Effect of sulphur vacancy on geometric and electronic structure of MoS2 induced by molecular hydrogen treatment at room temperature

Investigations into the interaction between molecular hydrogen and molybdenum disulphide have been in increasing demand to improve the understanding of the hydrodesulphurisation process, especially the creation of sulphur vacancies which result in coordinatively unsaturated sites in MoS2. Here we present comprehensive studies of the structural and electronic modulation caused by exposure of MoS2 to H-2 over a low temperature range, which may be helpful for industrial applications. Detail investigations were conducted with Raman spectroscopy, high resolution transmission electron microscopy (HRTEM), and electrical transport properties as a function of H-2 gas pressure up to 24 bar from 295 K to 350 K. Upon exposure to H-2, we observed bond-softening using Raman spectroscopy, a decrease in d-spacing from the TEM results, and an increase in conductance, all of which are consistent with the first-principles calculations. The results demonstrate the formation of sulphur vacancies even under low H-2 pressure at low temperature.