Benzotriazole and Poly(vinylidene Fluoride) Synergistically Promote the Selectivity of Carbon Dioxide Reduction on Copper toward C2 Products.

Electrochemical reduction of carbon dioxide (CO2RR) to valuable chemicals offers a promising solution to mitigate CO2 emissions and address the energy crisis. Surface modification of the catalyst surface with small molecules or polymers could modulate the product selectivity of the CO2RR. If a properly chosen polymer and molecule were combined together, a significant improvement in the CO2RR might be realized. Herein, we demonstrate that sequential coating of Cu catalyst with benzotriazole (BTA) and poly(vinylidene fluoride) (PVDF) significantly enhances the product selectivity toward C2 species. The Faradaic efficiency (FE) of C2 hydrocarbons increased from 49 to 70% at -1.05 V vs the reversible hydrogen electrode (RHE) in an H-type electrochemical cell, with stable performance maintained over 10 h. The coated BTA molecules could enhance the CO2RR activity and promote the production of C2 species, while the PVDF layer prevents the BTA molecules from dissolving/detaching and regulates the surface coverage of *CO and *H intermediates. This dual-layer modification strategy provides a simple and effective approach to improve the Faradaic efficiencies (FEs) of the CO2RR on Cu. Furthermore, this strategy may be integrated with other strategies to further optimize the CO2RR performance, offering a versatile pathway for advancing sustainable energy conversion technologies.