Anionic Ionomer: Released Surface-Immobilized Cations and an Established Hydrophobic Microenvironment for Efficient and Durable CO-to-Ethylene Electrosynthesis at High Current over One Month.

Electrosynthesis of multicarbon products, such as CH, from CO reduction on copper (Cu) catalysts holds promise for achieving carbon neutrality. However, maintaining a steady high current-level CH electrosynthesis still encounters challenges, arising from unstable alkalinity and carbonate precipitation caused by undesired ion migration at the cathode under a repulsive electric field. To address these issues, we propose a universal "charge release" concept by incorporating tiny amounts of an oppositely charged anionic ionomer (e.g., perfluorinated sulfonic acid, PFSA) into a cationic covalent organic framework on the Cu surface (cCOF/PFSA). This strategy effectively releases the hidden positive charge within the cCOF, enhancing surface immobilization of cations to impede both outward migration of generated OH and inward migration of cations, inhibiting carbonate precipitation and creating a strong alkaline microenvironment. Meanwhile, the ionomer's hydrophobic chains create a hydrophobic environment within the cCOF, facilitating efficient gas transport. In situ characterizations and theoretical calculations demonstrate that the cCOF/PFSA catalyst establishes a hydrophobic strong alkaline microenvironment, optimizing the adsorption strength and configuration of *CO intermediates to promote the CH formation. The optimized catalyst achieves a 70.5% Faradaic efficiency for CH with a partial current density over 470 mA cm. Notably, it delivers a high single-pass carbon efficiency of 96.5% for CORR and sustains an exceptional stability over 760 h. When implemented in a large-area MEA electrolyzer and a 5-cell MEA stack, the system achieves an industrial current of 15 A and continuous CH production exceeding 19 mL min, marking a significant step toward industrial feasibility in CORR-to-CH conversion.