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 CO2RR; however, Cu+, the active site for C–C coupling, is unstable under reduction conditions. Herein, Mg2+ is doped into the Cu2O/CuO interface and generates high-activity Cu+–O-Mg2+ sites following electrochemical activation. The electron-withdrawing effect of Mg2+ in the Cu+–O-Mg2+ site stabilizes Cu+ and optimizes the reaction pathway for CO2RR. At a partial current density of 567.21 ± 5.18 mA cm–2, the Faraday efficiency (FE) for C2+ products can reach 81.03 ± 0.74%. In situ Raman and in situ infrared spectroscopy reveal that the Cu+–O-Mg2+ site significantly enhances the coverage and stability of *CO, which contributes to the ultrahigh selectivity of CO2 toward C2+ products. Density functional theory (DFT) studies indicate that *CO2 is readily adsorbed on the Cu+–O-Mg2+ site, facilitating the more effective generation of *CO, which subsequently promotes the electrochemical C–C coupling step and accelerates the production of C2+ products.