Application of Hydrogen Spillover Effect in Electrocatalytic Hydrogenation Reaction

Hydrogenation is a fundamental reaction in chemical industry, but conventional thermocatalytic approaches depend on energy-intensive, high-pressure hydrogen, which has driven increasing interest in more environmentally friendly alternatives such as electrocatalytic hydrogenation. A major challenge in electrocatalytic hydrogenation is the limited availability and utilization of active hydrogen atoms, which often remain confined to metal surfaces where competitive hydrogen evolution occurs. The hydrogen spillover effect (HSPE), which enables the migration of active hydrogen species from metals to adjacent supports, offers a promising pathway to overcome this limitation by expanding the reactive interface, enhancing selectivity, and enabling more efficient hydrogen utilization. Although HSPE has been extensively investigated in thermal catalysis, its role in electrocatalytic hydrogenation has not been comprehensively summarized. This review integrates current understanding of HSPE fundamentals, advanced characterization methods, and mechanistic insights across different supports, and highlights its emerging applications in electrocatalytic hydrogenation, including CO 2 reduction, nitrate reduction, biomass upgrading, and organic transformations. The critical influence of HSPE on reaction pathways and catalytic efficiency is outlined, followed by a discussion of key challenges and prospective research directions aimed at advancing HSPE strategies for next-generation electrocatalytic hydrogenation systems.