Insights into Restrained C-C Coupling on an Aniline-Modified Copper Catalyst in Electroreduction of Carbon Dioxide

The electrochemical reduction of carbon dioxide (CO₂) is potentially a sustainable approach to mitigating global CO₂ emissions and simultaneously producing valuable feedstock. Though copper (Cu) is able to convert CO₂ to various products, ranging from single-carbon molecules to even C₃ product, the selectivity of polycrystalline Cu cathode is poor. Herein, we modify polycrystalline Cu through the interaction between Cu and the functional group by covering the surface with aniline. The interaction between aniline and Cu is intensively characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. Interestingly, the modified electrode shows an excellent activity toward the production of CO and HCOO^-. Specifically, the aniline-modified electrode achieves a Faradaic efficiency of 68.1 ± 3.0% for the C₁ product at a current density of -96 mA cm^-2. Through a combined analysis of CO reduction, CO adsorption, and in situ Raman spectroscopy, we propose that the electronic interaction between aniline and Cu influences the adsorption strength of the CO intermediate, hence suppressing C-C coupling and promoting the formation of the C₁ product. Our study provides new insight into developing modified Cu catalysts to promote the selectivity of Cu for CO₂ electroreduction.