Transition metal sulfides/selenides as cathode electrocatalysts for enhanced hydrogen evolution: Nanostructure engineering strategies and recent progress

The depletion of fossil fuels and ecological concerns drive the urgent need for clean energy alternatives. Hydrogen (H 2 ), with its high energy density and carbon-neutral combustion producing only water, is a promising low-carbon carrier. Traditional methods like methane conversion and coal gasification yield low-purity hydrogen and emit CO 2 , pushing for cleaner alternatives such as electrocatalytic water splitting, which relies on efficient electrocatalysts for the hydrogen evolution reaction (HER) to overcome kinetic barriers. Though noble metals like platinum are effective, their cost and scarcity limit use. Transition metal sulfides (TMS) and selenides (TMSe) offer affordable alternatives with unique layered structures, despite challenges like poor conductivity and limited active sites. This review condenses recent nanostructure engineering strategies: morphology and phase engineering, defect engineering and doping, heterostructures, and nanocomposites to boost TMS/TMSe cathode performance for HER, assessing improvements in active site availability, charge transfer, and durability. The recent progress has been examined and explored using contemporary methods, followed by an analysis of the relationship between catalytic performance and the customization of electrocatalysts. The review concludes with insights into recent advancements, identifies and outlines challenges, and prospects for future innovations. • Transition metal sulfides/selenides as cost-effective HER electrocatalysts. • Nanostructure engineering enhances conductivity, activity, and durability. • Critical strategies to enhance performance are highlighted and discussed. • Recent advances show potential to rival or surpass platinum in performance. • Outlined challenges and prospects for sustainable hydrogen production.