Cu-Doped MoSe₂ Monolayer: A Novel Candidate for Dissolved Gas Analysis in Transformer Oil

Dissolved gas analysis (DGA) in transformer oil is a workable approach to evaluate the operation status of transformers. In this paper, we proposed a Cu-doped Se-vacancy MoSe₂ (Cu-MoSe₂) monolayer as a promising sensing material for DGA based on first-principles theory. Three typical dissolved gases, namely, CO, C₂H₂, and C₂H₄, are the representatives to investigate the potential of the Cu-MoSe₂ monolayer upon their adsorption and sensing. Our results indicate that Cu-doping causes strong n-doping for the Se-vacancy MoSe₂ monolayer, and the Cu-MoSe₂ monolayer exhibits strong chemisorption the three gas molecules, with a calculated adsorption energy (E _ad) of -1.25, -1.06, and -1.16 eV, respectively. Such strong interactions lead to remarkable changes in the electrical conductivity of the Cu-MoSe₂ monolayer, allowing its application as a resistance-type sensor. Besides, work function (WF) analysis shows the potential of the Cu-MoSe₂ monolayer as a promising field-effect transistor sensor as well. It is our hope that our work can stimulate more leading-edge studies of the TM-doped MoSe₂ monolayer for sensing applications in many fields.