One‐Step Hydrothermal Synthesis of MoS 2 /NiS Heterojunctions for Efficient Electrocatalytic Hydrogen Evolution in Alkaline Media

ABSTRACT Developing efficient and low‐cost electrocatalysts for the hydrogen evolution reaction (HER) in alkaline media remains challenging because the sluggish water dissociation kinetics substantially limit the catalytic efficiency of most non‐noble‐metal catalysts. Herein, we report a facile one‐step hydrothermal strategy for the direct construction of a self‐supported MoS 2 /NiS heterojunction on acid‐pretreated nickel foam, where the substrate simultaneously serves as the conductive scaffold and the in situ Ni source. This integrated synthesis enables the concurrent formation of NiS nanorods and MoS 2 nanosheets, producing a tightly coupled hierarchical heterointerface without additional sulfurization, post‐annealing, or binder‐assisted electrode fabrication. Structural characterizations demonstrate the successful formation of the MoS 2 /NiS heterostructure with intimate interfacial contact and strong electronic coupling, as evidenced by the opposite binding‐energy shifts of the Mo and Ni species. Such interfacial charge redistribution promotes electron transport, increases the electrochemically accessible surface area, and accelerates alkaline HER kinetics. Consequently, the optimized MoS 2 /NiS electrode delivers an overpotential of only 71 mV at 10 mA cm −2 , a Tafel slope of 69 mV dec −1 , a large apparent double‐layer capacitance of 55 mF cm −2 , and excellent structural stability after 2000 CV cycles together with continuous operation for 24 h in 1.0 M KOH.