Lattice-hydrogen cycling mechanism enables pH-universal hydrogen evolution at ampere-level current densities

Abstract Controllable supply of hydrogen intermediate across a wide pH range is crucial for electroreduction reactions, but is hindered by pH-dependent hydrogen species formation on conventional catalysts. We report a lattice-hydrogen cycling mechanism that dissociates hydrogen intermediate availability from electrolyte pH. By integrating proton-blocking Ru with thermally-hydrogenated H x WO 3 , we create a dynamic hydrogen reservoir, enabling efficient hydrogen supply. In-situ Raman spectroscopy, isotopic labeling, and theoretical simulations reveal the lattice hydrogen in H x WO 3 migrates swiftly to Ru active sites via low-energy-barrier pathways, while consumed hydrogen is spontaneously replenished via proton adsorption (acidic) or water dissociation (alkaline/neutral). Consequently, this catalyst achieves a competitive pH-universal performance for hydrogen evolution reaction, with low overpotentials (125 mV acidic, 142 mV alkaline, 219 mV neutral @1 A cm -2 ) alongside 500-hour stability.