cs5b02666_si_001.pdf (8.24 MB)
Elucidating the Nature of the Active Phase in Copper/Ceria Catalysts for CO Oxidation
journal contribution
posted on 2016-02-04, 00:00 authored by Joseph
S. Elias, Nongnuch Artrith, Matthieu Bugnet, Livia Giordano, Gianluigi
A. Botton, Alexie M. Kolpak, Yang Shao-HornThe active phase responsible for
low-temperature CO oxidation in
nanoparticulate CuO/CeO2 catalysts was identified as surface-substituted
CuyCe1–yO2–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 CuyCe1–yO2–x phase is
active for CO oxidation. Using in situ X-ray absorption
spectroscopy, we found that the copper ions in CuyCe1–yO2–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 CuyCe1–yO2–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.