Single-Layer MoS₂ with Sulfur Vacancies: Structure and Catalytic Application

Abstract

Single-layer MoS 2 is proving to be a versatile material for a wide variety of electronic, optical, and chemical applications. Sulfur depletion, without destabilization of the single layer, is considered a prudent way for making the basal plane of the layer catalytically active. Based on the results of our density-functional-theory examination of vacancy structures on one side of an MoS 2 layer, we show that the formation energy per sulfur vacancy is the lowest (energetically favorable) when the vacancies form a row and that the longer the row, the lower the formation energy. In addition, we find that the lowest energy barrier for the diffusion of sulfur vacancy at the row structures through the exchange of a vacancy with a nearby sulfur atom is 0.79 eV and that this barrier increases as the row elongates. We also evaluate the propensity for catalytic activity of an MoS 2 layer with two types of sulfur-vacancy structures (row and patch) and find the energetics for alcohol synthesis from syngas to be more favorable for the layer with a sulfur-vacancy patch.

Hydrogen adsorption on MoS2-surfaces: a DFT study on preferential sites and the effect of sulfur and hydrogen coverage

“…Even though the differences are rather small (−0.06 eV, −0.10 eV and −0.04 eV), already the observation that the energetic cost of forming divacancies is approximately equal to forming monovacancies can intuitively be regarded as rather surprising. Nevertheless, this behavior is in line with results reported by Le et al 63 as well as Sensoy et al 64 . In the latter work it is shown that the defect-induced lattice reorganization in the 2H-MoS 2 basal plane is very small and local, and that the interaction between isolated monovacancies is negligible.…”

Control of structure of WSe x /C nanocoatings synthesized via pulsed laser deposition

“…According to modern con cepts, the edges sites formed by cutting the laminar packing perpendicular to the orientation of the basal planes are catalytically active. In accordance with the calculations, the most catalytically active metal atoms can be on the surface layer, in the vicinity of which chalcogene atom is absent [5].…”

Defect Engineering of MoS2 and Its Impacts on Electrocatalytic and Photocatalytic Behavior in Hydrogen Evolution Reactions

“…Insertion of 1T‐MoS 2 into 2H‐MoS 2 as a phase defect is expected to be a potential method to enhance conductivity and to increase active sites for MoS 2 under relatively mild synthetic condition . Besides phase change, another strategy to promote catalytically performance of MoS 2 is the introduction of S‐vacancies into MoS 2 crystal structure . It has been reported that the exposed atoms adjacent to S‐vacancies are activated; the uncoordinated Mo atoms allow their d‐states to bind adsorbed species and also allow S atoms to bind hydrogen atoms, resulting in an increased concentration of active sites .…”