Built-In Hydrogen Spillover Effect in Supported Catalysts for Efficient Alkaline Water Electrolysis

The hydrogen (H) spillover effect on metal-support electrocatalysts plays a significant role in improving the catalytic efficiency of the hydrogen evolution reaction (HER). However, the long reaction path and undesirable interfacial resistance cause considerable barriers in the H migration process. Herein, a small platinum atom-island (Pt_ai) featuring multifunctional active centers embedded in Mo₂C is designed, which exhibits an interface-free atomic-scale H spillover effect typically observed in single-component catalysts. Experiments and calculations co-reveal that a built-in ultra-short H spillover channel is established within the Pt_ai, which strikingly mitigates H migration barriers. When applied in alkaline HER, exceptionally low overpotentials (η₁₀ = 11.8 mV, η₁₀₀ = 52.9 mV) are obtained for the catalyst. More importantly, corresponding alkaline anion-exchange membrane water electrolyzers exhibit an ultralow cell voltage (1.77 V_cell) and high stability (200 h) at an industrial current density of 1.0 A·cm⁻². This study proposes a novel strategy to accelerate hydrogen spillover in multicomponent catalysts through the design of interface-free multifunctional active centers.