Highly selective CO2 electroreduction to ethylene on long alkyl chains-functionalized copper nanowires

Abstract

Electrochemical reduction of carbon dioxide (CO₂RR) is a promising approach to complete the carbon cycle and potentially convert CO₂ into valuable chemicals and fuels. Cu is unique among transition metals in its ability to catalyze the CO₂RR and produce multi-carbon products. However, achieving high selectivity for C₂₊ products is challenging for copper-based catalysts, as C–C coupling reactions proceed slowly. Herein, a surface modification strategy involving grafting long alkyl chains onto copper nanowires (Cu NWs) has been proposed to regulate the electronic structure of Cu surface, which facilitates *CO-*CO coupling in the CO₂RR. The hydrophobicity of the catalysts increases greatly after the introduction of long alkyl chains, therefore the hydrogen evolution reaction (HER) has been inhibited effectively. Such surface modification approach proves to be highly efficient and universal, with the Faradaic efficiency (FE) of C₂H₄ up to 53% for the optimized Cu–SH catalyst, representing a significant enhancement compared to the pristine Cu NWs (30%). In-situ characterizations and theoretical calculations demonstrate that the different terminal groups of the grafted octadecyl chains can effectively regulate the charge density of Cu NWs interface and change the adsorption configuration of *CO intermediate. The top-adsorbed *CO intermediates (*CO_top) on Cu–SH catalytic interface endow Cu–SH with the highest charge density, which effectively lowers the reaction energy barrier for *CO-*CO coupling, promoting the formation of the *OCCO intermediate, thereby enhancing the selectivity towards C₂H₄. This study provides a promising method for designing efficient Cu-based catalysts with high catalytic activity and selectivity towards C₂H₄.