Thousand-hour salt precipitation-free CO₂-to-ethylene electrosynthesis at high current densities

Salt precipitation remains a bottleneck in scaling carbon dioxide (CO₂) electroreduction to ethylene (C₂H₄), as it blocks gas transport, induces electrode flooding, and causes rapid performance degradation. Identifying electric field-driven cation accumulation and the consequent hydrophobicity loss as key factors, here, we show a wettability-engineered Cu-based electrode that decouples hydrophobicity from electronic conductivity. The electrode incorporates in situ embedded Cu active sites within an insulating, hydrophobic polymer matrix, forming localized "hydrophobic trap". This architecture preserves interfacial hydrophobicity under operation, suppresses cation accumulation, and confines locally generated OH⁻ ions to sustain an alkaline microenvironment for C-C coupling. The optimized electrode achieves a faradaic efficiency of 75.9% for C₂H₄ at 1.2 A cm^-2 in a flow cell, and operates for over 1000 h in a membrane electrode assembly electrolyzer. The electrode maintains high productivity under low CO₂ concentrations and in the presence of flue gas impurities. Techno-economic analysis confirms the feasibility of this strategy.