Enhancing Hydrogen Evolution Catalysis through Potential-Induced Structural Phase Transition in Transition-Metal Dichalcogenide Thin Sheets.

Enhancing electrocatalytic performance relies on effective phase control, which influences key catalytic properties, such as chemical stability and electrical conductivity. Traditional methods for manipulating the phase of transition-metal dichalcogenides (TMDs), including high-temperature synthesis, Li intercalation, and doping, involve harsh conditions and energy-intensive processes. This study introduces an innovative approach to crafting heterophase structures (2H-1T-WS) in TMDs, using WS as a model compound, encompassing both semiconducting (2H) and metallic (1T) types through a straightforward potential activation method. Insights from in situ electrochemical Raman spectroscopy, HR-TEM, and XPS measurements reveal distinctive partial phase-transition behavior. This behavior enables the partially exposed basal plane of 2H-1T-WS to demonstrate superior activity in the hydrogen evolution reaction (HER), attributed to enhanced electrical conductivity and the exposure of highly active sites. The potential-induced phase transition presents promising avenues for the development of catalysts with heterophase structures.