Phase Engineering of WS 2 for Enhanced Electrocatalytic Water Splitting: Mechanisms, Strategies, and Perspectives

Transition-metal dichalcogenides (TMDs), particularly tungsten disulfide (WS2), have emerged as promising electrocatalysts for electrochemical water splitting owing to their tunable electronic structures and abundant active sites. The phase transition between the semiconducting 2H phase and the metallic 1T phase of WS2 plays a pivotal role in optimizing the catalytic activities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). This review systematically summarizes the latest research advances in phase-controllable WS2 for electrochemical water splitting with a focus on phase transition mechanisms, synthesis strategies (including chemical intercalation, strain engineering, and doping modification), and structure-activity relationships. Furthermore, the challenges and future development directions in designing high-performance and stable phase-engineered WS2 catalysts are discussed, providing valuable insights for advancing next-generation energy conversion technologies.