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 H₂O 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.