3D Gas Diffusion Layer with Dual-Metal Sites for Enhanced CO2 Electrolysis to C2+ Products.

Achieving satisfactory C2+ products selectivity and current density in the electrochemical CO2 reduction reaction (eCO2RR) remains a challenge for the practical applications. Here, we design a 3D-CuAg-GDE for eCO2RR-to-C2+ products, which shows a remarkable C2+ Faradaic efficiency (FE) of 82.04% at -0.88 V versus RHE and a partial current density of 565.18 mA cm-2. Experimental and theoretical analyses demonstrate that the chitosan with multiple functional groups induces the formation of 3D architecture, which enhances the accessibility of reactive sites and mitigates the limitations associated with CO2 diffusion. The abundant hydrogen bonds between chitosan and CO2 promote the adsorption and enrichment of reactant. Furthermore, the Cu site exhibits stronger activation capacity for CO2 and facilitates the subsequent electron transfer process for the formation of intermediate *CO. The DFT simulation also reveals the thermodynamic favorable for *CO migrating from Cu site to Ag site. Moreover, the Ag site exhibits a more negative Gibbs free energy for the protonation of *CO to *CHO, which facilitates the asymmetric coupling of *CO (Cu site) and *CHO (Ag site), ultimately enhancing the generation of C2+ products. Consequently, the unique 3D structure and tandem synergistic interaction of the Cu─Ag dual sites achieves high activity for eCO2RR-to-C2+ products.