Hydrophobic Cation-Immobilized Covalent Organic Frameworks Enable Selective and Stable Electrosynthesis of Ethylene from CO2

for ethylene. A developed COF-based practical zero-gap membrane electrode assembly electrolyzer is further demonstrated with stable ethylene production over 89.6 h. In situ spectra and density functional theoretical calculations unveil that the cationic COFs further enhance the local electric field strength, resulting in stronger *CO adsorption and a boosted *CO dimerization rate. Our study provides a new avenue to enhance multicarbon production via tuning the cathode local mass and charge transfer.