Ordered Interfacial Domain Expansion Catalysis Enhances Hydrogen Evolution for Proton Exchange Membrane Electrolysis

Metal/metal oxide composites represent a promising group of catalysts that can substantially reduce the platinum group metal (PGM) loading at the cathode for proton exchange membrane water electrolysis (PEM-WE). However, the complete hydrogen evolution reaction (HER) kinetics at the complex metal/support interface are not fully understood. Here, using Pt nanoparticles on boron-modified oxygen-defective tungsten oxide (Pt/B-WO2.9) as a model system, we establish an overall kinetic framework induced by strong metal-oxide interaction, termed as ordered interfacial domain expansion catalysis (OIDEC), to elucidate the hydrogen behavior through combining in-situ spectroscopic, in-situ electrochemical, and theoretical calculation studies. This mechanism allows favorable proton adsorption on active site (Pt) from ordered interfacial water, sequential hydrogen spillover from active site (Pt) to auxiliary sites (W, O), and direct H-H coupling on auxiliary sites (W, O) for H2 evolution. In a practical PEM-WE device, Pt/B-WO2.9 shows high mass activity (1237 A mgPt-1 at 1.8 V) with a total Pt loading of 8.6×10-4 mg cm−2 and outstanding durability over 850 h multistep operation at industrial current densities from 1 to 2 A cm⁻² and 60°C.