Curvature-engineered interfacial hydrogen-bond networks driving proton-coupled electron transfer boosts hydrogen oxidation in alkaline fuel cells

Precise manipulation of interfacial microenvironments within the electrical double layer remains a fundamental challenge, primarily due to dynamic structural rearrangements and competitive adsorption processes during reactions. Here, we employ nanoscale curvature engineering to construct three RuIr-based electrocatalysts with precisely controlled surface curvatures, establishing a direct correlation between geometric effects and hydrogen oxidation reaction efficiency. Finite-element simulations coupled with electrochemical analysis reveal that concave nanocage (CNC) morphology enhances localized electric field, simultaneously weakening adsorbed hydrogen (Hads) binding and promoting its subsequent cooperative oxidation with more OHads. Operando spectroscopy and ab initio molecular dynamics simulations demonstrate that high-curvature RuIr CNC drives ordered O-down H2O alignment at the electrode-electrolyte interface, strengthening hydrogen-bond networks and accelerating proton-coupled electron transfer kinetics. The optimized RuIr CNCs achieve a mass activity of 7.51 mA μg−1 (three-electrode system) and enable a peak power density of 1.52 W cm−2 (H2/O2 anion-exchange membrane fuel cell), with stability over 150 hours. The sluggish hydrogen oxidation reaction hinders the development of anion exchange membrane fuel cells. Here, the authors develop high-curvature RuIr CNCs that induce an O-down water orientation, thereby strengthening hydrogen-bond networks and reducing proton transfer barriers.