Fabrication of Cu-CeO2 Catalyst with Abundant Interfacial Cu+-O-Ce3+-OV (Oxygen Vacancy) Sites for Boosting CO2 Electroreduction to Methane

Accelerating the conversion of *CO to *CHO and promoting the adsorption and hydrogenation of *CHO are the keys to achieving a highly selective electrocatalytic CO2 reduction reaction (CO2RR) to CH4 over Cu-based catalysts. Herein, a novel electrocatalyst comprising highly dispersed Cu nanoclusters (Cu-NCs) supported on oxygen vacancy (O-V)-rich CeO2 on carbon paper (Cu-NCs-CeO2/CP) with plentiful interfacial Cu+-O-Ce3+-O-V sites is constructed via a facile electrodeposition method. Various in situ/ex situ characterizations and theoretical calculations unveil that the Cu+-O-Ce3+-O-V sites can effectively regulate the pathway of the CO2RR, accelerate the *CO -> *CHO process, stabilize the *CHO and *OCH3 intermediates, and promote their hydrogenation to produce CH4. Furthermore, the critical role of Ce3+ and the O-V species in forming Cu+-O-Ce3+-O-V to maintain the electrocatalytic CO2RR activity is revealed. The optimized Cu-NCs-CeO2/CP electrocatalyst exhibits a CH4 Faradaic efficiency of 68.3% at 500 mA cm(-2), with a high partial current density of 340 mA cm(-2).