Activating Basal Planes and S-Terminated Edges of MoS2 toward More Efficient Hydrogen Evolution

Molybdenum disulfide (MoS2) has been considered as a promising alternative to platinum (Pt)-based catalyst for hydrogen evolution reaction (HER) due to its low cost and high catalytic activity. However, stable 2H phase of MoS2 (2H-MoS2) exhibits low catalytic activity in HER due to the inert basal plane and S-edge. Thus, to exploit the basal plane and S-edge for additional electrocatalytic activity, a facile strategy is developed to prepare P-doped 2H-MoS2 film on conductive substrate via low-temperature heat treatment. Due to the inherent difficulty of P-doping into MoS2 crystal structure, oxygen (O)-doping is utilized to aid the P-doping process, as supported by the first-principles calculations. Interestingly, P-doping could dramatically reduce Mo valence charge, which results in the functionalization of the inert MoS2 basal plane and S-edge. In agreement with simulation results, P-doped 2H-MoS2 electrode exhibits enhanced catalytic performance in H-2 generation with low onset potential (130 mV) and small Tafel slope of 49 mV dec(-1). The enhanced catalytic performance arises from the synergistic effect of the activated basal plane, S-edge, and Mo-edge sites, leading to favorable hydrogen adsorption energies. Most importantly, improved cyclic stability is achieved, which reveals chemically inert properties of P-doped 2H-MoS2 in acidic electrolyte.