Using Single-Layer HfS2 as Prospective Sensing Device Toward Typical Partial Discharge Gas in SF6-Based Gas-Insulated Switchgear

We performed density functional theory study on the adsorption properties of five typical SF6 decomposition products in gas-insulated switchgear on singlelayerHfS(2). The adsorption structure, adsorption energy, and electron transfer were discussed. We also considered the physical and chemical interactions between the adsorbed gas molecule and the HfS2 monolayer with the discussion of the charge density difference configurations, the electron localization functional configurations, and the density of states (DOSs). To assess the sensing property of singlelayer HfS2-based gas sensor, we built a simulated device with three parts, including left lead, scattering region, and right lead and the response to different gas molecules was evaluated. The results indicated that the SO2F2 molecule exhibited the largest adsorption energy but the HF molecule had the largest electron transfer. Only H2S adsorption leads to the obvious decrease of the bandgap. All the gas molecules could have chemical interactions with the HfS2 monolayer with different degrees based on the DOS analysis. For the simulated sensing device, according to the nonequilibrium Green's function method, it showed better response and selectivity in the voltage range between 1.2 and 1.6 V. The device exhibited the maximum current after HF adsorption and the minimum current after SO2F2 adsorption.