Dissolved gases analysis in transformer oil using TM (Pd, Ir, Au) modified MoSSe monolayer: A DFT study

In this work, the DFT is employed to systematically investigate the adsorption and sensing mechanisms of major thermal runaway gases(CO, C2H2, and C2H4) on Pd-MoSSe, Ir-MoSSe, and Au-MoSSe monolayer. [Display omitted] •The adsorption of the three gases on TM-MoSSe (TM = Pd, Ir, Au) monolayers is chemisorption, which is more stable compared to physisorption, resulting in superior adsorption efficiency.•The introduction of transition metal (TM) doping into MoSSe monolayers significantly enhances their conductivity and gas sensitivity. Thus, for the detection of thermal runaway fault gases, TM-MoSSe (TM = Pd, Ir, Au) gas sensors are strongly supported by theoretical research for practical applications.•By comparing the transferred charge, adsorption energy, minimum adsorption distance, and recovery time of the three adsorption systems, it was found that Au-MoSSe monolayers exhibit the best adsorption and sensing performance for CO, followed by C2H4 and C2H2. Pd-MoSSe monolayers show good adsorption and sensing performance for C2H4 and C2H2, while Ir-MoSSe has good adsorption and sensing performance for C2H4 only under certain conditions, which still require further investigation. This study applied density functional theory to investigate gas-sensitive devices based on transition metal-doped MoSSe (Pd-MoSSe, Ir-MoSSe, Au-MoSSe), exploring their adsorption and sensing performance towards three characteristic gases (CO, C2H2, C2H4) generated during the use or faults of transformer oil. The results indicate that Pd, Ir, and Au transition metal atoms preferentially anchor to the S surface of the pristine MoSSe monolayer. The doped monolayers exhibit significantly improved sensing characteristics in all aspects, suggesting chemical adsorption of the three characteristic gases. Through the analysis of band structures (BS), adsorption configurations, deformation charge densities (DCD), density of states (DOS), recovery time, and various adsorption parameters, the conclusion is drawn that while TM-MoSSe outperforms the pristine MoSSe monolayer in terms of adsorption and sensing performance, Pd-MoSSe and Au-MoSSe exhibit relatively good recovery times across a broader temperature range, whereas Ir-MoSSe is limited in this aspect. This study provides theoretical guidance for the potential application of transition metal-doped MoSSe monolayers as sensors for gases generated during the thermal runaway of transformer oil.