Interfacial Oxygen Vacancy‐Copper Pair Sites on Inverse CeO2/Cu Catalyst Enable Efficient CO2 Electroreduction to Ethanol in Acid

Abstract Renewable electricity‐driven electrochemical reduction of CO 2 offers a promising route for the production of high‐value ethanol. However, the current state of this technology is hindered by low selectivity and productivity, primarily due to a limited understanding of the atomic‐level active sites involved in ethanol formation. Herein, we identify that the interfacial oxygen vacancy‐neighboring Cu (O v ‐Cu) pair sites are the active sites for CO 2 electroreduction to ethanol. A linear correlation between the density of O v ‐Cu pair sites and ethanol productivity is experimentally evidenced. Moreover, a high Faradaic efficiency of 48.5 % and a partial current density of 344.0 mA cm −2 for ethanol production are achieved over the inverse CeO 2 /Cu catalyst with a high density of O v ‐Cu pair sites in acid. Mechanistic studies that combine density functional theory calculations and spectroscopic techniques propose an O v ‐involved mechanism where interfacial O v sites directly activate and dissociate CO 2 into *CO in a thermodynamically spontaneous manner, thus favoring the subsequent *CHO formation and asymmetric CHO‐CO coupling. Besides, the asymmetric O v ‐Cu pair sites could preferentially stabilize the *CH 2 CHOH intermediate, resulting in the favorable formation of ethanol over ethylene. Our findings provide new atomic‐level insights into CO 2 electroreduction to ethanol, paving the way for the rational design of future catalysts.