Facilitating the Hydrogen Evolution Reaction on Basal-Plane S Sites on MoS₂@Ni₃S₂ by Dual Ti and N Plasma Treatment

Atomic engineering of the basal plane active sites in MoS₂ holds great promise to boost the electrocatalytic activity for hydrogen evolution reactions (HER), yet the performance optimization and mechanism exploration are still not satisfactory. Herein, we proposed a dual-plasma engineering strategy to implant Ti and N heteroatoms into the basal plane of MoS₂ supported by Ni₃S₂ nanorods on nickel foam (MSNF) for efficient electrocatalysis of HER. Owing to the low formation energy of Ti dopants in MoS₂ and the extra charge carriers introduced by N dopants, the optimally codoped samples N1.0@Ti500-MSNF demonstrate significant morphology changes from nanorods to urchin-like nanospheres with the surface active areas increased by seven-fold, as well as enhanced electrical conductivity in comparison with the nondoped counterparts. The HER performance of N1.0@Ti500-MSNF is comparable with the Pt-based catalyst: overpotential of 26 mV at 20 mA cm^-2, Tafel slope of 35.6 mV dec^-1, and long-term stability over 50 h. First-principles calculation reveals that N doping accelerates the dissociation of water molecules while Ti doping activates the adjacent S sites for hydrogen adsorption by lowering the Gibbs free energy, resulting in excellent HER activity. This work thus provides an effective strategy for basal plane engineering of MoS₂ heterostructures toward high-performance HER and sustainable energy supply at reasonable costs.