Progress in Compositional Regulation of Molybdenum Sulfide for Electrocatalytic Hydrogen Evolution

Against the backdrop of the accelerating global energy transition and the continued pursuit of carbon-peaking and carbon-neutrality targets, hydrogen is regarded as an important secondary energy carrier for building a low-carbon energy system because of its high gravimetric energy density, suitability for storage and transport across temporal and spatial scales, and strong compatibility with renewable energy. Water electrolysis is a key technological route for large-scale green hydrogen production; however, interfacial charge transfer and intermediate adsorption/desorption kinetics of the cathodic hydrogen evolution reaction (HER) still introduce additional energy losses. Pt-based catalysts exhibit outstanding intrinsic HER activity, but their scarcity and high cost constrain large-scale deployment. Molybdenum disulfide (MoS₂), featuring favorable hydrogen adsorption thermodynamics, abundant resources, good chemical stability, and low cost, is among the most representative non-noble-metal candidates for HER catalysis. This review discusses the crystal structure, electronic properties, and HER mechanism of MoS₂, with emphasis on the key limitations of 2H-MoS₂, including the low activity of basal planes, limited electrical conductivity, and low density of accessible active sites. The effects of phase engineering, defect and elemental doping, heterostructure construction, and morphology regulation on active-site exposure, electronic-structure optimization, and interfacial charge transport are systematically analyzed. On this basis, the major challenges facing MoS₂-based catalysts under high current densities, long-term operation, and scalable synthesis are summarized, and their prospects for industrial water electrolysis are discussed.