Single-Atom (Sc, V, Cr) Decoration of 1T-TiS ₂ Monolayers for Gas Sensing of CF ₄ , HF, and SO ₂ : A First-Principles Study

Trifluoromethanesulfonyl fluoride (CF₃SO₂F), a promising eco-friendly alternative to SF₆, may generate hazardous gases such as CF₄, HF, and SO₂ upon decomposition, highlighting the need for reliable detection. Using first-principles calculations, we show that single-atom (Sc, V, and Cr) decoration substantially enhances the surface reactivity of the 1T-TiS₂ monolayer. While CF₄ interacts only weakly with the decorated surface, HF and SO₂ exhibit strong adsorption enabled by pronounced charge transfer and orbital hybridization. Notably, Sc- and Cr-decorated TiS₂ are identified as potential reversible sensors for HF and SO₂, respectively, under appropriate working temperatures. In contrast, Sc- and V-decorated TiS₂ show strong adsorption and capture capability for SO₂. Furthermore, significant work-function shifts are observed in the decorated systems upon exposure to these gases, indicating their promise for MOSFET-based gas sensing applications. Overall, these results identify Sc-, V-, and Cr-decorated TiS₂ as effective candidates for the detection or capture of HF and SO₂, providing a viable route to managing CF₃SO₂F decomposition products in next-generation power systems.