Diving into the interface-mediated Mars-van Krevelen (M−vK) characteristic of CuOx-supported CeO2 catalysts

Abstract

The unique interface synergistic catalytic properties for metal oxide-supported catalysts have long been explored in several critical heterogeneous catalytic processes (e.g., CO oxidation reactions). However, interfacial synergistic catalysis is still a hitherto undescribed mechanism due to the lack of direct evidence at the atomic level. Thereinto, the CuOx-supported CeO2 (CuOx/CeO2) catalyst is a typical case. Herein, a combination study including representative theoretical calculations, in situ DRIFTS spectra and tailored molecular probe experiments supports a new carbonate-interface mediated Mars-van Krevelen (M−vK) mechanism for CO oxidation, i.e., CO molecules form carbonate intermediate species directly between spatial proximity (2.99 Å) double lattice oxygen sites with low oxygen vacancies formation energy (EformOv = 0.82 eV/0.83 eV) at the copper−ceria interface. The reaction energy barrier of this process is 0.32 eV, much lower than the 1.23 eV of the conventional M−vK mechanism. Besides, the spatial effect of double oxygen vacancies (Ov) generated by the depletion of intermediate carbonate species promotes the sustained and dynamic activation of O2, hence facilitating the efficient operation of the M−vK mechanism at low temperatures.