First-principles investigations upon Pd-decorated Janus WSSe monolayer for sensing typical gases in overload dry-type transformers

In a long-running dry-type transformer, the insulation defects, such as partial discharge and overload, can decompose the inside insulation medium, epoxy resin, into several toxic gases, including HCHO and C2H3Cl, called typical gases spreading around the transformer substations. In this work, we purpose Pd-doped Janus WSSe (Pd-WSSe) monolayer as a novel sensing material for detections of HCHO and C2H3Cl, based on the firstprinciples theory, in order to evaluate the operation status of the dry-type transformers. The Pd-doping behavior is studied and we find that the Pd dopant prefers to be adsorbed on the S-surface through the TW1 site with the binding energy of -2.54 eV. Besides, the Pd-WSSe monolayer performs chemisorption upon HCHO and C2H3Cl molecules with Ead of -0.83 and -1.21 eV, resulting in the sensing response of -93.2 % and -99.2 % in two systems, respectively. Moreover, it is proved that the existence of H2O molecule impact little to the adsorption and sensing performance of Pd-WSSe monolayer. The findings herein are meaningful to explore more sensing materials for applications in the power system.