Enhancing CO2 Electroreduction with the Metal-Oxide Interface.

The electrochemical CO2 reduction reaction (CO2RR) typically uses transition metals as the catalysts. To improve the efficiency, tremendous efforts have been dedicated to tuning the morphology, size, and structure of metal catalysts and employing electrolytes that enhance the adsorption of CO2. We report here a strategy to enhance CO2RR by constructing the metal-oxide interface. We demonstrate that Au-CeOx shows much higher activity and Faradaic efficiency than Au or CeOx alone for CO2RR. In situ scanning tunneling microscopy and synchrotron-radiation photoemission spectroscopy show that the Au-CeOx interface is dominant in enhancing CO2 adsorption and activation, which can be further promoted by the presence of hydroxyl groups. Density functional theory calculations indicate that the Au-CeOx interface is the active site for CO2 activation and the reduction to CO, where the synergy between Au and CeOx promotes the stability of key carboxyl intermediate (*COOH) and thus facilitates CO2RR. Similar interface-enhanced CO2RR is further observed on Ag-CeOx, demonstrating the generality of the strategy for enhancing CO2RR.