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.