[ { "id": "authors:rtswq-8ac16", "collection": "authors", "collection_id": "rtswq-8ac16", "cite_using_url": "https://authors.library.caltech.edu/records/rtswq-8ac16", "type": "article", "title": "Organic Film-Modified Copper Electrodes Enhance CO\u2082 Reduction and Inhibit O\u2082 Reduction with Simulated Flue Gas", "author": [ { "family_name": "Salazar", "given_name": "Matthew", "orcid": "0009-0002-9643-7276", "clpid": "Salazar-Matthew" }, { "family_name": "Lai", "given_name": "Yungchieh", "orcid": "0000-0001-9392-1447", "clpid": "Lai-Yungchieh" }, { "family_name": "Heim", "given_name": "Gavin P.", "orcid": "0000-0002-9244-6565", "clpid": "Heim-Gavin-P" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Peters", "given_name": "Jonas C.", "orcid": "0000-0002-6610-4414", "clpid": "Peters-J-C" }, { "family_name": "Agapie", "given_name": "Theodor", "orcid": "0000-0002-9692-7614", "clpid": "Agapie-T" } ], "abstract": "

Commercial-scale applications of CO2 conversion technologies are limited by the cost of purifying feedstocks such as flue gas, an industrial source of CO2 also containing O2. Direct usage of flue gas for electrochemical CO2 reduction (eCO2R) is challenging due to both a lower concentration of CO2 and O2 impurities introducing the oxygen reduction reaction (ORR) as a competing process. Herein, we report the ability of organic films formed in situ on Cu by the reduction of electrolyte-soluble N,N′-ethylene-phenanthrolinium (12+) and N-tolylpyridinium (2+) to maintain eCO2R selectivity toward multicarbon products (C2+) in the presence of O2. With a 1:1 CO2/O2 ratio, the film derived from 12+ reduced the current density toward ORR by a factor higher than 2.5 under acidic electrolytes. Further studies revealed that these coatings can impact the O2 diffusion coefficient and ORR kinetics. Under a simulated flue gas feedstock, the 12+-derived film showed stable ∼60% FE toward C2+ products (∼50% C2H4) for 6 h, demonstrating a pathway for direct flue gas utilization.

", "doi": "10.1021/acsenergylett.6c00692", "issn": "2380-8195", "publisher": "American Chemical Society", "publication": "ACS Energy Letters", "publication_date": "2026-05-08", "series_number": "5", "volume": "11", "issue": "5", "pages": "4103-4109" }, { "id": "authors:w9zr2-86c25", "collection": "authors", "collection_id": "w9zr2-86c25", "cite_using_url": "https://authors.library.caltech.edu/records/w9zr2-86c25", "type": "article", "title": "Chloride Treatments Improve Zinc Telluride Absorbers for Photoelectrochemical Carbon Dioxide Reduction", "author": [ { "family_name": "Muzzillo", "given_name": "Christopher P.", "orcid": "0000-0002-6492-0098" }, { "family_name": "Lai", "given_name": "Yungchieh", "orcid": "0000-0001-9392-1447", "clpid": "Lai-Yungchieh" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Zakutayev", "given_name": "Andriy", "orcid": "0000-0002-3054-5525" } ], "abstract": "
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Utilizing sunlight for photoelectrochemical carbon dioxide reduction reaction (PEC CO2 RR) is a carbon-neutral path to valuable liquid fuels. Higher quality photoabsorbers are needed to improve the efficiency of the PEC CO2 RR process. We show how the optoelectronic properties of sputtered ZnTe absorbers can be improved for this purpose via chloride treatments. MnCl2 and MgCl2 heat treatments recrystallize ZnTe absorbers to enlarge grains and improve photoluminescence. These material improvements result in the highest PEC CO2 RR photocurrent density reported for planar ZnTe and >50% Faradaic efficiency to CO formation with diaryliodonium additive in the solution. These results pave the way to integration of polycrystalline thin-film photoabsorbers in PEC CO2 RR systems.

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", "doi": "10.1021/acsaem.4c02498", "issn": "2574-0962", "publisher": "American Chemical Society", "publication": "ACS Applied Energy Materials", "publication_date": "2025-01-27", "series_number": "2", "volume": "8", "issue": "2", "pages": "983-990" }, { "id": "authors:djvrc-zcv46", "collection": "authors", "collection_id": "djvrc-zcv46", "cite_using_url": "https://authors.library.caltech.edu/records/djvrc-zcv46", "type": "article", "title": "Accelerated screening of carbon dioxide capture by liquid sorbents", "author": [ { "family_name": "Jones", "given_name": "Ryan J. R.", "orcid": "0000-0002-4629-3115", "clpid": "Jones-Ryan-J-R" }, { "family_name": "Lai", "given_name": "Yungchieh", "orcid": "0000-0001-9392-1447", "clpid": "Lai-Yungchieh" }, { "family_name": "Kan", "given_name": "Kevin", "orcid": "0000-0002-5840-8928", "clpid": "Kan-Kevin" }, { "family_name": "Guevarra", "given_name": "Dan", "orcid": "0000-0002-9592-3195", "clpid": "Guevarra-Dan" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Ramirez", "given_name": "Natalia M.", "clpid": "Ramirez-Natalia-M" }, { "family_name": "Zito", "given_name": "Alessandra", "orcid": "0000-0002-1111-5415", "clpid": "Zito-Alessandra" }, { "family_name": "Li", "given_name": "Clarabella", "orcid": "0000-0002-5551-4506", "clpid": "Li-Clarabella" }, { "family_name": "Yang", "given_name": "Jenny Y.", "orcid": "0000-0002-9680-8260", "clpid": "Yang-Jenny-Y" }, { "family_name": "Appel", "given_name": "Aaron M.", "orcid": "0000-0002-5604-1253", "clpid": "Appel-Aaron-M" }, { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" } ], "abstract": "
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The ideation of carbon capture, concentration, and utilization technologies is establishing a need for carbon dioxide sorbents with specific binding, release, and chemical specifications. While computational workflows can help navigate the broad search space of molecular sorbents, automated experimental screening platforms are relatively underdeveloped. We present a carbon capture screening instrument to characterize the carbon dioxide binding and sorption capacity of liquid sorbent media. We discuss the extension of this capability to characterize the loaded liquid sorbent as well as the headspace to facilitate study of the carbon dioxide adduct, for example its electrochemical activation. The fabrication and computer automation instructions are provided so that the experimental technique can be implemented in a broad range of materials acceleration platforms involving gas sorption.

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", "doi": "10.1039/d3dd00232b", "issn": "2635-098X", "publisher": "Royal Society of Chemistry", "publication": "Digital Discovery", "publication_date": "2024-04", "series_number": "4", "volume": "3", "issue": "4", "pages": "674-680" }, { "id": "authors:v4z42-npf09", "collection": "authors", "collection_id": "v4z42-npf09", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230725-857124000.42", "type": "article", "title": "Combinatorial synthesis for AI-driven materials discovery", "author": [ { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" }, { "family_name": "Zhou", "given_name": "Lan", "orcid": "0000-0002-7052-266X", "clpid": "Zhou-Lan" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" } ], "abstract": "Combinatorial synthesis of solid-state materials comprises the use of automation or parallelization to systematically vary synthesis parameters. This approach to materials synthesis is a natural fit for accelerated mapping of composition\u2013structure\u2013property relationships, a central tenet of materials research. By considering combinatorial synthesis in the context of experimental workflows, we envision a future for accelerated materials science promoted by the co-development of combinatorial synthesis and artificial intelligence (AI) techniques. To evaluate the suitability of a synthesis technique for a given experimental workflow, we establish a collection of ten metrics spanning speed, scalability, scope and quality of synthesis. We summarize select combinatorial synthesis techniques in the context of these metrics, elucidating opportunities for further development. These opportunities span initial deployment in high-throughput experimentation through to seminal demonstrations of automated decision-making using AI. Historical analysis of combinatorial synthesis in the context of the Gartner hype cycle establishes a recent rise in productivity, indicating that the field is poised to realize accelerated materials science workflows that transform materials discovery and development.", "doi": "10.1038/s44160-023-00251-4", "issn": "2731-0582", "publisher": "Nature Publishing Group", "publication": "Nature Synthesis", "publication_date": "2023-06", "series_number": "6", "volume": "2", "issue": "6", "pages": "493-504" }, { "id": "authors:tp3zs-m5s61", "collection": "authors", "collection_id": "tp3zs-m5s61", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220217-686997000", "type": "article", "title": "Stability and Activity of Cobalt Antimonate for Oxygen Reduction in Strong Acid", "author": [ { "family_name": "Zhou", "given_name": "Lan", "clpid": "Zhou-Lan" }, { "family_name": "Li", "given_name": "Hao", "orcid": "0000-0002-7577-1366", "clpid": "Li-Hao" }, { "family_name": "Lai", "given_name": "Yungchieh", "orcid": "0000-0001-9392-1447", "clpid": "Lai-Yungchieh" }, { "family_name": "Richter", "given_name": "Matthias", "orcid": "0000-0003-0091-2045", "clpid": "Richter-M-H" }, { "family_name": "Kan", "given_name": "Kevin", "clpid": "Kan-Kevin" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Kelly", "given_name": "Sara", "orcid": "0000-0001-9424-2489", "clpid": "Kelly-Sara" }, { "family_name": "Wang", "given_name": "Zhenbin", "orcid": "0000-0002-7016-9245", "clpid": "Wang-Zhenbin" }, { "family_name": "Lu", "given_name": "Yubing", "clpid": "Lu-Yubing" }, { "family_name": "Kim", "given_name": "R. Soyoung", "clpid": "Kim-R-Soyoung" }, { "family_name": "Li", "given_name": "Xiang", "orcid": "0000-0002-3780-7735", "clpid": "Li-Xiang" }, { "family_name": "Yano", "given_name": "Junko", "orcid": "0000-0001-6308-9071", "clpid": "Yano-Junko" }, { "family_name": "N\u00f8rskov", "given_name": "Jens K.", "orcid": "0000-0002-4427-7728", "clpid": "N\u00f8rskov-Jens-K" }, { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" } ], "abstract": "Guided by computational Pourbaix screening and high-throughput experiments aimed at the development of precious-metal-free fuel cells, we investigate rutile CoSb\u2082O\u2086 as an electrocatalyst for oxygen reduction in 1 M sulfuric acid. Following 4 h of catalyst conditioning at 0.7 V vs RHE, operation at this potential for 20 h yielded an average current density of \u22120.17 mA cm\u207b\u00b2 with corrosion at a rate of 0.04 nm hour\u207b\u00b9 that is stoichiometric with catalyst composition. Surface Pourbaix analysis of the (111) surface identified partial H coverage under operating conditions. The Sb active site has an HO* binding free energy of 0.49 eV, which is near the peak of the kinetic 4e\u207b ORR volcano for transition-metal oxides in acidic conditions. The experimental demonstration of operational stability and computational identification of a reaction pathway with favorable energetics place rutile CoSb\u2082O\u2086 among the most promising precious-metal-free electrocatalysts for oxygen reduction in acidic media.", "doi": "10.1021/acsenergylett.1c02673", "issn": "2380-8195", "publisher": "American Chemical Society", "publication": "ACS Energy Letters", "publication_date": "2022-03-11", "series_number": "3", "volume": "7", "issue": "3", "pages": "993-1000" }, { "id": "authors:benpx-wj703", "collection": "authors", "collection_id": "benpx-wj703", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220301-900116000", "type": "article", "title": "Molecular Coatings Improve the Selectivity and Durability of CO\u2082 Reduction Chalcogenide Photocathodes", "author": [ { "family_name": "Lai", "given_name": "Yungchieh", "orcid": "0000-0001-9392-1447", "clpid": "Lai-Yungchieh" }, { "family_name": "Watkins", "given_name": "Nicholas B.", "orcid": "0000-0001-7251-9387", "clpid": "Watkins-Nicholas-B" }, { "family_name": "Muzzillo", "given_name": "Christopher", "orcid": "0000-0002-6492-0098", "clpid": "Muzzillo-Christopher" }, { "family_name": "Richter", "given_name": "Matthias", "orcid": "0000-0003-0091-2045", "clpid": "Richter-Matthias-H" }, { "family_name": "Kan", "given_name": "Kevin", "clpid": "Kan-Kevin-S" }, { "family_name": "Zhou", "given_name": "Lan", "orcid": "0000-0002-7052-266X", "clpid": "Zhou-Lan" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Zakutayev", "given_name": "Andriy", "orcid": "0000-0002-3054-5525", "clpid": "Zakutayev-Andriy" }, { "family_name": "Peters", "given_name": "Jonas C.", "orcid": "0000-0002-6610-4414", "clpid": "Peters-J-C" }, { "family_name": "Agapie", "given_name": "Theodor", "orcid": "0000-0002-9692-7614", "clpid": "Agapie-T" }, { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" } ], "abstract": "The quest for solar-driven conversion of carbon dioxide to chemicals and fuels hinges upon the identification of an efficient, durable, and selective photocathode. Chalcogenide p-type semiconductors exemplified by chalcopyrite Cu(In,Ga)Se\u2082 (CIGS) have been effectively deployed as photocathodes. However, selectivity toward CO\u2082 reduction and durability of the commonly used CdS adlayer remain primary challenges. Here, we demonstrate that for the wide band gap CuGa\u2083Se\u2085 chalcopyrite absorber these challenges are well addressed by an organic coating generated in situ from an N,N\u2032-(1,4-phenylene)bispyridinium ditriflate salt in the electrolyte. The molecular additive provides a 30-fold increase in selectivity toward CO\u2082R products compared to the unmodified system and lowers Cd corrosion at least 10-fold. This dual functionality highlights the promise of hybrid solid-state-molecular photocathodes for enabling durable and efficient solar fuel systems.", "doi": "10.1021/acsenergylett.1c02762", "issn": "2380-8195", "publisher": "American Chemical Society", "publication": "ACS Energy Letters", "publication_date": "2022-03-11", "series_number": "3", "volume": "7", "issue": "3", "pages": "1195-1201" }, { "id": "authors:g145k-tex15", "collection": "authors", "collection_id": "g145k-tex15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220124-215443000", "type": "article", "title": "Overcoming Hurdles in Oxygen Evolution Catalyst Discovery via Codesign", "author": [ { "family_name": "Rao", "given_name": "Karun K.", "clpid": "Rao-Karun-K" }, { "family_name": "Lai", "given_name": "Yungchieh", "orcid": "0000-0001-9392-1447", "clpid": "Lai-Yungchieh" }, { "family_name": "Zhou", "given_name": "Lan", "orcid": "0000-0002-7052-266X", "clpid": "Zhou-Lan" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Bajdich", "given_name": "Michal", "orcid": "0000-0003-1168-8616", "clpid": "Bajdich-Michal" }, { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" } ], "abstract": "The oxygen evolution reaction (OER) is central to several sustainable energy technologies. Catalyst development has largely focused on lowering the overpotential and eliminating reliance on precious metals, revealing stark differences in alkaline and acidic OER. In alkaline electrolyte, precious metal-free catalysts have approached the limiting overpotential from established free energy scaling relationships, and our survey of complex metal oxides shows that this limit can be approached with a broad range of catalysts. In acidic electrolyte, electrochemical instabilities create a dual challenge of a dearth of nonprecious metal OER catalysts with overpotential below 0.5 V and a high dissolved metals concentration for most precious metal-free catalysts. On device-relevant time scales, the high dissolved metals concentrations compromise device stability, for example, through a decrease of performance and due to metal exchange between anode and cathode catalysts due to finite permeability of ion exchange membranes. These considerations motivate a substantial increase in monitoring and reporting of dissolved metals concentrations in OER experiments. To facilitate durability-based screening in continued catalyst discovery campaigns, we introduce a durability descriptor based on the d-electron count of each metal element compared to that of its Pourbaix-stable oxidation state, which enables rapid down-selection of candidate metal oxide catalysts. We discuss the importance of a codesign approach to catalyst development, where a device architecture can set specific requirements for dissolved metals concentrations and/or cathode and anode catalysts can be designed to tolerate cross-contamination. This device-level guidance of basic science will facilitate deployment of new catalysts to meet the societal needs for accelerated sustainable technology development.", "doi": "10.1021/acs.chemmater.1c04120", "issn": "0897-4756", "publisher": "American Chemical Society", "publication": "Chemistry of Materials", "publication_date": "2022-02-08", "series_number": "3", "volume": "34", "issue": "3", "pages": "899-910" }, { "id": "authors:344g6-s0176", "collection": "authors", "collection_id": "344g6-s0176", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211201-175953649", "type": "article", "title": "High Throughput Discovery of Complex Metal Oxide Electrocatalysts for the Oxygen Reduction Reaction", "author": [ { "family_name": "Guevarra", "given_name": "Dan", "orcid": "0000-0002-9592-3195", "clpid": "Guevarra-Dan-W" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Wang", "given_name": "Yu", "clpid": "Wang-Yu" }, { "family_name": "Zhou", "given_name": "Lan", "clpid": "Zhou-Lan" }, { "family_name": "Kan", "given_name": "Kevin", "clpid": "Kan-Kevin" }, { "family_name": "Richter", "given_name": "Matthias H.", "orcid": "0000-0003-0091-2045", "clpid": "Richter-Matthias-H" }, { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" } ], "abstract": "The oxygen reduction electrocatalysis is a key reaction for energy technologies such as fuel cells and air breathing batteries for which development of stable and efficient electrocatalysts remains a substantial challenge, especially when excluding precious metals. Multi-component metal oxides are complex materials that offer opportunities for catalyst development and challenges for prediction of optimal compositions. We use high throughput synthesis and electrochemistry to explore metal oxide electrocatalysts containing 1 to 4 of the elements Mg, Ca, Mn, Fe, Ni, Y, In, and La. Mining the resulting dataset of 7798 unique metal oxide compositions guides additional activity and stability experiments that reveal multiple avenues for further catalyst development based on (i) stabilization of Mn through incorporation in Mn-Ni\u2013Fe oxides, (ii) discovery of Ni\u2013Fe-La oxide electrocatalysts with excellent stability, and (iii) discovery of Mn-Ni\u2013Fe-La oxide electrocatalysts that optimize activity while retaining excellent operational stability.", "doi": "10.1007/s12678-021-00694-3", "issn": "1868-2529", "publisher": "Springer", "publication": "Electrocatalysis", "publication_date": "2022-01", "series_number": "1", "volume": "13", "issue": "1", "pages": "1-10" }, { "id": "authors:n4c8k-21638", "collection": "authors", "collection_id": "n4c8k-21638", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210914-182227400", "type": "article", "title": "Discovery of complex oxides via automated experiments and data science", "author": [ { "family_name": "Yang", "given_name": "Lusann", "orcid": "0000-0001-5071-2936", "clpid": "Yang-Lusann" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Armstrong", "given_name": "Zan", "clpid": "Armstrong-Zan" }, { "family_name": "Yang", "given_name": "Samuel J.", "orcid": "0000-0003-2460-6456", "clpid": "Yang-Samuel-J" }, { "family_name": "Kan", "given_name": "Kevin", "clpid": "Kan-Kevin" }, { "family_name": "Zhou", "given_name": "Lan", "clpid": "Zhou-Lan" }, { "family_name": "Richter", "given_name": "Matthias H.", "orcid": "0000-0003-0091-2045", "clpid": "Richter-Matthias-H" }, { "family_name": "Roat", "given_name": "Christopher", "clpid": "Roat-Christopher" }, { "family_name": "Wagner", "given_name": "Nicholas", "clpid": "Wagner-Nicholas" }, { "family_name": "Coram", "given_name": "Marc", "clpid": "Coram-Marc" }, { "family_name": "Berndl", "given_name": "Marc", "orcid": "0000-0001-6750-5861", "clpid": "Berndl-Marc" }, { "family_name": "Riley", "given_name": "Patrick", "clpid": "Riley-Patrick" }, { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" } ], "abstract": "The quest to identify materials with tailored properties is increasingly expanding into high-order composition spaces, with a corresponding combinatorial explosion in the number of candidate materials. A key challenge is to discover regions in composition space where materials have novel properties. Traditional predictive models for material properties are not accurate enough to guide the search. Herein, we use high-throughput measurements of optical properties to identify novel regions in three-cation metal oxide composition spaces by identifying compositions whose optical trends cannot be explained by simple phase mixtures. We screen 376,752 distinct compositions from 108 three-cation oxide systems based on the cation elements Mg, Fe, Co, Ni, Cu, Y, In, Sn, Ce, and Ta. Data models for candidate phase diagrams and three-cation compositions with emergent optical properties guide the discovery of materials with complex phase-dependent properties, as demonstrated by the discovery of a Co-Ta-Sn substitutional alloy oxide with tunable transparency, catalytic activity, and stability in strong acid electrolytes. These results required close coupling of data validation to experiment design to generate a reliable end-to-end high-throughput workflow for accelerating scientific discovery.", "doi": "10.1073/pnas.2106042118", "pmcid": "PMC8449358", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences", "publication_date": "2021-09-14", "series_number": "37", "volume": "118", "issue": "37", "pages": "Art. No. e2106042118" }, { "id": "authors:ywtpy-nka66", "collection": "authors", "collection_id": "ywtpy-nka66", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210324-112501603", "type": "article", "title": "Analysis of the limitations in the oxygen reduction activity of transition metal oxide surfaces", "author": [ { "family_name": "Li", "given_name": "Hao", "clpid": "Li-Hao" }, { "family_name": "Kelly", "given_name": "Sara", "orcid": "0000-0001-9424-2489", "clpid": "Kelly-Sara" }, { "family_name": "Guevarra", "given_name": "Dan", "orcid": "0000-0002-9592-3195", "clpid": "Guevarra-Dan-W" }, { "family_name": "Wang", "given_name": "Zhenbin", "orcid": "0000-0002-7016-9245", "clpid": "Wang-Zhenbin" }, { "family_name": "Wang", "given_name": "Yu", "orcid": "0000-0003-3589-9274", "clpid": "Wang-Yu" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Anand", "given_name": "Megha", "orcid": "0000-0003-2707-3587", "clpid": "Anand-Megha" }, { "family_name": "Gunasooriya", "given_name": "G. T. Kasun Kalhara", "orcid": "0000-0003-1258-7841", "clpid": "Gunasooriya-G-T-Kasun-Kalhara" }, { "family_name": "Abraham", "given_name": "Christina Susan", "orcid": "0000-0001-9991-0976", "clpid": "Abraham-Christina-Susan" }, { "family_name": "Vijay", "given_name": "Sudarshan", "orcid": "0000-0001-8242-0161", "clpid": "Vijay-Sudarshan" }, { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" }, { "family_name": "N\u00f8rskov", "given_name": "Jens K.", "orcid": "0000-0002-4427-7728", "clpid": "N\u00f8rskov-Jens-K" } ], "abstract": "The oxygen reduction reaction (ORR) is the key bottleneck in the performance of fuel cells. So far, the most active and stable electrocatalysts for the reaction are based on Pt group metals. Transition metal oxides (TMOs) constitute an alternative class of materials for achieving operational stability under oxidizing conditions. Unfortunately, TMOs are generally found to be less active than Pt. Here, we identify two reasons why it is difficult to find TMOs with a high ORR activity. The first is that TMO surfaces consistently bind oxygen atoms more weakly than transition metals do. This makes the breaking of the O\u2013O bond rate-determining for the broad range of TMO surfaces investigated here. The second is that electric field effects are stronger at TMO surfaces, which further makes O\u2013O bond breaking difficult. To validate the predictions and ascertain their generalizability for TMOs, we report experimental ORR catalyst screening for 7,798 unique TMO compositions that generally exhibit activity well below that of Pt.", "doi": "10.1038/s41929-021-00618-w", "issn": "2520-1158", "publisher": "Springer Nature", "publication": "Nature Catalysis", "publication_date": "2021-06", "series_number": "6", "volume": "4", "issue": "6", "pages": "463-468" }, { "id": "authors:mvrm0-qa846", "collection": "authors", "collection_id": "mvrm0-qa846", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201030-154047149", "type": "article", "title": "Bi Alloying into Rare Earth Double Perovskites Enhances Synthesizability and Visible Light Absorption", "author": [ { "family_name": "Newhouse", "given_name": "Paul F.", "orcid": "0000-0003-2032-3010", "clpid": "Newhouse-Paul-F" }, { "family_name": "Zhou", "given_name": "Lan", "orcid": "0000-0002-7052-266X", "clpid": "Zhou-Lan" }, { "family_name": "Umehara", "given_name": "Mitsutaro", "orcid": "0000-0001-8665-0028", "clpid": "Umehara-Mitsutaro" }, { "family_name": "Boyd", "given_name": "David A.", "clpid": "Boyd-David-A" }, { "family_name": "Soedarmadji", "given_name": "Edwin", "clpid": "Soedarmadji-Edwin" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" } ], "abstract": "A high throughput combinatorial synthesis utilizing inkjet printing of precursor inks was used to rapidly evaluate Bi-alloying into double perovskite oxides for enhanced visible light absorption. The fast visual screening of photo image scans of the library plates identifies 4-metal oxide compositions displaying an increase in light absorption, which subsequent UV\u2013vis spectroscopy indicates is due to bandgap reduction. Structural characterization by X-ray diffraction (XRD) and Raman spectroscopy demonstrates that the visually darker composition range contains Bi-alloyed Sm\u2082MnNiO\u2086 (double perovskite structure), of the form (Bi,Sm)\u2082MnNiO\u2086. Bi alloying not only increases the visible absorption but also facilitates crystallization of this structure at the relatively low annealing temperature of 615 \u00b0C. Investigation of additional seven combinations of a rare earth (RE) and a transition metal (TM) with Bi and Mn indicates that Bi-alloying on the RE site occurs with similar effect in the family of rare earth oxide double perovskites.", "doi": "10.1021/acscombsci.0c00177", "issn": "2156-8952", "publisher": "American Chemical Society", "publication": "ACS Combinatorial Science", "publication_date": "2020-12-14", "series_number": "12", "volume": "22", "issue": "12", "pages": "895-901" }, { "id": "authors:37y1k-4kp94", "collection": "authors", "collection_id": "37y1k-4kp94", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200110-151145517", "type": "article", "title": "Benchmarking the Acceleration of Materials Discovery by Sequential Learning", "author": [ { "family_name": "Rohr", "given_name": "Brian", "orcid": "0000-0003-4696-0149", "clpid": "Rohr-Brian" }, { "family_name": "Stein", "given_name": "Helge S.", "orcid": "0000-0002-3461-0232", "clpid": "Stein-Helge-S" }, { "family_name": "Guevarra", "given_name": "Dan", "orcid": "0000-0002-9592-3195", "clpid": "Guevarra-Dan-W" }, { "family_name": "Wang", "given_name": "Yu", "orcid": "0000-0003-3589-9274", "clpid": "Wang-Yu" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Aykol", "given_name": "Muratahan", "orcid": "0000-0001-6433-7217", "clpid": "Aykol-Muratahan" }, { "family_name": "Suram", "given_name": "Santosh K.", "orcid": "0000-0001-8170-2685", "clpid": "Suram-Santosh-K" }, { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" } ], "abstract": "Sequential learning (SL) strategies, i.e. iteratively updating a machine learning model to guide experiments, have been proposed to significantly accelerate materials discovery and research. Applications on computational datasets and a handful of optimization experiments have demonstrated the promise of SL, motivating a quantitative evaluation of its ability to accelerate materials discovery, specifically in the case of physical experiments. The benchmarking effort in the present work quantifies the performance of SL algorithms with respect to a breadth of research goals: discovery of any \"good\" material, discovery of all \"good\" materials, and discovery of a model that accurately predicts the performance of new materials. To benchmark the effectiveness of different machine learning models against these goals, we use datasets in which the performance of all materials in the search space is known from high-throughput synthesis and electrochemistry experiments. Each dataset contains all pseudo-quaternary metal oxide combinations from a set of six elements (chemical space), the performance metric chosen is the electrocatalytic activity (overpotential) for the oxygen evolution reaction (OER). A diverse set of SL schemes is tested on four chemical spaces, each containing 2121 catalysts. The presented work suggests that research can be accelerated by up to a factor of 20 compared to random acquisition in specific scenarios. The results also show that certain choices of SL models are ill-suited for a given research goal resulting in substantial deceleration compared to random acquisition methods. The results provide quantitative guidance on how to tune an SL strategy for a given research goal and demonstrate the need for a new generation of materials-aware SL algorithms to further accelerate materials discovery.", "doi": "10.1039/c9sc05999g", "issn": "2041-6520", "publisher": "Royal Society of Chemistry", "publication": "Chemical Science", "publication_date": "2020-03-14", "series_number": "10", "volume": "11", "issue": "10", "pages": "2696-2706" }, { "id": "authors:7vafc-kct91", "collection": "authors", "collection_id": "7vafc-kct91", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181116-091613557", "type": "article", "title": "Interface engineering for light-driven water oxidation: unravelling the passivating and catalytic mechanism in BiVO\u2084 overlayers", "author": [ { "family_name": "Liu", "given_name": "Guiji", "orcid": "0000-0002-3943-4119", "clpid": "Liu-Guiji" }, { "family_name": "Eichhorn", "given_name": "Johanna", "orcid": "0000-0003-2413-6079", "clpid": "Eichhorn-Johanna" }, { "family_name": "Jiang", "given_name": "Chang-Ming", "orcid": "0000-0001-8327-5760", "clpid": "Jiang-Chang-Ming" }, { "family_name": "Scott", "given_name": "Mary C.", "clpid": "Scott-Mary-C" }, { "family_name": "Hess", "given_name": "Lucas H.", "clpid": "Hess-Lucas-H" }, { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Sharp", "given_name": "Ian D.", "orcid": "0000-0001-5238-7487", "clpid": "Sharp-Ian-D" }, { "family_name": "Toma", "given_name": "Francesca M.", "orcid": "0000-0003-2332-0798", "clpid": "Toma-Francesca-M" } ], "abstract": "Artificial photosynthetic approaches require the combination of light absorbers interfaced with overlayers that enhance charge transport and collection to perform catalytic reactions. Despite numerous efforts that have coupled various catalysts to light absorbing semiconductors, the optimization of semiconductor/catalyst as well as catalyst/electrolyte interfaces and the identification of the role of the catalyst still remain a key challenge. Herein, we assemble (NiFeCoCe)O\u2093 multi-component overlayers, interfaced with bismuth vanadate photoanodes, and determine the roles of different elements on promoting interfacial charge transfer and catalytic reaction over competitive photocarrier recombination loss processes. Through this understanding, and aided by complementary macroscopic photoelectrochemical measurements and nanoscale atomic force microscopy techniques, a bifunctional (CoFeCe/NiFe)O\u2093 overlayer was rationally engineered. The resulting multi-functional coating yields BiVO\u2084 photoanodes with almost 100% efficient surface collection of holes under oxygen evolving reaction conditions. The (CoFeCe)O\u2093 component excels at efficient capture and transport of photogenerated holes in BiVO\u2084 through the availability of redox active states, whereas (NiFe)O\u2093 plays a vital role in reducing charge recombination at the BiVO\u2084/electrolyte interface. In addition, this study supports the hypothesis that catalytic sites act as electronically active trap states on uncoated BiVO\u2084 photoanodes.", "doi": "10.1039/C8SE00473K", "issn": "2398-4902", "publisher": "Royal Society of Chemistry", "publication": "Sustainable Energy and Fuels", "publication_date": "2019-01-01", "series_number": "1", "volume": "3", "issue": "1", "pages": "127-135" }, { "id": "authors:se2rq-d4z07", "collection": "authors", "collection_id": "se2rq-d4z07", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180927-134054550", "type": "article", "title": "Balancing Surface Passivation and Catalysis with Integrated BiVO_4/(Fe-Ce)O_x Photoanodes in pH 9 Borate Electrolyte", "author": [ { "family_name": "Zhou", "given_name": "Lan", "orcid": "0000-0002-7052-266X", "clpid": "Zhou-Lan" }, { "family_name": "Shinde", "given_name": "Aniketa", "orcid": "0000-0003-2386-3848", "clpid": "Shinde-Aniketa-A" }, { "family_name": "Guevarra", "given_name": "Dan", "orcid": "0000-0002-9592-3195", "clpid": "Guevarra-Dan-W" }, { "family_name": "Toma", "given_name": "Francesca M.", "orcid": "0000-0003-2332-0798", "clpid": "Toma-Francesca-M" }, { "family_name": "Stein", "given_name": "Helge S.", "orcid": "0000-0002-3461-0232", "clpid": "Stein-Helge-S\u00f6ren" }, { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" } ], "abstract": "The performance of oxygen-evolving photoanodes based on bismuth vanadate (BiVO_4) is critically determined by the surface coating. While these coatings passivate surface defects, transport photogenerated holes, protect against corrosion, and aid catalysis, their optimal composition changes with operating pH, thus affecting overall performance. We use high-throughput photoelectrochemistry methods to map photoanode performance to enable the discovery of optimal composition and loading of Ce-rich sputter-deposited (Fe\u2013Ce)O_x overlayers on undoped BiVO_4 in pH 9 borate buffer electrolyte. The optimal composition is found to be 20% Fe and 80% Ce with an optimal Fe + Ce metal loading of 0.9 nmol mm^(\u20132). Analysis of the composition and loading dependence of (i) the photocurrent transients upon illumination toggling, (ii) stabilized photocurrent densities, and (iii) photogenerated hole-transfer efficiency reveals the confluence of phenomena that gives rise to the optimal performance yielding nearly perfect transfer efficiency over a narrow composition window.", "doi": "10.1021/acsaem.8b01377", "issn": "2574-0962", "publisher": "American Chemical Society", "publication": "ACS Applied Energy Materials", "publication_date": "2018-10-22", "series_number": "10", "volume": "1", "issue": "10", "pages": "5766-5771" }, { "id": "authors:ry7d7-mrk71", "collection": "authors", "collection_id": "ry7d7-mrk71", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180423-104401758", "type": "article", "title": "Combinatorial Alloying Improves Bismuth Vanadate Photoanodes via Reduced Monoclinic Distortion", "author": [ { "family_name": "Newhouse", "given_name": "P. F.", "orcid": "0000-0003-2032-3010", "clpid": "Newhouse-Paul-F" }, { "family_name": "Guevarra", "given_name": "D.", "orcid": "0000-0002-9592-3195", "clpid": "Guevarra-Dan" }, { "family_name": "Umehara", "given_name": "M.", "orcid": "0000-0001-8665-0028", "clpid": "Umehara-Mitsutaro" }, { "family_name": "Reyes-Lillo", "given_name": "S. E.", "orcid": "0000-0003-0012-9958", "clpid": "Reyes-Lillo-Sebastian-E" }, { "family_name": "Zhou", "given_name": "L.", "orcid": "0000-0002-7052-266X", "clpid": "Zhou-Lan" }, { "family_name": "Boyd", "given_name": "D. A.", "clpid": "Boyd-David-A" }, { "family_name": "Suram", "given_name": "S. K.", "orcid": "0000-0001-8170-2685", "clpid": "Suram-Santosh-K" }, { "family_name": "Cooper", "given_name": "J. K.", "orcid": "0000-0002-7953-4229", "clpid": "Cooper-Jason-K" }, { "family_name": "Haber", "given_name": "J. A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Neaton", "given_name": "J. B.", "orcid": "0000-0001-7585-6135", "clpid": "Neaton-Jeffrey-B" }, { "family_name": "Gregoire", "given_name": "J. M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" } ], "abstract": "Improving the efficiency of solar-powered oxygen evolution is both critical for development of solar fuels technologies and challenging due to the broad set of properties required of a solar fuels photoanode. Bismuth vanadate, in particular the monoclinic clinobisvanite phase, has received substantial attention and has exhibited the highest radiative efficiency among metal oxides with a band gap in the visible range. Efforts to further improve its photoelectrochemical performance have included alloying one or more metals onto the Bi and/or V sites, with progress on this frontier stymied by the difficulty in computational modelling of substitutional alloys and the high dimensionality of co-alloying composition spaces. Since substitutional alloying concurrently changes multiple materials properties, understanding the underlying cause for performance improvements is also challenging, motivating our application of combinatorial materials science techniques to map photoelectrochemical performance of 948 unique bismuth vanadate alloy compositions comprising 0 to 8% alloys of P, Ca, Mo, Eu, Gd, and W along with a variety of compositions from each pairwise combination of these elements. Upon identification of substantial improvements in the (Mo,Gd) co-alloying space, structural mapping was performed to reveal a remarkable correlation between performance enhancement and a lowered monoclinic distortion. First-principles density functional theory calculations indicate that the improvements are due to a lowered hole effective mass and hole polaron formation energy, and collectively, our results identify the monoclinic distortion as a critical parameter in the optimization and understanding of bismuth vanadate-based photoanodes.", "doi": "10.1039/c8ee00179k", "issn": "1754-5692", "publisher": "Royal Society of Chemistry", "publication": "Energy and Environmental Science", "publication_date": "2018-09-01", "series_number": "9", "volume": "11", "issue": "9", "pages": "2444-2457" }, { "id": "authors:p2ke1-fmg24", "collection": "authors", "collection_id": "p2ke1-fmg24", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161109-115755580", "type": "article", "title": "Detecting structural variances of Co\u2083O\u2084 catalysts by controlling beam-induced sample alterations in the vacuum of a transmission electron microscope", "author": [ { "family_name": "Kisielowski", "given_name": "C.", "orcid": "0000-0001-6425-0779", "clpid": "Kisielowski-Christian" }, { "family_name": "Frei", "given_name": "H.", "clpid": "Frei-H" }, { "family_name": "Specht", "given_name": "P.", "clpid": "Specht-P" }, { "family_name": "Sharp", "given_name": "I. D.", "orcid": "0000-0001-5238-7487", "clpid": "Sharp-Ian-D" }, { "family_name": "Haber", "given_name": "J. A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Helveg", "given_name": "S.", "clpid": "Helveg-S" } ], "abstract": "This article summarizes core aspects of beam-sample interactions in research that aims at exploiting the ability to detect single atoms at atomic resolution by mid-voltage transmission electron microscopy. Investigating the atomic structure of catalytic Co\u2083O\u2084 nanocrystals underscores how indispensable it is to rigorously control electron dose rates and total doses to understand native material properties on this scale. We apply in-line holography with variable dose rates to achieve this goal. Genuine object structures can be maintained if dose rates below ~100 e/\u0172 s are used and the contrast required for detection of single atoms is generated by capturing large image series. Threshold doses for the detection of single atoms are estimated. An increase of electron dose rates and total doses to common values for high resolution imaging of solids stimulates object excitations that restructure surfaces, interfaces, and defects and cause grain reorientation or growth. We observe a variety of previously unknown atom configurations in surface proximity of the Co\u2083O\u2084 spinel structure. These are hidden behind broadened diffraction patterns in reciprocal space but become visible in real space by solving the phase problem. An exposure of the Co\u2083O\u2084 spinel structure to water vapor or other gases induces drastic structure alterations that can be captured in this manner.", "doi": "10.1186/s40679-016-0027-9", "pmcid": "PMC5093192", "issn": "2198-0926", "publisher": "Springer", "publication": "Advanced Structural and Chemical Imaging", "publication_date": "2016-11-02", "volume": "2", "pages": "Art. No. 13" }, { "id": "authors:gscf9-tq458", "collection": "authors", "collection_id": "gscf9-tq458", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160909-133249863", "type": "article", "title": "The role of the CeO_2/BiVO_4 interface in optimized Fe-Ce oxide coatings for solar fuels photoanodes", "author": [ { "family_name": "Shinde", "given_name": "A.", "orcid": "0000-0003-2386-3848", "clpid": "Shinde-Aniketa-A" }, { "family_name": "Li", "given_name": "G.", "clpid": "Li-Guiji" }, { "family_name": "Zhou", "given_name": "L.", "orcid": "0000-0002-7052-266X", "clpid": "Zhou-Lan" }, { "family_name": "Guevarra", "given_name": "D.", "orcid": "0000-0002-9592-3195", "clpid": "Guevarra-Dan-W" }, { "family_name": "Suram", "given_name": "S. K.", "orcid": "0000-0001-8170-2685", "clpid": "Suram-Santosh-K" }, { "family_name": "Toma", "given_name": "F. M.", "orcid": "0000-0003-2332-0798", "clpid": "Toma-Francesca-M" }, { "family_name": "Yan", "given_name": "Q.", "clpid": "Yan-Q" }, { "family_name": "Haber", "given_name": "J. A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Neaton", "given_name": "J. B.", "orcid": "0000-0001-7585-6135", "clpid": "Neaton-Jeffrey-B" }, { "family_name": "Gregoire", "given_name": "J. M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" } ], "abstract": "Solar fuel generators entail a high degree of materials integration, and efficient photoelectrocatalysis of the constituent reactions hinges upon the establishment of highly functional interfaces. The recent application of high throughput experimentation to interface discovery for solar fuels photoanodes has revealed several surprising and promising mixed-metal oxide coatings for BiVO_4. Using sputter deposition of composition and thickness gradients on a uniform BiVO_4 film, we systematically explore photoanodic performance as a function of the composition and loading of Fe\u2013Ce oxide coatings. This combinatorial materials integration study not only enhances the performance of this new class of materials but also identifies CeO_2 as a critical ingredient that merits detailed study. A heteroepitaxial CeO_2(001)/BiVO_4(010) interface is identified in which Bi and V remain fully coordinated to O such that no surface states are formed. Ab initio calculations of the integrated materials and inspection of the electronic structure reveals mechanisms by which CeO_2 facilitates charge transport while mitigating deleterious recombination. The results support the observations that addition of Ce to BiVO_4 coatings greatly enhances photoelectrocatalytic activity, providing an important strategy for developing a scalable solar fuels technology.", "doi": "10.1039/c6ta04746g", "issn": "2050-7488", "publisher": "Royal Society of Chemistry", "publication": "Journal of Materials Chemistry A", "publication_date": "2016-10-07", "series_number": "37", "volume": "4", "issue": "37", "pages": "14356-14363" }, { "id": "authors:ddeg4-mch47", "collection": "authors", "collection_id": "ddeg4-mch47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160907-090003256", "type": "article", "title": "Discovery of Fe\u2013Ce Oxide/BiVO\u2084 Photoanodes through Combinatorial Exploration of Ni\u2013Fe\u2013Co\u2013Ce Oxide Coatings", "author": [ { "family_name": "Shinde", "given_name": "Aniketa", "orcid": "0000-0003-2386-3848", "clpid": "Shinde-Aniketa-A" }, { "family_name": "Guevarra", "given_name": "Dan", "orcid": "0000-0002-9592-3195", "clpid": "Guevarra-Dan-W" }, { "family_name": "Liu", "given_name": "Guiji", "orcid": "0000-0002-3943-4119", "clpid": "Liu-Guiji" }, { "family_name": "Sharp", "given_name": "Ian D.", "orcid": "0000-0001-5238-7487", "clpid": "Sharp-Ian-D" }, { "family_name": "Toma", "given_name": "Francesca M.", "orcid": "0000-0003-2332-0798", "clpid": "Toma-Francesca-M" }, { "family_name": "Gregoire", "given_name": "John M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" }, { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" } ], "abstract": "An efficient photoanode is a prerequisite for a viable solar fuels technology. The challenges to realizing an efficient photoanode include the integration of a semiconductor light absorber and a metal oxide electrocatalyst to optimize corrosion protection, light trapping, hole transport, and photocarrier recombination sites. To efficiently explore metal oxide coatings, we employ a high-throughput methodology wherein a uniform BiVO\u2084 film is coated with 858 unique metal oxide coatings covering a range of metal oxide loadings and the full (Ni\u2013Fe\u2013Co\u2013Ce)O\u2093 pseudoquaternary composition space. Photoelectrochemical characterization of the photoanodes reveals that specific combinations of metal oxide composition and loading provide up to a 13-fold increase in the maximum photoelectrochemical power generation for oxygen evolution in pH 13 electrolyte. Through mining of the high-throughput data we identify composition regions that form improved interfaces with BiVO\u2084. Of particular note, integrated photoanodes with catalyst compositions in the range Fe_((0.4\u20130.6))Ce_((0.6\u20130.4))O\u2093 exhibit high interface quality and excellent photoelectrochemical power conversion. Scaled-up inkjet-printed electrodes and photoanodic electrodeposition of this composition on BiVO\u2084 confirms the discovery and the synthesis-independent interface improvement of (Fe\u2013Ce)O\u2093 coatings on BiVO\u2084.", "doi": "10.1021/acsami.6b06714", "issn": "1944-8244", "publisher": "American Chemical Society", "publication": "ACS Applied Materials & Interfaces", "publication_date": "2016-09-14", "series_number": "36", "volume": "8", "issue": "36", "pages": "23696-23705" }, { "id": "authors:2y54h-z8z44", "collection": "authors", "collection_id": "2y54h-z8z44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151221-160606238", "type": "article", "title": "Development of solar fuels photoanodes through combinatorial integration of Ni\u2013La\u2013Co\u2013Ce oxide catalysts on BiVO\u2084", "author": [ { "family_name": "Guevarra", "given_name": "D.", "orcid": "0000-0002-9592-3195", "clpid": "Guevarra-Dan" }, { "family_name": "Shinde", "given_name": "A.", "orcid": "0000-0003-2386-3848", "clpid": "Shinde-Aniketa-A" }, { "family_name": "Suram", "given_name": "S. K.", "orcid": "0000-0001-8170-2685", "clpid": "Suram-Santosh-K" }, { "family_name": "Sharp", "given_name": "I. D.", "orcid": "0000-0001-5238-7487", "clpid": "Sharp-Ian-D" }, { "family_name": "Toma", "given_name": "F. M.", "orcid": "0000-0003-2332-0798", "clpid": "Toma-Francesca-M" }, { "family_name": "Haber", "given_name": "J. A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Gregoire", "given_name": "J. M.", "orcid": "0000-0002-2863-5265", "clpid": "Gregoire-J-M" } ], "abstract": "The development of an efficient photoanode remains the primary materials challenge in the establishment of a scalable technology for solar water splitting. The typical photoanode architecture consists of a semiconductor light absorber coated with a metal oxide that serves a combination of functions, including corrosion protection, electrocatalysis, light trapping, hole transport, and elimination of deleterious recombination sites. To date, such coatings have been mostly limited to simple materials such as TiO\u2082 and Co-Pi, with extensive experimental and theoretical effort required to provide an understanding of the physics and chemistry of the semiconductor-coating interface. To provide a more efficient exploration of metal oxide coatings for a given light absorber, we introduce a high throughput methodology wherein a uniform BiVO\u2084 thin film is coated with 858 unique metal oxides covering a range of metal oxide loadings and the full Ni\u2013La\u2013Co\u2013Ce oxide quaternary composition space. Photoelectrochemical characterization of each photoanode reveals that approximately one third of the coatings lower the photoanode performance while select combinations of metal oxide composition and loading provide up to a 14-fold increase in the maximum photoelectrochemical power generation for oxygen evolution in pH 13 electrolyte. Particular Ce-rich coatings also exhibit an anti-reflection effect that further amplifies the performance, yielding a 20-fold enhancement in power conversion efficiency compared to bare BiVO\u2084. By use of in situ optical spectroscopy and comparisons between the metal oxide coatings and their extrinsic optical and electrocatalytic properties, we present a suite of data-driven discoveries, including composition regions which form optimal interfaces with BiVO\u2084 and photoanodes that are suitable for integration with a photocathode due to their excellent power conversion and solar transmission efficiencies. The high throughput experimentation and informatics provides a powerful platform for both identifying the pertinent interfaces for further study and discovering high performance photoanodes for incorporation into efficient water splitting devices.", "doi": "10.1039/c5ee03488d", "issn": "1754-5692", "publisher": "Royal Society of Chemistry", "publication": "Energy and Environmental Science", "publication_date": "2016-02", "series_number": "2", "volume": "9", "issue": "2", "pages": "565-580" }, { "id": "authors:4trep-9qe72", "collection": "authors", "collection_id": "4trep-9qe72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170607-104931347", "type": "article", "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", "author": [ { "family_name": "Haber", "given_name": "Joel A.", "orcid": "0000-0001-7847-5506", "clpid": "Haber-Joel-A" }, { "family_name": "Lewis", "given_name": "Nathan S.", "orcid": "0000-0001-5245-0538", "clpid": "Lewis-N-S" } ], "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.", "doi": "10.1021/jp0102872", "issn": "1520-6106", "publisher": "American Chemical Society", "publication": "Journal of Physical Chemistry B", "publication_date": "2002-04-11", "series_number": "14", "volume": "106", "issue": "14", "pages": "3639-3656" } ]