Elucidating the structure evolution and reaction mechanism of the Cu-In bimetallic catalysts during CO2RR

Abstract

In-based bimetallic catalysts show great potential to reduce CO2 electrochemically. However, the nature of active sites and reaction mechanisms are not fully understood. This study systematically investigates the role of Cu in the Cu-In bimetallic catalysts during the reaction. The partial current densities of formate and CO show a linear correlation with increased Cu content. CuIn3 shows a total current density of 6.40 mA cm−2 and the highest Faradic efficiency for C1 products of 99.3% at −0.7 V vs RHE. A series of characterizations reveal that the Cu1+ species dope into the In(OH)3 lattice for the Cu-In catalysts, while small CuO nanoparticles also form on the surface of catalyst with high Cu contents. The CuO and Cu1+ species are reduced to metallic Cu0, leading to the formation of the Cu0-In(OH)3 interfacial sites. Adding Cu is found to facilitate the adsorption of CO2 and shift the rate-determining step for formate production.