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 GH) 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 GH as Pt, the best HER catalyst, at low vacancy density. Δ GH 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 GH at anion vacancy of TMDs.