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Dissolved gas analysis (DGA) is the most commonly used transformer fault diagnosis technology at present. In this paper, according to the method of first principles of density function theory (DFT), the gas-sensitive mechanisms of four oil-soluble characteristic gases (H2, CO, C2H2, C2H4) on intrinsic SnS2and Cr3–SnS2were studied. The adsorption energy and electron transfer were calculated, and the density of states, energy bands, and recovery times were analyzed. It was concluded that H2and C2H4were physisorbed on the Cr3–SnS2monolayer, while CO and C2H2were chemisorbed. It is believed that the Cr3–SnS2material can be used in gas sensing for CO and C2H2. Cr3–SnS2is expected to serve as a gas detector for the detection of CO with both a good response and reusability. Therefore, Cr3–SnS2has very promising applications in the evaluation of the operation of oil-immersed transformers. This study will provide some help and inspiration for the development of the Cr3–SnS2monolayer in gas-sensitive materials.

Detecting the types and concentrations of dissolved gases in insulating oil by resistivity-type sensors is an extremely effective means for diagnosing faults in an oil-immersed transformer. However, further breakthroughs and innovations are needed in gas-sensitive materials for preparing high-performance resistivity-type sensors. In this investigation, the application possibility of using Pt-doped HfS2(Pt-HfS2) as gas-sensitive materials for the detection of dissolved H2, CO2, CH4, and C2H2in oil has been verified by analyzing the adsorption energy (Ead), differential charge density (DCD), density of states (DOS), frontier molecular orbital, and desorption time based on density functional theory (DFT). The outcomes suggest that the band gap of HfS2is obviously narrowed after doping Pt at the position of the bridge between the S and Hf atoms, resulting in a significant increase in the conductivity of HfS2. The low adsorption energy implies that there is only weak physical adsorption between Pt-HfS2and CO2(−0.783 eV). In contrast, the highly hybridized atomic orbitals of Pt with H2, CH4, and C2H2indicate that strong chemical adsorption reactions occur. Two-dimensional Pt-HfS2as a gas sensor has a great monitoring performance for CH4at 298 K (room temperature). This research serves as theoretical guidelines for probing the application potential of Pt-HfS2in fault diagnosis and predictive maintenance of an oil-immersed transformer.