Anhui Normal University

About: Anhui Normal University is a education organization based out in Wuhu, China. It is known for research contribution in the topics: Catalysis & Population. The organization has 7955 authors who have published 7309 publications receiving 117443 citations.

Twisted MX2/MoS2 heterobilayers: effect of van der Waals interaction on the electronic structure

Abstract: A comprehensive first-principles study of the electronic properties of twisted 2D transition metal dichalcogenide (TMDC) heterobilayers MX2/MoS2 (M = Mo, Cr, W; X = S, Se) with different rotation angles has been performed. The van der Waals (vdW) interaction is found to have an important effect on the electronic structure of two-dimensional (2D) TMDC heterobilayers. Compared to non-twisted heterobilayers, the interlayer distance of twisted heterobilayers increases appreciably, thereby changing the vdW interaction of the heterobilayers as well as the electronic structure of the MX2/MoS2 systems. As a result, for CrSe2/MoS2 and MoSe2/MoS2 systems, the indirect bandgap (Γ–K) exhibits a notable enlargement (about 0.1 eV), leading to the indirect-to-direct gap transition. At twisting angles between 13.2° and 46.8°, the interlayer distance is nearly constant for the mismatched lattices over the entire sample, resulting in nearly the same electronic structure. Even after considering the spin–orbit coupling (SOC) effect, the indirect-to-direct transition is still predicted to occur in the WS2/MoS2 heterobilayer due to the large spin–orbit splitting.

Preparation of hollow porous Co-doped SnO2 microcubes and their enhanced gas sensing property

Abstract: Hollow porous Co-doped SnO2 microcubes were achieved by a template-free chemical solution route combined with subsequent alkali-washing, calcination and acid-washing process. Spontaneous phase segregation yields such a special hollow porous structure. Several techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric-differential thermal analysis, and Brunauer–Emmett–Teller N2 adsorption–desorption analyses, were used to characterize the structure and morphology of the products. During the process, alkali-washing in the first step is critical to the formation of the hollow structure. The process of inducing porosity starts with a crystalline single-phase hydroxide precursor CoSn(OH)6 formed by co-precipitation of the metal ions from aqueous solution. Thermal decomposition of the precursors leads to an intimate mixture of Co3O4 and porous tetragonal SnO2. The hollow porous Co-doped SnO2 microcubes are obtained after the Co3O4 phase has been removed by acid-washing. A decomposition–aggregation–dissolution process is proposed to demonstrate the formation of such a special structure. Furthermore, the gas sensing properties of the as-prepared hollow, porous, Co-doped SnO2 microcubes for some volatile organic vapors were tested, which exhibited a much better sensing performance than that of the porous Co-doped SnO2 microcubes, indicating that the special hollow porous Co-doped SnO2 structures are highly promising for applications as gas sensors.