Hydrogen Spillover by Synergy at Ir─O─Ru Interfaces for Ampere‐Level Hydrogen Evolution

Industrial‐scale hydrogen production via alkaline water electrolysis requires electrocatalysts capable of sustaining ampere‐level current densities, yet the sluggish Volmer step remains a fundamental kinetic bottleneck. In this study, we report a surface‐microenvironment engineered catalyst in which atomically dispersed iridium atoms are selectively decorated on ruthenium nanoparticles through coordination with surface ─OH groups and defect oxygen sites, forming electronically coupled Ir─O─Ru interfacial ensembles. Density functional theory calculations based on the Ir─O─Ru interfacial model reveal a cooperative hydrogen‐spillover mechanism, in which the positively polarized Ir─O microenvironment promotes H 2 O activation, while the electronically tuned adjacent Ru sites accommodate the spilled‐over H* and drive the H─H coupling, thereby reducing the rate‐determining barrier to 0.19 eV. As a result, the catalyst achieves 1.0 A cm −2 at an overpotential of 103 mV in 1.0 M KOH and shows outstanding durability (3038 h at 1.0 A cm −2 ; 1593 h at 2.0 A cm −2 ). It further maintains stable operation in alkaline seawater (1427 h at 1.0 A cm −2 ) and anion‐exchange‐membrane electrolyzer (910 h at 80°C). These findings demonstrate that single‐atom surface decoration can effectively reconfigure interfacial reaction pathways, providing an efficient strategy for high‐flux alkaline hydrogen evolution.