In situ doping Pt single atoms into 3D flower-like 1T-MoS₂ via Pt-S bond for efficient hydrogen evolution reaction

Combining single atoms via phase transition engineering (from 2H to 1T) remains a challenge in MoS₂-based catalysts. Herein, we report that Pt single atoms (Pt_SA) were doped into a 3D flower-like 1T-MoS₂ catalyst (Pt_SA@MoS₂) using a Pt-S bonding strategy. Doping with Pt_SA induced a phase transition in MoS₂ from the 2H phase to the 1T phase. Pt_SA@MoS₂ exhibited outstanding hydrogen evolution reaction (HER) performance, featuring an overpotential of 25 mV at 10 mA cm^-2, a Tafel slope of 43.6 mV dec^-1, and excellent long-term stability. The Pt-S first-shell scattering of Pt_SA@MoS₂ in extended X-ray absorption fine structure (EXAFS) directly indicated that the Pt_SA was anchored near S atoms, forming Pt-S bonds. Furthermore, S atoms proximal to Pt functioned as catalytically active sites for HER, with Pt acting as an electron transfer mediator, facilitating the electron transfer from Mo to Pt and then to S. The p-band center of S showed a positive shift, indicating that Pt_SA@MoS₂ interacted weakly with hydrogen, thereby accelerating the desorption of H atoms to generate H₂. Additionally, Pt_SA@MoS₂ exhibited a ΔG_H* of only -0.13 eV, which also favored H₂ production.