Defect-Driven hydrogen Evolution: Enhanced hydrogen spillover on Pt-MoS2 interface via sulfur vacancies

The hydrogen spillover is considered a powerful strategy for improving the kinetics of hydrogen evolution reaction (HER) due to the decoupling of hydrogen adsorption and desorption. However, the hydrogen spillover rate strongly depends on the metal-support interfaces, and the Fermi levels (E f ) difference between metal and support hinders the occurrence of hydrogen spillover. Here, we prepared platinum (Pt) doped on molybdenum disulfide (MoS 2 ) with sulfur vacancies (Sv) catalyst (Pt/Sv-MoS 2 ) and investigated the internal relationship between metal-support interfaces and hydrogen spillover mechanism. The experimental and theoretical results show that sulfur (S) vacancies reduce the work function (ΔΦ) at the metal-support interface, thus accelerating the migration rate of hydrogen from Pt to Sv-MoS 2 . Meanwhile, the introduction of S vacancies promotes the high dispersion of Pt nanoparticles (Pt NPs) and weakens the electron supply from Pt to MoS 2 , facilitating active hydrogen (*H) adsorption step and thus increasing the hydrogen coverage on the Pt sites. Consequently, the prepared Pt/Sv-MoS 2 catalyst exhibited significantly enhanced HER activity, achieving an overpotential of 26 mV at 10 mA·cm −2 and a Tafel slope of only 28 mV·dec −1 , which is superior to commercial 20 % Pt/C.