Bidirectional Electron Relay at TiN‐TiO₂ Interfaces Enables Oxidation‐Resistant Ru for High‐Potential Hydrogen Oxidation Catalysis

Abstract Ruthenium‐based catalysts are pivotal as cost‐effective alternatives to Pt for alkaline hydrogen oxidation reaction (HOR). However, they typically face irreversible deactivation above 0.2 V vs. RHE due to synergistic Ru oxidation/OH ad over‐adsorption. We propose a Taichi‐inspired TiN‐TiO 2 heterophase‐segregated electron‐relay mechanism that dynamically balances bidirectional electron flow (Ru→TiN electron donation and TiO 2 →Ru electron replenishment), achieving complete activity retention (100%) even under 1.1 V operation. This potential‐adaptive regulation can significantly inhibit electron redistribution and band compression under the high potential induced electric field, and effectively alleviate the d‐ band upshift and OH adsorption energy surge. Spatially decoupled Ti(TiN)‐Ru bridge sites simultaneously adsorb OH ad (E ads = ‐1.40 eV) and decouple H ad /OH ad adsorption domains, eliminating competitive binding. This configuration delivers triple synergies: 1) geometric isolation of reactive intermediates adsorption, 2) potential‐responsive Ru 0 stabilization, and 3) accelerated Volmer kinetics via interfacial hydroxyl migration. The Ru/TiN‐TiO 2 catalyst achieves 100% activity retention at 1.1 V vs. RHE (vs. >60% loss for Ru/TiN) with 73.23% metallic Ru 0 preserved after 10 h operation. This work resolves the intrinsic activity‐stability trade‐off in Ru HOR catalysts and establishes dynamic charge‐relay interfaces as a universal design paradigm for oxidation‐prone electrocatalysts.