Liquid gallium-mediated vapor deposition induces strong metal-support interaction for ultrafine platinum nanocatalysts in high-current-density alkaline hydrogen evolution

Engineering strong metal-support interaction (SMSI) is a powerful strategy for enhancing the activity and durability of platinum catalysts under industrial alkaline hydrogen evolution conditions, yet controllable fabrication of such interfaces remains challenging. Here, we report a liquid gallium-mediated vapor deposition approach that induces pronounced SMSI between ultrafine platinum nanoparticles and nickel oxide supported on nickel foam. The liquid Ga layer acts as a dynamic transport medium that regulates precursor diffusion and decomposition, enabling controlled nucleation of 1.77 nm Pt nanoparticles and promoting interfacial electronic coupling with the NiO support. Spectroscopic analysis and theoretical calculations reveal charge redistribution across the Pt-NiO interface, leading to modified hydrogen adsorption energetics and a reduced water dissociation energy barrier. The resulting catalyst achieves an overpotential of 20 mV at 10 mA cm^-2 and sustains stable operation for 800 h at 500 mA cm^-2 in alkaline electrolyte. When implemented in an anion-exchange membrane water electrolyzer, the catalyst maintains ampere-level current densities with excellent durability. This work demonstrates liquid metal-mediated vapor deposition as a versatile platform for inducing strong metal-support interaction in ultrafine electrocatalysts for high-current alkaline energy conversion.