Unveiling the reconstruction of copper bimetallic catalysts during CO₂ electroreduction

Efficient electrocatalysts should provide optimal binding sites for intermediates under operating conditions. Atomic rearrangements in catalysts during electrochemical CO₂ reduction reaction (CO₂RR) alter the original structures of active sites. Here we report a general principle for understanding and predicting the reconstruction of Cu bimetallic catalysts during CO₂RR in terms of selective dissolution–redeposition. We categorize the reconstruction trends of Cu bound to a secondary metal (X, where X = Ag, Fe, Zn or Pd) according to the oxophilicity and miscibility of Cu and X. Cross-sectional microscopy analysis of gas diffusion electrodes reveals that the surface states of reconstructed Cu–X are determined by atomic miscibility. We find that CO₂RR intermediates alter elemental preferences for dissolution, shifting them away from oxophilicity-governed behaviour and leading to selective Cu dissolution–redeposition in Cu–X. This reconstruction affects spillover in CO₂RR, controlling the selectivities of ethylene/ethanol and C₁/C₂ products. We also develop a methodology for the control of reconstruction dynamics. Our findings provide insights into designing catalysts that undergo reconstruction during electrolysis. (Figure presented.)