Modulating the interfacial solvation structure to promote hydroxyl migration for alkaline hydrogen oxidation

Alkaline hydrogen oxidation reaction (HOR) kinetics are fundamentally governed by electrode-electrolyte interfacial water structure and hydrogen-bond (H-bond) networks, yet their dynamic regulatory mechanism remains elusive. Here we show that precise modulation of the P coordination environment of Ir-based catalysts effectively enhances alkaline HOR catalytic performance. A series of Ir-based model catalysts with tunable P-coordination numbers are synthesized on nitrogen-doped carbon (NC) (IrP₂-Ir₂P@NC, IrP₂@NC, Ir@NC). The optimal Ir-P coordination (5.1 ± 0.7) induces controlled partial dissolution of Ir cations, a dynamic phenomenon rarely exploited in alkaline HOR catalysis. This effect reconstructs the interfacial H-bond network via enriched gap-H₂O and strengthened network connectivity, while optimizing hydrogen and hydroxyl adsorption to accelerate the Volmer step. The optimized IrP₂-Ir₂P@NC delivers a mass activity of 1.72 mA μg^-1 and a prominent alkaline exchange membrane fuel cell (AEMFC) peak power density of 1.59 W cm^-2. Ab initio molecular dynamics simulations confirm modified solvation structure elevates interfacial H-bond density, thereby elucidating the previously unresolved mechanism by which cation dissolution dynamically templates the H-bond network for enhanced HOR performance.