Enhanced electrochemical reduction of CO₂ to ethylene using boosted hydrophobicity of polyvinyl dichloride‐coated CuO electrodes

Cu-based materials have gathered significant attention as efficient electrocatalysts for converting carbon dioxide (CO₂) to ethylene. CuO electrode was coated with Polyvinyl dichloride (PVDC) to finely tune its surface hydrophobicity, thereby effectively suppressing the hydrogen evolution reaction (HER) while promoting CO₂ conversion to ethylene. PVDC modification on modulating proton transfer and enhancing the stability of the electrocatalysts was investigated systematically by varying the coating material, coating amount, and coating order. The CuO-PVDC electrode with a 50 μg/cm² PVDC coating demonstrated an optimal level of hydrophobicity where the water contact angle (WCA) increased from 94.8 ° to 122.0 °) and led to highly efficient production of ethylene (FE_ethylene increased from 32.2 % to 41.4 %) at a low potential of −0.89 V vs. RHE, while effectively suppressing hydrogen evolution. Comparative tests and calculations revealed that PVDC modification balances proton transfer and CO₂ availability. Hence, PVDC regulates the degree of reduction in CuO, leading to an increased proportion of Cu ions on the surface of the CuO-PVDC electrode, which facilitates the C-C coupling process exhibiting long-lasting hydrophobic properties without sacrificing conductivity, which is a promising strategy for mitigating the environmental impact of CO₂ and their efficient conversion to produce valuable chemicals.