Adsorption characteristic of Rh-doped MoSe2 monolayer towards H2 and C2H2 for DGA in transformer oil based on DFT method

Density functional theory (DFT) method was performed to investigate the adsorption behavior of Rh-doped MoSe₂ (Rh-MoSe₂) monolayer towards H₂ and C₂H₂ in transformer oil. Density of state, electron localization function and charge density difference were analyzed to study the electronic behavior of Rh-MoSe₂ monolayer upon gas adsorption. Meanwhile, the desorption performance analysis was conducted as well to determine the recyclability of our proposed material for sensing application. It is found that, Rh-MoSe₂ monolayer behaves good adsorption and desorption performances upon H₂ molecule, which allows its exploration of H₂ sensor at room temperature. On the other hand, the inferior desorption behavior of Rh-MoSe₂ monolayer with poor reversibility upon C₂H₂ molecule (1.65 × 10¹⁵ s at 298 K) make it one-off operation for C₂H₂ detection. However, its potential adsorbent application could be awaken to scavenge C₂H₂ impurity from transformer oil, which offers another prospective alternative to guarantee the stable operation of transformers. At room temperature, it is found that Rh-MoSe₂ monolayer has superior response for H₂ and C₂H₂ detection provided the sensitivity of −98.56% and − 99.63%, respectively. Moreover, frontier molecular orbital theory is employed to confirm the sensing mechanism of Rh-MoSe₂ monolayer upon two gases, according to the increased energy gaps that indicate the reduced conductivity after gas adsorption. From this aspect, our theoretical calculations in this paper would be beneficial to provide a novel insight into the application of Rh-MoSe₂ monolayer in engineering research.