Elucidating the active phases of CoOx films on Au(111) in the CO oxidation reaction

被引：18
作者：
Chen H. [1 ]
Falling L.J. [2 ,3 ]
Kersell H. [2 ,4 ]
Yan G. [5 ]
Zhao X. [3 ,6 ]
Oliver-Meseguer J. [1 ]
Jaugstetter M. [1 ]
Nemsak S. [2 ,7 ]
Hunt A. [8 ]
Waluyo I. [8 ]
Ogasawara H. [9 ]
Bell A.T. [1 ,10 ]
Sautet P. [5 ,11 ]
Salmeron M. [3 ,6 ]
机构：
[1] Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, 94720, CA
[2] Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, 94720, CA
[3] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, 94720, CA
[4] School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, 97331, OR
[5] Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, 90095, CA
[6] Department of Materials Science and Engineering, University of California, Berkeley, 94720, CA
[7] Department of Physics and Astronomy, University of California, Davis, 95616, CA
[8] National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, 11973, NY
[9] SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, 94025, CA
[10] Department of Chemical and Biomolecular Engineering, University of California, Berkeley, 94720, CA
[11] Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, 90095, CA
来源：
Nature Communications | / 14卷 / 1期
基金：
美国国家科学基金会;
关键词：
D O I：
10.1038/s41467-023-42301-7
中图分类号：
学科分类号：
摘要：
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. © 2023, The Author(s).
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