DFT simulations of Al-doped MoTe ₂ monolayer as an HCHO and C ₂ H ₃ Cl gas sensor for status evaluation of a dry-type reactor in the HVDC converter station

This paper using the density functional theory (DFT) investigates the adsorption property of Al-doped MoTe2 (Al-MoTe2) monolayer upon two fault gas species of a dry-type reactor in the high-voltage direct-current (HVDC) convert station, namely HCHO and C2H3Cl molecules, to explore its potential as a typical gas sensor. Results reveal that the Al dopant can be stably anchored on the MoTe2 surface by replacing the Te atom, and the Al-MoTe2 monolayer performs chemisorption for two gas species. The analysis of charge density difference confirms the charge-transfer behaviour using the Hirshfeld population analysis, and the analysis of electronic property and desorption property uncovers the resistive gas sensing potential of Al-MoTe2 monolayer with higher sensing response in the HCHO system and shorter recovery time in the C2H3Cl system. Also, the work function-based and optical sensing potential of the Al-MoTe2 monolayer is elucidated from the analyses of the work function and dielectric function. All the findings in this work shed light on the favourable potential of the Al-MoTe2 monolayer as a resistance-type, work function-based or optical gas sensor upon two faults gases, which are beneficial for further exploration of such sensing material to evaluate the operation status of the dry-type reactors in the HVDC convert station.