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 (MO x -Pt/C) as model catalysts to improve the HER kinetics at a wide cathodic potential range in alkaline conditions. The MO x -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 H 2 evolution especially under strong potential polarization. Our work discloses important clues about how multiple components play a role in HER electrocatalysis.