Reversible hydrogen spillover in Ru-WO₃₋ₓ enhances hydrogen evolution activity in neutral pH water splitting

Noble metal electrocatalysts (e.g., Pt, Ru, etc.) suffer from sluggish kinetics of water dissociation for the electrochemical reduction of water to molecular hydrogen in alkaline and neutral pH environments. Herein, we found that an integration of Ru nanoparticles (NPs) on oxygen-deficient WO3-x manifested a 24.0-fold increase in hydrogen evolution reaction (HER) activity compared with commercial Ru/C electrocatalyst in neutral electrolyte. Oxygen-deficient WO3-x is shown to possess large capacity for storing protons, which could be transferred to the Ru NPs under cathodic potential. This significantly increases the hydrogen coverage on the surface of Ru NPs in HER and thus changes the rate-determining step of HER on Ru from water dissociation to hydrogen recombination.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)Published versionWe are grateful for the financial support from the National Key R&D Program of China (2021YFB3801600), the National Natural Science Foundation of China (21872121, 21908189), the Fundamental Research Funds for the Central Universities (2017XZZX002−16), Ministry of Education of Singapore (Tier 1: RG4/20 and Tier 2: MOET2EP10120-0002), and Agency for Science, Technology and Research (AME IRG: A20E5c0080)