Modulating ultrafast carrier dynamics behavior via vacancy engineering of ReSe2 with Se vacancy for efficient electrochemical activity

Vacancy engineering is powerful for manipulating material properties. Selenium vacancies (VSe) exert significantly impact on the physicochemical properties of rhenium diselenide (ReSe2), triggering applications in catalysis and photoelectric devices. However, the effects on electronic structure, carrier lifetime, and electrochemical activity are inadequately explored and poorly elucidated. Herein, hydrothermal-controlled growth of ReSe2 with VSe is synthesized by different strategies. The ethanol-assisted hydrothermal method can adjust VSe concentration of ReSe2 on carbon paper by time parameters. Mediated excitonic effects were characterized in the transient absorption spectroscopy and photoluminescence of VSe-regulated ReSe2. The defect level produces unique defect emission peak, and the VSe-mediated exciton dynamics problem was discussed. The transient absorption result shows that high VSe concentration can optimize carrier lifetime, carrier separation efficiency, and electron utilization. The electrocatalytic hydrogen evolution reaction of ReSe2 catalyst revealed the electrochemical activity regulation by VSe concentration, which provides ideas for enhancing catalyst performance. Density functional theory result confirms the role of selenium vacancies in the regulation of the electronic structure of ReSe2. This work proffers an optimal solution strategy for hydrothermal preparation of ReSe2, and demonstrates the feasibility of regulating electrochemical activity by vacancy engineering. The excellent performance is beneficial for water cracking and physical devices.