Synergistic Effect of Bimetallic Sites in Cu-Au Metallic Aerogels for Carbon Dioxide Electroreduction

The bimetallic aerogel strategy addresses the limitations of monometallic catalysts in selectivity, activity, and stability by leveraging the tripartite synergistic effects of electronic structure modulation, interfacial active site engineering, and three-dimensional structural optimization. Here, we report the synthesis of bimetallic Cu-Au metallic aerogels (MAs) via the freeze-thaw method as efficient electrocatalysts for the electrochemical CO₂ reduction reaction (CO₂RR). Electrochemical measurements reveal that Cu-Au MAs exhibit remarkably high Faradaic efficiency for CO (FE_CO) over a broad potential window (-0.7 to -1.1 V versus reversible hydrogen electrode (RHE)), with a peak FE_CO of 86.4% at -0.8 V_RHE, outperforming monometallic Au MAs (81.5%) and Cu MAs (9.2%). Moreover, Cu-Au MAs demonstrate excellent long-term stability, showing negligible activity decay after 20 h of continuous testing at -0.8 V_RHE. Mechanistic investigations indicate that the incorporation of Au sites in Cu-Au MAs optimizes the electronic structure of Cu, accelerates electron transfer, and modulates the adsorption strength of CO₂ on the catalyst surface, thereby enhancing CO₂RR performance. This study not only highlights the superior electrocatalytic performance of the bimetallic strategy for CO₂ conversion but also provides insights into the synergistic effect of bimetallic sites, paving the way for industrial-scale CO₂ recycling and utilization.