Hydrogen Evolution Reaction at Anion Vacancy of Two-Dimensional Transition-Metal Dichalcogenides: Ab Initio Computational Screening

The catalytic activity for the hydrogen evolution reaction (HER) at the anion vacancy of 40 2D transition-metal dichalcogenides (TMDs) is investigated using the hydrogen adsorption free energy (Δ G_H) as the activity descriptor. While vacancy-free basal planes are mostly inactive, anion vacancy makes the hydrogen bonding stronger than clean basal planes, promoting the HER performance of many TMDs. We find that ZrSe₂ and ZrTe₂ have similar Δ G_H as Pt, the best HER catalyst, at low vacancy density. Δ G_H depends significantly on the vacancy density, which could be exploited as a tuning parameter. At proper vacancy densities, MoS₂, MoSe₂, MoTe₂, ReSe₂, ReTe₂, WSe₂, IrTe₂, and HfTe₂ are expected to show the optimal HER activity. The detailed analysis of electronic structure and the multiple linear regression results identifies the vacancy formation energy and band-edge positions as key parameters correlating with Δ G_H at anion vacancy of TMDs.