Stabilizing and Activating Active Sites: 1T-MoS₂ Supported Pd Single Atoms for Efficient Hydrogen Evolution Reaction

Metallic 1T-MoS₂ with high intrinsic electronic conductivity performs Pt-like catalytic activity for hydrogen evolution reaction (HER). However, obtaining pure 1T-MoS₂ is challenging due to its high formation energy and metastable properties. Herein, an in situ SO₄ ^2--anchoring strategy is reported to synthesize a thin layer of 1T-MoS₂ loaded on commercial carbon. Single Pd atoms, constituting a substantial loading of 7.2 wt%, are then immobilized on the 1T-phase MoS₂ via Pd─S bonds to modulate the electronic structure and ensure a stable active phase. The resulting Pd₁/1T-MoS₂/C catalyst exhibits superior HER performance, featuring a low overpotential of 53 mV at the current density of 10 mA cm^-2, a small Tafel slope of 37 mV dec^-1, and minimal charge transfer resistance in alkaline electrolyte. Moreover, the catalyst also demonstrates efficacy in acid and neutral electrolytes. Atomic structural characterization and theoretical calculations reveal that the high activity of Pd₁/1T-MoS₂/C is attributed to the near-zero hydrogen adsorption energy of the activated sulfur sites on the two adjacent shells of atomic Pd.