Electrochemical CO₂ reduction to ethylene by ultrathin CuO nanoplate arrays

Electrochemical reduction of CO₂ to multi-carbon fuels and chemical feedstocks is an appealing approach to mitigate excessive CO₂ emissions. However, the reported catalysts always show either a low Faradaic efficiency of the C₂₊ product or poor long-term stability. Herein, we report a facile and scalable anodic corrosion method to synthesize oxygen-rich ultrathin CuO nanoplate arrays, which form Cu/Cu₂O heterogeneous interfaces through self-evolution during electrocatalysis. The catalyst exhibits a high C₂H₄ Faradaic efficiency of 84.5%, stable electrolysis for ~55 h in a flow cell using a neutral KCl electrolyte, and a full-cell ethylene energy efficiency of 27.6% at 200 mA cm^-2 in a membrane electrode assembly electrolyzer. Mechanism analyses reveal that the stable nanostructures, stable Cu/Cu₂O interfaces, and enhanced adsorption of the *OCCOH intermediate preserve selective and prolonged C₂H₄ production. The robust and scalable produced catalyst coupled with mild electrolytic conditions facilitates the practical application of electrochemical CO₂ reduction.