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Chen H, Falling LJ, Kersell H, Yan G, Zhao X, Oliver-Meseguer J, Jaugstetter M, Nemsak S, Hunt A, Waluyo I, Ogasawara H, Bell AT, Sautet P, Salmeron M. Elucidating the active phases of CoO x films on Au(111) in the CO oxidation reaction. Nat Commun 2023; 14:6889. [PMID: 37898599 PMCID: PMC10613203 DOI: 10.1038/s41467-023-42301-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 10/06/2023] [Indexed: 10/30/2023] Open
Abstract
Noble metals supported on reducible oxides, like CoOx and TiOx, exhibit superior activity in many chemical reactions, but the origin of the increased activity is not well understood. To answer this question we studied thin films of CoOx supported on an Au(111) single crystal surface as a model for the CO oxidation reaction. We show that three reaction regimes exist in response to chemical and topographic restructuring of the CoOx catalyst as a function of reactant gas phase CO/O2 stoichiometry and temperature. Under oxygen-lean conditions and moderate temperatures (≤150 °C), partially oxidized films (CoOx<1) containing Co0 were found to be efficient catalysts. In contrast, stoichiometric CoO films containing only Co2+ form carbonates in the presence of CO that poison the reaction below 300 °C. Under oxygen-rich conditions a more oxidized catalyst phase (CoOx>1) forms containing Co3+ species that are effective in a wide temperature range. Resonant photoemission spectroscopy (ResPES) revealed the unique role of Co3+ sites in catalyzing the CO oxidation. Density function theory (DFT) calculations provided deeper insights into the pathway and free energy barriers for the reactions on these oxide phases. These findings in this work highlight the versatility of catalysts and their evolution to form different active phases, both topological and chemically, in response to reaction conditions exposing a new paradigm in the catalyst structure during operation.
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Affiliation(s)
- Hao Chen
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Lorenz J Falling
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Heath Kersell
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, OR, 97331, USA
| | - George Yan
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Xiao Zhao
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Judit Oliver-Meseguer
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Max Jaugstetter
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Slavomir Nemsak
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics and Astronomy, University of California, Davis, CA, 95616, USA
| | - Adrian Hunt
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Iradwikanari Waluyo
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Hirohito Ogasawara
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Alexis T Bell
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, 94720, USA
| | - Philippe Sautet
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Miquel Salmeron
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
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D'Elia A, Cepek C, de Simone M, Macis S, Belec B, Fanetti M, Piseri P, Marcelli A, Coreno M. Interplay among work function, electronic structure and stoichiometry in nanostructured VO x films. Phys Chem Chem Phys 2020; 22:6282-6290. [PMID: 32129435 DOI: 10.1039/d0cp00216j] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The work function is the parameter of greatest interest in many technological applications involving charge exchange mechanisms at the surface. The possibility to produce samples with a controlled work function is then particularly interesting, albeit challenging. We synthetized nanostructured vanadium oxide films by a room temperature supersonic cluster beam deposition method, obtaining samples with tunable stoichiometry and work function (3.7-7 eV). We present an investigation of the electronic structure of several vanadium oxide films as a function of the oxygen content via in situ Auger, valence-band photoemission spectroscopy and work function measurements. The experiments probed the partial 3d density of states, highlighting the presence of strong V 3d-O 2p and V 3d-V 4s hybridizations which influence 3d occupation. We show how controlling the stoichiometry of the sample implies control over work function, and that the access to nanoscale quantum confinement can be exploited to increase the work function of the sample relative to the bulk analogue. In general, the knowledge of the interplay among work function, electronic structure, and stoichiometry is strategic to match nanostructured oxides to their target applications.
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Affiliation(s)
- Alessandro D'Elia
- Department of Physics, University of Trieste, Via A. Valerio 2, 34127 Trieste, Italy. and IOM-CNR, Laboratorio TASC, Basovizza SS-14, km 163.5, 34149 Trieste, Italy
| | - Cinzia Cepek
- IOM-CNR, Laboratorio TASC, Basovizza SS-14, km 163.5, 34149 Trieste, Italy
| | - Monica de Simone
- IOM-CNR, Laboratorio TASC, Basovizza SS-14, km 163.5, 34149 Trieste, Italy
| | - Salvatore Macis
- Department of Physics, Università Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - BlaŽ Belec
- Materials Research Laboratory, University of Nova Gorica, Vipavska 13, 5000 Nova Gorica, Slovenia
| | - Mattia Fanetti
- Materials Research Laboratory, University of Nova Gorica, Vipavska 13, 5000 Nova Gorica, Slovenia
| | - Paolo Piseri
- Dipartimento di Fisica & CIMaINa, Università degli Studi di Milano, via Celoria 16, 20133 Milano, Italy
| | - Augusto Marcelli
- Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, 00044 Frascati, Italy and Rome International Centre for Material Science Superstripes, RICMASS, Via dei Sabelli 119A, 00185 Rome, Italy and ISM-CNR, Istituto Struttura della Materia, LD2 Unit, Basovizza Area Science Park, 34149 Trieste, Italy
| | - Marcello Coreno
- ISM-CNR, Istituto Struttura della Materia, LD2 Unit, Basovizza Area Science Park, 34149 Trieste, Italy and Elettra-Sincrotrone Trieste, Basovizza 34149, Italy
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Huang M, Zhang Y, Wang C, Ren JG, Wu QH, Li QB. Growth of graphene films on Cu catalyst in hydrogen plasma using polymethylmethacrylate as carbon source. Catal Today 2015. [DOI: 10.1016/j.cattod.2014.12.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Qu B, Huang ML, Ren JG, Wu QH. Influence of ambient conditions on the electronic structure of graphene/copper interface. SURF INTERFACE ANAL 2015. [DOI: 10.1002/sia.5776] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Bo Qu
- Department of Chemistry, College of Chemistry and Life Science; Quanzhou Normal University; Quanzhou 362000 China
| | - Miao-Ling Huang
- Department of Chemistry, College of Chemistry and Life Science; Quanzhou Normal University; Quanzhou 362000 China
| | - Jian-Guo Ren
- Department of Chemistry, College of Chemistry and Life Science; Quanzhou Normal University; Quanzhou 362000 China
- Centre of Super-Diamond and Advanced Films and Department of Physics and Materials Science; City University of Hong Kong; Hong Kong SAR China
| | - Qi-Hui Wu
- Department of Chemistry, College of Chemistry and Life Science; Quanzhou Normal University; Quanzhou 362000 China
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Zhou Y, Lawrence NJ, Wang L, Kong L, Wu TS, Liu J, Gao Y, Brewer JR, Lawrence VK, Sabirianov RF, Soo YL, Zeng XC, Dowben PA, Mei WN, Cheung CL. Resonant Photoemission Observations and DFT Study of s-d Hybridization in Catalytically Active Gold Clusters on Ceria Nanorods. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201301383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Zhou Y, Lawrence NJ, Wang L, Kong L, Wu TS, Liu J, Gao Y, Brewer JR, Lawrence VK, Sabirianov RF, Soo YL, Zeng XC, Dowben PA, Mei WN, Cheung CL. Resonant Photoemission Observations and DFT Study of s-d Hybridization in Catalytically Active Gold Clusters on Ceria Nanorods. Angew Chem Int Ed Engl 2013; 52:6936-9. [DOI: 10.1002/anie.201301383] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Indexed: 11/06/2022]
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Bergner C, Vashook V, Leoni S, Langbein H. VNb9O25−δ—Synthesis, electrical conducting behaviour and density functional theory (DFT) calculation. J SOLID STATE CHEM 2009. [DOI: 10.1016/j.jssc.2009.05.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Li ZY, Lin XZ, Wu QH. Influences of Li Intercalation on the Electronic Structures of O2p and V3d Orbitals in -V2O5. CHINESE J CHEM PHYS 2009. [DOI: 10.1088/1674-0068/22/03/241-245] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Goclon J, Grybos R, Witko M, Hafner J. Relative stability of low-index V(2)O(5) surfaces: a density functional investigation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:095008. [PMID: 21817381 DOI: 10.1088/0953-8984/21/9/095008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Ab initio density functional calculations of the structural and electronic properties of V(2)O(5) bulk and its low-index surfaces are presented. For the bulk oxide and the (010) surface (the natural cleavage plane) a good agreement with experiment and with earlier ab initio calculations is found. For the first time, the investigations are extended to other low-index surfaces: (001) and (100). On both surfaces, termination conserving a bulk-like stoichiometry is preferred, but-in contrast to the (010) surface-a strong structural relaxation takes place. Relaxation reduces the surface energy from 1.16 to 0.48 J m(-2) for the (001) and from 0.61 to 0.55 J m(-2) for the (100) surface. Although the relaxed surface energies are still one order of magnitude higher than calculated for the (010) surface (0.047 J m(-2)), the Wulff construction demonstrates that (001) and (100) surfaces contribute about 15% of the total surface area of a V(2)O(5) crystallite, indicating a non-negligible role in the catalytic activity of V(2)O(5).
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Affiliation(s)
- Jakub Goclon
- Institute of Catalysis and Surface Chemistry PAS, Krakow, Poland
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Li ZY, Wu QH. Electronic Structures of LixV2O5 (x=0.5 and 1): A Theoretical Study. Chemphyschem 2008; 9:300-4. [DOI: 10.1002/cphc.200700560] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Laubach S, Schmidt PC, Thissen A, Fernandez-Madrigal FJ, Wu QH, Jaegermann W, Klemm M, Horn S. Theoretical and experimental determination of the electronic structure of V2O5, reduced V2O5−xand sodium intercalated NaV2O5. Phys Chem Chem Phys 2007; 9:2564-76. [PMID: 17508089 DOI: 10.1039/b612489e] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work the electronic structure of V(2)O(5), reduced V(2)O(5-x) (V(16)O(39)) and sodium intercalated NaV(2)O(5) has been studied by both theoretical and experimental methods. Theoretical band structure calculations have been performed using density functional methods (DFT). We have investigated the electron density distribution of the valence states, the total density of states (total DOS) and the partial valence band density of states (PVBDOS). Experimentally, amorphous V(2)O(5) thin films have been prepared by physical vapour deposition (PVD) on freshly cleaved highly oriented pyrolytic graphite (HOPG) substrates at room temperature with an initial oxygen understoichiometry of about 4%, resulting in a net stoichiometry of V(2)O(4.8). These films have been intercalated by sodium using vacuum deposition with subsequent spontaneous intercalation (NaV(2)O(5)) at room temperature. Resonant V3p-V3d photoelectron spectroscopy (ResPES) experiments have been performed to determine the PVBDOS focusing on the calculation of occupation numbers and the determination of effective oxidation state, reflecting ionicity and covalency of the V-O bonds. Using X-ray absorption near edge spectra (XANES) an attempt is made to visualize the changes in the unoccupied DOS due to sodium intercalation. For comparison measurements on nearly stoichiometric V(2)O(5) single crystals have been performed. The experimental data for the freshly cleaved and only marginally reduced V(2)O(5) single crystals and the NaV(2)O(5) results are in good agreement with the calculated values. The ResPES results for V(2)O(4.8) agree in principle with the calculations, but the trends in the change of the ionicity differ between experiment and theory. Experimentally we find partly occupied V 3d states above the oxygen 2p-like states and a band gap between these and the unoccupied states. In theory one finds this occupation scheme assuming oxygen vacancies in V(2)O(5) and by performing a spin-polarized calculation of an antiferromagnetic ordered NaV(2)O(5.).
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Affiliation(s)
- Stefan Laubach
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Petersenstrasse 21, D-64287 Darmstadt, Germany
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