Designing Pd/O co-doped MoSx for boosting the hydrogen evolution reaction

Abstract

Molybdenum disulfide has great potential as an electrocatalyst to drive the hydrogen evolution reaction (HER), but HER catalysts based on transition metal (TM) and non-metal (NM) co-doped MoS₂ have rarely been reported because of the difficulty of preparation. Herein, we design an upgraded sacrificial-counter-electrode method to create a favorable environment for atomic-scale substitution to synthesize Pd/O co-doped MoS_x (sub-MoS_x/CNTs/Pd_gly), which exhibits a small overpotential of 23 mV at a current density of 10 mA cm⁻², a low Tafel slope of 18 mV dec⁻¹ and good catalytic stability. Density functional theory (DFT) calculations reveal that the Pd/O co-doped MoS₂ tends to form defect-pairs (Pd_Mo + O_S) in MoS₂, and the unsaturated S atoms around the defects enormously promote the HER activity.