Interface electronic coupling engineering of Ni(OH)x/Mo-Ni3S2 nanosheet heterostructure for enhanced alkaline hydrogen evolution

• A novel self-supporting Ni(OH) x /Mo-Ni 3 S 2 /NF heterostructure catalyst is reported. • Ni(OH) x /Mo-Ni 3 S 2 /NF exhibits excellent HER activity (33 mV @10 mA cm −2 ) in 1 M KOH. • The HER performance of the heterostructure catalyst exceeds commercial Pt/C. • The heterostructure catalyst has an excellent stability for 300 h at ∼ 130 mA cm −2 . • An atomic-scale insight into the structure–property relation is revealed by DFT. Developing low-cost, highly efficient and stable non-noble metal-based electrocatalysts for the hydrogen evolution reaction (HER) is crucial for promoting large-scale alkaline water electrolysis. Here, we report a novel self-supporting Ni(OH) x /Mo-Ni 3 S 2 nanosheet heterostructure grown on nickel foam, demonstrating outstanding catalytic performance for alkaline HER. This heterostructure electrocatalyst exhibits an exceptionally low overpotential of just 33 mV at a current density of 10 mA cm −2 in 1 M KOH solution, surpassing commercial Pt/C catalyst. Moreover, it can operate continuously for 300 h at a high current density of around 130 mA cm −2 . Both experimental and theoretical calculations show that strong electronic coupling at the heterojunction interface optimizes the adsorption energy of molecular water and hydrogen on active sites, thereby enhancing the intrinsic activity. This work offers novel insights for designing high-performance alkaline HER electrocatalysts through coupling doping and heterostructure engineering.