Two-dimensional Mo3-TiS2 monolayer hosting high moisture resistance and abundant surface-chemisorbed oxygen for effective detection of SF6 decomposition gases: Atomic-scale study

Monitoring the SF6 decomposition gas (DPA) by gas sensors can be used to predict the operating status of power equipment, and the sensitivity performance of gas sensors is deeply influenced by the humidity resistance and surface oxygen adsorption performance of their sensing materials. The present research aims to explore a highvalence transition-metal ion doped transition metal dichalcogenide (TMD) monolayer that hosts high moisture resistance and abundant surface-chemisorbed oxygen suitable for detecting DPA. Using first-principles methods, the adsorption behavior of three representative types of gases (HF, SO2, and CO2) in DPA, H2O, and O2 on Mo3TiS2 monolayer are considered. Our results show that SO2 and CO2 molecules are adsorbed above the Mo3 cluster through chemical adsorption, while HF molecule is physically adsorbed. The desorption times for SO2 and CO2 on Mo3-TiS2 adsorbent are 9.89 s at 348 K and 34.96 s at 398 K, respectively. Introducing dopant Mo3 resulted in better anti-humidity performance of TiS2, as the force of Mo3-TiS2 monolayer towards H2O molecule is weakened compared to the intrinsic adsorption system. Additionally, Mo3-TiS2 monolayer exhibits an exceptionally high affinity for O2 molecule, leading to the rupture of chemical bond in O2, and the chemisorbed oxygen ions are acquired through the charge transfer between Mo3 cluster and O2 molecule. The computational findings in this article offer theoretical backing for advancing the development of gas sensors utilizing Mo3-TiS2 and its utilization in the realm of DPA detection.