Elucidating the Nature of the Active Phase in Copper/Ceria Catalysts for CO Oxidation

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• 作者：Joseph S. Elias ; Nongnuch Artrith ; Matthieu Bugnet ; Livia Giordano ; Gianluigi A. Botton ; Alexie M. Kolpak ; Yang Shao-Horn
• 刊名：ACS Catalysis
• 出版年：2016
• 出版时间：March 4, 2016
• 年：2016
• 卷：6
• 期：3
• 页码：1675-1679
• 全文大小：351K
• ISSN：2155-5435

文摘

The active phase responsible for low-temperature CO oxidation in nanoparticulate CuO/CeOub>2ub> catalysts was identified as surface-substituted Cuub>yub>Ceub>1–yub>Oub>2–xub>. Contrary to previous studies, our measurements on a library of well-defined CuO/CeOub>2ub> catalysts have proven that the CuO phase is a spectator species, whereas the surface-substituted Cuub>yub>Ceub>1–yub>Oub>2–xub> phase is active for CO oxidation. Using in situ X-ray absorption spectroscopy, we found that the copper ions in Cuub>yub>Ceub>1–yub>Oub>2–xub> remain at high oxidation states (Cuup>3+up> and Cuup>2+up>) under oxygen-rich catalytic conditions without any evidence for Cuup>+up>. Artificial neural network potential Monte Carlo simulations suggest that Cuup>3+up> and Cuup>2+up> preferentially segregate to the {100} surface of the Cuub>yub>Ceub>1–yub>Oub>2–xub> nanoparticle, which is supported by aberration-corrected electron microscopy measurements. These results pave the way for understanding, at the atomic level, the mechanisms and descriptors pertinent for CO oxidation on these materials and hence the rational design of next-generation catalysts.