Janus WSSe, WSTe, and WSeTe Nanosheets as Resistive and Optical Sensors for the Detection of SF6 Decomposition Gases

Janus, a class of transition metal–sulfur compounds, exhibits special physicochemical properties and thus has attracted a lot of attention. In this work, we studied the adsorption behavior of SF6 decomposition gases (HF, SO2, SF2, and SF4) on perfect and vacancy-defected Janus WSSe, WSTe, and WSeTe substrates. The results showed that the pristine WSSe, WSTe, and WSeTe substrates have a weak adsorption for HF, SF2, and SO2 gases, while the interaction between SF4 and substrates was stronger than that of others. After the introduction of vacancy defects, the adsorption stability of SF6 decomposition gases was improved. Furthermore, the electron localization function, partial density of states, and charge density difference calculations showed that the vacancy-defected substrates adsorbed SF6 decomposition gases by chemisorption. The sensitivity calculations showed that the vacancy-defected substrates exhibited high sensitivity to SF2, SF4, and SO2 gases. Moreover, the optical absorption coefficients and reflectance of defected substrates after the absorption of SF2 and SO2 gases were higher than before adsorption. The calculations showed that vacancy-defected WSSe, WSTe, and WSeTe substrates can be used as resistive and optical sensor materials for the detection of SF6 decomposition gas.