Sensing Characteristics of the SnSe/GeSe Heterojunction on Dissolved Gases in Transformer Oil

Oil immersed power transformers are important pieces of equipment in the power transmission and distribution system. The gas generated by partial discharge and other faults is dissolved in transformer oil, which reduces the insulation performance of equipment and seriously affects the safe and stable operation of the power system. The analysis of dissolved gas (DGA) in transformer oil can realize the monitoring and fault diagnosis of an oil immersed transformer. Based on the first-principles density functional theory, the adsorption characteristics of dissolved gases (H₂, CO, C₂H₂, CH₄, C₂H₄, C₂H₆) in the SnSe/GeSe heterojunction were studied. First, the optimized SnSe/GeSe heterostructure is obtained, and the large formation energy indicates that the heterostructure is stable. At the same time, compared with the intrinsic SnSe monolayer and GeSe monolayer, its conductivity is improved. The gas adsorption on both sides of the SnSe/GeSe heterojunction was considered, and the adsorption mechanism was further analyzed by the density of states and charge difference density. The results show that the adsorption capacity of the SnSe/GeSe heterojunction for dissolved gas in transformer oil is slightly improved, but the adsorption is still physical adsorption. The adsorption energies of the six gases are arranged as follows: C₂H₆ > C₂H₄ > C₂H₂ > CH₄ > CO > H₂. Although the sensitive gas monitoring based on the change of conductance is not realized in this study, it provides a theoretical basis for understanding the physical adsorption mechanism between such heterojunctions and gas molecules.