First-principles study of oxygen-rich W3-doped TiS2 monolayers for selective detection of CO2 at low temperature

The use of gas sensors to monitor dissolved gas enables the prediction of power transformer operation, and their sensitivity capability depends greatly on the amount of chemically adsorbed oxygen on the surface of its gas sensing layer. The objective of this research is to investigate a monolayer of transition metal dichalcogenide (TMD) doped with high-valence transition metal ions, which can provide a large amount of surface-chemisorbed oxygen for improving the responsiveness to dissolved gas in oil. First-principles methods are employed to study the adsorptive capacities of three typical types of characteristic gases (H2, CO2, and CH4) in transformer oil, as well as the adsorption of O2 in the surrounding environment on the W3-TiS2 monolayer. Our findings indicate that the CO2 molecule undergoes chemical adsorption, whereas the H2 and CH4 molecules are physically adsorbed above the W3 cluster. At a temperature of 358 K, the desorption time for CO2 on the W3-TiS2 adsorbent is measured to be 80.23 s. Furthermore, the W3-TiS2 monolayer demonstrates an exceptionally strong attraction towards O2 molecules, bringing the breaking of the chemical bond within the O2 molecule. As a result, rich chemisorbed oxygen ions are obtained via the transfer of charges between the O2 molecule and the W3 cluster. The computational results presented in this research provide theoretical support for promoting further expansion of the gas sensor family and their application in detecting dissolved gas.