Interfacial Water Enrichment and Reorientation on Pt/C Catalysts Induced by Metal Oxides Participation for Boosting the Hydrogen Evolution Reaction

State-of-the-art hydrogen evolution reaction (HER) catalysts have been Pt- or Pt-based alloys so far due to their extremely low onset potential; however, their HER kinetics become worse under strong cathodic polarization. Herein, we take commercial Pt/C decorated with a small amount of metal oxides (MOx-Pt/C) as model catalysts to improve the HER kinetics at a wide cathodic potential range in alkaline conditions. The MOx-Pt/C catalysts markedly reduce the Tafel slope and overpotential under both small and large cathodic polarization. Multiscale simulations reveal that the metal oxides can cause a so-called local electric field enhancement and induce interfacial water enrichment and reorientation. It accelerates the diffusion of hydrated K+ and facilitates the activation of interfacial water, which boosts the Volmer step to match the fast H2 evolution especially under strong potential polarization. Our work discloses important clues about how multiple components play a role in HER electrocatalysis.