Pt-MoO_x Hybrid Electrocatalysts Modulating Local Environment for Enhanced Activity toward Hydrogen Electrocatalysis

The alkaline hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) are crucial for achieving high efficiency in anion-exchange membrane water electrolyzers and fuel cells. While Pt is highly active for HER/HOR at low pH, its activity decreases ∼200-fold under alkaline conditions due to stronger hydrogen binding. Manipulating the local environment around the electrode is an effective but underexplored strategy in hydrogen electrocatalysis. In this study, we prepared nanohybrid electrocatalysts comprising Pt nanoparticles and Mo oxides (Pt-MoO x ). Pt-MoO x exhibited a 2.6-fold increase in alkaline HER/HOR activity compared to that of Pt black. It demonstrated a low overpotential of 65 mV at −10 mA cm –2, with stability for 3 days. The enhanced reaction kinetics were attributed to the decreased hydrogen binding strength by MoO x and stabilized local environment resulting from H+/H 2 O exchange equilibria by the acidic Mo−OH species. This work provides an alternative design strategy for fine-tuning electrosorption properties.