Pt decorated Janus WSSe monolayer: A gas-sensitive material candidate for SF6 decomposition gases based on the first-principles

In gas insulated switchgear, unavoidable partial discharge faults cause SF6 to decompose various low-fluorine compounds. These compounds react with micro-water to form acids, leading to gas insulated switchgear corrosion as well as reduced insulation properties. For this reason, on-line monitoring of SF6 decomposition gases is essential. In this work, based on density functional theory, the structures of pristine WSSe and platinum doped WSSe monolayer are established, and eight adsorption systems of SO2, SO2F2, SOF2 and HF gas molecules on pristine WSSe and Pt-WSSe monolayer are constructed by geometrical optimization. By analyzing parameters such as adsorption energy, charge density, density of states, orbital theory, conductivity, sensing response and recovery time, the adsorption performance and gas-sensing mechanism of each adsorption system were investigated. The analytical results showed that both intrinsic WSSe and Pt-WSSe were unsuitable for HF gas detection and exhibited physical adsorption. The adsorption energies of Pt-WSSe for SO2, SO2F2, and SOF2 were −1.596 eV, −1.702 eV, and −2.288 eV, respectively, which showed strong chemisorption. At the optimum operating temperature, the Pt-WSSe/SO2F2 system has a fast recovery time of 1.928 s, a high response of 28.436 and a strong resistivity change, and this gas-sensitive material is well suited for the detection of this gas molecule. The Pt-WSSe/SO2 system has a small response value of 1.928 and the Pt-WSSe/SOF2 system has a strong adsorption energy of −2.288 eV. Therefore, the Pt-WSSe monolayer is not suitable as a gas-sensitive material for SO2 and SOF2 detection. This work provides theoretical guidance for the future development of low power, highly sensitive, fast response gas sensors for gas insulated switchgear fault detection.