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

Abstract

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.