Surface Morphology and Sulfur Reduction Pathways of MoS Mo Edges of the Monolayer and (100) and (103) Surfaces by Molecular Hydrogen: A DFT Study.

We have performed a density functional theory study of the MoS monolayer and the MoS (100) and (103) surfaces in relation to the early stages of the hydrodesulfurization reaction. In many X-ray diffraction (XRD) results, the (103) surface exhibits a higher peak than the (100) surface, yet one of the most frequently occurring surface has not been studied extensively. By analyzing experimental studies, we conclude that the (103) surface of MoS is the most frequently occurring edge surface when the sample size is thicker than ∼10-15 nm. Herein, we report the first comparison of reaction paths for the formation of a sulfur vacancy on the (103) surface of MoS, monolayer, and (100) surface of MoS. The reason for the occurence of the (103) surface in the XRD patterns has been established. We point out the similarity in the reaction barriers for the monolayer and (100) and (103) surfaces and discuss the reason for it. Moreover, we found a more energetically favorable step in the reaction pathway for the formation of a sulfur vacancy, which allowed us to refine the previously established pathway.