Gas–Proton Microenvironment Modulation for Enhanced CO ₂ ‐to‐Formate Electroreduction

Abstract Precise control of interfacial water structure is essential for suppressing side reactions and enabling selective CO 2 electroreduction at industrial current densities. Here, we synthesize a series of bismuth‐based catalysts with spatially encoded superhydrophilic–superhydrophobic nanodomains by partially embedding polyvinylidene fluoride (PVDF) into Bi nanoparticles. This strategy creates interfacial polarity patterns that stabilize *OCHO intermediates while suppressing hydrogen and CO evolution. Compared to the PVDF‐free control, the optimized Bi–PVDF catalyst exhibits significantly enhanced formate partial current density, Faradaic efficiency (FE), and long‐term stability. It achieves > 90% FE at −200 mA cm −2 for 50 h and maintains high selectivity up to −700 mA cm −2 . Operando spectroscopy and multiscale simulations reveal that the dual‐wettability interface modulates local hydration and charge distribution, promoting selective intermediate formation while kinetically suppressing side pathways. By addressing the longstanding challenge of coupled gas–proton transport, this work offers a mechanism‐driven and scalable strategy to construct interfacial microenvironments for high‐rate, selective CO 2 electroreduction.