Optimizing the Interfacial Water Network via Electron‐Enriched Ru Single Atoms for Ultrafast Hydrogen Evolution Kinetics

ABSTRACT The rational design of the water structure at the electrode–solution interface, where electrochemical reactions take place, is critical in electrochemistry but remains a significant challenge. Here, we demonstrate that electron‐rich single‐atom sites can weaken the hydrogen bond (HB) network of water, thereby enhancing the proton transport efficiency in alkaline microenvironments. Specifically, by anchoring single Ru atoms onto defected Mo 2 C supports (Ru SA /d‐Mo 2 C), the intrinsic strong HB network with random proton transfer pathways is transformed into a two‐coordinated HB‐dominated H 2 O network (2‐HB•H 2 O), which serves as a “proton highway” to accelerate hydrogen evolution. Advanced in situ characterizations, coupled with theoretical calculations, reveal that the electron‐enriched Ru sites facilitate proton capture through the 2‐HB•H 2 O network following water dissociation on d‐Mo 2 C, thereby accelerating the sluggish alkaline hydrogen evolution kinetics. As a result, the optimized Ru SA /d‐Mo 2 C requires only 1.89 V to achieve an industrial current density of 1 A cm −2 and demonstrates a high durability in anion exchange membrane water electrolyzers (AEMWEs). This work provides new insights into how HB networks can be tailored in hetero‐catalytic systems to enhance electrocatalytic efficiency.