Exploring Janus MoSSe monolayer as a workable media for SOF6 decompositions sensing based on DFT calculations

In modern electric systems, partial discharge (PD) or local overheating happens inevitably, leading to the SF₆ insulated switchgears decomposition into several types of gas molecules. Thus, online monitoring these decomposition gases is considered as a promising way to detect PD to timely alarm and guarantee the safety operation of power equipments. Here, we propose recently synthesized Janus monolayer MoSSe as a superior gas sensing material by investigating the adsorption behaviors of SF₆ decompositions, including H₂S, SO₂, SOF₂ and SO₂F₂ on Janus surfaces by first-principles calculations. The adsorption patten of SF₆ decompositions on MoSSe monolayer is: SO₂ > SO₂F₂ > H₂S > SOF₂, in which all the absorptions exhibit physisorption. Besides, the binding strengths of the molecules adsorbed on S-layer are weaker than these on Se-layer due to the presence of out-of-plane polarization in Janus monolayer. While the adsorption strengths can be slightly enhanced by intrinsic S/Se vacancies or strain-driven of MoSSe monolayer. Importantly, the adsorption intensity can be modulated effectively by the applied electric fields. Furthermore, the response and desorption time of gas molecules on MoSSe monolayer are evaluated. With high gas sensitivity and selectivity towards SF₆ decompositions, Janus MoSSe monolayer is demonstrated to be a promising material to be used in gas-insulated switch-gear (GIS) and constructed ultrahigh sensitivity nanodevices.