Crystal phase dependent hydrogen spillover effect in Ru/WO3 for hydrogen evolution electrocatalysis

Supported Ru nanoparticles with high utilization are promising for the hydrogen evolution reaction (HER) but the effect of the crystal phase engineering of supports on their performance remains unclear. Here, the impact of the crystal phase of the support on the catalytic activity of Ru was probed by anchoring Ru nanoparticles onto precisely synthesized hexagonal (WO 3 -H), orthorhombic (WO 3 -O), and monoclinic (WO 3 -M) supports followed by thorough evaluation for HER. Among them, WO 3 -H demonstrated superior performance by providing enhanced Ru anchoring and uniform dispersion, maximizing active site availability. A critical finding is the small work function difference (Δ W F ) between Ru and WO 3 -H, which minimizes interfacial charge accumulation and facilitates efficient hydrogen spillover, thereby accelerating HER kinetics. In contrast, WO 3 -O and WO 3 -M exhibited larger Δ W F and less effective Ru dispersion, resulting in a larger hydrogen spillover barrier and suboptimal hydrogen adsorption/desorption dynamics. As a result, Ru/WO 3 -H exhibited the best performance, achieving an overpotential of 43.8 mV at 10 mA cm −2 and a Tafel slope of 49.1 mV dec −1 . This work highlights the critical role of the crystal phase in optimizing the intrinsic catalytic activity of catalysts, offering new insights for designing efficient HER catalysts.