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/CeO₂ catalysts was identified as surface-substituted Cu_yCe_1–yO_2–x. Contrary to previous studies, our measurements on a library of well-defined CuO/CeO₂ catalysts have proven that the CuO phase is a spectator species, whereas the surface-substituted Cu_yCe_1–yO_2–x phase is active for CO oxidation. Using in situ X-ray absorption spectroscopy, we found that the copper ions in Cu_yCe_1–yO_2–x remain at high oxidation states (Cu³⁺ and Cu²⁺) under oxygen-rich catalytic conditions without any evidence for Cu⁺. Artificial neural network potential Monte Carlo simulations suggest that Cu³⁺ and Cu²⁺ preferentially segregate to the {100} surface of the Cu_yCe_1–yO_2–x 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.