Promoting Electrocatalytic CO 2 Reduction via Oxophilic Amorphous Metal Oxide‐Mediated Interfacial Water Activation and Structure Evolution

ABSTRACT Interfacial water serves as the intrinsic proton source for CO 2 hydrogenation, yet synchronizing its activation with on‐demand active hydrogen ( * H) supply without triggering the hydrogen evolution reaction (HER) remains challenging. Herein, we construct an oxophilic amorphous MnO x overlayer on Ag to regulate the interfacial water network. In situ characterization and theoretical calculations demonstrate that under over 45% of interfacial water reorganizes into an ordered four‐coordinate hydrogen‐bonded (4‐HB‐H 2 O) structure under operation, facilitating targeted proton transfer to CO 2 reduction intermediates. The distorted Mn‐O polyhedra lower the water dissociation barrier by 0.54 eV while raising the HER barrier by 0.61 eV. It achieves a CO production rate of 12.8 mol h −1 g −1 and 68.6% Faraday efficiency (FE) at −1000 mA cm −2 and maintains >95% FE CO over 500 h at −200 mA cm −2 . It also enables efficient nitrate‐to‐ammonia conversion with the FE of 88.5 %, and the maximum NH 3 production rate is 831.4 mmol h −1 g −1 , and a Zn–CO 2 rechargeable battery with FE CO of 98.5% and power density of 2.1 mW cm −2 . This study underscores the amorphous metal oxide‐mediated interfacial water activation as a versatile and scalable strategy for enhancing selectivity in water‐involved electrocatalytic reactions.