Kinetically Accelerating Elementary Steps via Bridged Ru‐H State for the Hydrogen‐Evolution in Anion‐Exchange Membrane Electrolyzer

Designing hydrogen evolution reaction (HER) electrocatalysts for facilitating its sluggish adsorption kinetics is crucial in generating green hydrogen via sustainable water electrolysis. Herein, a high‐performance ultra‐low Ruthenium (Ru) catalyst is developed consisting of atomically‐layered Ru nanoclusters with adjacent single Ru sites, which executs a bridging‐Ru‐H activation strategy to kinetically accelerate the HER elementary steps. Owing to its optimal electronic structure and unique adsorption configuration, the hybrid Ru catalyst simultaneously displayed a drastically reduced overpotential of 16 mV at 10 mA cm −2 as well as a low Tafel slope of 35.2 mV dec −1 in alkaline electrolyte. When further coupled with a commercial IrO 2 anode catalyst, the ensembled anion‐exchange membrane water electrolyzer achievs a current density of 1.0 A cm −2 at a voltage of only 1.70 V cell . In situ spectroscopic analysis verified that Ru single atom and atomically‐layered Ru nanoclusters in the hybrid materials play a critical role in facilitating water dissociation and weakening *H adsorption, respectively. Theoretical calculations further elucidate the underlaying mechanism, suggesting that the dissociated proton at the single atom Ru site orients itself adjacently with Ru nanoclusters in a bridged structure through targeted charge transfer, thus promoting Volmer‐Heyrovsky dynamics and boosting the HER activity.