Tuning the configuration of Ag–Cu aerogels for electrocatalytic applications

Abstract

Ag-based electrocatalyst systems have garnered considerable attention due to the moderate interplay between their active sites and carbon-terminated intermediates, conferring high selectivity towards value-added CO products during the CO₂ electroreduction process. Existing performance-enhanced strategies mainly focus on fine-tunability of the size, morphology, facet, composition, inner strain, etc., but an in-depth investigation into interface-dominated configuration tuning during catalyst synthesis remains lacking. In this contribution, Ag–Cu bimetallic aerogels with promising electrochemical CO₂ reduction activity are synthesized under ambient temperature, featuring a highly nanoporous and nano-skeletal architecture. The results show that the preferential nucleation of Cu particles enables a homogeneous distribution of Ag and Cu, while reaction gas-induced micro-turbulence promotes the formation of a distinctive three-dimensional aerogel skeleton via a nonclassical growth mechanism dominated by twin boundaries. As expected, the Ag-based aerogels demonstrate excellent CO₂ electroreduction performance. Specifically, the FE(CO) reaches 94.5% at −0.8 V vs. RHE, with a negligible decline in both FE(CO) and current density after 14 h of electrocatalysis at a cell potential of 2.7 V, demonstrating the high durability of the metallic aerogel. In situ characterization further suggests that the excellent performance for CO₂ electroreduction is attributed to the decoupled proton–electron-transfer pathway over high-density twin boundaries. This work provides both experimental and theoretical insights to unveil the growth behaviors and electroreduction mechanisms of Ag–Cu metallic aerogels, offering new perspectives for metallic aerogel development and electrocatalytic performance enhancement.