Electronic structure and reactivity of defect MoS2

Electronic structure and reactivity of defect MoS2 II. Bonding and activation of hydrogen on surface defect sites and clusters

“…These authors also examined adsorption of hydrogen on the MoS 2 edges and relative stabilities of various edge structures as a function of H 2 S/H 2 and the systemÕs thermodynamic potentials. We have previously reported some common features regarding the hydrogen-free MoS 2 edge electronic structure, in particular the metallic character of extended edge surface states [29] that agree well with the earlier results of Byskov et al [22].…”

“…The computational tools employed in this study have been described in detail previously [29]. Briefly, all calculations use density functional theory (DFT) [37,38].…”

“…Monohydrides and dihydrides are predicted to be formed on exposed low-coordinated Mo sites on edge facets of the periodic MoS 2 crystals broken along crystallographic directions shown to form edges of varying degree of stability in our preceding paper [29]. The question of heteropolar splitting of molecular hydrogen to surface Mo-H and S-H moieties and homopolar splitting into two S-H groups that has been suggested to occur on pyritic sulfides [36] is also addressed.…”

“…2a) had the symmetry C 2v and a singlet spin state. The spin is somewhat surprising, as the H 2 molecule is a singlet while the MoS 2 monomer was found to be most stable in the triplet state [29,30]. The H-H distance was 3.08 Å and the Mo-H distances were 1.72 Å , consistent with a dihydride configuration.…”

MoS2/TiO2 Edge‐On Heterostructure for Efficient Photocatalytic Hydrogen Evolution

“…Such configuration leads to a low exposure of the active edge sites. [18][19][20] Furthermore, in such lay-down configuration of MoS 2 flakes, the photoexcited electrons in the semiconductor have to hop through each layer to reach the active edge sites in the MoS 2 flakes, resulting in a much higher electron resistance (≈2200 times higher than the electron moving in the same layer). [21,22] According to the fact that edges of MoS 2 is more conductive than its basal plane, [13,21,23,24] making MoS 2 standing on the semiconductor surface, e.g., connecting the edges of few-layered MoS 2 flakes with the semiconductor, serves as a promising heterostructures for improving the efficiency of the hydrogen evolution, owing to a better electronic contact and an optimized electron transport pathway.…”