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Verma R, Singh J, Samdarshi SK, Srivastava A. Autonomous self-optimizing defects by refining energy levels through hydrogenation in CeO 2–x polymorphism: a walking mobility of oxygen vacancy with enhanced adsorption capabilities and photocatalytic stability. NEW J CHEM 2022. [DOI: 10.1039/d2nj00057a] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The proposed work on ceria photocatalyst shows facile reactivity of oxygen anions with hydrogen molecules, turning inefficient highly disordered CeO2−x into optimized disordered H-CeO2−x which sustains optimized oxygen vacancies and Ce3+ defects.
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Affiliation(s)
- Ranjana Verma
- Department of Physics, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
| | - Jay Singh
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
| | - Sanjoy Kumar Samdarshi
- Centre for Energy Engineering and Centre of Excellence in Green and Efficient Energy Technology (CoE-GEET), Central University of Jharkhand, Ranchi, Jharkhand, India
| | - Anchal Srivastava
- Department of Physics, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
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Chen Z, Wasson MC, Drout RJ, Robison L, Idrees KB, Knapp JG, Son FA, Zhang X, Hierse W, Kühn C, Marx S, Hernandez B, Farha OK. The state of the field: from inception to commercialization of metal–organic frameworks. Faraday Discuss 2021; 225:9-69. [DOI: 10.1039/d0fd00103a] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We provide a brief overview of the state of the MOF field from their inception to their synthesis, potential applications, and finally, to their commercialization.
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Affiliation(s)
- Zhijie Chen
- Department of Chemistry and International Institute for Nanotechnology
- Northwestern University
- Evanston
- USA
| | - Megan C. Wasson
- Department of Chemistry and International Institute for Nanotechnology
- Northwestern University
- Evanston
- USA
| | - Riki J. Drout
- Department of Chemistry and International Institute for Nanotechnology
- Northwestern University
- Evanston
- USA
| | - Lee Robison
- Department of Chemistry and International Institute for Nanotechnology
- Northwestern University
- Evanston
- USA
| | - Karam B. Idrees
- Department of Chemistry and International Institute for Nanotechnology
- Northwestern University
- Evanston
- USA
| | - Julia G. Knapp
- Department of Chemistry and International Institute for Nanotechnology
- Northwestern University
- Evanston
- USA
| | - Florencia A. Son
- Department of Chemistry and International Institute for Nanotechnology
- Northwestern University
- Evanston
- USA
| | - Xuan Zhang
- Department of Chemistry and International Institute for Nanotechnology
- Northwestern University
- Evanston
- USA
| | | | | | | | | | - Omar K. Farha
- Department of Chemistry and International Institute for Nanotechnology
- Northwestern University
- Evanston
- USA
- Department of Chemical & Biological Engineering
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3
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Lee CJ, Sayal A, Vashishtha S, Weaver JF. Redox-mediated transformation of a Tb 2O 3(111) thin film from the cubic fluorite to bixbyite structure. Phys Chem Chem Phys 2019; 22:379-390. [PMID: 31819939 DOI: 10.1039/c9cp05083c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We used temperature programmed desorption (TPD) and low energy electron diffraction (LEED) to investigate the isomeric structural transformation of a Tb2O3 thin film grown on Pt(111). We find that repeated oxidation and thermal reduction to 1000 K transforms an oxygen-deficient, cubic fluorite (CF) Tb2O3(111) thin film to the well-defined bixbyite, or c-Tb2O3(111) structure, whereas annealing the CF-Tb2O3(111) film in UHV is ineffective in causing this structural transformation. We estimate that the final stabilized film consists of about ten layers of c-Tb2O3(111) in the surface region plus about eight layers of CF-Tb2O3(111) located between the c-Tb2O3(111) and the Pt(111) substrate. Our measurements reveal the development of two distinct O2 TPD peaks during the CF to bixbyite transformation that arise from oxidation of c-Tb2O3 domains to the stoichiometrically-invariant ι-Tb7O12 and δ-Tb11O20 phases and demonstrate that the c-Tb2O3 phase oxidizes more facilely than CF-Tb2O3. We present evidence that nucleation and growth of c-Tb2O3 domains occurs at the buried TbOx/CF-Tb2O3 interface, and that conversion of the interfacial CF-Tb2O3 to bixbyite takes place mainly during thermal reduction of TbOx above ∼900 K and causes newly-formed c-Tb2O3 to advance deeper into the film. The avoidance of low Tb oxidation states may facilitate the CF to bixbyite transformation via this redox mechanism.
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Affiliation(s)
- Christopher J Lee
- Department of Chemical Engineering, University of Florida, Gainesville, FL 32611, USA.
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4
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Kettner M, Duchoň T, Wolf MJ, Kullgren J, Senanayake SD, Hermansson K, Veltruská K, Nehasil V. Anion-mediated electronic effects in reducible oxides: Tuning the valence band of ceria via fluorine doping. J Chem Phys 2019; 151:044701. [PMID: 31370552 DOI: 10.1063/1.5109955] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Combining experimental spectroscopy and hybrid density functional theory calculations, we show that the incorporation of fluoride ions into a prototypical reducible oxide surface, namely, ceria(111), can induce a variety of nontrivial changes to the local electronic structure, beyond the expected increase in the number of Ce3+ ions. Our resonant photoemission spectroscopy results reveal new states above, within, and below the valence band, which are unique to the presence of fluoride ions at the surface. With the help of hybrid density functional calculations, we show that the different states arise from fluoride ions in different atomic layers in the near surface region. In particular, we identify a structure in which a fluoride ion substitutes for an oxygen ion at the surface, with a second fluoride ion on top of a surface Ce4+ ion giving rise to F 2p states which overlap the top of the O 2p band. The nature of this adsorbate F--Ce4+ resonant enhancement feature suggests that this bond is at least partially covalent. Our results demonstrate the versatility of anion doping as a potential means of tuning the valence band electronic structure of ceria.
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Affiliation(s)
- Miroslav Kettner
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Tomáš Duchoň
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Matthew J Wolf
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden
| | - Jolla Kullgren
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden
| | - Sanjaya D Senanayake
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Kersti Hermansson
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden
| | - Kateřina Veltruská
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Václav Nehasil
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
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6
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Luches P, Gasperi G, Sauerbrey M, Valeri S, Falta J, Flege JI. Dynamics of the Interaction Between Ceria and Platinum During Redox Processes. Front Chem 2019; 7:57. [PMID: 30800651 PMCID: PMC6375856 DOI: 10.3389/fchem.2019.00057] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 01/21/2019] [Indexed: 11/13/2022] Open
Abstract
The work is focused on understanding the dynamics of the processes which occur at the interface between ceria and platinum during redox processes, by investigating an inverse catalytic model system made of ceria epitaxial islands and ultrathin films supported on Pt(111). The evolution of the morphology, structure and electronic properties is analyzed in real-time during reduction and oxidation, using low-energy electron microscopy and spatially resolved low-energy electron diffraction. The reduction is induced using different methods, namely thermal treatments in ultra-high vacuum and in H2 as well as deposition of Ce on the oxide surface, while re-oxidation is obtained by exposure to oxygen at elevated temperature. The use of two different epitaxial systems, continuous films and nanostructures, allows determining the influence of platinum proximity on the stabilization of the specific phases observed. The factors that limit the reversibility of the observed modifications with the different oxidation treatments are also discussed. The obtained results highlight important aspects of the cerium oxide/Pt interaction that are relevant for a complete understanding of the behavior of Pt/CeO2 catalysts.
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Affiliation(s)
- Paola Luches
- Istituto Nanoscienze, Consiglio Nazionale delle Ricerche, Modena, Italy
| | - Gabriele Gasperi
- Istituto Nanoscienze, Consiglio Nazionale delle Ricerche, Modena, Italy.,Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - Marc Sauerbrey
- Institute of Solid State Physics, University of Bremen, Bremen, Germany.,MAPEX Center for Materials and Processes, University of Bremen, Bremen, Germany
| | - Sergio Valeri
- Istituto Nanoscienze, Consiglio Nazionale delle Ricerche, Modena, Italy.,Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - Jens Falta
- Institute of Solid State Physics, University of Bremen, Bremen, Germany.,MAPEX Center for Materials and Processes, University of Bremen, Bremen, Germany
| | - Jan Ingo Flege
- Institute of Solid State Physics, University of Bremen, Bremen, Germany.,MAPEX Center for Materials and Processes, University of Bremen, Bremen, Germany.,Applied Physics and Semiconductor Spectroscopy, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany
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Zhang Y, Feng W, Yang F, Bao X. Interface-controlled synthesis of CeO2(111) and CeO2(100) and their structural transition on Pt(111). CHINESE JOURNAL OF CATALYSIS 2019. [DOI: 10.1016/s1872-2067(18)63171-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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8
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Bekheet MF, Grünbacher M, Schlicker L, Gili A, Doran A, Epping JD, Gurlo A, Klötzer B, Penner S. On the structural stability of crystalline ceria phases in undoped and acceptor-doped ceria materials under in situ reduction conditions. CrystEngComm 2019; 21:145-154. [PMID: 30930690 PMCID: PMC6394889 DOI: 10.1039/c8ce01726c] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 12/01/2018] [Indexed: 11/21/2022]
Abstract
The reduction of pure and Sm-doped ceria in hydrogen has been studied by synchrotron-based in situ X-ray diffraction to eventually prove or disprove the presence of crystalline cerium hydride (CeH x ) phases and the succession of potential structural phase (trans)formations of reduced cerium oxide phases during heating-cooling cycles up to 1273 K. Despite a recent report on the existence of bulk and surface CeH x phases during reductive treatment of pure CeO2 in H2, structural analysis by Rietveld refinement as well as additional 1H-NMR spectroscopy did not reveal the presence of any crystalline CeH x phase. Rather, a sequence of phase transformations during the re-cooling process in H2 has been observed. In both samples, the reduced/defective fluorite lattice undergoes at first a transformation into a bixbyite-type lattice with a formal stoichiometry Ce0.58 3+Ce0.42 4+O1.71 and Sm0.15 3+Ce0.39 3+Ce0.46 4+O1.73, before a transformation into rhombohedral Ce7O12 takes place in pure CeO2. This phase is clearly absent for the Sm-doped material. Finally, a triclinic Ce11O20 phase appears for both materials, which can be recovered to room temperature, and on which a phase mixture of bixbyite Ce0.66 3+Ce0.34 4+O1.67, rh-Ce0.60 3+Ce0.40 4+O1.70 and tri-Ce0.48 3+Ce0.52 4+O1.76 (for pure CeO2) or bixbyite Sm0.15 3+Ce0.47 3+Ce0.38 4+O1.69 and tri-Sm0.15 3+Ce0.31 3+Ce0.54 4+O1.77 (for Sm-doped CeO2) prevails. The absence of the rhombohedral phase indicates that Sm doping leads to the stabilization of the bixbyite phase over the rhombohedral one at this particular oxygen vacancy concentration. It is worth noting that recent work proves that hydrogen is indeed incorporated within the structures during the heat treatments, but under the chosen experimental conditions it has apparently no effect on the salient structural principles during reduction.
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Affiliation(s)
- Maged F Bekheet
- Fachgebiet Keramische Werkstoffe/Chair of Advanced Ceramic Materials , Institut für Werkstoffwissenschaften und -technologien , Technische Universität Berlin , Hardenbergstr. 40 , 10623 Berlin , Germany
| | - Matthias Grünbacher
- Institute of Physical Chemistry , University of Innsbruck , Innrain 52c , A-6020 Innsbruck , Austria . ; Tel: +43 512 507 58003
| | - Lukas Schlicker
- Fachgebiet Keramische Werkstoffe/Chair of Advanced Ceramic Materials , Institut für Werkstoffwissenschaften und -technologien , Technische Universität Berlin , Hardenbergstr. 40 , 10623 Berlin , Germany
| | - Albert Gili
- Fachgebiet Keramische Werkstoffe/Chair of Advanced Ceramic Materials , Institut für Werkstoffwissenschaften und -technologien , Technische Universität Berlin , Hardenbergstr. 40 , 10623 Berlin , Germany
| | - Andrew Doran
- Advanced Light Source , Lawrence Berkeley National Laboratory Berkeley , California 94720 , USA
| | - Jan Dirk Epping
- Fakultät II : Mathematik & Naturwissenschaften , Institut für Chemie , Technische Universität Berlin , Hardenbergstr. 40 , 10623 Berlin , Germany
| | - Aleksander Gurlo
- Fachgebiet Keramische Werkstoffe/Chair of Advanced Ceramic Materials , Institut für Werkstoffwissenschaften und -technologien , Technische Universität Berlin , Hardenbergstr. 40 , 10623 Berlin , Germany
| | - Bernhard Klötzer
- Institute of Physical Chemistry , University of Innsbruck , Innrain 52c , A-6020 Innsbruck , Austria . ; Tel: +43 512 507 58003
| | - Simon Penner
- Institute of Physical Chemistry , University of Innsbruck , Innrain 52c , A-6020 Innsbruck , Austria . ; Tel: +43 512 507 58003
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Flege JI, Höcker J, Sadowski JT, Senanayake SD, Falta J. Nucleation, morphology, and structure of sub‐nm thin ceria islands on Rh(111). SURF INTERFACE ANAL 2018. [DOI: 10.1002/sia.6567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Jan Ingo Flege
- Institute of Solid State Physics University of Bremen Otto‐Hahn‐Allee 1 28359 Bremen Germany
- Applied Physics and Semiconductor Spectroscopy Brandenburg University of Technology Cottbus‐Senftenberg Konrad‐Zuse‐Str. 1 03046 Cottbus Germany
| | - Jan Höcker
- Institute of Solid State Physics University of Bremen Otto‐Hahn‐Allee 1 28359 Bremen Germany
| | - Jerzy T. Sadowski
- Center for Functional Nanomaterials, Brookhaven National Laboratory Upton NY 11973 USA
| | | | - Jens Falta
- Institute of Solid State Physics University of Bremen Otto‐Hahn‐Allee 1 28359 Bremen Germany
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10
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New Insights into the Kinetics of Structural Transformation and Hydrogenation Activity of Nano-crystalline Molybdenum Carbide. Catal Letters 2018. [DOI: 10.1007/s10562-017-2274-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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