Experimental and theoretical study of catalytic dye degradation and bactericidal potential of multiple phase Bi and MoS2 doped SnO2 quantum dots†

First principle study of the effect of doping on the optoelectronic properties of Cr-adsorbed MoS2

CONTEXT

This study explores, for the first time, using first principles, the impact of substitutional doping with boron (B), carbon (C), and nitrogen (N) on the adsorption of chromium (Cr) on monolayer MoS2. The effects of doping on the Cr adsorption behavior of MoS2 were investigated using four MoS2 systems, namely, pure, boron (B)-doped, carbon (C)-doped, and nitrogen (N)-doped, in order to gain an in-depth understanding of the mechanism of the effects of doping on the electronic structure and optical properties of Cr adsorbed by MoS2, to optimize the properties of MoS2, to explore new areas of application, and to promote the development of materials science. Four MoS2 adsorption systems of Cr adsorption on pure, B-doped, C-doped, and N-doped MoS2 were optimized, and the optimized results showed that the stable adsorption location of Cr on both pure and doped MoS2 was the hollow location at the top of the folded hexagon. The findings reveal that pure MoS2 has an adsorption effect on Cr, and doped elements B, C, and N can promote the adsorption of Cr on MoS2, and the strong and weak order of this promotion is B > C > N.

METHODS

In this paper, we use the CASTEP module in the simulation software Materials Studio to perform simulation calculations and analyses to optimize the simulation of Cr adsorption by MoS2 doped with B, C, and N atoms using the generalized gradient approximation (GGA) plane-wave pseudo-potential method (Perdew et al. Phys Rev Lett 77(18):3865-3968, 1996), as well as Perdew-Burke-Ernzerhof (PBE) generalized functionals (Segall et al. J Phys: Condens Matter 14(11):2717-2744, 2022). The convergence test reveals that it is more reasonable to set the K-point network to 3 × 3 × 1 and the truncation energy to 400 eV. In this paper, a 3 × 3 × 1 supercell structure with 18 S atoms and 9 Mo atoms is selected. The convergence value of the iteration accuracy is 1.0e - 5eV/atom, and all the atomic forces are less than 0.02eV/Å. Additionally, to prevent MoS2 interlayer interaction, a vacuum layer with a thickness of 18 Å is set in the C direction. The geometrical optimization of the model is performed first, and then the corresponding adsorption energies of the model and the nature of the electronic structure are analyzed.

Defect engineered magnetism induction and electronic structure modulation in monolayer MoS2

The electronic, magnetic, and optical characteristics of a defective monolayer MoS2 were examined by employing density functional theory (DFT)-based first-principles calculations. The effects of several defects on the electrical, magnetic, and optical properties, including Mo vacancies, MoS3 vacancies, and the substitution of a single Mo atom by two S atoms were studied in this work. Our first-principles calculations revealed that different types of defects produced distinct energy states within the band gap, leading to a band gap reduction after the introduction of various types of defects, which caused a change from semiconducting to metallic behavior. The spin-up and spin-down states were separated in the case of MoS3 vacancy. The total magnetization was ∼ -0.83 μ B /cell, and the absolute magnetization was ∼ 1.23 μ B /cell. Moreover, spin-up states had a 0.45 eV band gap, whereas spin-down states were metallic. Consequently, it can be promising for spin filter applications. It was disclosed that the broadband part of the electromagnetic spectrum has a high absorption coefficient, which is necessary for applications including impurity detection, photodiodes, and solar cells. Designing spintronic and optoelectronic devices will benefit from the modification of the electrical, optical, and magnetic properties by defect engineering of MoS2 monolayers presented here.