Localization of edge states at triangular defects in periodic MoS2 monolayers

Closed‐Loop Defect States in 2D Materials with Honeycomb Lattice Structure: Molybdenum Disulfide

“…As the localized midgap states are unoccupied, the partial charges on the single atoms do not differ significantly between defective and pristine areas of the MoS 2 monolayer. [8] As experimental results indicate that the (electro-)catalytic properties of defective MoS 2 depend on the size and density of the triangular holes, [48] this study investigates the evolution of the densities of electronic states of triangular pores in MoS 2 as a function of the hole size and the hole distance, which both affect the average density of potentially catalytic defects. The obtained results for the densities of electronic states as a function of the energy are shown in Figure 4 for holes with low sulfur excess along the edges and in Figure 5 for holes terminated with high sulfur excess.…”

“…In contrast to platelets and isolated point defects, only few theoretical studies have been devoted to holes in TMDC layers. [8,41,44,47] Our preliminary investigations for two selected hole geometries with different lateral spacing analyzed the local atom relaxations and the atom-and orbital-resolved electron density distribution with particular focus on the localization of edge states within the same computational setting as in this study. [8] A very small structural relaxation of 0.16 Å occurs for the atoms located in the corners of the holes; all other relaxations are 60% of this value or smaller and limited to the atoms in the next nearest vicinity of the edges and corners.…”

“…[8,41,44,47] Our preliminary investigations for two selected hole geometries with different lateral spacing analyzed the local atom relaxations and the atom-and orbital-resolved electron density distribution with particular focus on the localization of edge states within the same computational setting as in this study. [8] A very small structural relaxation of 0.16 Å occurs for the atoms located in the corners of the holes; all other relaxations are 60% of this value or smaller and limited to the atoms in the next nearest vicinity of the edges and corners. For comparing the localization of different orbitals quantitatively a participation ratio was defined in the study by Niebur et al [8] It indicates the percentage of all atoms within the structure model that contribute to a specific orbital.…”

“…They may split off the electronic states of the extended 2D layer and possess distinctly different physical and chemical properties, for instance, even exhibit chiral features. [3,6] For holes, which are inner boundaries in 2D materials, such states have been addressed less frequently, but results from high-resolution transmission electron microscopy, [7] electron holography, [2] and model calculations with the density-functional theory [8] indicate their presence.…”

“…For MoS 2 DFT calculations indicate that localized electronic states are formed at point defects such as sulfur or molybdenum vacancies, but 1D extended states may be formed along the edges of ribbons, platelets, and triangular holes. [8,44,47] This study focuses on the evolution of 1D extended electronic states along the edges of holes in the MoS 2 monolayer as a prototypical TMDC, their interplay with extended 2D and localized defects and the relative thermodynamic stabilities. Section 2 briefly describes the model systems used in the study: sulfurterminated triangular platelets with the composition MoS 2þx , sulfur-poor and sulfur-rich terminations of triangular holes in the extended MoS 2 layer and a more general pore with hexagonal shape, that combines both termination types.…”