Cohesive Co and Mo2C heterostructure catalysts strongly confined to hollow carbon support for enhanced kinetics and durability in the alkaline hydrogen evolution reaction†

Water electrolysis technologies in alkaline environments have drawn considerable interest for their potential in low-cost hydrogen production without noble metals. However, it remains challenging to achieve high performance and durability in the alkaline hydrogen evolution reaction (HER) using non-noble metal catalysts because of their intrinsically poor water dissociation kinetic properties. Here, we address this challenge by introducing a cohesive Co and Mo₂C heterostructure catalyst strongly confined to N-doped carbon hollow polyhedron (NCHP) supports. Computational analysis and X-ray spectroscopic analysis results reveal that the charge redistribution between metallic Co and Mo₂C not only promotes water dissociation on Mo₂C sites but also accelerates hydrogen gas evolution kinetics at their interfaces, leading to enhanced HER performance. The Co–Mo₂C/NCHP catalyst reduces the HER overpotential by 66% at 10 mA cm⁻² compared to the single-active-site catalyst (Co/NCHP). Moreover, the Co–Mo₂C/NCHP catalyst demonstrates enhanced durability, exhibiting a 38% lower HER overpotential than commercial Pt/C at 10 mA cm⁻² after 1000 cycles. By forming a cohesive structure of Co and Mo₂C within the hollow carbon framework, the formation of interfaces is maximized, and physical and chemical degradation is prevented. This study presents key strategies for designing interfaces to overcome the limitations of alkaline HER kinetics and durability.