and\nenthusiastic co-workers and colleagues over the past nine years and gratefully acknowledge their efforts for initiating and carrying through the work described in this Account. The National Science Foundation, Department of Energy, and Office of Naval Research have provided generous support for these projects, and crucial unrestricted funding was provided by IBM Corp., the Dreyfus Foundation, the A. P. Sloan Foundation, and the Presidential Young Investigator Program.", "abstract": "The energy crisis of the early 1970s stimulated numerous\ninvestigations of semiconductor/liquid junctions for the conversion and storage of solar energy. Although similar in concept to solid-state photovoltaic devices, semiconductor /liquid junctions offered the potential for inexpensive, chemically based energy-conversion devices, with the accompanying potential to effect the direct conversion of light into chemical fuels.", "date": "1990-06-01", "date_type": "published", "publication": "Accounts of Chemical Research", "volume": "23", "number": "6", "publisher": "American Chemical Society", "pagerange": "176-183", "id_number": "CaltechAUTHORS:20171107-123825465", "issn": "0001-4842", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171107-123825465", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "Department of Energy (DOE)" }, { "agency": "Office of Naval Research (ONR)" }, { "agency": "IBM Corp." }, { "agency": "Henry and Camille Dreyfus Foundation" }, { "agency": "Alfred P. Sloan Foundation" } ] }, "other_numbering_system": { "items": [ { "id": "8056", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/ar00174a002", "resource_type": "article", "pub_year": "1990", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hfk1p-e4h83", "eprint_id": 120998, "eprint_status": "archive", "datestamp": "2023-08-22 07:37:31", "lastmod": "2023-10-18 18:06:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "More efficient solar cells", "ispublished": "pub", "full_text_status": "public", "keywords": "Multidisciplinary", "note": "\u00a9 1990 Nature Publishing Group.", "abstract": "As the search continues for an inexpensive, efficient solar-energy-conversion device, conventional photovoltaic devices are under increasing competition from 'wet' photoelectrochemical cells. Photoelectrochemical cells are relatively simple (and potentially inexpensive) to construct, because they require merely the immersion of the desired photoactive solid into an ionically conducting liquid. On page 330, a team led by S. Licht describe how in certain cases it is possible to achieve the desirable combination of high efficiency and low corrosion rates by manipulating the composition of the conducting liquid. With their approach, Licht et al. demonstrate that cadmium selenide electrodes can be coaxed into stable operation in an aqueous solution with an overall energy-conversion efficiency of 17 per cent.", "date": "1990-05-24", "date_type": "published", "publication": "Nature", "volume": "345", "number": "6273", "publisher": "Nature Publishing Group", "pagerange": "293-294", "id_number": "CaltechAUTHORS:20230419-898248000.6", "issn": "0028-0836", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-898248000.6", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1038/345293a0", "resource_type": "article", "pub_year": "1990", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/377b4-kj384", "eprint_id": 2493, "eprint_status": "archive", "datestamp": "2023-08-22 07:36:56", "lastmod": "2023-10-13 23:33:50", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kumar-Amit", "name": { "family": "Kumar", "given": "Amit" } }, { "id": "Rosenblum-Mark-D", "name": { "family": "Rosenblum", "given": "Mark D." } }, { "id": "Gilmore-Delwyn-L", "name": { "family": "Gilmore", "given": "Delwyn L." } }, { "id": "Tufts-Bruce-J", "name": { "family": "Tufts", "given": "Bruce J." } }, { "id": "Rosenbluth-Mary-L", "name": { "family": "Rosenbluth", "given": "Mary L." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Fabrication of minority-carrier-limited n-Si/insulator/metal diodes", "ispublished": "pub", "full_text_status": "public", "keywords": "SEMICONDUCTOR DIODES; FABRICATION; ANODIZATION; PHOTOELECTROCHEMICAL CELLS; CHARGE CARRIERS; SOLAR CELLS; PHOTODIODES; MIS JUNCTIONS; MINORITY CARRIERS", "note": "\u00a9 1990 American Institute of Physics \n\n(Received 11 December 1989; accepted 26 February 1990) \n\nWe thank the Department of Energy, Office of Basic Energy Sciences, for support of this work. Generous support for D.L.G was provided by the SURF program at Caltech. We acknowledge F. J. Grunthaner, P. J. Grunthaner, R. P. Vasquez, and M. H. Hecht of the Jet Propulsion Laboratory, Pasadena, CA for access to the XPS instrument used in this study and for helpful discussions regarding this work. This work was performed at Division of Chemistry and Chemical Engineering, California Institute of Technology, contribution No. 8072.", "abstract": "A photoelectrochemical anodization technique has been used to fabricate n-Si/insulator/metal (MIS) diodes with improved electrical properties. MIS structures fabricated with Au have provided the first experimental observation of a solid-state n-Si surface barrier device whose open circuit voltage Voc is controlled by minority-carrier bulk diffusion/recombination processes. For these diodes, variation of the minority-carrier diffusion length and majority-carrier dopant density produced changes in Voc that were in accord with bulk diffusion/recombination theory. Additionally, the variation in Voc in response to changes in the work function of the metal overlayer indicated that these MIS devices were not subject to the Fermi level pinning restrictions observed for n-Si Schottky structures. X-ray photoelectron spectroscopic characterization of the anodically grown insulator indicated 8.2\u00b10.9 \u00c5 of a strained SiO2 layer as the interfacial insulator resulting from the photoanodization process.", "date": "1990-05-07", "date_type": "published", "publication": "Applied Physics Letters", "volume": "56", "number": "19", "publisher": "American Institute of Physics", "pagerange": "1919-1921", "id_number": "CaltechAUTHORS:KUMapl90b", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:KUMapl90b", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Caltech Summer Undergraduate Research Fellowship (SURF)" } ] }, "other_numbering_system": { "items": [ { "id": "8072", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1063/1.103044", "primary_object": { "basename": "KUMapl90b.pdf", "url": "https://authors.library.caltech.edu/records/377b4-kj384/files/KUMapl90b.pdf" }, "resource_type": "article", "pub_year": "1990", "author_list": "Kumar, Amit; Rosenblum, Mark D.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/q2qjr-kj552", "eprint_id": 86137, "eprint_status": "archive", "datestamp": "2023-08-19 22:41:25", "lastmod": "2023-10-18 19:17:05", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Schmidt-Michael-H", "name": { "family": "Schmidt", "given": "Michael H." } }, { "id": "Miskelly-Gordon-M", "name": { "family": "Miskelly", "given": "Gordon M." }, "orcid": "0000-0003-4748-0083" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Effects of redox potential, steric configuration, solvent, and alkali metal cations on the binding of carbon dioxide to cobalt(I) and nickel(I) macrocycles", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1990 American Chemical Society. \n\nReceived September 14, 1989. \n\nWe gratefully acknowledge J. Endicott for forwarding a preprint of ref 29 and thank E. Fujita and C. Creutz of Brookhaven National Laboratories for numerous helpful discussions concerning unpublished research on similar systems. We thank B. Balazs for a sample of Ni(cyclam)(ClO_4)_2. This research was funded by the Gas Research Institute. N.S.L. also acknowledges support as a Dreyfus Teacher-Scholar and from the NSF Presidential Young Investigator Program.", "abstract": "The binding of CO\u2082 to metal macrocycles has been determined electrochemically by using cyclic voltammetry or differential pulse polarography. The CO\u2082 binding constants, K_(CO\u2082), for a series of Co(I) tetraazamacrocycle complexes in (CH\u2083)\u2082SO showed a strong correlation with the Co(II/I) redox potential. Although meso and d,l stereoisomers of [Co\u1d35(Me\u2086[14]4,l 1-diene)]\u207a had identical redox potentials, K_(CO\u2082) differed by a factor of 10\u00b2 for these stereoisomers, suggesting a large steric effect on CO\u2082 binding. Binding of CO\u2082 to Ni(I) tetraazamacrocycles in (CH\u2083)\u2082SO yielded a redox potential dependence similar to that of Co(I) macrocycles. A weak correlation between K_(CO\u2082) and the solvent dielectric constant was found for d,l-[Co(Me\u2086[14]4,11-diene)]\u207a. In tetrahydrofuran (THF), d,l-[Co(Me\u2086[14]4,11-diene)]\u207a was found to bind CO\u2082 more strongly in the presence of 0.1 M Li\u207a than in the presence of 0.1 M tetrabutylammonium (TBA\u207a). Electrochemically determined K_(CO\u2082)'s for Co(salen)\u207b and Co(Me\u2082salen)\u207b in THF indicated a strong dependence on redox potential and electrolyte cation.", "date": "1990-04-25", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "112", "number": "9", "publisher": "American Chemical Society", "pagerange": "3420-3426", "id_number": "CaltechAUTHORS:20180430-145301844", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180430-145301844", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Gas Research Institute" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "NSF" } ] }, "other_numbering_system": { "items": [ { "id": "7916", "name": "Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/ja00165a027", "resource_type": "article", "pub_year": "1990", "author_list": "Schmidt, Michael H.; Miskelly, Gordon M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rx17j-t0576", "eprint_id": 120999, "eprint_status": "archive", "datestamp": "2023-09-15 07:48:40", "lastmod": "2023-10-23 21:38:46", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Forbes-Malcolm-D-E", "name": { "family": "Forbes", "given": "Malcolm D. E." }, "orcid": "0000-0003-4040-386X" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Real-time measurements of interfacial charge transfer rates at silicon/liquid junctions", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1990 American Chemical Society. \n\nWe thank B. J. Tufts for running the XPS experiments, P. G. Santangelo and A. Kumar for experimental assistance, and E. Yablonovitch, T. Gmitter, M. Kunst, J. Warman, and H. Tributsch for helpful discussions regarding the experimental setup. We are also grateful to R. Swanson and R. Sinton of Stanford University for providing the Si samples. M.D.E.F. is grateful for financial support from the National Science Foundation through its Postdoctoral Fellowship Program in Chemistry. This work was supported by Grant No. CHE-8814263 from the National Science Foundation.", "abstract": "The rates of interfacial charge transfer from photogenerated carriers in semiconductor electrodes to solution donors and acceptors are fundamentally important in the area of semiconductor electrochemistry. However, to date there have been no real-time measurements of the charge-transfer rates between semiconductors and outer sphere redox couples. Previous steady-state current-voltage experiments have led to the suggestion that such rates might be extremely fast (>10\u00b9\u00b9 s\u207b\u00b9), because evidence has been obtained for interfacial charge transfer events competing with thermalization of the photoexcited carriers (i.e. \"hot carrier injection processes\"). Additionally, luminescence decay measurements on CdS surfaces in contact with strongly adsorbing, inner sphere redox reagents such as 1.0 M KOH/l.O M S\u00b2\u207b have indicated high surface recombination velocities (> 10\u2075 cm/s) and have yielded photoexcited carrier lifetimes of less than 100 ps. In contrast, simple theoretical estimates of the interfacial charge transfer rate constants for outer sphere redox systems can be used to predict carrier lifetimes between 10\u207b\u2076 and 10\u207b\u00b3 s under common experimental conditions. To address these issues, we report herein the first real-time kinetic rate measurements from carriers in a semiconductor to outer sphere redox donors and acceptors in the liquid phase.", "date": "1990-04-25", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "112", "number": "9", "publisher": "American Chemical Society", "pagerange": "3682-3683", "id_number": "CaltechAUTHORS:20230419-898249000.7", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-898249000.7", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Postdoctoral Fellowship" }, { "agency": "NSF", "grant_number": "CHE-8814263" } ] }, "other_numbering_system": { "items": [ { "id": "8097", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/ja00165a076", "resource_type": "article", "pub_year": "1990", "author_list": "Forbes, Malcolm D. E. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/97v96-fns64", "eprint_id": 121000, "eprint_status": "archive", "datestamp": "2023-08-22 07:07:38", "lastmod": "2023-10-18 18:06:46", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Collman-James-P", "name": { "family": "Collman", "given": "James P." } }, { "id": "Wagenknecht-Paul-S", "name": { "family": "Wagenknecht", "given": "Paul S." }, "orcid": "0000-0001-8698-073X" }, { "id": "Hembre-Robert-T", "name": { "family": "Hembre", "given": "Robert T." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Dihydrogen complexes of metalloporphyrins: characterization and hydrogen-transfer reactivity", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1990 American Chemical Society. \n\nP.S.W. acknowledges support as a National Science Foundation Graduate Research Fellow, 1986-1989. R.T.H. acknowledges support as a National Institutes of Health Postdoctoral Fellow, 1987-1989. Support from the National Science Foundation (NSF CHE88-14949), the National Institutes of Health (NIH 5R37-GM17880), and the Gas Research Institute is acknowledged. Helpful discussions with Greg Venburg, Jim Hutchison, Dean Harman, and Scott Bohle are gratefully acknowledged. Contribution No. 8032 from the Division of Chemistry and Chemical Engineering, California Institute of Technology.", "abstract": "Extensive reports of \u03b7\u00b2 coordination of dihydrogen to transition metals have recently led to speculation that the \u03b7\u00b2-dihydrogen complexes and their corresponding transition-metal hydrides may be important in the biological activation of molecular hydrogen. We now report that protonation of transition-metal porphyrin hydrides has yielded the first known dihydrogen complex of a metalloporphyrin and a system that performs some functions of hydrogenase enzymes.", "date": "1990-01-31", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "112", "number": "3", "publisher": "American Chemical Society", "pagerange": "1294-1295", "id_number": "CaltechAUTHORS:20230419-898259000.9", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-898259000.9", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Graduate Research Fellowship" }, { "agency": "NIH Postdoctoral Fellowship" }, { "agency": "NSF", "grant_number": "CHE88-14949" }, { "agency": "NIH", "grant_number": "5R37-GM17880" }, { "agency": "Gas Research Institute" } ] }, "other_numbering_system": { "items": [ { "id": "8032", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/ja00159a087", "resource_type": "article", "pub_year": "1990", "author_list": "Collman, James P.; Wagenknecht, Paul S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/59rpm-qts14", "eprint_id": 53846, "eprint_status": "archive", "datestamp": "2023-08-19 22:00:41", "lastmod": "2023-10-19 22:17:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Miskelly-Gordon-M", "name": { "family": "Miskelly", "given": "Gordon M." }, "orcid": "0000-0003-4748-0083" }, { "id": "Heben-Michael-J", "name": { "family": "Heben", "given": "Michael J." }, "orcid": "0000-0002-3788-3471" }, { "id": "Kumar-Amit", "name": { "family": "Kumar", "given": "Amit" } }, { "id": "Penner-Reginald-M", "name": { "family": "Penner", "given": "Reginald M." }, "orcid": "0000-0003-2831-3028" }, { "id": "Sailor-Michael-J", "name": { "family": "Sailor", "given": "Michael J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Analysis of the Published Calorimetric Evidence for Electrochemical Fusion of Deuterium in Palladium", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1989 American Association for the Advancement of Science.\n\n21 June1 989; Accepted2 9 August 1989.\n\nSupported by the Office of Naval Research and under a special grant from the California Institute of Technology. We thank G. Kreysa and W. Meyerhof for supplying preprints of related work. We thank C. A. Barnes and S. E. Kellogg for helpful criticism of this manuscript. Contribution 7969 from the Division of Chemistry and Chemical Engineering at the Californian Institute of Technology.", "abstract": "Estimates are given of the raw data that are the basis for the claims of excess power production by the electrochemical charging of palladium in deuterium oxide (D\u2082O). Calorimetric results are also presented that show no anomalous power production in either 0.1M LiOD/D\u2082O or 0.1M LiOH/H\u2082O (LiOH is lithium hydroxide). Several possible sources of error in open-system calorimetry are discussed that can confound interpretation of temperature changes in terms of anomalous power production.", "date": "1989-11-10", "date_type": "published", "publication": "Science", "volume": "246", "number": "4931", "publisher": "American Association for the Advancement of Science", "pagerange": "793-796", "id_number": "CaltechAUTHORS:20150116-153715370", "issn": "0036-8075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150116-153715370", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)" }, { "agency": "Caltech" } ] }, "other_numbering_system": { "items": [ { "id": "7969", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1126/science.246.4931.793", "resource_type": "article", "pub_year": "1989", "author_list": "Miskelly, Gordon M.; Heben, Michael J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nvrpf-4dr06", "eprint_id": 120973, "eprint_status": "archive", "datestamp": "2023-08-22 06:49:09", "lastmod": "2023-10-18 18:05:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Heben-Michael-J", "name": { "family": "Heben", "given": "Michael J." }, "orcid": "0000-0002-3788-3471" }, { "id": "Kumar-Amit", "name": { "family": "Kumar", "given": "Amit" } }, { "id": "Zheng-Chong", "name": { "family": "Zheng", "given": "Chong" } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Efficient photovoltaic devices for InP semiconductor/liqud junctions", "ispublished": "pub", "full_text_status": "public", "keywords": "Multidisciplinary", "note": "\u00a9 1989 Nature Publishing Group. \n\nWe thank Dr N. Newman, Prof. W. Spicer and Dr S. C. Pyke for supplying some InP samples and for discussions. We also thank B. J. Tufts for performing photoemission experiments. This work was supported in part by the Office of Naval Research. N.S.L. also acknowledges support as a Dreyfus Teacher-Scholar and as an A. P. Sloan Foundation Fellow. This is contribution number 7882 from the Division of Chemistry and Chemical Engineering.", "abstract": "An alternative to conventional solid-state photovoltaic devices is the semiconductor/liquid junction. Liquid-junction cells not only offer the possibility of integrating energy conversion and storage functions1, but also may exhibit electrical properties that are fundamentally different from those in solid-state systems. We have investigated the photovoltaic behaviour of n-InP/metal and n-InP/liquid junctions. We have found that the electrical properties of these semiconductor/liquid junctions are superior to those of n-InP/metal (Schottky barrier) systems, and that the current-voltage characteristics are a strong function of the electrochemical potential of the liquid phase. Liquid contacts thus provide a possibility for the construction of more efficient photovoltaic devices than those available at present from Schottky barriers.", "date": "1989-08-24", "date_type": "published", "publication": "Nature", "volume": "340", "number": "6235", "publisher": "Nature Publishing Group", "pagerange": "621-623", "id_number": "CaltechAUTHORS:20230418-318371000.8", "issn": "0028-0836", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230418-318371000.8", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Alfred P. Sloan Foundation" } ] }, "other_numbering_system": { "items": [ { "id": "7882", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1038/340621a0", "resource_type": "article", "pub_year": "1989", "author_list": "Heben, Michael J.; Kumar, Amit; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/nc5b2-d7936", "eprint_id": 60191, "eprint_status": "archive", "datestamp": "2023-08-19 21:50:25", "lastmod": "2023-10-24 15:25:19", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Barnes-Charles-A", "name": { "family": "Barnes", "given": "C. A." } }, { "id": "Heben-Michael-J", "name": { "family": "Heben", "given": "M. J." }, "orcid": "0000-0002-3788-3471" }, { "id": "Kumar-Amit", "name": { "family": "Kumar", "given": "A." } }, { "id": "Lunt-Sharon-R", "name": { "family": "Lunt", "given": "S. R." } }, { "id": "McManis-G-E", "name": { "family": "McManis", "given": "G. E." } }, { "id": "Miskelly-Gordon-M", "name": { "family": "Miskelly", "given": "G. M." }, "orcid": "0000-0003-4748-0083" }, { "id": "Penner-Reginald-M", "name": { "family": "Penner", "given": "R. M." }, "orcid": "0000-0003-2831-3028" }, { "id": "Sailor-Michael-J", "name": { "family": "Sailor", "given": "M. J." }, "orcid": "0000-0002-4809-9826" }, { "id": "Santangelo-Patrick-G", "name": { "family": "Santangelo", "given": "P. G." } }, { "id": "Shreve-Gary-A", "name": { "family": "Shreve", "given": "G. A." } }, { "id": "Tufts-Bruce-J", "name": { "family": "Tufts", "given": "B. J." } }, { "id": "Youngquist-Michael-G", "name": { "family": "Youngquist", "given": "M. G." } }, { "id": "Kavanagh-R-W", "name": { "family": "Kavanagh", "given": "R. W." } }, { "id": "Kellogg-S-E", "name": { "family": "Kellogg", "given": "S. E." } }, { "id": "Vogelaar-R-B", "name": { "family": "Vogelaar", "given": "R. B." } }, { "id": "Wang-T-R", "name": { "family": "Wang", "given": "T. R." } }, { "id": "Kondrat-R", "name": { "family": "Kondrat", "given": "R." } }, { "id": "New-R", "name": { "family": "New", "given": "R." } } ] }, "title": "Searches for low-temperature nuclear fusion of deuterium in palladium", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1989 Nature Publishing Group. \n\nReceived 23 May; accepted 14 July 1989.\n\nPreliminary reports of these results were presented in invited papers at the 1 May 1989 meeting of the American Physical Society in Baltimore and at the 8 May 1989 meeting of the Electrochemical Society in Los Angeles. We thank B. Miller and C. R. Martin for supplying some of the Pd samples used in this work. We also thank N. l-loffmann for obtaining a He analysis of the Pd rods, J. Campbell for use of the tritium scintillation counter, W. Johnson and H. Fecht for supplying the r.f. melted Pd, E.-H. Cirlin for use of the X-ray photoelectron spectrometer, J. Beckett for aid in recasting Pd rods and S. Koonin and R. E. Azuma for discussions. R. Petrasso and S. Luckhardt are acknowledged for several discussions and for a preprint of their analysis of the y-ray data. This work was supported in part by a discretionary grant from Caltech, by the Office of Naval Research, and by the NSF. This work is contribution 7959 from The Division of Chemistry and Chemical Engineering.", "abstract": "A series of experiments has been performed to determine whether nuclear fusion processes occur in palladium rods that have been electrochemically charged with deuterium. With a variety of metallurgical pretreatment procedures and different electrolytes, no evidence has been obtained for any excess enthalpy, neutron, gamma ray, tritium or helium production during electrolysis of D_20 with palladium cathodes.", "date": "1989-08-17", "date_type": "published", "publication": "Nature", "volume": "340", "number": "6234", "publisher": "Nature Publishing Group", "pagerange": "525-530", "id_number": "CaltechAUTHORS:20150911-122141920", "issn": "0028-0836", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150911-122141920", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech" }, { "agency": "Office of Naval Research (ONR)" }, { "agency": "NSF" } ] }, "other_numbering_system": { "items": [ { "id": "7959", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1038/340525a0", "resource_type": "article", "pub_year": "1989", "author_list": "Lewis, N. S.; Barnes, C. A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5m0ga-wgt48", "eprint_id": 121002, "eprint_status": "archive", "datestamp": "2023-08-22 06:48:37", "lastmod": "2023-10-18 18:06:51", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Santangelo-Patrick-G", "name": { "family": "Santangelo", "given": "Patrick G." } }, { "id": "Miskelly-Gordon-M", "name": { "family": "Miskelly", "given": "Gordon M." }, "orcid": "0000-0003-4748-0083" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Voltammetry of semiconductor electrodes. 2. Cyclic voltammetry of freely diffusing redox species and rotating semiconductor disk voltammetry", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1989 American Chemical Society. \n\nWe thank the Department of Energy, Office of Basic Energy Sciences, and the donors of the Petroleum Research Fund, administered by the American Chemical Society, for support of this work. N.S.L. also acknowledges support as a Dreyfus Teacher-Scholar and as an A. P. Sloan Foundation Fellow. We are indebted to Dr. Stephen Feldberg of Brookhaven National Laboratory for a critical reading of the manuscript and for numerous helpful discussions. We also acknowledge helpful suggestions regarding computing methodology from Professor Hans Andersen of Stanford University.", "abstract": "A model electrode circuit has been utilized to describe the cyclic voltammetric response of a semiconductor photoelectrode in contact with a freely diffusing reversible redox system. This equivalent circuit formalism also has been used to generate a set of working curves for the steady-state voltammetric behavior of a reversible redox system at a rotating semiconductor disk electrode. The model electrode circuit consisted of an ideal photodiode in series with a metal electrode. The current-voltage solutions have been obtained under varying conditions of illumination, scan rate, or rotation velocity, and the results are presented in a working curve format.", "date": "1989-08-10", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "93", "number": "16", "publisher": "American Chemical Society", "pagerange": "6128-6136", "id_number": "CaltechAUTHORS:20230419-898271000.11", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-898271000.11", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "American Chemical Society Petroleum Research Fund" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Alfred P. Sloan Foundation" } ] }, "doi": "10.1021/j100353a036", "resource_type": "article", "pub_year": "1989", "author_list": "Santangelo, Patrick G.; Miskelly, Gordon M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qf6dk-8m767", "eprint_id": 121005, "eprint_status": "archive", "datestamp": "2023-09-15 07:48:45", "lastmod": "2023-10-23 21:38:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Penner-Reginald-M", "name": { "family": "Penner", "given": "Reginald M." }, "orcid": "0000-0003-2831-3028" }, { "id": "Heben-Michael-J", "name": { "family": "Heben", "given": "Michael J." }, "orcid": "0000-0002-3788-3471" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Preparation and electrochemical characterization of conical and hemispherical ultramicroelectrodes", "ispublished": "pub", "full_text_status": "public", "keywords": "Analytical Chemistry", "note": "\u00a9 1989 American Chemical Society. \n\nThe authors acknowledge the Office of Naval Research, Grant No. N00014-88-K-0482, for support of the research, and N.S.L. acknowledges additional support from the Camille and Henry Dreyfus Foundation Teacher-Scholar Program. This is Contribution No. 7861 from the Division of Chemistry and Chemical Engineering at Caltech.", "abstract": "We describe a new ultramicroelectrode fabrication technique that has allowed the preparation of conical Pt-Ir ultramicroelectrodes with radii of 0.5-10 \u00b5m. These electrodes have been characterized by scanning electron microscopy, cyclic voltammetry, and chronoamperometry. The smallest radii electrodes (r < 2 \u00b5m) exhibited dlffusional behavior at times longer than 70 \u00b5s in accord with a hemispherical geometry, while larger radii electrodes exhibited dlffusional behavior consistent with a conical geometry. A first-order mathematical approach to diffusion at conical surfaces has been developed to explain these results", "date": "1989-08-01", "date_type": "published", "publication": "Analytical Chemistry", "volume": "61", "number": "15", "publisher": "American Chemical Society", "pagerange": "1630-1636", "id_number": "CaltechAUTHORS:20230419-898287000.15", "issn": "0003-2700", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-898287000.15", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-88-K-0482" }, { "agency": "Camille and Henry Dreyfus Foundation" } ] }, "other_numbering_system": { "items": [ { "id": "7861", "name": "Caltech Division of Chemistry and Chemical Engineering" } ] }, "doi": "10.1021/ac00190a009", "resource_type": "article", "pub_year": "1989", "author_list": "Penner, Reginald M.; Heben, Michael J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cyd5m-2a606", "eprint_id": 121003, "eprint_status": "archive", "datestamp": "2023-08-22 06:22:42", "lastmod": "2023-10-18 18:06:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Rosenbluth-Mary-L", "name": { "family": "Rosenbluth", "given": "Mary L." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "\"Ideal\" behavior of the open circuit voltage of semiconductor/liquid junctions", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1989 American Chemical Society. \n\n\nWe acknowledge numerous helpful discussions with Dr. B. Miller of AT&T Bell Laboratories and Prof. R. Marcus of Caltech. Support for this work was provided by the Department of Energy, Office of Basic Energy Sciences. N.S.L. also acknowledges support as an A. P. Sloan Fellow and as a Dreyfus Teacher-Scholar.", "abstract": "Using simple bimolecular kinetic expressions for interfacial charge-transfer rates at semiconductor/liquid junctions, we present an analysis of the dependence of the open circuit voltage, V_(oc), on the solution redox potential E(A\u207a/A). It is found that if E(A\u207a/A) is varied by using a series of redox couples with identical heterogeneous rate constants and the concentrations [A] and [A\u207a] are held constant, V_(oc) should change as E(A\u207a/A) is varied. However, if E(A\u207a/A) is manipulated for a given redox system by changing [A\u207a] and holding [A] constant, \"ideal\" behavior predicts no change in V_(oc) at different solution redox potentials. These considerations are of importance both in diagnosing the presence of Fermi level pinning at semiconductor electrodes and in the design of photoelectrochemical cells for use in solar energy conversion.", "date": "1989-05-04", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "93", "number": "9", "publisher": "American Chemical Society", "pagerange": "3735-3740", "id_number": "CaltechAUTHORS:20230419-898278000.13", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-898278000.13", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "Camille and Henry Dreyfus Foundation" } ] }, "doi": "10.1021/j100346a072", "resource_type": "article", "pub_year": "1989", "author_list": "Rosenbluth, Mary L. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/y6n9m-qg156", "eprint_id": 5625, "eprint_status": "archive", "datestamp": "2023-08-22 06:20:37", "lastmod": "2023-10-16 19:19:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Heben-Michael-J", "name": { "family": "Heben", "given": "Michael J." }, "orcid": "0000-0002-3788-3471" }, { "id": "Penner-Reginald-M", "name": { "family": "Penner", "given": "Reginald M." }, "orcid": "0000-0003-2831-3028" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Dovek-Moris-M", "name": { "family": "Dovek", "given": "Moris M." } }, { "id": "Quate-Calvin-F", "name": { "family": "Quate", "given": "Calvin F." } } ] }, "title": "Atomic resolution imaging of electrode surfaces in solutions containing reversible redox species", "ispublished": "pub", "full_text_status": "public", "keywords": "GRAPHITE; ELECTROCHEMISTRY; SURFACE REACTIONS; SURFACE STRUCTURE; TOPOGRAPHY; RESOLUTION; GLASS; POLYMERS; SCANNING TUNNELING MICROSCOPY", "note": "\u00a9 2006 American Institute of Physics \n\n(Received 21 November 1988; accepted 30 January 1989) \n\nWe thank J. Schneir and Professor A. J. Bard for preprints of related STM work on electrodes, and acknowledge helpful discussions with Professor P. Hansma. We also acknowledge partial support of this research at Caltech by the Office of Naval Research and at Stanford by the Defense Advanced Research Projects Agency.\n\nPublished - HEBapl89.pdf
", "abstract": "Procedures are described for insulating metal scanning tunneling microscope (STM) tips with either glass or polymer coatings. In solutions containing 0.10 M of a reversible redox couple, Fe(CN) - 3/-46 , the faradaic limiting current to polymer coated tips was 200\u2013500 pA and that for glass coated tips was <10 pA. For polymer insulated tips, steady-state currents of 10\u2013100 pA were observed at tip-sample displacements less than 0.3 \u00b5m. The suppression of faradaic current achieved by these coating procedures enabled the collection of the first atomic resolution STM images of highly ordered pyrolytic graphite electrodes in contact with redox-active electrolytes. Preliminary data for the in situ electrochemical characterization of these tips are also discussed.", "date": "1989-04-10", "date_type": "published", "publication": "Applied Physics Letters", "volume": "54", "number": "15", "publisher": "American Institute of Physics", "pagerange": "1421-1423", "id_number": "CaltechAUTHORS:HEBapl89", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:HEBapl89", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" } ] }, "doi": "10.1063/1.100686", "primary_object": { "basename": "HEBapl89.pdf", "url": "https://authors.library.caltech.edu/records/y6n9m-qg156/files/HEBapl89.pdf" }, "resource_type": "article", "pub_year": "1989", "author_list": "Heben, Michael J.; Penner, Reginald M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/gqn7h-2bc82", "eprint_id": 120986, "eprint_status": "archive", "datestamp": "2023-08-22 06:07:07", "lastmod": "2023-10-18 18:06:18", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Heben-Michael-J", "name": { "family": "Heben", "given": "Michael J." }, "orcid": "0000-0002-3788-3471" }, { "id": "Dovek-Moris-M", "name": { "family": "Dovek", "given": "Moris M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Penner-Reginald-M", "name": { "family": "Penner", "given": "Reginald M." }, "orcid": "0000-0003-2831-3028" }, { "id": "Quate-Calvin-F", "name": { "family": "Quate", "given": "Calvin F." } } ] }, "title": "Preparation of STM tips for in-situ characterization of electrode surfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "Histology; Pathology and Forensic Medicine", "note": "\u00a9 1988 Blackwell Science. \n\nThe authors would like to thank Christopher Lang and Alison Baski for assisting in the construction of the microscope. We acknowledge the Office of Naval Research, grant no. N00014-85-K-0805, for support of this research. N.S.L. acknowledges additional support from the Camille and Henry Dreyfus Foundation Teacher-Scholar program. C.F.Q. acknowledges support from the Defense Advanced Research Projects Agency.", "abstract": "The total current between the tip and the sample in a scanning tunnelling microscopy study of a solid/liquid interface can be dominated by Faradaic charge transfer currents. In such a situation, feedback control of the tunnelling gap, and imaging, is precluded. In this contribution we describe the preparation of glass and polymer coated STM tips that possess < 100 \u0172 of exposed metal. These tips effectively discriminate against Faradaic current and enable STM imaging in the presence of reversible electroactive solution species at appreciable tip/sample biases.", "date": "1988-12", "date_type": "published", "publication": "Journal of Microscopy", "volume": "152", "number": "3", "publisher": "Royal Microscopical Society", "pagerange": "651-661", "id_number": "CaltechAUTHORS:20230418-318458000.22", "issn": "0022-2720", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230418-318458000.22", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-85-K-0805" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" } ] }, "doi": "10.1111/j.1365-2818.1988.tb01434.x", "resource_type": "article", "pub_year": "1988", "author_list": "Heben, Michael J.; Dovek, Moris M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/34gbp-atw82", "eprint_id": 121043, "eprint_status": "archive", "datestamp": "2023-08-19 21:01:35", "lastmod": "2024-01-16 01:05:57", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dovek-Moris-M", "name": { "family": "Dovek", "given": "Moris M." } }, { "id": "Heben-Michael-J", "name": { "family": "Heben", "given": "Michael J." }, "orcid": "0000-0002-3788-3471" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Penner-Reginald-M", "name": { "family": "Penner", "given": "Reginald M." }, "orcid": "0000-0003-2831-3028" }, { "id": "Quate-Calvin-F", "name": { "family": "Quate", "given": "Calvin F." } } ] }, "title": "Applications of Scanning Tunneling Microscopy to Electrochemistry", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1988 American Chemical Society. \n\nWe acknowledge the financial assistance of the Office of Naval Research, Grant # N00014-85-K-0805. We also acknowledge the assistance of Bruce J. Tufts. NSL also acknowledges support as a Dreyfus Teacher-Scholar and as a A.P. Sloan Fellow.", "abstract": "The Scanning Tunneling Microscope has demonstrated unique capabilities for the examination of electrode topography, the vibrational spectroscopic imaging of surface adsorbed species, and the high resolution electrochemical modification of conductive surfaces. Here we discuss recent progress in electrochemical STM. Included are a comparison of STM with other ex situ and in situ surface analytic techniques, a discussion of relevant STM design considerations, and a semi-quantitative examination of faradaic current contributions for STM at solution-covered surfaces. Applications of STM to the ex situ and in situ study of electrode surfaces are presented.", "date": "1988-11-11", "date_type": "published", "publisher": "American Chemical Society", "place_of_pub": "Washington, DC", "pagerange": "174-201", "id_number": "CaltechAUTHORS:20230419-953451000.38", "isbn": "9780841215429", "book_title": "Electrochemical Surface Science: Molecular Phenomena at Electrode Surfaces", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230419-953451000.38", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-85-K-0805" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Alfred P. Sloan Foundation" } ] }, "contributors": { "items": [ { "id": "Soriaga-Manuel-P", "name": { "family": "Soriaga", "given": "Manuel P." }, "orcid": "0000-0002-0077-6226" } ] }, "doi": "10.1021/bk-1988-0378.ch013", "resource_type": "book_section", "pub_year": "1988", "author_list": "Dovek, Moris M.; Heben, Michael J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4pcky-fw492", "eprint_id": 120981, "eprint_status": "archive", "datestamp": "2023-08-22 06:05:18", "lastmod": "2023-10-18 18:06:07", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Santangelo-Patrick-G", "name": { "family": "Santangelo", "given": "Patrick G." } }, { "id": "Miskelly-Gordon-M", "name": { "family": "Miskelly", "given": "Gordon M." }, "orcid": "0000-0003-4748-0083" }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Cyclic voltammetry at semiconductor photoelectrodes. 1. Ideal surface-attached redox couples with ideal semiconductor behavior", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1988 American Chemical Society. \n\nWe acknowledge the Department of Energy, Office of Basic Energy Sciences, Grant DE-FG03-84ER13222, for support of this work. We also acknowledge helpful discussions with Gail N. Ryba and Professor Hans Andersen of Stanford University, Dr. Steven Feldberg of Brookhaven National Laboratory, and Professor Carl Koval of the University of Colorado. N.S.L. also acknowledges support as a A. P. Sloan Fellow and a Dreyfus Teacher-Scholar.", "abstract": "Working curves for the cyclic voltammetric behavior of semiconductor electrodes have been generated by consideration of a model electrode circuit. The circuit consists of an ideal photodiode in series with a metal electrode. The electroactive material is considered to be an ideally behaving, surface attached redox couple. The solution for the diode/electrode current-voltage characteristic has been solved numerically. Simulations have been performed under varying levels of illumination and for different values of the diode barrier height, the voltage scan rate, and the amount of electroactive material. Chopped scans have also been simulated, where the forward scan is in the light and the reverse scan is in the dark. Emphasis has been placed on modeling cyclic voltammetric data under common experimental conditions, in order to provide a basis for comparison with experiments in the literature.", "date": "1988-11-03", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "92", "number": "22", "publisher": "American Chemical Society", "pagerange": "6359-6367", "id_number": "CaltechAUTHORS:20230418-318430000.17", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230418-318430000.17", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG03-84ER13222" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "Camille and Henry Dreyfus Foundation" } ] }, "doi": "10.1021/j100333a036", "resource_type": "article", "pub_year": "1988", "author_list": "Santangelo, Patrick G.; Miskelly, Gordon M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/j8pyw-srs07", "eprint_id": 31771, "eprint_status": "archive", "datestamp": "2023-08-19 20:59:07", "lastmod": "2023-10-17 21:07:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dovek-Moris-M", "name": { "family": "Dovek", "given": "Moris M." } }, { "id": "Heben-Michael-J", "name": { "family": "Heben", "given": "Michael J." } }, { "id": "Lang-Christoph-A", "name": { "family": "Lang", "given": "Christoph A." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Quate-Calvin-F", "name": { "family": "Quate", "given": "Calvin F." } } ] }, "title": "Design of a scanning tunneling microscope for electrochemical applications", "ispublished": "pub", "full_text_status": "public", "keywords": "ELECTRON MICROSCOPES, DESIGN, ELECTROCHEMISTRY, SCANNING ELECTRON MICROSCOPY, ELECTRON TUNNELING SPECTROSCOPY, OPERATION, SAMPLE HOLDERS, RESOLUTION, GRAPHITE, SURFACE ANALYSIS", "note": "\u00a9 1988 American Institute of Physics. \n\nReceived 9 May 1988; accepted 18 July 1988. \n\nThe authors would like to thank Alison Baski, Jun Nogami, and Reggie Penner for useful discussions and help with construction of the microscope. We acknowledge the\nsupport of an IBM Predoctoral Manufacturing Fellowship\n(M. M.D.) and a German National Scholarship Foundation\nOverseas Fellowship (C. A. L.). N. S. L. acknowledges\nsupport as a Dreyfus Teacher-Scholar and as an A. P. Sloan\nFellow. N. S. L. also acknowledges financial assistance from\nthe Office of Naval Research, Grant No. N00014-85-K-0805. C. F. Q. acknowledges support of the Defense Advanced Research Projects Agency.\n\nPublished - DOVrsi88.pdf
", "abstract": "A design for a scanning tunneling microscope that is well suited for electrochemical investigations is presented. The construction of the microscope ensures that only the tunneling tip and the sample participate in electrochemical reactions. The design also allows rapid replacement of the tip or sample, and enables facile introduction of auxiliary electrodes for use in electrochemical experiments. The microscope utilizes stepper motor driven approach mechanics in order to achieve fully remote operation and to allow reproducible coarse control of tip/sample spacings for electrochemical experiments. Highly ordered pyrolytic graphite images at atomic resolution in air and aqueous solutions can be obtained with this microscope.", "date": "1988-11", "date_type": "published", "publication": "Review of Scientific Instruments", "volume": "59", "number": "11", "publisher": "American Institute of Physics", "pagerange": "2333-2336", "id_number": "CaltechAUTHORS:20120601-105338500", "issn": "0034-6748", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120601-105338500", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "IBM" }, { "agency": "Studienstiftung des deutschen Volkes" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-85-K-0805" }, { "agency": "Defense Advanced Research Projects Agency (DARPA)" } ] }, "doi": "10.1063/1.1139957", "primary_object": { "basename": "DOVrsi88.pdf", "url": "https://authors.library.caltech.edu/records/j8pyw-srs07/files/DOVrsi88.pdf" }, "resource_type": "article", "pub_year": "1988", "author_list": "Dovek, Moris M.; Heben, Michael J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ywcf4-j5370", "eprint_id": 120984, "eprint_status": "archive", "datestamp": "2023-08-22 06:02:45", "lastmod": "2023-10-18 18:06:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lunt-Sharon-R", "name": { "family": "Lunt", "given": "Sharon R." } }, { "id": "Casagrande-Louis-G", "name": { "family": "Casagrande", "given": "Louis G." } }, { "id": "Tufts-Bruce-J", "name": { "family": "Tufts", "given": "Bruce J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Studies of polycrystalline n-GaAs junctions: effects of metal ion chemisorption on the photoelectrochemical properties of n-GaAs/KOH-Se^(-/2-), n-GaAs/CH\u2083CN-ferrocene^(+/0), and n-GaAs/Au interfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1988 American Chemical Society. \n\nWe thank Dr. S. Chu of Southern Methodist University for generously supplying polycrystalline material. We also thank the National Science Foundation (Grant CHE-8312692) for partial support of this work and the Department of Energy, Office of Basic Energy Sciences, for continuing support of these studies.", "abstract": "Current-voltage and spectral response properties were determined for polycrystalline n-GaAs photoanodes in contact with aqueous KOH-Se^(-/2-) and nonaqueous CH\u2083CN-ferrocene^(+/0)-LiC1O\u2084 electrolytes. The n-GaAs/KOH-Se^(-/2-) system initially exhibited poor junction behavior, but chemisorption of Ru\u1d35\u1d35\u1d35, Rh\u1d35\u1d35\u1d35, Ir\u1d35\u1d35\u1d35, Co\u1d35\u1d35\u1d35, or Os\u1d35\u1d35\u1d35 ions onto the GaAs photoanode was found to yield improved I-V properties. The trend in I-V improvement correlated with improved electrocatalysis of Se\u00b2\u207b oxidation at p-GaAs, n\u207a-GaAs, and In\u2082O\u2083 electrode surfaces. The n-GaAs/CH\u2083CN system displayed excellent junction behavior and did not respond to metal chemisorption treatments. These results are consistent with the metal-ion-induced improvement being predominantly due to electrocatalytic effects.", "date": "1988-10-06", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "92", "number": "20", "publisher": "American Chemical Society", "pagerange": "5766-5770", "id_number": "CaltechAUTHORS:20230418-318445000.20", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230418-318445000.20", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-8312692" }, { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1021/j100331a043", "resource_type": "article", "pub_year": "1988", "author_list": "Lunt, Sharon R.; Casagrande, Louis G.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/tc6qp-ryx28", "eprint_id": 120980, "eprint_status": "archive", "datestamp": "2023-08-22 05:48:08", "lastmod": "2023-10-18 18:06:04", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Schmidt-Michael-H", "name": { "family": "Schmidt", "given": "Michael H." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Reaction entropies and acid-base behavior of transition-metal complexes in recast Nafion films", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1988 American Chemical Society. \n\nWe acknowledge the Gas Research Institute for generous support of this research. N.S.L. also acknowledges support as a Dreyfus Teacher-Scholar (1985-1990) and A.P. Sloan Foundation Fellow (1985-1987). We are grateful to Prof. Fred C. Anson of Caltech for generously forwarding a preprint of ref 10a.", "abstract": "The effect of Donnan potentials on the apparent formal potentials of polymer-bound metal ions has been investigated for recast Nafion films and for spin-cast Nafion films on graphite electrodes. For the probe ions Ru(NH\u2083)\u2086^(3+/2+) and Ru(bpy)\u2083^(3+/2+), the behavior generally correlates with Donnan potentials expected for ideally permselective domains, and plots of the apparent E\u2070' vs ionic strength (\u00b5) have slopes of 59 mV/(decade increase in \u00b5) for 1:1 monovalent electrolytes. The observed reaction entropies, \u0394S_(obsd), have been determined as a function of solution ionic strength. The measured \u0394S_(obsd) values are found to consist of the intrinsic reaction entropy for the reaction and an entropy of transfer term. The latter term arises from the permselectivity properties of the Nafion films. Extraction of the intrinsic reaction entropy, \u0394S\u1d63\ua700, yields a revised interpretation of the reaction entropy behavior of Ru complexes in Nafion films. The pH vs E_(1/2) properties of Nafion-bound Ru-(NH\u2083)\u2085(H\u2082O)^(3+/2+), Ru(NH\u2083)\u2085(isna)^(3+/2+) (isna = isonicotinic acid), and Ru(NH\u2083)\u2085(pz)^(3+/2+) (pz =\npyrazine) have been investigated, and apparent p\u00a3a values have been determined for these complexes. Apparent pK\u2090 values in Nafion are generally higher than those in aqueous media by 1.5-2 pK units.", "date": "1988-04-07", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "92", "number": "7", "publisher": "American Chemical Society", "pagerange": "2018-2022", "id_number": "CaltechAUTHORS:20230418-318421000.16", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230418-318421000.16", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Gas Research Institute" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Alfred P. Sloan Foundation" } ] }, "doi": "10.1021/j100318a062", "resource_type": "article", "pub_year": "1988", "author_list": "Schmidt, Michael H. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/j5njm-46728", "eprint_id": 120952, "eprint_status": "archive", "datestamp": "2023-08-22 05:19:54", "lastmod": "2023-10-18 18:05:20", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Abrahams-Ian-L", "name": { "family": "Abrahams", "given": "Ian L." } }, { "id": "Tufts-Bruce-J", "name": { "family": "Tufts", "given": "Bruce J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Coordination chemistry of semiconductor photoelectrodes: reactions of etched n-gallium arsenide with cobalt(III) complexes", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1987 American Chemical Society. \n\nWe acknowledge support from the National Science Foundation, CHE-12692, for this work. N.S.L. acknowledges support under the Presidential Young Investigator program (CHE-8352151) with matching funds from Monsanto, Exxon, Mobil, Sohio, and IBM. N.S.L. also acknowledges support as a Dreyfus Teacher-Scholar and an Alfred P. Sloan Foundation Fellow. We thank R. Dominguez and C. M. Gronet for assistance with some of the experiments in this study and Dr. C. R. Lewis of Var\u00edan Associates, Palo Alto, CA, for a generous supply of GaAs.", "abstract": "We report studies of the reactivity of n-GaAs surfaces with transition-metal complexes. Generally, adsorption of metal ions at semiconductor junctions has been observed to increase carrier trapping rates. A notable exception is the improved performance of n-GaAs interfaces after exposure to acidic aqueous solutions of Ru(III) ions and other metal cations, but little information is available regarding the chemistry of these surface treatments. Except for systems in which metal ions act as precursors for the deposition of metals or metal alloys, no information is available regarding the oxidation state or chemical environment of chemisorbed transition-metal complexes on semiconductor electrodes. Possible but undocumented mechanisms of metal ion attachment to the semiconductor surface include electrostatic binding, ligand substitution processes, and redox reactions. To explore the various possible modes of reaction, we have investigated the chemistry of n-GaAs surfaces in contact with aqueous solutions of Co(III) complexes.", "date": "1987-05-01", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "109", "number": "11", "publisher": "American Chemical Society", "pagerange": "3472-3474", "id_number": "CaltechAUTHORS:20230418-571291000.10", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230418-571291000.10", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-12692" }, { "agency": "NSF", "grant_number": "CHE-8352151" }, { "agency": "Monsanto Corporation" }, { "agency": "Exxon Education Foundation" }, { "agency": "Mobil Oil Corporation" }, { "agency": "Sohio" }, { "agency": "IBM" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Alfred P. Sloan Foundation" } ] }, "doi": "10.1021/ja00245a055", "resource_type": "article", "pub_year": "1987", "author_list": "Abrahams, Ian L.; Tufts, Bruce J.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/c7z79-cqp09", "eprint_id": 67983, "eprint_status": "archive", "datestamp": "2023-08-19 19:21:05", "lastmod": "2023-10-19 22:10:42", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "name": { "family": "Abrahams", "given": "I. L." } }, { "name": { "family": "Casagrande", "given": "L. G." } }, { "name": { "family": "Rosenblum", "given": "M. D." } }, { "name": { "family": "Rosenbluth", "given": "M. L." } }, { "name": { "family": "Santangelo", "given": "P. G." } }, { "name": { "family": "Tufts", "given": "B. J." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "N. S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Opportunities in semiconductor photoelectrochemistry", "ispublished": "pub", "full_text_status": "public", "abstract": "Les problemes rencontres en photoelectrochimie des semiconducteurs sont rapportes: developpement de cellules solaires a jonction n-Si/liquide; croissance photoelectrochimique des cellules de type MIS; etude de la chimie interfaciale des materiaux III-V; processus chimiques pour minimiser les pertes de recombinaison aux joints de grain et aux etats de surface des interfaces de Si et de GaAs", "date": "1987-02", "date_type": "published", "publication": "New Journal of Chemistry", "volume": "11", "number": "2", "publisher": "CNRS/Gauthier-Villars", "pagerange": "157-165", "id_number": "CaltechAUTHORS:20160616-173827773", "issn": "1144-0546", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160616-173827773", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "article", "pub_year": "1987", "author_list": "Abrahams, I. L.; Casagrande, L. G.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rz89w-a1k65", "eprint_id": 120927, "eprint_status": "archive", "datestamp": "2023-08-22 05:00:32", "lastmod": "2023-10-18 18:04:33", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lieber-Charles-M", "name": { "family": "Lieber", "given": "Charles M." } }, { "id": "Schmidt-Michael-H", "name": { "family": "Schmidt", "given": "Michael H." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Kinetic studies of ligand substitution rates for the Ru(NH\u2083)\u2085(H\u2082O)\u00b2\u207a ion in Nafion films", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1986 American Chemical Society. \n\nWe gratefully acknowledge the Gas Research Institute for support of this work. N.S.L. also acknowledges generous support in the form of matching funds in the Presidential Young Investigator Program from Monsanto Co., Mobil Co., the Exxon Educational Foundation, and an IBM Young Faculty Development Award. C.M.L. acknowledges support as a Joseph W. Richards Summer Research Fellow of the Electrochemical Society, and N.S.L. acknowledges support as an Alfred P. Sloan Fellow (1985-1987) and a Camille and Henry Dreyfus Teacher-Scholar (1985-1990). We also thank Professors John Brauman and Henry Taube of Stanford University, Professor Harry Gray of Caltech, and Dr. W. Turnas for valuable discussion and comment on this work.", "abstract": "Substitution rates have been measured for reaction of a number of pyridines with the Nafion-bound Ru(NH\u2083)\u2085(H\u2082O)\u00b2\u207a complex. Reaction activities have been determined by electrochemical techniques, which also allow for determination of site thermodynamics and heterogeneity during the course of the reaction. Diffusion-coefficient effects are investigated by variation in polymer film thickness, and partition coefficients have been determined under equilibrium conditions by optical absorbance techniques. The partition-coefficient corrected rate law is found to be first order in Nafion-bound [Ru\u1d35\u1d35] and first order in ligand concentration in the polymer phase. The partition-coefficient corrected bimolecular rate constants for a variety of pyridine ligands are found to vary by a factor of 5, which contrasts with the relatively constant substitution rates observed in aqueous solution. Also, sterically hindered ligands, such as 2-propylpyridine, exhibit surprisingly high substitution rate constants on the Nafion-bound Ru\u1d35\u1d35 ion. These rate data indicate that pronounced molecular reactivity changes can occur upon electrode modification and have implications with respect to the design of chemically modified electrodes for use in electrocatalysis.", "date": "1986-10-01", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "108", "number": "20", "publisher": "American Chemical Society", "pagerange": "6103-6108", "id_number": "CaltechAUTHORS:20230417-377719000.12", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230417-377719000.12", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Gas Research Institute" }, { "agency": "Monsanto Corporation" }, { "agency": "Mobil Oil Corporation" }, { "agency": "Exxon Education Foundation" }, { "agency": "IBM" }, { "agency": "Electrochemical Society" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "Camille and Henry Dreyfus Foundation" } ] }, "doi": "10.1021/ja00280a001", "resource_type": "article", "pub_year": "1986", "author_list": "Lieber, Charles M.; Schmidt, Michael H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wtkm9-5ps56", "eprint_id": 120964, "eprint_status": "archive", "datestamp": "2023-08-22 04:56:35", "lastmod": "2023-10-18 18:05:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Rosenbluth-Mary-L", "name": { "family": "Rosenbluth", "given": "Mary L." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Kinetic studies of carrier transport and recombination at the n-silicon methanol interface", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1986 American Chemical Society. \n\nWe acknowledge the National Science Foundation, grant CHE-8312692, and the NSF Presidential Young Investigator Program for support of this work. N.S.L. also acknowledges support from PYI matching funds generously provided by Monsanto Co., the Exxon Educational Foundation, Mobil Corp., and the IBM Young Faculty Development Award Program and funds as an Alfred P. Sloan Foundation Fellow (1985-1987) and a Camille and Henry Dreyfus Teacher-Scholar (1985-1990). We also wish to thank Prof. Richard Swanson and Dr. Wendell Eades of Stanford University, Dr. Adam Heller of AT&T Bell Laboratories, and Dr. Karl Frese of SRI International for helpful discussions regarding surface recombination processes.", "abstract": "The response of the open-circuit photovoltage, V_(oc), has been investigated with regard to changes in the minority carrier diffusion length, majority carrier density, short-circuit photocurrent density, and cell temperature of n-Si/CH\u2083OH junctions. The reaction kinetics are observed to be first order in dopant density, minority carrier diffusion length, and photocurrent density. The activation barrier for carrier recombination, obtained from plots of V_(oc) vs. temperature, is 1.15 \u00b1 0.05 eV. An optimum dopant density for maximum V_(oc) is observed, and this is consistent with bulk lifetime measurements on similarly doped Si samples. The reaction kinetics are not sensitive to the concentration of redox species (at constant electrochemical potential), indicating minimal recombination losses due to poor interfacial charge transport rates. Vx values for optimally doped systems (V_(oc) = 670 mV for 0.015 \u03a9-cm n-Si samples at 20 mA/cm\u00b2 photocurrent densities) represent the highest photovoltages obtained to date for any n-Si-based surface barrier device. Surface recombination velocity measurements at the n-Si/CH\u2083OH interface have been performed, and correlations between the surface recombination rate and the improvement in current-voltage properties have been investigated.", "date": "1986-08-06", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "108", "number": "16", "publisher": "American Chemical Society", "pagerange": "4689-4695", "id_number": "CaltechAUTHORS:20230418-571490000.27", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230418-571490000.27", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-8312692" }, { "agency": "Monsanto Corporation" }, { "agency": "Exxon Education Foundation" }, { "agency": "IBM" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "Camille and Henry Dreyfus Foundation" } ] }, "doi": "10.1021/ja00276a001", "resource_type": "article", "pub_year": "1986", "author_list": "Rosenbluth, Mary L. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ck3ez-tbk63", "eprint_id": 120926, "eprint_status": "archive", "datestamp": "2023-08-22 04:45:21", "lastmod": "2023-10-18 18:04:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lieber-Charles-M", "name": { "family": "Lieber", "given": "Charles M." } }, { "id": "Schmidt-Michael-H", "name": { "family": "Schmidt", "given": "Michael H." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Reaction entropy measurements for transition-metal ions bound to Nafion-coated electrode surfaces", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 American Chemical Society. \n\nWe acknowledge funding for this research from the Gas Research Institute. N.S.L. also acknowledges support as an Alfred P. Sloan Fellow and a Dreyfus Teacher Scholar, and C.M.L. received partial summer support from the Joseph W. Richards Fellowship of the Electrochemical Society.", "abstract": "Reaction entropies, \u0394S\u2070_(rc), have been determined for a series of transition-metal ions electrostatically bound into Nafion films. Complexes with hydrophobic, \"shielding\" ligands such as Ru(2,2'-bipyridine)\u2083^(3+/2+) and Co(2,2'-bipyridine)\u2083^(3+/2+) yield similar \u0394S\u2070_(rc) values in Nafion films and in aqueous solution, indicating that the electrochemically active probes reside in a predominantly waterlike local environment in the polymer film. Complexes containing aquo and ammine ligands yield markedly lower \u0394S\u2070_(rc) values in Nafion than in aqueous media (\u00b5 = 0.1 M). The \u0394S\u2070_(rc) values for these Nafion-bound systems are similar to values measured for the Ru(NH\u2083)\u2086^(3+/2+) system in concentrated aqueous salt solutions (5 M LiCl). The \u0394S\u2070_(rc) measurements imply that the outer-sphere electron-transfer work terms for polymer bound ions may be lower than those observed in typical aqueous solutions. Differential free energies, enthalpies, and entropies of transfer for the redox reaction M(III) + e\u207b \u2192 M(II) from aqueous media to Nafion have also been determined.", "date": "1986-03-13", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "90", "number": "6", "publisher": "American Chemical Society", "pagerange": "1002-1003", "id_number": "CaltechAUTHORS:20230417-377709000.11", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230417-377709000.11", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Gas Research Institute" }, { "agency": "Alfred P. Sloan Foundation" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Eletrochemical Society" } ] }, "doi": "10.1021/j100278a007", "resource_type": "article", "pub_year": "1986", "author_list": "Lieber, Charles M.; Schmidt, Michael H.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rsftv-h2z45", "eprint_id": 120935, "eprint_status": "archive", "datestamp": "2023-08-22 04:33:40", "lastmod": "2023-10-18 18:04:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lieber-Charles-M", "name": { "family": "Lieber", "given": "Charles M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Probing polymer effects on chemical reactivity: ligand substitution kinetics of Ru(NH\u2083)\u2085(H\u2082O)\u00b2\u207a in Nafion films", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1985 American Chemical Society. \n\nWe acknowledge helpful discussions with Dr. W. Tumas and Profs. J. I. Brauman and H. Taube of Stanford University. Support for this work was provided by the Gas Research Institute. N.S.L. also received support from an IBM Young Faculty Development Award and from the Exxon Educational Foundation, Mobil Co., and Monsanto Co. under the Presidential Young Investigator Program.", "abstract": "Several studies have addressed electron transport by outer-sphere electron-transfer processes for polymer-coated electrodes. However, relatively little attention has been focused upon the effects that the polymer environment will have upon the intrinsic chemical reactivity of the reagent bound in the polymer phase. Difficulties in quantifying and separating the role of substrate and product diffusion from partition effects and from intrinsic changes in chemical reactivity have also been recognized in studies of catalysis by polymer-bound organometallic complexes. We report studies of a model catalyst-substrate system for which we have been able to address the independent kinetic effects of reaction site homogeneity, substrate diffusion into the polymer film, and changes in activation parameters.", "date": "1985-11-27", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "107", "number": "24", "publisher": "American Chemical Society", "pagerange": "7190-7191", "id_number": "CaltechAUTHORS:20230417-377789000.22", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230417-377789000.22", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Gas Research Institute" }, { "agency": "IBM" }, { "agency": "Exxon Education Foundation" }, { "agency": "Mobil Oil Corporation" }, { "agency": "Monsanto Corporation" } ] }, "doi": "10.1021/ja00310a080", "resource_type": "article", "pub_year": "1985", "author_list": "Lieber, Charles M. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3w5ww-q4z80", "eprint_id": 120938, "eprint_status": "archive", "datestamp": "2023-08-22 04:31:33", "lastmod": "2023-10-18 18:04:53", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Casagrande-Louis-G", "name": { "family": "Casagrande", "given": "Louis G." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Measurement of the activation barrier for carrier transport at n-gallium arsenide semiconductor/liquid junctions", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1985 American Chemical Society. \n\nWe acknowledge helpful discussions with W. Spicer, R. Bube, A. Fahrenbruch, and R. Swanson regarding this research. Funding for this work was provided by the Department of Energy, Office of Basic Energy Sciences. We also thank C.L.R. Lewis of Var\u00edan Associates for a generous supply of epitaxial n-GaAs samples, and N.S.L. acknowledges support for the Exxon Education Foundation and Monsanto Corp. under the Presidential Young Investigator Program.", "abstract": "The mechanism of carrier transport at semiconductor/liquid interfaces is an important and controversial topic in photoelectrochemistry. Of particular concern is the transport kinetics for interfaces whose open-circuit voltage, V_(OC), is constant over some range of solution redox potential. Fermi level pinning has been postulated to apply to n-GaAs, p-GaAs, and p-InP interfaces in both aqueous and nonaqueous solvents. However, direct identification of the various recombination mechanisms has been acknowledged to be difficult, and to date, few experimental techniques have been reported which allow correlation of the key photostationary state observable, the open circuit voltage, to the transport mechanism of these interfaces. We report here measurements of the temperature dependence of the open-circuit voltage for the n-GaAs semiconductor/liquid junction system", "date": "1985-10-02", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "107", "number": "20", "publisher": "American Chemical Society", "pagerange": "5793-5794", "id_number": "CaltechAUTHORS:20230417-377821000.28", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230417-377821000.28", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Exxon Education Foundation" }, { "agency": "Monsanto Corporation" } ] }, "doi": "10.1021/ja00306a031", "resource_type": "article", "pub_year": "1985", "author_list": "Casagrande, Louis G. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rs156-ec085", "eprint_id": 120884, "eprint_status": "archive", "datestamp": "2023-08-22 04:09:52", "lastmod": "2023-10-18 18:03:35", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gronet-Chris-M", "name": { "family": "Gronet", "given": "Chris M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Cogan-George-W", "name": { "family": "Cogan", "given": "George W." } }, { "id": "Gibbons-James-F", "name": { "family": "Gibbons", "given": "James F." } }, { "id": "Moddel-Garret-R", "name": { "family": "Moddel", "given": "Garret R." } }, { "id": "Wiesmann-Harold", "name": { "family": "Wiesmann", "given": "Harold" } } ] }, "title": "Correlation of the Photoelectrochemistry of the Amorphous Hydrogenated Silicon/Methanol Interface with Bulk Semiconductor Properties", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Electrochemistry; Surfaces, Coatings and Films; Condensed Matter Physics; Renewable Energy, Sustainability and the Environment; Electronic, Optical and Magnetic Materials", "note": "\u00a9 1984 ECS - The Electrochemical Society. \n\nWe thank L. Christel of SERA Solar Corporation for valuable discussions and supply of computer programs, and Jeff Marks of Stanford University for the use of the arc lamp source. We also thank Professor M. S. Wrighton of MIT for generously supplying a preprint describing work on p-i a-Si:H.\n\nPublished - Gronet_1984_J._Electrochem._Soc._131_2873.pdf
", "abstract": "Semiconductor/liquid junctions derived from 0.5 \u03bcm thick films of amorphous hydrogenated silicon, a\u2010Si:H, have been investigated in CH\u2083OH solvent. The a\u2010Si:H films consist of a weakly doped n\u2010type layer over a 200\u00c5 n+\u2010a\u2010Si:H layer on a stainless\u2010steel substrate. The low series resistance and high ratio of minority carrier collection length to film thickness in this arrangement allows a study of the properties of semiconductor/liquid interfaces with minimal interference from bulk resistance losses. We find that a\u2010Si:H anodes in 0.02M ferrocene, FeCp\u2082/0.5 mM FeCp\u2082\u207a/1.5 M LiClO\u2084/CH\u2083OH solutions exhibit poor short\u2010circuit quantum yields and low fill factors with 632.8 nm irradiation, but that these junctions display internal quantum yields of close to unity and high fill factors with short wavelength (\u03bb < 450 nm) irradiation. Photons absorbed within a distance comparable to the minority carrier collection length are efficiently collected, and the fill factors and quantum yields under such conditions are insensitive to increases in photocurrent density over a range of 0.1\u20132 mA/cm\u00b2. Solar\u2010simulated irradiation (88 mW/cm\u00b2) from a ELH\u2010type tungsten\u2010halogen lamp in the a-Si:H/0.02 M FeCp\u2082/0.5 mM FeCp\u2082\u207a/1.5 M LiClO\u2084/CH\u2083OH system yields open\u2010circuit photovoltages of 0.75\u20130.85V, short\u2010circuit photocurrents of 6\u20137 mA/cm\u00b2, and photoelectrode efficiencies for conversion of light to electricity of 2.7%\u20133.3%. Photovoltages with the acetylferrocene^(+/0) redox system are among the highest reported for any a\u2010Si:H surface barrier system, and can exceed 0.85V under AM1 illumination conditions. Variation in the redox potential of the solution leads to changes in open\u2010circuit photovoltage in accord with theory, and does not yield evidence for pinning of the a\u2010Si:H Fermi level by interface states or by surface oxides over the potential range investigated. The observed photoelectrochemical behavior of these a\u2010Si:H films is consistent with documented bulk transport and carrier collection properties of a\u2010Si:H, and does not show evidence for series resistance losses, unusual spectral response characteristics, or recombination sites at the semiconductor/liquid junction. Manipulation of the electronic properties of the a\u2010Si:H films can thus lead to improved energy conversion parameters and a clearer picture of the chemistry at the a\u2010Si:H/liquid interface.", "date": "1984-12", "date_type": "published", "publication": "Journal of the Electrochemical Society", "volume": "131", "number": "12", "publisher": "Electrochemical Society", "pagerange": "2873-2880", "id_number": "CaltechAUTHORS:20230414-547155000.3", "issn": "0013-4651", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230414-547155000.3", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1149/1.2115434", "primary_object": { "basename": "Gronet_1984_J._Electrochem._Soc._131_2873.pdf", "url": "https://authors.library.caltech.edu/records/rs156-ec085/files/Gronet_1984_J._Electrochem._Soc._131_2873.pdf" }, "resource_type": "article", "pub_year": "1984", "author_list": "Gronet, Chris M.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/szhv3-2rg97", "eprint_id": 32231, "eprint_status": "archive", "datestamp": "2023-08-19 17:15:29", "lastmod": "2023-10-17 23:03:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gibbons-James-F", "name": { "family": "Gibbons", "given": "James F." } }, { "id": "Cogan-George-W", "name": { "family": "Cogan", "given": "George W." } }, { "id": "Gronet-Chris-M", "name": { "family": "Gronet", "given": "Chris M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A 14% efficient nonaqueous semiconductor/liquid junction solar cell", "ispublished": "pub", "full_text_status": "public", "keywords": "EFFICIENCY, FABRICATION, ELECTRODES, OPERATION, SILICON SOLAR CELLS, SILICON, ELECTROLYTES, AQUEOUS SOLUTIONS, SOLVENTS, DESIGN, EXPERIMENTAL DATA, SEMICONDUCTOR\u2212ELECTROLYTIC CON", "note": "\u00a9 1984 American Institute of Physics. \n\nReceived 20 July 1984; accepted 21 August 1984. \n\n thank F. C. Wu, G. R. Moddel, L.A. Christel, J. T. Merchant, J. S. Olson, and R. Redse of SERA Solar Corp. and C. M. Lieber of Stanford University for valuable contributions to this work.\n\nPublished - GIBapl84.pdf
", "abstract": "We describe the most efficient semiconductor/liquid junction solar cell reported to date. Under W\u2010halogen (ELH) illumination, the device is a 14% efficient two\u2010electrode solar cell fabricated from an n\u2010type silicon photoanode in contact with a nonaqueous electrolyte solution. The cell\u2032s central feature is an ultrathin electrolyte layer which simultaneously reduces losses which result from electrode polarization, electrolyte light absorption, and electrolyte resistance. The thin electrolyte layer also eliminates the need for forced convection of the redox couple and allows for precise control over the amount of water (and other electrolyte impurities) exposed to the semiconductor. After one month of continuous operation under ELH light at 100 mW/cm^2, which corresponds to the passage of over 70\u2009000 C/cm^2, thin\u2010layer cells retained over 90% of their efficiency. In addition, when made with Wacker Silso cast polycrystalline Si, cells yield an efficiency of 9.8% under simulated AMl illumination. The thin\u2010layer cells employ no external compensation yet surpass their corresponding experimental (three\u2010electrode) predecessors in efficiency.", "date": "1984-11-15", "date_type": "published", "publication": "Applied Physics Letters", "volume": "45", "number": "10", "publisher": "American Institute of Physics", "pagerange": "1095-1097", "id_number": "CaltechAUTHORS:20120702-100148444", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120702-100148444", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1063/1.95028", "primary_object": { "basename": "GIBapl84.pdf", "url": "https://authors.library.caltech.edu/records/szhv3-2rg97/files/GIBapl84.pdf" }, "resource_type": "article", "pub_year": "1984", "author_list": "Gibbons, James F.; Cogan, George W.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/r2ywr-wqx71", "eprint_id": 120945, "eprint_status": "archive", "datestamp": "2023-08-22 04:07:09", "lastmod": "2023-10-18 18:05:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "A Quantitative Investigation of the Open\u2010Circuit Photovoltage at the Semiconductor/Liquid Interface", "ispublished": "pub", "full_text_status": "public", "keywords": "Materials Chemistry; Electrochemistry; Surfaces, Coatings and Films; Condensed Matter Physics; Renewable Energy, Sustainability and the Environment; Electronic, Optical and Magnetic Materials", "note": "\u00a9 1984 ECS - The Electrochemical Society. \n\nWe acknowledge helpful discussions with C. Gronet and R. Bube of Stanford University, as well as G. Cogan, J. Gibbons, and G. Moddel of SERA Solar Corporation, Santa Clara, California. This work was partially supported by the NSF through Stanford Center for Materials Research. N.S.L. also wishes to thank the IBM Corporation for generous support through receipt of a Young Faculty Development Award and support from NSF grant CHE-8312692.\n\nPublished - Lewis_1984_J._Electrochem._Soc._131_2496.pdf
", "abstract": "A quantitative analysis of the theoretical value for the open\u2010circuit photovoltage, V_(oc), of a semiconductor/liquid junction reveals that control of bulk carrier transport properties is crucial to interpreting the observables at the semiconductor/liquid interface. Use of characterized semiconductor samples yields quantitative agreement between the maximum theoretical V_(oc) and experimentally observed values for both n\u2010Si and p\u2010Si surfaces in nonaqueous solvents. This accord between theory and experiment rules out deleterious effects of charged surface states on the of these interfaces. Lower than ideal V_(oc) values in other systems might reflect poor diffusion lengths in the semiconductor, classical tunneling over the barrier, or the effects of surface states. The observation of large photovoltages from n\u2010 and p\u2010type\u2010based semiconductor interfaces (n\u2010Si, p\u2010Si, n-GaAs, p-GaAs) in the same solvent is used to rule out a fixed density of charged surface states as the mechanism for obtaining constant photovoltages at these junctions. Direct support for this interpretation is obtained by techniques which verify the presence of mobile surface charge on p\u2010type Si cathode surfaces in the inversion condition. Thus, control and investigation of bulk semiconductor properties that has been eminently significant to the understanding of p\u2010n junction solar cells is also crucial to developing a rational understanding of the observables at the semiconductor/liquid interface.", "date": "1984-11", "date_type": "published", "publication": "Journal of the Electrochemical Society", "volume": "131", "number": "11", "publisher": "Electrochemical Society", "pagerange": "2496-2503", "id_number": "CaltechAUTHORS:20230417-854176000.1", "issn": "0013-4651", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230417-854176000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE-8312692" }, { "agency": "IBM" } ] }, "doi": "10.1149/1.2115347", "primary_object": { "basename": "Lewis_1984_J._Electrochem._Soc._131_2496.pdf", "url": "https://authors.library.caltech.edu/records/r2ywr-wqx71/files/Lewis_1984_J._Electrochem._Soc._131_2496.pdf" }, "resource_type": "article", "pub_year": "1984", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/xx50g-bhz33", "eprint_id": 120942, "eprint_status": "archive", "datestamp": "2023-08-22 04:02:42", "lastmod": "2023-10-18 18:05:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lieber-Charles-M", "name": { "family": "Lieber", "given": "Charles M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Catalytic reduction of carbon dioxide at carbon electrodes modified with cobalt phthalocyanine", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1984 American Chemical Society. \n\nAcknowledgment is made to the donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support of this research. We also acknowledge support through the NIH Biomedical Fund at Stanford University, and N.S.L. acknowledges support from an\nIBM Corp. Young Faculty Development Award.", "abstract": "We report the electrocatalytic reduction of aqueous solutions of CO\u2082(g) to CO(g). The reaction occurs on carbon electrodes modified by adsorption of cobalt phthalocyanine, Co(Pc). The CO\u2082 reduction can be achieved within 300 mV of the thermodynamic CO\u2082/CO redox potential, and essentially the only carbon-containing product is CO(g). In contrast, Co(Pc) dissolved in homogeneous solution yields poor stability and low catalytic efficiency for CO\u2082 activation. Thus, in addition to an energy-efficient activation of CO\u2082(g), this system demonstrates the effectiveness of chemical modification of electrodes in suppressing deleterious decomposition pathways during electrocatalysis.", "date": "1984-08-22", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "106", "number": "17", "publisher": "American Chemical Society", "pagerange": "5033-5034", "id_number": "CaltechAUTHORS:20230417-377905000.35", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230417-377905000.35", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "American Chemical Society Petroleum Research Fund" }, { "agency": "NIH" }, { "agency": "IBM" } ] }, "doi": "10.1021/ja00329a082", "resource_type": "article", "pub_year": "1984", "author_list": "Lieber, Charles M. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/58786-v3463", "eprint_id": 10502, "eprint_status": "archive", "datestamp": "2023-08-22 04:02:24", "lastmod": "2023-10-16 22:54:13", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Rosenbluth-Mary-L", "name": { "family": "Rosenbluth", "given": "Mary L." } }, { "id": "Lieber-Charles-M", "name": { "family": "Lieber", "given": "Charles M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "630-mV open circuit voltage, 12% efficient n-Si liquid junction", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 1984 American Institute of Physics. \n\nReceived 23 April 1984; accepted 21 May 1984. \n\nWe acknowledge the National Science Foundation and the Research Corporation for support of this work. NSL also acknowledged support through and IBM Corp. Young Faculty Development Award. We thank Professor R. Swanson of Stanford for discussions concerning the high level injection regime, as well as for supply of the float zone Si samples. We also gratefully acknowledge the suggestion by Professor J. Gibbons of Stanford University and SERA Solar Corp. that residual series resistance losses might be important in improving the efficiency of the GaAs\u2081\u208b\u2093P\u2093/CH\u2083CN system, because this suggestion prompted our investigation of the photoelectrochemsitry of the n-Si/liquid interface.\n\nPublished - ROSapl84.pdf
", "abstract": "We report the first experimental observation of a semiconductor/liquid junction whose open circuit voltage Voc is controlled by bulk diffusion/recombination processes. Variation in temperature, minority-carrier diffusion length, and/or in majority-carrier concentration produces changes in the Voc of the n-Si/CH3OH interface in accord with bulk recombination/diffusion theory. Under AM2 irradiation conditions, the extrapolated intercept at 0 K of Voc vs T plots yields activation energies for the dominant recombination process of 1.1\u20131.2 eV, in accord with the 1.12-eV band gap of Si. A crucial factor in achieving optimum performance of the n-Si/CH3OH interface is assigned to photoelectrochemical oxide formation, which passivates surface recombination sites at the n-Si/CH3OH interface and minimizes deleterious effects of pinning of the Fermi level at the Si/CH3OH junction. Controlled Si oxide growth, combined with optimization of bulk crystal parameters in accord with diffusion theory, is found to yield improved photoelectrode output parameters, with 12.0\u00b11.5% AM2 efficiencies and AM1 Voc values of 632\u2013640 mV for 0.2-\u03a9 cm Si materials.", "date": "1984-08-15", "date_type": "published", "publication": "Applied Physics Letters", "volume": "45", "number": "4", "publisher": "American Institute of Physics", "pagerange": "423-425", "id_number": "CaltechAUTHORS:ROSapl84", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:ROSapl84", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "Research Corporation" }, { "agency": "IBM" } ] }, "doi": "10.1063/1.95244", "primary_object": { "basename": "ROSapl84.pdf", "url": "https://authors.library.caltech.edu/records/58786-v3463/files/ROSapl84.pdf" }, "resource_type": "article", "pub_year": "1984", "author_list": "Rosenbluth, Mary L.; Lieber, Charles M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6nzzv-6g287", "eprint_id": 32298, "eprint_status": "archive", "datestamp": "2023-08-19 17:04:26", "lastmod": "2023-10-17 23:06:52", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Photoeffects at the Semiconductor/Liquid Interface", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 1984 by Annual Reviews Inc.", "abstract": "The past decade has seen a revived interest in the study of photoeffects at\nsemiconductor/liquid interfaces. Most of the recent attention to this field\nhas been spurred by the desire to utilize such junctions for the conversion\nand storage of solar energy (1-4). The possibility of direct fuel formation\nthe semiconductor/liquid interface, combined with the potential low cost\nand ease of junction formation, are frequently cited as the most attractive\nfeatures of these systems.", "date": "1984-08", "date_type": "published", "publication": "Annual Review of Materials Science", "volume": "14", "publisher": "Annual Reviews", "pagerange": "95-117", "id_number": "CaltechAUTHORS:20120709-083435785", "issn": "0084-6600", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120709-083435785", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1146/annurev.ms.14.080184.000523", "resource_type": "article", "pub_year": "1984", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/gjbjv-x9981", "eprint_id": 120941, "eprint_status": "archive", "datestamp": "2023-08-22 04:00:04", "lastmod": "2023-10-18 18:04:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Rosenblum-Mark-D", "name": { "family": "Rosenblum", "given": "Mark D." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Stabilization of n-type silicon photoanodes in aqueous solution by electrostatic binding of redox ions into charged polymers", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1984 American Chemical Society. \n\nWe acknowledge the Research Corp. for support of this work through a Cottrell Research Grant, and N.S.L. is grateful to IBM Corp. for support through a Young Faculty Development Award. We also thank Prof. M. S. Wrighton of MIT for graciously providing preprints of his work on charge-transport properties of viologen films.", "abstract": "Electrostatic binding of redox-active ions into a polymer-coated electrode is demonstrated to be an effective method of improving photoelectrode stability. Pt and n-type Si electrodes have been coated with poly([4,4'-bipyridinium]-1,1'-diylmethylene-1,2-phenylenemethylene dibromide) (poly-oXV\u00b2\u207a) and other viologen-based polymer films. The poly-oXV^(2+/+). system is insoluble in aqueous solutions containing large anions such as C1O\u2084\u207b, BF\u2084\u207b, and Fe(CN)\u2086\u2074\u207b. Cyclic voltmmetry of modified electrodes in aqueous 1.0 M NaC1O\u2084 shows behavior consistent with a reversibly electroactive, surface-confined species, E\u00b0'\n(poly-oXV^(2+/+\u00b7)) = -0.45 V vs. SCE. In the presence of electroactive anions, n-type Si electrodes coated with poly-oXV\u00b2\u207a show substantial improvements in photocurrent stability compared to naked n-Si electrodes. Negative ions from solution are sorbed by the positively charged poly-oXV\u00b2\u207a units, providing efficient scavenging of photogenerated holes at the semiconductor surface. No improvement in stability is observed with positively charged solution ions, such as Fe(H\u2082O)\u2086\u00b2\u207a. Variation in coverage of the polymer coating causes changes in the observed stabilization of photocurrent. The method may provide a useful framework for design of improved coatings for the stabilization of aqueous semiconductor/liquid interfaces.", "date": "1984-07-05", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "88", "number": "14", "publisher": "American Chemical Society", "pagerange": "3103-3107", "id_number": "CaltechAUTHORS:20230417-377897000.33", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230417-377897000.33", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Cottrell Scholar of Research Corporation" }, { "agency": "IBM" } ] }, "doi": "10.1021/j150658a035", "resource_type": "article", "pub_year": "1984", "author_list": "Rosenblum, Mark D. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dmwe8-rng24", "eprint_id": 120944, "eprint_status": "archive", "datestamp": "2023-08-22 03:55:08", "lastmod": "2023-10-18 18:05:06", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Wrighton-Mark-S", "name": { "family": "Wrighton", "given": "Mark S." } } ] }, "title": "Effect of charge transport in electrode-confined N,N'-dialkyl-4,4'-bipyridinium polymers on the current-potential response for mediated, outer-sphere electron-transfer reactions", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1984 American Chemical Society. \n\nWe thank the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, for support of this research. N.S.L. acknowledges support as a Fannie and John Hertz Predoctoral Fellow.", "abstract": "Mediated outer-sphere redox processes have been examined at rotating disk Pt/[(PQ^(2+/+))\u2099]_(surf) electrodes. The [(PQ^(2+/+))\u2099]_(surf) is a redox polymer anchored to the surface and is formed from N,N'-bis[(trimethoxysilyl)propyl]-4,4'-bipyridinium, I. The polymer coverages for the electrodes selected for study are sufficiently great that Fe(phen)\u2083^(3+/,2+), E\u2070' = +1.03 V vs. SCE, shows no electrochemical response near its E\u2070'. The mediated reduction of Fe(phen)\u2083\u00b3\u207a and a number of other outer-sphere oxidants is mass-transport limited when the Pt/[(PQ^(2+/+)\u2099]_(surf) electrode is held ~ 100 mV more negative than E\u2070'[(PQ^(2+/+))\u2099]_(surf) = -0.45 V vs. SCE in CH\u2083CN/0.1 M [n-Bu\u2081N]C1O\u2084. However, contrary to theoretical expectations based only on the rate constant for reaction of Fe(phen)\u2083\u00b3\u207a with a surface PQ+, the onset of current for the mediated reduction is at the onset for [(PQ\u00b2\u207a)\u2099]_(surf) \u2192 [(PQ\u207a)\u2099]_(surf) reduction; in fact, the mediated reduction current in the onset region is directly proportional to the concentration of PQ\u207a in the surface-confined polymer. Data for Pt/[(PQ2+\u2022xFe(CN)\u2086^(3~/)4~)\u2099]_(surf) electrodes show directly that charge transport in the polymer can be a limitation to the maximum steady-state mediation current in aqueous electrolyte solution at the coverages of [(PQ^(2+/+))\u2099]_(surf) that have been employed. The charge-transport properties of the polymer are concluded to control the current-potential profile, as has been reported previously for other surface-modified electrodes, for the large polymer coverages employed in these studies.", "date": "1984-05-10", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "88", "number": "10", "publisher": "American Chemical Society", "pagerange": "2009-2017", "id_number": "CaltechAUTHORS:20230417-377918000.38", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230417-377918000.38", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Fannie and John Hertz Foundation" } ] }, "doi": "10.1021/j150654a017", "resource_type": "article", "pub_year": "1984", "author_list": "Lewis, Nathan S. and Wrighton, Mark S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ksc94-d4930", "eprint_id": 120885, "eprint_status": "archive", "datestamp": "2023-08-22 03:50:55", "lastmod": "2023-10-18 18:03:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gronet-Chris-M", "name": { "family": "Gronet", "given": "Chris M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Systematic studies of the semiconductor/liquid junction: n-gallium arsenide phosphide anodes in aqueous selenide (Se\u00b2\u207b/Se\u2082\u00b2\u207b) solutions", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1984 American Chemical Society. \n\nWe gratefully acknowledge C.L.R. Lewis of Var\u00edan Associates, Palo Alto, CA, and R. Farraro and L. Stinson of Hewlett-Packard, Inc., Palo Alto, for growth and characterization of some of the n-GaAs\u2081\u208b\u2093P\u2093, samples used in this study. We also thank G. Cogan, J. Gibbons, L. Christel, and G. Moddel of SERA Solar Corp., Santa Clara, CA, for many helpful discussions and for the use of metal evaporation and spectral response facilities. This work was supported by the Stanford Center for Materials Research, funded by the National Science Foundation, and by the donors of the Petroleum Research Fund, administered by the American Chemical Society.", "abstract": "Epitaxial layers of n-GaAs\u2081\u208b\u2093P\u2093 (0 < x < 1) have been studied as photoelectrodes and as Au Schottky junctions. We observe increases in open-circuit voltage, V_(OC), with increases in P content for n-GaAs\u2081\u208b\u2093P\u2093, (x < 0.4) and decreases in V_(OC) for x > 0.6. Under 88 mW/cm\u00b2 of ELH-type (3350 K color temperature with a dichroic rear reflector) tungsten-halogen irradiation, we observe that n-GaAs_(0.72)P_(0.28) anodes exhibit a V_(OC) of 0.95-0.99 V, short-circuit currents of 15-17 mA/cm\u00b2, and energy conversion efficiencies of 13.0 \u00b1 1.0%. Irradiation at 632.8-nm yields monochromatic conversion efficiencies of greater than 30%, and solar irradiation (85-100 mW/cm\u00b2) yields efficiencies of 11.0 \u00b1 1.0% in 1.0 M KOH/l.0 M Se\u00b2\u207b/0.01 M Se\u2082\u00b2\u207b solutions. The n-GaAs_(0.72)P_(0.28) anodes exhibit stable photocurrent for passage of over 3000 C/cm\u00b2 at AM1 photocurrent densities. Ru(H\u2082O)\u2086\u00b3\u207a ions are effective in improving photocurrent-voltage characteristics for n-GaAs\u2081\u208b\u2093P\u2093 (0 < x < 1) anodes but have no effect for n-GaP,. indicating chemical interactions of the Ru ion with As or As oxide sites at the semiconductor/liquid junction. Direct comparison of V_(OC) for n-GaAs\u2081\u208b\u2093P\u2093/Au junctions with n-GaAs\u2081\u208b\u2093P\u2093/Se\u00b2\u207b barriers indicates that liquid junctions have higher V_(OC) values than some Schottky barriers and that pinning of the Fermi level by intrinsic surface states may not play a dominant role in determining interface parameters for these junctions.", "date": "1984-03-29", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "88", "number": "7", "publisher": "American Chemical Society", "pagerange": "1310-1317", "id_number": "CaltechAUTHORS:20230414-547173000.5", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230414-547173000.5", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "American Chemical Society Petroleum Research Fund" } ] }, "doi": "10.1021/j150651a014", "resource_type": "article", "pub_year": "1984", "author_list": "Gronet, Chris M. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sybnc-gvh38", "eprint_id": 10715, "eprint_status": "archive", "datestamp": "2023-08-22 03:50:24", "lastmod": "2023-10-16 23:03:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Cogan-George-W", "name": { "family": "Cogan", "given": "George W." } }, { "id": "Gronet-Chris-M", "name": { "family": "Gronet", "given": "Chris M." } }, { "id": "Gibbons-James-F", "name": { "family": "Gibbons", "given": "James F." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "7.2% efficient polycrystalline silicon photoelectrode", "ispublished": "pub", "full_text_status": "public", "keywords": "polycrystals, etching, photoanodes, photocathodes, silicon, fabrication, efficiency, interfaces, grain boundaries, passivation, Fermi level, Schottky barrier diodes, platinum, photoelectric effect, electric conductivity, pinning, surface states", "note": "\u00a9 1984 American Institute of Physics. \n\nReceived 22 July 1983; accepted 19 December 1983.\n\nPublished - COGapl84.pdf
", "abstract": "After etching, n-type cast polycrystalline silicon photoanodes immersed in a solution of methanol and a substituted ferrocene reagent exhibit photoelectrode efficiencies of 7.2%\u00b10.7% under simulated AM2 illumination. Scanning laser spot data indicate that the grain boundaries are active; however, the semiconductor/liquid contact does not display the severe shunting effects which are observed at a polycrystalline Si/Pt Schottky barrier. Evidence for an interfacial oxide on the operating polycrystalline Si photoanode is presented. Some losses in short circuit current can be ascribed to bulk semiconductor properties; however, despite these losses, photoanodes fabricated from polycrystalline substrates exhibit efficiencies comparable to those of single crystal material. Two major conclusions of our studies are that improved photoelectrode behavior in the polycrystalline silicon/methanol system will primarily result from changes in bulk electrode properties and from grain boundary passivation, and that Fermi level pinning by surface states does not prevent the design of efficient silicon-based liquid junctions.", "date": "1984-03-01", "date_type": "published", "publication": "Applied Physics Letters", "volume": "44", "number": "5", "publisher": "American Institute of Physics", "pagerange": "539-541", "id_number": "CaltechAUTHORS:COGapl84", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:COGapl84", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1063/1.94831", "primary_object": { "basename": "COGapl84.pdf", "url": "https://authors.library.caltech.edu/records/sybnc-gvh38/files/COGapl84.pdf" }, "resource_type": "article", "pub_year": "1984", "author_list": "Cogan, George W.; Gronet, Chris M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pkkpv-rgf82", "eprint_id": 120943, "eprint_status": "archive", "datestamp": "2023-08-22 03:48:37", "lastmod": "2023-10-18 18:05:04", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lieber-Charles-M", "name": { "family": "Lieber", "given": "Charles M." } }, { "id": "Gronet-Chris-M", "name": { "family": "Gronet", "given": "Chris M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Evidence against surface state limitations on efficiency of p-Si/CH\u2083CN junctions", "ispublished": "pub", "full_text_status": "public", "keywords": "Multidisciplinary", "note": "\u00a9 1984 Nature Publishing Group. \n\nWe thank G. Cogan and J. Gibbons for helpful discussions, and for access to spectral response and metal evaporation facilities at SERA Solar Corporation. We acknowledge a Cottrell Grant from the Research Corporation for partial support of this work.", "abstract": "We report here the first efficient p-type Si-based semiconductor\u2013liquid junction system. p-Type Si photocathodes have been previously reported to yield open circuit photovoltages, V_(oc), of 0.38\u20130.40 V with several redox systems. Photocurrent\u2013voltage studies of p-Si cathodes in CH3CN solvent have demonstrated 2.5% efficiency for conversion of 632.8-nm light to electricity with the N,N\u2032-dimethyl-4,4\u2032-bipyridinium^(2+/+) redox system1, and 0.5\u20132.4% with other macrocyclic complexes. Such modest energy conversion efficiencies for small band gap semiconductors have been attributed to surface states which pin the semiconductor Fermi level and promote recombination processes. However, we find that p-type Si/CH\u2083CN interfaces can yield solar conversion efficiencies in excess of 10%, and can display open circuit photovoltages within 0.08 V of the theoretical limit for an ideal junction.", "date": "1984-02-09", "date_type": "published", "publication": "Nature", "volume": "307", "number": "5951", "publisher": "Nature Publishing Group", "pagerange": "533-534", "id_number": "CaltechAUTHORS:20230417-377915000.37", "issn": "0028-0836", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230417-377915000.37", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Cottrell Scholar of Research Corporation" } ] }, "doi": "10.1038/307533a0", "resource_type": "article", "pub_year": "1984", "author_list": "Lieber, Charles M.; Gronet, Chris M.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/w7fy9-rg373", "eprint_id": 120890, "eprint_status": "archive", "datestamp": "2023-08-22 03:39:30", "lastmod": "2023-10-18 18:03:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Chemistry: A novel solar cell", "ispublished": "pub", "full_text_status": "public", "keywords": "Multidisciplinary", "note": "\u00a9 1983 Nature Publishing Group.", "abstract": "Semiconductor-liquid junctions offer a possible alternative to conventional solid state photovoltaic solar energy conversion devices. Unfortunately, few of the semiconductor-liquid solar cell systems explored to date simultaneously meet the necessary criteria of excellent stability and high efficiency; thus, the search for novel electrode materials is proceeding with fervour. In the last issue of Nature, Menezes, Lewerenz, and Bachmann (Nature 305, 615; 1983) reported studies of a new semiconductor-liquid junction solar cell that demonstrates excellent stability in an atmospheric environment, and simultaneously displays solar-to-electrical energy conversion efficiencies of 9.5 per cent.", "date": "1983-10-20", "date_type": "published", "publication": "Nature", "volume": "305", "number": "5936", "publisher": "Nature Publishing Group", "pagerange": "671-671", "id_number": "CaltechAUTHORS:20230414-547217000.11", "issn": "0028-0836", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230414-547217000.11", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1038/305671a0", "resource_type": "article", "pub_year": "1983", "author_list": "Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/t4ety-37s78", "eprint_id": 10317, "eprint_status": "archive", "datestamp": "2023-08-22 03:33:17", "lastmod": "2023-10-16 22:47:57", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gronet-Chris-M", "name": { "family": "Gronet", "given": "Chris M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "n-type GaAs photoanodes in acetonitrile: Design of a 10.0% efficient photoelectrode", "ispublished": "pub", "full_text_status": "public", "keywords": "gallium arsenide solar cells, photoanodes, n\u2212type conductors, nitriles, organic compounds, efficiency, electrodes, radiation effects, liquids, junctions, ferrocene, redox reactions, electron\u2212hole coupling, recombination, charge carriers, length, electric currents, current density, electrolytes", "note": "\u00a9 1983 American Institute of Physics. \n\nReceived 10 January 1983; accepted 13 April 1983. \n\nWe thank G. Cogan, J. Gibbons, and G. Moddel of SERA Corp., Santa Clara, CA for many helpful discussions and for the use of evaporation facilities.\n\nPublished - GROapl83.pdf
", "abstract": "n-type GaAs semiconductor/liquid junctions have been studied in acetonitrile (ACN) solvent with the ferrocene/ferricenium redox couple. Previously reported inefficiencies in this system are demonstrated to be due to bulk electron-hole recombination and not to recombination at the junction. Increases in minority-carrier collection length lead to increases in short circuit current of the n-GaAs/ferrocene/ferricenium cell in ACN, with photocurrent densities in excess of 21 mA/cm\u00b2 at 88 mW/cm\u00b2 of ELH-type tungsten-halogen irradiation. Properly prepared n-GaAs samples yield photoelectrode efficiencies of 10.0%\u00b10.5% for conversion of natural sunlight (65 mW/cm\u00b2) to electricity, with open circuit voltages Voc of 0.70\u20130.72 V, short circuit currents of 16\u201317 mA/cm\u00b2, and fill factors of 0.52\u20130.56, when measured relative to the potential of a reversible reference electrode in the same solvent/redox couple/electrolyte solution.", "date": "1983-07-01", "date_type": "published", "publication": "Applied Physics Letters", "volume": "43", "number": "1", "publisher": "American Institute of Physics", "pagerange": "115-117", "id_number": "CaltechAUTHORS:GROapl83", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:GROapl83", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1063/1.94148", "primary_object": { "basename": "GROapl83.pdf", "url": "https://authors.library.caltech.edu/records/t4ety-37s78/files/GROapl83.pdf" }, "resource_type": "article", "pub_year": "1983", "author_list": "Gronet, Chris M. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/bn6nd-sw928", "eprint_id": 120892, "eprint_status": "archive", "datestamp": "2023-08-22 03:24:43", "lastmod": "2023-10-18 18:03:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gronet-Chris-M", "name": { "family": "Gronet", "given": "Chris M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Cogan-George-W", "name": { "family": "Cogan", "given": "George" } }, { "id": "Gibbons-James-F", "name": { "family": "Gibbons", "given": "James" } } ] }, "title": "n-Type silicon photoelectrochemistry in methanol: Design of a 10.1% efficient semiconductor/liquid junction solar cell", "ispublished": "pub", "full_text_status": "public", "keywords": "Multidisciplinary", "note": "\u00a9 1983 National Academy of Science.\n\nPublished - pnas00630-0262.pdf
", "abstract": "n-Type Si electrodes in MeOH solvent with 0.2 M (1-hydroxyethyl)ferrocene, 0.5 mM (1-hydroxyethyl)ferricenium, and 1.0 M LiClO\u2084 exhibit air mass 2 conversion efficiencies of 10.1% for optical energy into electricity. We observe open-circuit voltages of 0.53 V and short-circuit quantum efficiencies for electron flow of nearly unity. The fill factor of the cell does not decline significantly with increases in light intensity, indicating substantial reduction in efficiency losses in MeOH solvent compared to previous nonaqueous n-Si systems. Matte etch texturing of the Si surface decreases surface reflectivity and increases photocurrent by 50% compared to shiny, polished Si samples. The high values of the open-circuit voltage observed are consistent with the presence of a thin oxide layer, as in a Schottky metal-insulator-semiconductor device, which yields decreased surface recombination and increased values of open-circuit voltage and short-circuit current. The n-Si system was shown to provide sustained photocurrent at air mass 2 levels (20 mA/cm\u00b2) for charge through the interface of >2,000 C/cm\u00b2. The n-Si/MeOH system represents a liquid junction cell that has exceeded the 10% barrier for conversion of optical energy into electricity.", "date": "1983-02-01", "date_type": "published", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "volume": "80", "number": "4", "publisher": "National Academy of Sciences", "pagerange": "1152-1156", "id_number": "CaltechAUTHORS:20230414-547309000.15", "issn": "0027-8424", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230414-547309000.15", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1073/pnas.80.4.1152", "pmcid": "PMC393548", "primary_object": { "basename": "pnas00630-0262.pdf", "url": "https://authors.library.caltech.edu/records/bn6nd-sw928/files/pnas00630-0262.pdf" }, "resource_type": "article", "pub_year": "1983", "author_list": "Gronet, Chris M.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/q79nb-y6915", "eprint_id": 120920, "eprint_status": "archive", "datestamp": "2023-08-22 03:18:41", "lastmod": "2023-10-18 18:04:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gronet-Chris-M", "name": { "family": "Gronet", "given": "Chris M." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" } ] }, "title": "Design of a 13% efficient n-GaAs\u2081\u208b\u2093P\u2093 semiconductor\u2013liquid junction solar cell", "ispublished": "pub", "full_text_status": "public", "keywords": "Multidisciplinary", "note": "\u00a9 1982 Nature Publishing Group. \n\nWe thank J. Gibbons and G. Cogan of SERA Solar Corporation for helpful discussions and for formation of ohmic contacts to the crystals, and L. Stinson and R. Ferraro of Hewlett-Packard and C. L. R. Lewis of Varian Associates for donating samples.", "abstract": "We report here the design of the most efficient non-aqueous semiconductor\u2013liquid junction solar cell studied to date. Our approach involves the use of ternary semiconductor electrodes made from solid solutions of a large hand gap material, GaP, and a small band gap material, GaAs. We demonstrate here that photoanodes consisting of such materials are capable of simultaneously yielding high open circuit voltages and favourable wavelength response to the solar spectrum. A few n-type semiconductor\u2013liquid junction solar cells in aqueous solutions have been reported to yield high (>10%) solar-to-electrical conversion efficiencies. However, for most materials, rapid photoanodic corrosion dominates the interfacial photochemistry4\u20138. Non-aqueous solvent systems can suppress electrode decay due to corrosion; but modest (<6%) conversion efficiencies have been observed for all photoanodes studied in solar irradiation conditions. The photoanodes used here yield over 13% solar-to-electrical conversion efficiencies, or more than double the efficiency of any other non-aqueous semiconductor\u2013liquid junction solar cell previously reported.", "date": "1982-12-30", "date_type": "published", "publication": "Nature", "volume": "300", "number": "5894", "publisher": "Nature Publishing Group", "pagerange": "733-735", "id_number": "CaltechAUTHORS:20230417-377654000.4", "issn": "0028-0836", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230417-377654000.4", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1038/300733a0", "resource_type": "article", "pub_year": "1982", "author_list": "Gronet, Chris M. and Lewis, Nathan S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/txqjb-mft40", "eprint_id": 120921, "eprint_status": "archive", "datestamp": "2023-08-22 02:56:41", "lastmod": "2023-10-18 18:04:18", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dominey-Raymond-N", "name": { "family": "Dominey", "given": "Raymond N." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Bruce-James-A", "name": { "family": "Bruce", "given": "James A." } }, { "id": "Bookbinder-Dana-C", "name": { "family": "Bookbinder", "given": "Dana C." } }, { "id": "Wrighton-Mark-S", "name": { "family": "Wrighton", "given": "Mark S." } } ] }, "title": "Improvement of photoelectrochemical hydrogen generation by surface modification of p-type silicon semiconductor photocathodes", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1982 American Chemical Society. \n\nWe thank the U. S. Department of Energy, Basic Energy Sciences, Chemical Sciences Division, for support of this research. Support from the IBM Fund, M.I.T. Laboratory for Computer Science, is also gratefully acknowledged. N.S.L. acknowledges support as a John and Fannie Hertz Fellow, 1977-1981.", "abstract": "The improvement of H\u2082 evolution from two different types of catalytic p-type photocathode surfaces has been examined. p-Type Si has been platinized by photoelectrochemically plating Pt(0) onto the Si surface. Such a photocathode shows significant improvement (compared to naked p-type Si) for photochemical H\u2082 evolution with respect to output photovoltage, fill factor, and overall efficiency. Such photocathodes having an optimum amount of Pt(0) give a pH-dependent output voltage with respect to the H\u2082O/H\u2082 couple, but the dependence is not a simple 59-mV/pH dependence. No pH dependence would be expected if Pt(0) formed a Schottky barrier when plated onto p-type Si. A second kind of H\u2082 evolution catalyst has been confined to the surface of p-type Si. Polymeric quantities of an electroactive N,N'-dialkyl-4,4'-bipyridinium reagent, (PQ^(2+/+-))\u2099, have been confined to the surface. The Br~ counterions of the polymer are then exchanged by PtCl\u2086\u00b2\u207b. Photoreduction then yields Pt(0) dispersed in the polymer. Such a surface is again significantly improved compared to naked p-type Si with respect to H\u2082 evolution. A comparison of the naked p-Si, the simply platinized, and the [(PQ^(2+/+))\u2099\u2022nPt(0)]_(surf) system is made and contrasted to the expected behavior of an external Schottky barrier photocell driving an electrolysis cell with a Pt cathode. Experiments with n-type MoS\u2082, n-type Si, Pt, Au, and W cathodes functionalized with the [(PQ^(2+/+-))\u2099\u2022nPt(0)]_(surf) system compared to the same surfaces directly platinized confirm an important difference in the mechanism of H\u2082 evolution catalysis for the two surface catalyst systems. For the [(PQ^(2+/+-))\u2099\u2022nPt(0)]_(surf) system there is an optimum pH for the catalysis, consistent with the pH-independent formal potential of the (PQ2+/+\")\" system, -0.55 \u00b1 0.05 V vs. SCE, relative to the formal potential of the (H\u2082O/H\u2082) couple\nthat moves 59 mV per pH unit. Qualitative experiments with insulating glass surfaces derivatized with [(PQ^(2+/+-))\u2099]__(surf). establish directly that the Pt(0) is necessary, and sufficient, to equilibrate (PQ^(2+/+-))\u2099 with (H\u2082O/H\u2082). p-Type Si modified with optimum amounts of Pt(0) by direct platinization appears to give improved H\u2082 evolution efficiency by a mechanism where the Pt(0) serves as a catalyst that does not alter the interface energetics of the semiconductor.", "date": "1982-01-27", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "104", "number": "2", "publisher": "American Chemical Society", "pagerange": "467-482", "id_number": "CaltechAUTHORS:20230417-377658000.5", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230417-377658000.5", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Massachusetts Institute of Technology (MIT)" }, { "agency": "Fannie and John Hertz Foundation" } ] }, "doi": "10.1021/ja00366a016", "resource_type": "article", "pub_year": "1982", "author_list": "Dominey, Raymond N.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rtksb-c0z29", "eprint_id": 120840, "eprint_status": "archive", "datestamp": "2023-08-22 02:52:09", "lastmod": "2023-10-18 18:02:09", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bookbinder-Dana-C", "name": { "family": "Bookbinder", "given": "Dana C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Wrighton-Mark-S", "name": { "family": "Wrighton", "given": "Mark S." } } ] }, "title": "Heterogeneous one-electron reduction of metal-containing biological molecules using molecular hydrogen as the reductant: synthesis and use of a surface-confined viologen redox mediator that equilibrates with hydrogen", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1981 American Chemical Society. \n\nN.S.L. acknowledges support as a John and Fannie Hertz Fellow, 1977-1981. D.C.B. acknowledges partial support as an M.I.T. NPW Fellow, 1981. Partial support from the United States Department of Energy, Basic Energy Sciences, Division of Chemical Sciences, is acknowledged. We appreciate the generous assistance of Professor Edward I. Solomon and his research group and the use of their purified stellacyanin. Helpful discussions with Professors William H. Orme-Johnson, Alexander Klibanov, and George M. Whitesides are gratefully acknowledged.", "abstract": "Study and use of metal-containing biological reagents often\ninvolves the need to manipulate the redox level. We report herein the synthesis of a heterogeneous catalyst system that allows the use of H\u2082 as a reductant for the one-electron reduction of horseheart ferricytochrome c (cyt c\u2092\u2093), sperm whale myoglobin, and stellacyanin from the lacquer of Rhus vernicifera. Application of the principles illustrated by our catalyst in other systems is possible inasmuch as the reducing power of H\u2082 is sufficiently great that many biological systems are thermodynamically reducible with H\u2082. An advantage in using H\u2082 as a source of reducing power is that the oxidation product is H\u207a which is acceptable since most biological systems are studied in buffered media. A heterogeneous catalyst is desirable to facilitate the separation of the catalyst from the product.", "date": "1981-12-16", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "103", "number": "25", "publisher": "American Chemical Society", "pagerange": "7656-7659", "id_number": "CaltechAUTHORS:20230413-768760000.16", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230413-768760000.16", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Fannie and John Hertz Foundation" }, { "agency": "Massachusetts Institute of Technology (MIT)" }, { "agency": "Department of Energy (DOE)" } ] }, "doi": "10.1021/ja00415a045", "resource_type": "article", "pub_year": "1981", "author_list": "Bookbinder, Dana C.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/d7nf2-9aj42", "eprint_id": 120837, "eprint_status": "archive", "datestamp": "2023-08-22 02:39:12", "lastmod": "2023-10-18 18:02:03", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dominey-Raymond-N", "name": { "family": "Dominey", "given": "Raymond N." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Wrighton-Mark-S", "name": { "family": "Wrighton", "given": "Mark S." } } ] }, "title": "Fermi level pinning of p-type semiconducting indium phosphide contacting liquid electrolyte solutions: rationale for efficient photoelectrochemical energy conversion", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1981 American Chemical Society. \n\nWe thank the U.S. Department of Energy, Basic Energy Sciences, for support of this research. M.S.W. acknowledges support as a Dreyfus Teacher-Scholar Grant recipient, 1975-1980, and N.S.L. as a Fannie and John Hertz Foundation Fellow. We thank Dr. Jerry Iseler of the M.I.T. Lincoln Laboratories for donating InP samples.", "abstract": "A recent report concerning p-type InP-based photoelectrochemical cells prompts us to give this preliminary account of our work on p-type InP/liquid interfaces. We report data that show that p-type InP gives a photovoltage E\u1d65, of ~0.8 V with respect to solution redox couples where the formal potential of the redox couple, E\u00b0, can vary over a potential range that significantly exceeds the magnitude of the band gap, E_g, of InP. Indeed, for E\u00b0's more negative than ~ -0.40 V vs. SCE in CH\u2083CN/0.1 M n-Bu\u2084NClO\u2084, we find essentially a constant value for E\u1d65. When E\u1d65 is independent of E\u00b0 for a semiconductor /liquid interface the semiconductor is said to be \"Fermi level pinned\". One intriguing finding is that the ratio E\u1d65/Eg_ for p-type InP is the highest reported thus far for a semiconductor/liquid interface.", "date": "1981-03-11", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "103", "number": "5", "publisher": "American Chemical Society", "pagerange": "1261-1263", "id_number": "CaltechAUTHORS:20230413-768654000.10", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230413-768654000.10", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Fannie and John Hertz Foundation" } ] }, "doi": "10.1021/ja00395a065", "resource_type": "article", "pub_year": "1981", "author_list": "Dominey, Raymond N.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9kk3c-hba38", "eprint_id": 120864, "eprint_status": "archive", "datestamp": "2023-08-22 02:38:03", "lastmod": "2023-10-18 18:02:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Wrighton-Mark-S", "name": { "family": "Wrighton", "given": "Mark S." } } ] }, "title": "Electrochemical Reduction of Horse Heart Ferricytochrome C at Chemically Derivatized Electrodes", "ispublished": "pub", "full_text_status": "public", "keywords": "Multidisciplinary", "note": "\u00a9 1981 American Association for the Advancement of Science.", "abstract": "Platinum or gold electrodes derivatized with an N,N\u2032-dialkyl-4,4\u2032-bipyridinium reagent can be used to reduce horse heart ferricytochrome c, whereas reduction does not occur at the \"naked\" electrodes. From 3 to 17.7 millimoles per liter, the reduction of ferricytochrome c is mass transport-limited at electrode potentials more negative than about -0.6 volt against a saturated calomel reference electrode. Data for the photoreduction of ferricytochrome c at derivatized p-type silicon photocathodes show directly that the rate of reduction is mass transport-limited. Use of derivatized electrodes may allow convenient manipulation and analysis of biological molecules that do not ordinarily respond at conventional electrodes.", "date": "1981-02-27", "date_type": "published", "publication": "Science", "volume": "211", "number": "4485", "publisher": "American Association for the Advancement of Science", "pagerange": "944-947", "id_number": "CaltechAUTHORS:20230414-200029000.1", "issn": "0036-8075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230414-200029000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1126/science.6258225", "resource_type": "article", "pub_year": "1981", "author_list": "Lewis, Nathan S. and Wrighton, Mark S." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jd327-bt240", "eprint_id": 120849, "eprint_status": "archive", "datestamp": "2023-08-22 02:30:23", "lastmod": "2023-10-18 18:02:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bookbinder-Dana-C", "name": { "family": "Bookbinder", "given": "Dana C." } }, { "id": "Bruce-James-A", "name": { "family": "Bruce", "given": "James A." } }, { "id": "Dominey-Raymond-N", "name": { "family": "Dominey", "given": "Raymond N." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Wrighton-Mark-S", "name": { "family": "Wrighton", "given": "Mark S." } } ] }, "title": "Synthesis and characterization of a photosensitive interface for hydrogen generation: Chemically modified p-type semiconducting silicon photocathodes", "ispublished": "pub", "full_text_status": "public", "keywords": "Multidisciplinary", "note": "\u00a9 1980 National Academy of Sciences. \n\nWe thank the United States Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, for support of this research. N.S.L. acknowledges support as a John and Fannie Hertz Predoctoral Fellow, 1977 to present, and M.S.W. acknowledges support as a Dreyfus Teacher-Scholar Grant recipient, 1975-1980. Partial support from the Massachusetts Institute of Technology Laboratory for Computer Science, IBM Fund, is gratefully acknowledged.\n\nPublished - pnas00498-0033.pdf
", "abstract": "p-Si photocathodes functionalized first with an N,N\u2032-dialkyl-4,4\u2032-bipyridinium redox reagent, (PQ^(2+/+-))_(surf), and then with a Pt precursor, PtCl\u2086\u00b2\u207b, give significant efficiency (up to 5%) for photoelectrochemical H\u2082 generation with 632.8-nm light. Naked p-Si photocathodes give nearly zero efficiency, owing to poor H\u2082 evolution kinetics that are improved by the (PQ^(2+/+-))_(surf)/Pt modification. The mechanism of H\u2082 evolution from p-Si/(PQ^(2+/+-))_(surf)/Pt is first photoexcitation of electrons to the conduction band of Si followed by (PQ\u00b2\u207a)_(surf) \u2192 (PQ\u207a\u207b)_(surf) reduction. The dispersion of Pt then catalyzes H\u2082O reduction to give H2 and regeneration of (PQ\u00b2\u207a)_(surf). The overall energy conversion efficiency rivals the best direct optical to chemical conversion systems reported to date.", "date": "1980-11", "date_type": "published", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "volume": "77", "number": "11", "publisher": "National Academy of Sciences", "pagerange": "6280-6284", "id_number": "CaltechAUTHORS:20230413-768824000.34", "issn": "0027-8424", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230413-768824000.34", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Fannie and John Hertz Foundation" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Massachusetts Institute of Technology (MIT)" } ] }, "doi": "10.1073/pnas.77.11.6280", "pmcid": "PMC350266", "primary_object": { "basename": "pnas00498-0033.pdf", "url": "https://authors.library.caltech.edu/records/jd327-bt240/files/pnas00498-0033.pdf" }, "resource_type": "article", "pub_year": "1980", "author_list": "Bookbinder, Dana C.; Bruce, James A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/20sg1-0fv14", "eprint_id": 120848, "eprint_status": "archive", "datestamp": "2023-08-22 02:25:40", "lastmod": "2023-10-18 18:02:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Bocarsly-Andrew-B", "name": { "family": "Bocarsly", "given": "Andrew B." } }, { "id": "Wrighton-Mark-S", "name": { "family": "Wrighton", "given": "Mark S." } } ] }, "title": "Heterogeneous electron transfer at designed semiconductor/liquid interfaces. Rate of reduction of surface-confined ferricenium centers by solution reagents", "ispublished": "pub", "full_text_status": "public", "keywords": "Physical and Theoretical Chemistry; General Engineering", "note": "\u00a9 1980 American Chemical Society. \n\nThe authors thank the United States Department of Energy, Office of Basic Energy Science for their support. N.S.L. acknowledges support by the John and Fannie Hertz Foundation, 1977-present. M.S.W. acknowledges support as a Dreyfus Teacher-Scholar Grant Recipient, 1975-1980.", "abstract": "Reduction of surface-confined ferricenium by solution reductants iodide, diindenyliron, (\u03b7\u2075-C\u2086H\u2085)4Fe\u2084(CO)\u2084, 1,l'-dimethylferrocene, ferrocene, and phenylferrocene has been studied in EtOH-O.l M [n-Bu4N]C1O\u2084 and also in H\u2082O-NaC1O\u2084 for iodide. The surface-confined ferricenium can be generated on n-type Si by illumination of the electrode at some potential more positive than ~-0.2 V vs. SCE. Owing to the two stimuli (light and potential) response of the derivatized photoelectrode it is possible to directly measure (by linear sweep voltammetry) the time dependence of the surface ferricenium concentration in the dark and in the presence of the various reducing agents mentioned above. At a given concentration of iodide in solution we find the rate\nof reduction of surface ferricenium to be directly proportional to the surface ferricenium concentration. By measuring rate of ferricenium reduction at various iodide concentrations, the rate law is thus determined to\nbe rate = k\u2091\u209c[Fe(Cp)\u2082\u207a][T] where [Fe(Cp)\u2082\u207a] is the surface ferricenium concentration in mol/cm\u00b2 and [I\u207b] is the solution concentration of iodide in mol/cm3. We find k\u2091\u209c to be (3 \u00b1 1) X 10\u2074 cm\u00b3/(mol s) in EtOH solvent and only (1 \u00b1 0.5) X 10\u00b3 cm\u00b3/(mol s) in H\u2082O. The value in EtOH is somewhat lower than would be estimated from homogeneous solution reaction of ferricenium with iodide under the same conditions. All other reductants mentioned above reduce the surface ferricenium in EtOH solvent with a value of k\u2091\u209c > 6 X 10\u2077 cm\u00b3/(mol s); that is, the reduction rate is mass transport, not charge transfer, limited under the conditions employed including well-stirred solutions with stationary electrodes or rotated (up to 2000 rpm) disk electrodes. However, the relative ordering of the \"fast\" reductants has been determined to be diindenyliron > (\u03b7\u2075-C\u2085H\u2085)\u2084Fe\u2084(CO)\u2084 ~\n1,l'-dimethylferrocene > ferrocene ~ phenylferrocene. A large value of k\u2091\u209c is expected based on the fast self-exchange rates of ferrocene and its derivatives. Acetylferrocene is not expected to be able to reduce ferricenium on thermodynamic grounds, and we find that surface ferricenium is inert in its presence. Most of the derivatized surfaces have been prepared from (l,1'-ferrocenediyl)dichlorosilane, but preliminary results with polyvinylferrocene modified and (1,1'-ferrocenediyl) dimethylsilane derivatized surfaces are similar. Very high coverage surfaces from (1,l'-ferrocenediyl)dichlorosilane show some evidence for selective reduction of the more accessible ferricenium centers when a \"fast\" reductant is used. Steady-state photoanodic current at a given concentration of reductant generally accords well with the measured k\u2091\u209c values, and for the iodide experiments the steady-state photocurrent is directly proportional to surface coverage of electroactive ferrocene. Such studies are relevant to use of derivatized photoelectrodes in energy conversion applications.", "date": "1980-08-07", "date_type": "published", "publication": "Journal of Physical Chemistry", "volume": "84", "number": "16", "publisher": "American Chemical Society", "pagerange": "2033-2043", "id_number": "CaltechAUTHORS:20230413-768817000.32", "issn": "0022-3654", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230413-768817000.32", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Fannie and John Hertz Foundation" }, { "agency": "Camille and Henry Dreyfus Foundation" } ] }, "doi": "10.1021/j100453a008", "resource_type": "article", "pub_year": "1980", "author_list": "Lewis, Nathan S.; Bocarsly, Andrew B.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5mpkd-ce919", "eprint_id": 120850, "eprint_status": "archive", "datestamp": "2023-08-22 02:21:06", "lastmod": "2023-10-18 18:02:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bocarsly-Andrew-B", "name": { "family": "Bocarsly", "given": "Andrew B." } }, { "id": "Bookbinder-Dana-C", "name": { "family": "Bookbinder", "given": "Dana C." } }, { "id": "Dominey-Raymond-N", "name": { "family": "Dominey", "given": "Raymond N." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Wrighton-Mark-S", "name": { "family": "Wrighton", "given": "Mark S." } } ] }, "title": "Photoreduction at illuminated p-type semiconducting silicon photoelectrodes. Evidence for Fermi level pinning", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1980 American Chemical Society. \n\nWe thank the National Aeronautics and Space Administration (support for A.B.B.) and the U.S. Department of Energy, Office of Basic Energy Sciences (support for R.N.D. and D.C.B.), for support of this research. M.S.W. acknowledges support as a Dreyfus Teacher-Scholar, 1975-1980, and N.S.L. acknowledges support as a John and Fannie Hertz Predoctoral Fellow, 1977-present.", "abstract": "Studies of p- and n-type Si electrodes are reported which show that semiconducting Si electrode surfaces do not allow\nefficient H\u2082 evolution in the dark (n type) or upon illumination with band gap or greater energy light (p type). The key experiment is that N,N'-dimethyl-4,4'-bipyridinium (PQ\u00b2\u207a) is reversibly reduced at n-type Si in aqueous media at a pH where H\u2082 should be evolved at nearly the same potential, but no H\u2082 evolution current is observable. The PQ^(2+/+\u00b7) system may be useful as an electron-transfer mediator, since PQ\u207a\u00b7 can be used to effect generation of H\u2082 from H\u2082O using a heterogeneous catalyst.\nThe PQ\u207a\u00b7 can be produced in an uphill sense by illumination of p-type Si in aqueous solutions. Studies of p-type Si in nonaqueous solvents show that PQ\u00b2\u207a, PQ\u207a\u00b7, Ru(bpy)\u2083\u00b2\u207a, Ru(bpy)\u2083\u207a, and Ru(bpy)\u2083\u00b0 are all reducible upon illumination of the p-type Si. Interestingly, each species can be photoreduced at a potential ~500 mV more positive than at a reversible electrode in the dark. This result reveals that a p-type Si-based photoelectrochemical cell based on PQ^(2+/+\u00b7), PQ^(+/0), Ru(bpy)\u2083^(2+/+), Ru(bpy)\u00b2\u207a^(+/0), or Ru(bpy)\u00b2\u207a^(0/~) would all yield a common output photovoltage, despite the fact that the formal potentials for these couples vary by more than the band gap (1.1 V) of the photocathode. These data support the notion that p-type Si exhibits Fermi level pinning under the conditions employed. Fermi level pinning refers to the fact that surface states pin the Fermi level to a given value such that band bending (barrier height) is fixed and any additional potential drop occurs across the Helmholtz layer of the electrolyte solution at charge-transfer equilibrium. Surface chemistry is shown to be able to effect changes in interface kinetics for electrodes exhibiting Fermi level pinning.", "date": "1980-05-21", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "102", "number": "11", "publisher": "American Chemical Society", "pagerange": "3683-3688", "id_number": "CaltechAUTHORS:20230413-768873000.36", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230413-768873000.36", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" }, { "agency": "Department of Energy (DOE)" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Fannie and John Hertz Foundation" } ] }, "doi": "10.1021/ja00531a003", "resource_type": "article", "pub_year": "1980", "author_list": "Bocarsly, Andrew B.; Bookbinder, Dana C.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5j0r9-58740", "eprint_id": 120856, "eprint_status": "archive", "datestamp": "2023-08-22 02:12:01", "lastmod": "2023-10-18 18:02:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bookbinder-Dana-C", "name": { "family": "Bookbinder", "given": "Dana C." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Bradley-Mark-G", "name": { "family": "Bradley", "given": "Mark G." } }, { "id": "Bocarsly-Andrew-B", "name": { "family": "Bocarsly", "given": "Andrew B." } }, { "id": "Wrighton-Mark-S", "name": { "family": "Wrighton", "given": "Mark S." } } ] }, "title": "Photoelectrochemical reduction of N,N'-dimethyl-4,4'-bipyridinium in aqueous media at p-type silicon: sustained photogeneration of a species capable of evolving hydrogen", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1979 American Chemical Society. \n\nWe thank the National Aeronautics and Space Administration for support of this research. N.S.L. acknowledges support as a John and Fannie Hertz Fellow and M.S.W. acknowledges support as a Dreyfus Teacher-Scholar Grant recipient, 1975-1980. Support from the M.I.T. Cabot Solar Energy Fund is also gratefully acknowledged.", "abstract": "We report here a new approach to the energetically uphill generation of H\u2082 from H\u2082O. There have been numerous recent claims concerning chemical systems for the photoinduced evolution of H\u2082 from aqueous media, but in many of the systems reported there are sacrificial reducing agents used which cloud the overall thermodynamics and preclude sustained evolution of H\u2082. However, these studies have resulted in several interesting procedures for manipulating charge-transfer kinetics such that generation of H\u2082 is possible by schemes such as that represented:...", "date": "1979-12-19", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "101", "number": "26", "publisher": "American Chemical Society", "pagerange": "7721-7723", "id_number": "CaltechAUTHORS:20230413-768904000.46", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230413-768904000.46", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" }, { "agency": "Fannie and John Hertz Foundation" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Massachusetts Institute of Technology (MIT)" } ] }, "doi": "10.1021/ja00520a019", "resource_type": "article", "pub_year": "1979", "author_list": "Bookbinder, Dana C.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/q9740-24g53", "eprint_id": 120857, "eprint_status": "archive", "datestamp": "2023-09-15 07:47:56", "lastmod": "2023-10-23 21:38:34", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bolts-Jeffrey-M", "name": { "family": "Bolts", "given": "Jeffrey M." } }, { "id": "Bocarsly-Andrew-B", "name": { "family": "Bocarsly", "given": "Andrew B." } }, { "id": "Palazzotto-Michael-C", "name": { "family": "Palazzotto", "given": "Michael C." } }, { "id": "Walton-Erick-G", "name": { "family": "Walton", "given": "Erick G." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Wrighton-Mark-S", "name": { "family": "Wrighton", "given": "Mark S." } } ] }, "title": "Chemically derivatized n-type silicon photoelectrodes. Stabilization to surface corrosion in aqueous electrolyte solutions and mediation of oxidation reactions by surface-attached electroactive ferrocene reagents", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1979 American Chemical Society. \n\nWe thank the U.S. Department of Energy, Office of Basic Energy Sciences, for support of this research. M.S.W. acknowledges support as a Dreyfus Teacher-Scholar grant recipient, 1975-1980, and N.S.L. acknowledges support as a John and Fannie Hertz Foundation Fellow, 1977-present.", "abstract": "Derivatization of n-type Si photoelectrode surfaces with (1,1'-ferrocenediyljdichlorosilane results in the persistent attachment of photoelectroactive ferrocene species. Derivatized surfaces have been characterized by cyclic voltammetry in EtOH or H\u2082O electrolyte solutions. Such surfaces exhibit persistent oxidation and reduction waves, but the oxidation requires illumination as expected for an n-type semiconductor. The oxidation wave is observed at potentials ~300 mV more negative than at Pt, reflecting the ability to oxidize ferrocene contrathermodynamically by irradiation. Derivatized n-type Si can be used to sustain the oxidation of solution-dissolved ferrocene under conditions where \"naked\" Si is incapable of doing so. Further, derivatized n-type Si has been used in an aqueous electrolyte to oxidize Fe(CN)\u2086\u2074\u207b. Finally, the photooxidation of solution species has been demonstrated to occur via photogeneration of holes in the Si, oxidation of the surface-attached species, and then oxidation of the solution species by the surface-attached oxidant, providing the first direct proof of mediated electron transfer for any derivatized electrode. Derivatized electrodes can be used to sustain the conversion of light to electricity but the efficiencies are low. Based on results for 632.8-nm irradiation, solar energy conversion efficiencies of ~1% can be obtained.", "date": "1979-03-14", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "101", "number": "6", "publisher": "American Chemical Society", "pagerange": "1378-1385", "id_number": "CaltechAUTHORS:20230413-768911000.48", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230413-768911000.48", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)" }, { "agency": "Camille and Henry Dreyfus Foundation" }, { "agency": "Fannie and John Hertz Foundation" } ] }, "doi": "10.1021/ja00500a004", "resource_type": "article", "pub_year": "1979", "author_list": "Bolts, Jeffrey M.; Bocarsly, Andrew B.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/72rmv-c9g69", "eprint_id": 120873, "eprint_status": "archive", "datestamp": "2023-08-22 01:43:14", "lastmod": "2023-10-18 18:03:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Mann-Kent-R", "name": { "family": "Mann", "given": "Kent R." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Williams-Roger-M", "name": { "family": "Williams", "given": "Roger M." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" }, { "id": "Gordon-J-G-II", "name": { "family": "Gordon", "given": "J. G., II" } } ] }, "title": "Further studies of metal-metal bonded oligomers of rhodium(I) isocyanide complexes. Crystal structure analysis of octakis(phenyl isocyanide)dirhodium bis(tetraphenylborate)", "ispublished": "pub", "full_text_status": "public", "keywords": "Inorganic Chemistry; Physical and Theoretical Chemistry", "note": "\u00a9 1978 American Chemical Society. \n\nWe thank R. E. Marsh for helpful comments. Research at the California Institute of Technology was supported by the National Science Foundation (Grant No. CHE75-19086). Acknowledgment is also made to the donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support of this research. K.R.M. acknowledges a National Science Foundation Energy Postdoctoral Fellowship (1976-1977). Matthey-Bishop, Inc. is acknowledged for a generous loan of rhodium trichloride.", "abstract": "The room temperature absorption spectra of [Rh(CNR)\u2084]\u207a (R = Ph, i-Pr, cyclohexyl, t-Bu, vinyl) in solution do not follow Beer's law. This behavior has been attributed to oligomerization of [Rh(CNR)\u2084]\u207a units to form species of the type [Rh\u2099(CNR)\u2084\u2099]\u207f\u207a. Band maxima attributable to oligomers are as follows: R = Ph, 568 nm (n = 2), 727 nm (n = 3), in acetonitrile solution; R = t-Bu, 490 nm (n = 2), 622 nm (n = 3), in aqueous solution; R = i-Pr, 495 nm (n = 2), 610 nm (n = 3) in aqueous solution; R = cyclohexyl, 516 nm (n = 2), in acetonitrile solution; R = vinyl, 555 nm (n = 2), 715 nm (n = 3), 962 nm (n = 4), in aqueous solution. The molar extinction coefficients (\u03f5\u2099) and formation constants K\u2099\u208b\u2081 have been obtained for R = Ph in acetonitrile solution and R = t-Bu in aqueous solution. Parameter values are as follows: for R = Ph, K\u2081 = 35 (15) M\u207b\u00b9, \u03f5\u2082 = 1.05 (20) x 10\u2074, \u03f5\u2083K\u2082 = 1.83 (40) x 10\u2075 M\u207b\u00b9, for R = t-Bu, K\u2081 = 250m (125) M\u207b\u00b9, \u03f5\u2082 = 1.69 (34) x 10\u2074. The x-ray crystal structure of Rh(CNPh)\u2084BPh\u2084 has been completed (final R = 00.057). The compound crystallizes in the Pbcn space group (a = 23.80 (1), b = 19.23 (1), c = 19.08 (1) \u00c5) with four discrete cationic [Rh\u2082(CNR)\u2088]\u00b2\u207a units and eight BPh\u207b\u2074 anions. The dimeric cation has idealized D_(4d) symmetry; the two [Rh(CNR)\u2084]\u207a units are bonded face to face so as to give a staggered configuration of ligands. The Rh-Rh distance is 3.193 \u00c5. The electronic absorption spectra of D_(4d) [Rh\u2082(CNR)\u2088]\u00b2\u207a and assumed D\u2084\u2095 [Rh\u2083(CNR)\u2081\u2082]\u00b3\u207a complexes are interpreted in terms of the interactions expected between the occupied a_(1g)d_(z\u00b2) and unoccupied a_(2u)[p_z, \u03c0*(CNR)] monomer orbitals. The lowest band in each of the [Rh\u2082(CNR)\u2088]\u00b2\u207a complexes is assigned to the allowed 1 b\u2082 \u2192 2a\u2081 transition. In the spectra of [Rh\u2083(CNR)\u2081\u2082]\u00b3\u207a complexes, the lowest band is attributed to 2a_(1g) \u2192 2a_(2u).", "date": "1978-04-01", "date_type": "published", "publication": "Inorganic Chemistry", "volume": "17", "number": "4", "publisher": "American Chemical Society", "pagerange": "828-834", "id_number": "CaltechAUTHORS:20230414-532626000.14", "issn": "0020-1669", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230414-532626000.14", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE75-19086" }, { "agency": "American Chemical Society Petroleum Research Fund" }, { "agency": "NSF Postdoctoral Fellowship" } ] }, "other_numbering_system": { "items": [ { "id": "5649", "name": "Arthur Amos Noyes Laboratory of Chemical Physics" } ] }, "doi": "10.1021/ic50182a008", "resource_type": "article", "pub_year": "1978", "author_list": "Mann, Kent R.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fnr8f-jca76", "eprint_id": 120872, "eprint_status": "archive", "datestamp": "2023-08-22 01:39:31", "lastmod": "2023-10-18 18:03:08", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Miskowski-Vincent-M", "name": { "family": "Miskowski", "given": "Vincent M." } }, { "id": "Nobinger-Glenn-L", "name": { "family": "Nobinger", "given": "Glenn L." } }, { "id": "Kliger-David-S", "name": { "family": "Kliger", "given": "David S." } }, { "id": "Hammond-G-S", "name": { "family": "Hammond", "given": "George S." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Mann-Kent-R", "name": { "family": "Mann", "given": "Kent R." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Flash kinetic spectroscopic studies of dinuclear rhodium(I) complexes", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1978 American Chemical Society. \n\nResearch at the California Institute of Technology was supported by the National Science Foundation. K.R.M. was a National Science Foundation Energy Postdoctoral Fellow (1976-1977). Matthey-Bishop, Inc., is acknowledged for a generous loan of rhodium trichloride.", "abstract": "Excitation of concentrated acetonitrile solutions of [Rh(tol)\u2084]PF\u2086 (tol is p-methylphenyl isocyanide) at 562 nm,\nwhere strong absorption attributable to [Rh\u2082(tol\u2084)\u2088]\u00b2\u207a occurs, produces emission (\u03bb\u2098\u2090\u2093 697 nm) with a quantum yield of 0.0065 and a lifetime of \u2a7d2 ns. Excitation of [Rh\u2082(bridge)\u2084](BPh\u2084)\u2082 (bridge is 1,3-diisocyanopropane) in acetonitrile solution at 553 nm gives emission at 656 nm with a quantum yield of 0.056 and a lifetime of \u2a7d2 ns. The emission is assigned to \u00b9A_(2u) \u2192 \u00b9A_(1g) (2a_(ig) \u2192 \u00b9a_(2u)) in both dinuclear Rh(I) complexes. Excitation also gives rise to long-lived transient absorptions attributable to the following dinuclear and trinuclear species: ~8 ms, Rh\u2082(bridge)\u2084](BPh\u2084)\u2082; 0.09 ms, [Rh\u2082(tol\u2084)\u2088]\u00b2\u207a; and 0.14 ms, [Rh\u2083(tol)\u2081\u2082]\u00b3\u207a. In the dinuclear complexes, this transient is most likely \u00b3A_(2u), which is the triplet excited-state partner of \u00b9A_(2u). The results suggest that the spin-orbit components of \u00b3A_(2u) possess very little singlet character.", "date": "1978-01-18", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "100", "number": "2", "publisher": "American Chemical Society", "pagerange": "485-488", "id_number": "CaltechAUTHORS:20230414-532625000.13", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230414-532625000.13", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF Postdoctoral Fellowship" } ] }, "other_numbering_system": { "items": [ { "id": "5561", "name": "Arthur Amos Noyes Laboratory of Chemical Physics" } ] }, "doi": "10.1021/ja00470a020", "resource_type": "article", "pub_year": "1978", "author_list": "Miskowski, Vincent M.; Nobinger, Glenn L.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/20311-7m074", "eprint_id": 120880, "eprint_status": "archive", "datestamp": "2023-08-22 01:31:51", "lastmod": "2023-10-18 18:03:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Mann-Kent-R", "name": { "family": "Mann", "given": "Kent R." } }, { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Miskowski-Vincent-M", "name": { "family": "Miskowski", "given": "Vincent M." } }, { "id": "Erwin-David-K", "name": { "family": "Erwin", "given": "David K." } }, { "id": "Hammond-G-S", "name": { "family": "Hammond", "given": "George S." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Solar energy storage. Production of hydrogen by 546-nm irradiation of a dinuclear rhodium(I) complex in acidic aqueous solution", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1977 American Chemical Society. \n\nWe thank Bruce Parkinson, Bob Richman, John Thich, and Mark Wrighton for helpful discussions. Matthey-Bishop, Inc., is acknowledged for a generous loan of rhodium trichloride. This research was supported by the National Science Foundation (CHE 75-19086).", "abstract": "We have reported1 previously on the synthesis and characterization of a novel dinuclear rhodium(I) complex, [Rh\u2082(bridge)\u2084]\u00b2\u207a (bridge = 1,3-diisocyanopropane). The orbital interactions between the directly coupled rhodium(I) centers give rise to striking electronic absorption spectral properties, the most prominent being a low-lying system (\u03bb\u2098\u2090\u2093 553 nm (\u03f5 14 500), [Rh\u2082(bridge)\u2084](BPh\u2084)\u2082 in acetonitrile solution) attributable to the \u00b9A_1g) \u2192 \u00b9A_(2u) (la_(2u) \u2192 2a_(1g)) excitation. A logical avenue for exploratory research on [Rh\u2082(bridge)\u2084]\u00b2\u207a involves its excited-state reactivity behavior, as a directly coupled dinuclear redox center might be able to channel charge-transfer excitation energy into redox-substrate chemical bond formation at rates that are competitive with back electron transfer. The purpose of the present communication is to report that we have achieved this goal in one important case, namely, in the reduction of protons to hydrogen through 546-nm irradiation of [Rh\u2082(bridge)\u2084]\u00b2\u207a in aqueous HCl solution.", "date": "1977-08-03", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "99", "number": "16", "publisher": "American Chemical Society", "pagerange": "5525-5526", "id_number": "CaltechAUTHORS:20230414-532660000.24", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230414-532660000.24", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CHE 75-19086" } ] }, "other_numbering_system": { "items": [ { "id": "5587", "name": "Arthur Amos Noyes Laboratory of Chemical Physics" } ] }, "doi": "10.1021/ja00458a071", "resource_type": "article", "pub_year": "1977", "author_list": "Mann, Kent R.; Lewis, Nathan S.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8qydp-x9253", "eprint_id": 120808, "eprint_status": "archive", "datestamp": "2023-08-22 01:15:34", "lastmod": "2023-10-18 18:00:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lewis-N-S", "name": { "family": "Lewis", "given": "Nathan S." }, "orcid": "0000-0001-5245-0538" }, { "id": "Mann-Kent-R", "name": { "family": "Mann", "given": "Kent R." } }, { "id": "Gordon-J-G", "name": { "family": "Gordon", "given": "J. G." } }, { "id": "Gray-H-B", "name": { "family": "Gray", "given": "Harry B." }, "orcid": "0000-0002-7937-7876" } ] }, "title": "Oligomerization and two-center oxidative addition reactions of a dimeric rhodium(I) complex", "ispublished": "pub", "full_text_status": "public", "keywords": "Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis", "note": "\u00a9 1976 American Chemical Society. \n\nWe thank Drs. D. M. Roundhill, H. J. Schugar, M. Kubota, and A. L. Balch for helpful discussions. This research was supported by the National Science Foundation.", "abstract": "We have shown previously that cationic arylisocyanide complexes of rhodium(I) aggregate in solution through formation of metal-metal bonds. The chemical behavior of these oligomeric species should be quite interesting, as the opportunity for two-center oxidative addition exists. In order to explore this possibility in a simple case, we have synthesized and characterized a dimeric Rh(I) complex containing four 1,3-diisocyanopropane (bridge) ligands. We have found that this dimer aggregates still further in solution to form higher oligomers, and that it undergoes two-center oxidative addition reactions with several substrates.", "date": "1976-10-01", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "98", "number": "23", "publisher": "American Chemical Society", "pagerange": "7461-7463", "id_number": "CaltechAUTHORS:20230413-139337000.5", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230413-139337000.5", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" } ] }, "other_numbering_system": { "items": [ { "id": "5374", "name": "Arthur Amos Noyes Laboratory of Chemical Physics" } ] }, "doi": "10.1021/ja00439a078", "resource_type": "article", "pub_year": "1976", "author_list": "Lewis, Nathan S.; Mann, Kent R.; et el." } ]