Selective Formation of Multi‐Carbon Products via Interface‐Driven Electrochemical CO Reduction on Cu–Ag Catalysts

Electrochemical CO reduction to multi‐carbon (C 2+ ) products present a promising strategy to address global warming and energy shortages. However, this reaction is often hindered by inefficient C─C coupling and the instability of key intermediates on catalysts. Here, a Cu─Ag bimetallic catalyst (CuAg‐PMB) with abundant interfacial sites is prepared using a novel differential‐precipitation microzone‐barrier reduction method. Owing to its high interface density, the CuAg‐PMB catalyst achieves a record Faradaic efficiency of 93.2% for C 2+ products at a current density of −200 mA cm −2 . In situ electrochemical spectroscopy and DFT calculations reveal that the enriched Cu─Ag interfaces enhance * CO adsorption, facilitate water dissociation, and promote the hydrogenation of * CO to * COH, thereby boosting C─C coupling efficiency. These results underscore the critical role of interfacial engineering in enabling selective C 2+ formation and offer a compelling design strategy for next generation electrocatalysts.