Comparison of the adsorption characteristics and sensing performance of Janus WSSe, WSe2 and WS2 materials for power transformer winding deformation fault gas: A DFT study

This study employs density functional theory (DFT) to explore the gas adsorption behavior and sensing performance of WSSe, WSe₂, and WS₂ monolayers doped with metal Mo_n (n = 1–3). The target gases CO, C₂H₂, and CH₄ are typical decomposition products associated with winding faults in power transformers. To assess the potential superiority of WSSe, a comprehensive analysis was conducted using parameters such as binding energy (E_b), charge transfer (Q_t), deformation charge density (DCD), band gap (B_g), and density of states (DOS) to reveal the structural and electronic features of the doped systems. The results showed that metal Mo can significantly improve the adsorption performance of the three substrates. Then, the adsorption effect of the three intrinsic substrates on the fault gas was studied using parameters such as adsorption energy (E_ads). The results showed that the adsorption behavior of the target gas on the initial substrate was poor, further indicating the necessity of metal doping. The adsorption energy (E_ads), charge transfer (Q_t), DCD and density of states (DOS) of the adsorbed gas after the substrate was doped with metal were evaluated in depth to obtain the adsorption and detection capabilities of the doped material for the target gas. The results show that the three substrates with the best adsorption effect on gas CO are: Mo₃-WSe₂＞Mo-WSe₂＞Mo₂-WSSe, and the three substrates with the highest adsorption affinity for gas C₂H₂ are: Mo₃-WSe₂＞Mo₂-WSSe＞Mo₂-WSe₂. Gas CH₄ showed physical adsorption on all nine substrates, and Mo₃-WSSe has the potential to be upgraded to chemical adsorption. In addition, the article also studied the adsorption of water molecules on the substrate, as well as the recovery time and sensitivity of the fault gas on the substrate, to explore the adsorption of the target gas on the substrate in a humid working environment, the reusability and responsiveness of the gas on the nine modified substrates, and whether the substrate has the ability to accurately detect the three target gases. This study provides a theoretical basis for the design, detection and prevention of deformation faults of power transformer windings, and also provides a reference for whether Janus materials have the ability to replace traditional TMDs.