Establishing\nActive Cu<sup>+</sup>–O–Mg<sup>2+</sup> Sites at the\nCu<sub>2</sub>O/CuO Interface for Efficient\nElectroreduction of CO<sub>2</sub> to C<sub>2+</sub> Products

Cu-based materials are regarded as\neffective electrocatalysts\nfor\nCO<sub>2</sub>RR; however, Cu<sup>+</sup>, the active site for C–C\ncoupling, is unstable under reduction conditions. Herein, Mg<sup>2+</sup> is doped into the Cu<sub>2</sub>O/CuO interface and generates high-activity\nCu<sup>+</sup>–O-Mg<sup>2+</sup> sites following electrochemical\nactivation. The electron-withdrawing effect of Mg<sup>2+</sup> in\nthe Cu<sup>+</sup>–O-Mg<sup>2+</sup> site stabilizes Cu<sup>+</sup> and optimizes the reaction pathway for CO<sub>2</sub>RR.\nAt a partial current density of 567.21 ± 5.18 mA cm<sup>–2</sup>, the Faraday efficiency (FE) for C<sub>2+</sub> products can reach\n81.03 ± 0.74%. In situ Raman and in situ infrared spectroscopy\nreveal that the Cu<sup>+</sup>–O-Mg<sup>2+</sup> site significantly\nenhances the coverage and stability of *CO, which contributes to the\nultrahigh selectivity of CO<sub>2</sub> toward C<sub>2+</sub> products.\nDensity functional theory (DFT) studies indicate that *CO<sub>2</sub> is readily adsorbed on the Cu<sup>+</sup>–O-Mg<sup>2+</sup> site, facilitating the more effective generation of *CO, which subsequently\npromotes the electrochemical C–C coupling step and accelerates\nthe production of C<sub>2+</sub> products.