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

The active phase responsible for low-temperature CO oxidation in nanoparticulate CuO/CeO2 catalysts was identified as surface-substituted Cu y Ce1–y O2–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 y Ce1–y O2–x phase is active for CO oxidation. Using in situ X-ray absorption spectroscopy, we found that …