Janus WSSe, WSTe,and WSeTe Nanosheets as Resistiveand Optical Sensors for the Detection of SF₆ DecompositionGases

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.