Tailored Two‐Dimensional Transition Metal Dichalcogenides for Water Electrolysis: Doping, Defect, Phase, and Heterostructure

Abstract The demand for hydrogen production technology to replace fossil fuels and address the global climate crisis has become one of the most urgent tasks in the modern era. Among the promising breakthroughs, electrochemical water splitting using renewable energy sources offers a path to green hydrogen production that is both feasible and economically viable. However, the current state‐of‐the‐art catalysts for the water‐splitting reaction predominantly rely on scarce and costly noble metals, posing a significant challenge to the mass production of green hydrogen. In this context, two‐dimensional transition metal dichalcogenides (2D TMDs) have emerged as compelling candidates to replace noble metals, owing to their impressive reactivity and cost‐effectiveness. These TMD‐based electrocatalysts demonstrate exceptional reactivity at their active edge sites, while the basal planes remain catalytically inert. Several tailored strategies can activate these basal planes by modifying the chemical bonding nature and electronic band structure of the constituent atoms, thus enhancing the overall reactivity of TMDs. This review summarizes recent advancements in the modulation methodologies of 2D TMDs to enhance their water‐splitting reactivity. We highlight various chemical modification strategies, including heteroatom doping, defect‐engineering, and heterostructure formation, and provide insights into future research directions for the development of advanced 2D TMD‐based water‐splitting catalysts.