The ionic liquids diisopropylimidazolium bromide (DIPI) and diisobutylimidazolium bromide (DIBU) were used both as solvents and structure-directing agents (SDAs) to obtain AlPO4-5 and MnAPO-5 (Mn-AFI) molecular sieves. For increasing level of manganese, DIBU always yielded pure-phase Mn-AFI whereas DIPI led to amorphous product when more than 0.13 eq of Mn was added. Varying amounts of water, HF and metal led to AFI, cristobalite or tridymite phases. We also explored the use of nickel as the metal dopant, and although AFI phase were obtained under certain conditions, no framework incorporation of the metal was observed. Because of the vanishingly low vapor pressure of the ILs, the synthesis does not carry the risk of pressure build-up. The ILs were easily and fully recyclable and used for multiple syntheses. The MnAPO-5 material was characterized with powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), electron paramagnetic resonance (EPR), multinuclear solid-state nuclear magnetic resonance (SS-NMR) and X-ray absorption fine structure (XAFS). These findings provide new insight into the ionothermal synthesis of metal-doped AFI frameworks with possible implications in catalytic applications.
", "doi": "10.1016/j.micromeso.2024.113400", "issn": "1387-1811", "publisher": "Elsevier", "publication": "Microporous and Mesoporous Materials", "publication_date": "2025-01", "volume": "382", "pages": "113400" }, { "id": "authors:m6p7b-wxn74", "collection": "authors", "collection_id": "m6p7b-wxn74", "cite_using_url": "https://authors.library.caltech.edu/records/m6p7b-wxn74", "type": "article", "title": "Scalable Atomic\u2010Layer Tailoring of Abundant Oxide Supports Unlocks Superior Interfaces for Low\u2010Metal\u2010Loading Dehydrogenation", "author": [ { "family_name": "Kwak", "given_name": "Yeonsu", "orcid": "0000-0002-4437-0025" }, { "family_name": "Lee", "given_name": "Yu\u2010Jin", "orcid": "0009-0002-9587-890X" }, { "family_name": "Moon", "given_name": "Seongeun" }, { "family_name": "Lee", "given_name": "Kimoon", "orcid": "0000-0003-4839-1592" }, { "family_name": "Ramadhani", "given_name": "Safira", "orcid": "0000-0001-9872-8208" }, { "family_name": "On", "given_name": "Eui\u2010Rim" }, { "family_name": "Ahn", "given_name": "Chang\u2010il" }, { "family_name": "Hwang", "given_name": "Son\u2010Jong", "orcid": "0000-0002-3210-466X", "clpid": "Hwang-Sonjong" }, { "family_name": "Sohn", "given_name": "Hyuntae", "orcid": "0000-0001-8432-6224" }, { "family_name": "Jeong", "given_name": "Hyangsoo", "orcid": "0000-0002-0101-5699" }, { "family_name": "Nam", "given_name": "Suk Woo", "orcid": "0000-0002-4884-8137" }, { "family_name": "Yoon", "given_name": "Chang Won" }, { "family_name": "Kim", "given_name": "Yongmin", "orcid": "0000-0003-3152-3405" } ], "abstract": "Liquid organic hydrogen carriers (LOHCs) offer a promising solution for global hydrogen infrastructure, but their practical application faces two key challenges: sluggish dehydrogenation processes and the reliance on catalysts with high noble metal loadings. This study presents a scalable approach to reduce noble metal usage while maintaining high catalytic activity. We synthesized an ultralow Pt content (0.1\u2005wt %) catalyst using γ-Al2O3-based pellet support with atomic layer deposition (ALD) of TiO2. Advanced characterization techniques reveal that the thin ALD-TiO2 shell provides a heterogeneous interface, confining electronically rich Pt-nanoparticle ensembles. The catalyst outperforms both equivalent Pt-content catalysts and a commercial 0.5\u2005wt % Pt/γ-Al2O3 catalyst in homocyclic LOHC dehydrogenation. This study provides insights into the beneficial role of ALD-engineered interfaces for catalytic supports and offers an efficient approach for scalable production of low-noble-metal-content catalysts, with implications for various catalytic processes.
", "doi": "10.1002/anie.202417598", "issn": "1433-7851", "publisher": "Wiley", "publication": "Angewandte Chemie International Edition", "publication_date": "2024-11-21", "pages": "e202417598" }, { "id": "authors:hn14h-a6x59", "collection": "authors", "collection_id": "hn14h-a6x59", "cite_using_url": "https://authors.library.caltech.edu/records/hn14h-a6x59", "type": "article", "title": "The spectroscopy of hydride in single crystals of SrTiO\u2083 perovskite", "author": [ { "family_name": "Palfey", "given_name": "William R.", "orcid": "0000-0002-9555-7877", "clpid": "Palfey-William-R" }, { "family_name": "Hwang", "given_name": "Son-Jong", "orcid": "0000-0002-3210-466X", "clpid": "Hwang-Sonjong" }, { "family_name": "Goddard", "given_name": "William A.", "orcid": "0000-0003-0097-5716", "clpid": "Goddard-W-A-III" }, { "family_name": "Rossman", "given_name": "George R.", "orcid": "0000-0002-4571-6884", "clpid": "Rossman-G-R" } ], "abstract": "Under reducing conditions, SrTiO3 perovskite can exchange up to 20% of its O2− ions for H− (hydride), greatly influencing its material properties. This not only presents intriguing possibilities for material design, but also for hydrogen sequestration in the deep earth, where perovskite-structured minerals are abundant. However, uncertainties remain surrounding hydride incorporation in SrTiO3, including details of the hydride structural state, and how hydride interacts with the broader defect chemistry of SrTiO3. Additionally, experimental studies of hydride in SrTiO3 and other perovskites may face analytical limitations. The most common methods for characterizing hydride, namely 1H NMR, may not be suitable in all experimental contexts, including materials with relatively low hydride concentrations and in situ high-pressure, high-temperature experiments. Here, we present an investigation of hydride in single crystals of SrTiO3 focused on detailed spectroscopic measurements. Through a combination of density functional theory (DFT)-assisted Fourier transform infrared (FTIR) spectroscopy and UV-vis spectroscopy, we observe structural hydride and its effects on the electronic transitions in SrTiO3. These results are compared directly against 1H NMR. We find that, although hydride is sometimes difficult to identify via FTIR, infrared spectroscopy is significantly more sensitive to hydride than 1H NMR. We also find that DFT makes accurate predictions about the spectroscopic behavior of hydride in SrTiO3, pointing to the value of ab initio techniques in future studies.
", "doi": "10.1039/d4cp02852j", "issn": "1463-9076", "publisher": "Royal Society of Chemistry", "publication": "Physical Chemistry Chemical Physics", "publication_date": "2024-10-21", "series_number": "39", "volume": "26", "issue": "39", "pages": "25439-25451" }, { "id": "authors:sjez0-mxg64", "collection": "authors", "collection_id": "sjez0-mxg64", "cite_using_url": "https://authors.library.caltech.edu/records/sjez0-mxg64", "type": "article", "title": "Modular MPS\u2083-Based Frameworks for Superionic Conduction of Monovalent and Multivalent Ions", "author": [ { "family_name": "Iton", "given_name": "Zachery W. B.", "orcid": "0000-0002-2226-9006", "clpid": "Iton-Zachery-W-B" }, { "family_name": "Irving-Singh", "given_name": "Zion", "orcid": "0000-0002-6053-4763", "clpid": "Irving-Singh-Zion" }, { "family_name": "Hwang", "given_name": "Son-Jong", "orcid": "0000-0002-3210-466X", "clpid": "Hwang-Sonjong" }, { "family_name": "Bhattacharya", "given_name": "Amit", "orcid": "0000-0002-3104-9187" }, { "family_name": "Shaker", "given_name": "Sammy", "orcid": "0000-0003-1751-4908", "clpid": "Shaker-Sammy" }, { "family_name": "Das", "given_name": "Tridip", "orcid": "0000-0002-3320-2157", "clpid": "Das-Tridip" }, { "family_name": "Cl\u00e9ment", "given_name": "Rapha\u00eble J.", "orcid": "0000-0002-3611-1162" }, { "family_name": "Goddard", "given_name": "William A.", "orcid": "0000-0003-0097-5716", "clpid": "Goddard-W-A-III" }, { "family_name": "See", "given_name": "Kimberly", "orcid": "0000-0002-0133-9693", "clpid": "See-Kimberly" } ], "abstract": "Next-generation batteries based on more sustainable working ions could offer improved performance, safety, and capacity over lithium-ion batteries while also decreasing the cost. Development of next-generation battery technology using “beyond-Li” mobile ions, especially multivalent ions, is limited due to a lack of understanding of solid state conduction of these ions. Here, we introduce ligand-coordinated ions in MPS3-based (M = Mn, Cd) solid host crystals to simultaneously increase the size of the interlayer spacing, through which the ions can migrate, and screen the charge-dense ions. The ligand-assisted conduction mechanism enables ambient temperature superionic conductivity of various next-generation mobile ions in the electronically insulating MPS3-based solid. Without the coordinating ligands, all of the compounds show little to no ionic conductivity. Pulsed-field gradient nuclear magnetic resonance spectroscopy suggests that the ionic conduction occurs through a hopping mechanism, where the cations are moving between H2O molecules, instead of a vehicular mechanism which has been observed in other hydrated layered solids. This modular system not only facilitates tailoring to different potential applications but also enables us to probe the effect of different host structures, mobile ions, and coordinating ligands on the ionic conductivity. This research highlights the influence of cation charge density, diffusion channel size, and effective charge screening on ligand-assisted solid state ionic conductivity. The insights gained can be applied in the design of other ligand-assisted solid state ionic conductors, which will be especially impactful in realizing solid state multivalent ionic conductors. Additionally, the ion-intercalated MPS3-based frameworks could potentially serve as a universal solid state electrolyte for various next-generation battery chemistries.
", "doi": "10.1021/jacs.4c06263", "issn": "0002-7863", "publisher": "American Chemical Society", "publication": "Journal of the American Chemical Society", "publication_date": "2024-09-04", "series_number": "35", "volume": "146", "issue": "35", "pages": "24398\u201324414" }, { "id": "authors:qwem4-c6y71", "collection": "authors", "collection_id": "qwem4-c6y71", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230714-170229200.3", "type": "article", "title": "Application of a Functionalized K\u2081\u208b\u2093Ni\u2093NbO\u2083 Structure: Enhancing the Photocatalytic Activity of a CdS/K\u2081\u208b\u2093Ni\u2093NbO\u2083 Composite", "author": [ { "family_name": "Ryu", "given_name": "Su Young", "orcid": "0000-0002-3246-6126", "clpid": "Ryu-Su-Young" }, { "family_name": "Hwang", "given_name": "Sonjong", "orcid": "0000-0002-3210-466X", "clpid": "Hwang-Sonjong" }, { "family_name": "Lee", "given_name": "Tai Kyu", "clpid": "Lee-Tai-Kyu" }, { "family_name": "Hoffmann", "given_name": "Michael R.", "orcid": "0000-0001-6495-1946", "clpid": "Hoffmann-M-R" } ], "abstract": "Herein we report a K\u2081\u208b\u2093Ni\u2093NbO\u2083 composite undergoing a phase transition from orthorhombic to rhombohedral, resulting in a Ni particle and a short Nb\u2013O^(\u03b4-) on the surface caused by a structural distortion. The Ni particles are dispersed on the overall surface of the structure, and the short bonded Nb\u2013O^(\u03b4-) sticks out to the structure interstices on the surface. The properties of the structure and surface of K\u2081\u208b\u2093Ni\u2093NbO\u2083 are defined by spectroscopic analysis of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Raman, nuclear magnetic resonance (\u00b9H NMR), and X-ray photoelectron spectroscopy (XPS). This unique surface property enables the formation of two hybrid composites that deposit CdS on either site of the Ni/Ni\u2013H particle or short Nb\u2013O^(\u03b4-), resulting in a different interface between CdS and K\u2081\u208b\u2093Ni\u2093NbO\u2083. The one that deposits CdS on the Ni/Ni\u2013H particles is denoted as SCdS/K\u2081\u208b\u2093Ni\u2093NbO\u2083, and the other that deposits CdS on the short Nb\u2013O^(\u03b4-) is denoted as CdS/K_(0.9)Ni_(0.1)NbO\u2083. SCdS/K\u2081\u208b\u2093Ni\u2093NbO\u2083 exhibits a delayed kinetics for CdS photoinduced electrons compared to that of CdS/K\u2081\u208b\u2093Ni\u2093NbO\u2083 as decayed fluorescence at ca. 311 ps, while indicating ca. 238 ps for CdS/K\u2081\u208b\u2093Ni\u2093NbO\u2083. As a result, SCdS/K\u2081\u208b\u2093Ni\u2093NbO\u2083 exhibits a superior photocatalytic activity for H\u2082 production of ca. 3.1 mmol g\u207b\u00b9 h\u207b\u00b9 compared to CdS/K\u2081\u208b\u2093Ni\u2093NbO\u2083 with ca. 2.7 mmol g\u207b\u00b9 h\u207b\u00b9.", "doi": "10.1021/acs.jpcc.2c07533", "issn": "1932-7447", "publisher": "American Chemical Society", "publication": "Journal of Physical Chemistry C", "publication_date": "2023-06-01", "series_number": "21", "volume": "127", "issue": "21", "pages": "10140-10147" } ]