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

Vacancy engineering has repeatedly proven to be a powerful strategy for manipulating material properties. The important influence of selenium vacancies (VSe) on the physicochemical properties of rhenium diselenide (ReSe2), exciting applications can be opened in areas such as catalysis and photoelectric devices. However, the effects of VSe on electronic structure, carrier lifetime, and electrochemical activity of ReSe2 have remained inadequately explored and poorly elucidated. Herein, hydrothermal controlled growth of ReSe2 with vacancy (VSe-ReSe2) is used by different synthesis strategies, revealing its growth mechanism. An ethanol-assisted hydrothermal method based on carbon paper was used to adjust the VSe concentration by changing the time parameters. Mediated excitonic effects in the transient absorption (TA) spectroscopy and photoluminescence response of ReSe2 regulated by VSe were characterized. The defect level (DL) leads VSe-ReSe2 to produce a unique defect emission peak, and the VSe-mediated exciton dynamics problem was discussed. Moreover, the TA result of VSe-ReSe2 shows that high VSe concentration prolongs carrier lifetime and causes high carrier separation efficiency and electron utilization. The electrocatalytic hydrogen evolution reaction of ReSe2 catalyst revealed the ability of VSe concentration to regulate the electrochemical activity, which provides ideas for vacancy management catalyst performance. The presence of DL and the reduction of band gap are indicated by density functional theory, which confirms the regulatory effect of VSe concentration on the electronic structure of ReSe2. This work proffers an optimal solution strategy for hydrothermal preparation of ReSe2, which demonstrates the feasibility of regulating electrochemical activity by vacancy engineering, and the excellent performance of VSe-ReSe2 makes it show great potential in many fields such as water cracking and physical devices. [Display omitted] •A regulation strategy for the successful construction of VSe rich ReSe2 nanoflowers was developed.•DFT investigated the reduction of the band gap and orbital contribution of ReSe2 regulated by VSe.•Mediated excitonic effects in the TA and PL response of ReSe2 regulated by VSe were analyzed.•The effectively regulate the HER activity of VSe-ReSe2 were analyzed. Vacancy engineering is powerful for manipulating material properties. Selenium vacancies (VSe) exert significantly impact on the physicochemical properties of rhenium dis