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With the development of industrialization, the use of mercury in industry has become more and more widespread, causing serious impacts on the environment. It is therefore urgent to find new effective ways to combat mercury pollution. In this paper, The effect of C, O, P, Ni and Au doping on the adsorption of Hg atoms by WS 2 has been investigated based on the first nature principle of density functional theory. The electronic structures and optical properties of the adsorbed systems were calculated after atomic doping. The results show that the absolute value of the adsorption energy of the intrinsic adsorption system is small and does not favour the adsorption of Hg on WS 2. However, after C, P, Ni and Au doping, the adsorption energy of the system is significantly increased and a strong charge transfer between WS 2 and Hg atoms occurs, as well as a significant change in the band gap of the structure. This suggests that atomic doping favors the adsorption of Hg by WS 2. The effect of O doping on the adsorption system is not significant. In addition, a study of the optical properties revealed that the static dielectric constants of the system appeared to increase to varying degrees after the doping of the atoms. The doping of P, Ni and Au atoms increases the light absorption coefficient and contributes to the photocatalytic efficiency of the structures. The doped atoms cause a red shift in the reflectivity peak of the adsorbed system. In summary, the doping of C, P, Ni and Au enhances the adsorption of Hg atoms on WS 2. O doping has less effect on the adsorption of Hg on WS 2. • In this paper, the effect of C, O, P, Ni and Au doping on the adsorption of Hg atoms by WS2 was investigated. • The results show that atomic doping favors the adsorption of Hg by WS2. • Atomic doping alters the electronic properties of the structure. • Atomic doping alters the optical properties of the structure. [ABSTRACT FROM AUTHOR]

The electronic and optical properties of hydrogenated silicene at different torsion angles are investigated using the density functional theory (DFT). It was found that when silicene was hydrogenated, the Si atoms were pulled out of plane due to covalent interactions between the Si and H atoms, increasing their flexural height to 0.731 Å. Torsional deformation decreases the structural stability of hydrogenated silicene and its adsorption energy decreases with increasing twist angle. Under the effect of torsion deformation, the bandgap of hydrogenated silicene increases and then decreases. The bandgap is 2.168 eV at a torsion angle of 0∘, indicating a wide bandgap semiconductor. Mulliken's charge population analysis shows that charge transfer occurs between Si–H atoms, with Si atoms losing electrons and becoming positively charged and H atoms gaining electrons and becoming negatively charged. From the analysis of optical properties, the torsional deformation induced the maximum absorption and reflection peaks of all the hydrogenated silicene systems to appear in the ultraviolet region. Compared with the system without torsional deformation, these peaks exhibit varying degrees of red and blue shifts. The above findings provide guidance for the application of silicene in nanooptoelectronic devices. [ABSTRACT FROM AUTHOR]

Based on first-principle calculations using density functional theory, the effects of alternate substituting of Fe, Ru, Os, Co, and Ni on the magnetic properties of the silicone system were investigated, and the stability, charge density, electronic structure, and optical properties of the system were analyzed. The results show that all the substituting systems show subferromagnetic properties except for the Ru atom–substituting silicone system which shows magnetic quenching and exhibits paramagnetism. Within the current study, the substituting of Fe, Ru, Os, Co, and Ni atoms does not change the metallic properties of silicone. Comparing the four substituting atoms of Fe, Os, Co, and Ni, it is revealed that the magnetic moment of the Fe-, Os-, and Co-substituting silicone system is mainly provided by the dopant atoms, and the magnetic moment of the Ni-substituting system is not contributed by the Ni atoms, but by the Si atoms in the silicone that are not covalently bonded to the Ni atoms induced by the dopants. The possible reason for the paramagnetic properties of Ru atom–substituting silicone systems is the strong hybridization and resonance between the dopant Ru atom and Si atom orbitals, which leads to the formation of stable covalent bonds between Ru–Si and quenching of the orbital magnetic moment. The magnetic properties induced by the transition metal can enhance the light absorption intensity and have an effect on the photocatalytic activity. [ABSTRACT FROM AUTHOR]