Interplay between transition-metal dopants and sulfur vacancies in MoS2 electrocatalyst

We investigate the effect of single-atom doping on the hydrogen evolution reaction (HER) activity of MoS2 using first-principles calculations. In Ru-doped MoS2 that was recently suggested as a promising HER catalyst, we show that sulfur vacancy (V-S) prefers to form defect complexes with Ru substituting for Mo (Ru-Mo). We examine hydrogen adsorption free energy at various potential active sites, which underlines that V-S in the defect complex can serve as important active centers for HER. We also examine various transition-metal (TM) dopants for MoS2. The results show that several TMs such as Sn, Tc, Ir, Rh, Ru, Re, Os, Pd, and Pt can be used as dopants to promote the HER process on MoS2. By uncovering the active sites for HER in single-atom doped MoS2 as well as suggesting several promising dopants, this work will open the way to developing novel 2D catalysts for HER.