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-CeO_x shows much higher activity and Faradaic efficiency than Au or CeO_x alone for CO₂RR. In situ scanning tunneling microscopy and synchrotron-radiation photoemission spectroscopy show that the Au-CeO_x 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-CeO_x interface is the active site for CO₂ activation and the reduction to CO, where the synergy between Au and CeO_x promotes the stability of key carboxyl intermediate (*COOH) and thus facilitates CO₂RR. Similar interface-enhanced CO₂RR is further observed on Ag-CeO_x, demonstrating the generality of the strategy for enhancing CO₂RR.