Comparative Investigations on Ni-Doped and ZnTe Monolayers for SF₆ Decomposition Characteristic Gases Based on Density Functional Theory

When SF₆ decomposition is caused by partial discharges, characteristic gases such as H₂S, SO₂, SOF₂, and SO₂F₂ are generated in high-voltage equipment, which poses a great threat to the regular operation of power equipment. Based on density functional theory, the adsorption and sensing characteristics of these four gases on a ZnTe monolayer and Ni-ZnTe are investigated in terms of adsorption energy, charge transfer, differential charge density, microscopic state density, desorption time, and sensitivity in this paper. Through comparative analysis, the doping of transition metal significantly opens the band gap and ensures that the desorption times of H₂S (538 s at 298 K), SO₂ (1.76 s at 498 K), and SOF₂ (4.30 s at 498 K) are effectively reduced in the case of more intense chemisorption. The adsorption energies of the three gases on Ni-ZnTe are -1.25, -0.87, and -1.21 eV, respectively. The values of band gap changes are -0.508, +0.458, and -0.748 eV, respectively, compared to the values before adsorption (1.110 eV). The more obvious difference between the band gaps of the four adsorption systems after doping also ensures that the substrate has a better resistance to cross-talk when detecting gases. Therefore, the Ni-ZnTe monolayer shows excellent potential in monitoring H₂S, SO₂, and SOF₂ when the three gases coexist and works well as an adsorbent for SO₂F₂.