Establishing Active Cu⁺–O–Mg²⁺ Sites at the Cu₂O/CuO Interface for Efficient Electroreduction of CO₂ to C₂₊ Products

Cu-based materials are regarded as effective electrocatalysts for CO 2 RR; however, Cu +, the active site for C–C coupling, is unstable under reduction conditions. Herein, Mg 2+ is doped into the Cu 2 O/CuO interface and generates high-activity Cu + –O-Mg 2+ sites following electrochemical activation. The electron-withdrawing effect of Mg 2+ in the Cu + –O-Mg 2+ site stabilizes Cu + and optimizes the reaction pathway for CO 2 RR. At a partial current density of 567.21 ± 5.18 mA cm –2, the Faraday efficiency (FE) for C 2+ products can reach 81.03 ± 0.74%. In situ Raman and in situ infrared spectroscopy reveal that the Cu + –O-Mg 2+ site significantly enhances the coverage and stability of *CO, which contributes to the ultrahigh selectivity of CO 2 toward C 2+ products. Density functional theory (DFT) studies indicate that *CO 2 is readily adsorbed on the Cu + –O-Mg 2+ site, facilitating the more effective generation of *CO, which subsequently promotes the electrochemical C–C coupling step and accelerates the production of C 2+ products.