Hydrophobicity-controlled CuO Electrode for Enhanced Electrochemical CO₂ Reduction to Ethylene

Cu-based materials are effective electrocatalysts for converting carbon dioxide to ethylene. However, the hydrogen evolution reaction (HER) in aqueous solutions competes with the desired carbonaceous product, leading to poor selectivity. To overcome this issue, a PVDC coating was applied to a CuO electrode to regulate surface hydrophobicity, suppressing HER and promoting ethylene production. The influence of the PVDC layer on proton transfer and electrocatalyst stabilization was thoroughly investigated by varying the coating amount and order. The modified CuO electrode with a coating layer of only 50 µg/cm2 induced an optimal surface hydrophobicity (WCA=122°). It exhibited a highly efficient and selective ethylene production (FEC2H4=41.4%, |j|C2H4=6.8mA/cm2) and suppressed hydrogen evolution (FEH2=22.7%) at a low potential of-0.89V vs. RHE. The spent modified CuO electrode exhibited an increased presence of Cu+ , facilitating the CC coupling process. The stable hydrophobic properties and good electrical conductivity of PVDC-modified electrodes offer a simple and successful approach for advanced electrocatalyst development.