Pt-Doped HfS 2 Monolayer as a Novel Sensor and Scavenger for Dissolved Gases (H 2 , CO 2 , CH 4 , and C 2 H 2 ) in Transformer Oil: A Density Functional Theory Study.

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 HfS 2 (Pt-HfS 2 ) as gas-sensitive materials for the detection of dissolved H 2 , CO 2 , CH 4 , and C 2 H 2 in oil has been verified by analyzing the adsorption energy ( E ad ), 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 HfS 2 is 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 HfS 2 . The low adsorption energy implies that there is only weak physical adsorption between Pt-HfS 2 and CO 2 (-0.783 eV). In contrast, the highly hybridized atomic orbitals of Pt with H 2 , CH 4 , and C 2 H 2 indicate that strong chemical adsorption reactions occur. Two-dimensional Pt-HfS 2 as a gas sensor has a great monitoring performance for CH 4 at 298 K (room temperature). This research serves as theoretical guidelines for probing the application potential of Pt-HfS 2 in fault diagnosis and predictive maintenance of an oil-immersed transformer.