Liquid‐Liquid Interface ‐Driven Reconstruction of CuAg Nanocomposites for Selective CO ₂ to C ₂ H ₄ Electroreduction

Abstract The electrochemical CO 2 reduction reaction (CO 2 RR) to multicarbon products such as C 2 H 4 is critical for sustainable energy conversion but remains a significant challenge. Cu‐based nanocatalysts can facilitate C─C coupling for C 2+ product generation, yet their catalytic efficiency and selectivity require further improvement. In this study, a liquid‐liquid interface etching strategy is employed, using Cu nanocubes as templates and aqueous AgNO 3 as the etchant to synthesize well‐defined CuAg nanocomposites. Among these, the optimized Cu 67 Ag 33 composite nanocubes achieved a ethylene (C 2 H 4 ) Faraday efficiency (FE) of 43.90% and a partial current density of 21.50 mA cm −2 at −1.50 V RHE . This work demonstrates a versatile approach to integrate secondary metal active sites via directional confined etching, while reconstructing catalytic interfaces to enhance C─C coupling and C 2 H 4 selectivity. These findings provide a strategic framework for the rational design of efficient CO 2 RR catalysts, advancing the development of sustainable carbon conversion technologies.