Theoretical understanding of electronic and mechanical properties of 1T′ transition metal dichalcogenide crystals

Abstract

Transition metal dichalcogenides (TMDs) with a 1T′ layer structure have recently received intense interest due to their outstanding physical and chemical properties. While the physicochemical behaviors of 1T′ TMD monolayers have been widely investigated, the corresponding properties of layered 1T′ TMD crystals have rarely been studied. As TMD monolayers do not have interlayer interactions, their physicochemical properties will differ from those of layered TMD materials. In this study, the electronic and mechanical characteristics of a range of 1T′ TMDs are systematically examined by means of density functional theory (DFT) calculations. Our results reveal that the properties of 1T′ TMDs are mainly affected by their anions. The disulfides are stiffer and more rigid, diselenides are more brittle. In addition, the 1T′ polytype is softer than 2H TMDs. Comparison with the properties of the monolayers shows that the interlayer van der Waals forces can slightly weaken the TM–X covalent bonding strength, which can further influence the mechanical properties. These insights revealed by our theoretical studies may boost more applications of 1T′ TMD materials.

Machine learning predicted inelasticity in defective two-dimensional transition metal dichalcogenides using SHAP analysis

“…This conclusion is in agreement with previous reports on pristine 2D TMDCs wherein an identical trend was observed for elastic constants and microhardness. 43,44 This same trend remains intact for samples with isolated defects as well. Future explorations should look into the effect of interacting defects.…”

Defect engineering of 1T′ MX 2 (M = Mo, W and X = S, Se) transition metal dichalcogenide-based electrocatalyst for alkaline hydrogen evolution reaction

“…In general, the stronger adsorption of H on Low X is reflected by the slightly short X-H bond lengths listed in table S1. The stronger adsorption of H on Low X can be ascribed to the weaker interaction between M and Low X, which can be evidenced by the longer bond length between Low X and M [41,42]. Interestingly, the ∆G H * values on Low S are close to the desired one of 0.0 eV.…”

Simulation of Emission Spectra of Transition Metal Dichalcogenide Monolayers with the Multimode Brownian Oscillator Model

“…Another common spectral feature for WSe 2 , WS 2 , and MoS 2 is that there exists a certain temperature above which S drops precipitously to a much lower value that no longer changes with temperature. A smaller S at higher temperatures can be attributed to the decrease in normal coordinate displacement caused by an increase in disorder-induced localization. ,− Furthermore, the low HR factor is also related to geometric modifications such as the increase in bond length and bond angle caused by high temperature. A modifying factor has been calculated to bridge fitted exciton–phonon coupling strengths to the semiempirical Varshni equation for the first time.…”