Ag nanoparticles induced abundant Cuδ+ sites in Cu2Se nanoflower rods to promote efficient carbon dioxide electroreduction to ethanol

Electrocatalytic carbon dioxide reduction reaction (eCO 2 RR) is one of the attractive approaches to CO 2 utilization. Nevertheless, it remains a challenge to prepare highly efficient and selective electrocatalysts to realize deep conversion of multi-carbon products. The absence of active sites due to the reconfiguration of copper-based catalysts leads to migration deactivation during catalysis, rendering low catalytic efficiency. In this work, Cu 2 Se nanowires (NWs) were obtained from the Cu foam. After further electroreduction for 90 s, Ag nanoparticles (NPs) were modified on the flower rod-shaped Cu 2 Se NWs (Ag 2.69% /Cu 2 Se NWs). This interfacial modification strategy, balanced the Cu δ+ active valence state on the surface of the Ag 2.69% /Cu 2 Se NWs, led to a high Faradaic efficiency (FE) of ethanol (∼70 %) at −0.52 V (vs. reversible hydrogen electrode (RHE)). Besides, the Ag 2.69% /Cu 2 Se NWs achieved a high partial current (∼13.9 mA) for ethanol, 18.5 μmol/h ethanol yield and an energy efficiency of 47.1 % in the H-type electrolytic cell. The reaction mechanism was investigated at the molecular level through density functional theory (DFT) calculation. The interface-modified Ag NPs provided stable *COOH intermediates during the reaction process, effectively achieving surface *CO enrichment. Besides, the presence of Ag NPs resulted in the generation of abundant Cu δ+ active species. The *CO migrated to the Cu δ+ active sites to accelerate the asymmetric coupling of *CO and *CHO, which significantly improved the FE of CO 2 electroreduction to ethanol. Our work offers a promising approach for designing Cu 2 Se-based nanowires electrocatalysts for CO 2 reduction with excellent activity and selectivity.