Gas-Sensing Mechanisms and Detection Optimization of ZnO/TiO₂–MoTe₂ Composites for CF₃SO₂F Decomposition Products

This study focuses on the detection requirements for breakdown products (HF, SO₂, SO₂F₂, and CF₄) produced by the partial discharge of the innovative, environmentally friendly insulating gas CF₃SO₂F in high-voltage electrical apparatus. A doping modification technique utilizing a metal oxide (ZnO/TiO₂) based on two-dimensional MoTe₂ is proposed. The method for enhancing gas sensing is being systematically investigated through multiscale theoretical computations. Molecular dynamics simulations are initially utilized to ascertain the structural stability of the doped systems, confirming that ZnO-MoTe₂ and TiO₂-MoTe₂ maintain robust structural integrity in a thermodynamic equilibrium condition. Subsequently, density functional theory is utilized to compare and analyze the adsorption behaviors of the intrinsic MoTe₂ and its doped systems toward the four characteristic decomposition products. The findings indicate that doping ZnO markedly improves MoTe₂'s adsorption capacity for SO₂. Adsorption configuration analysis reveals that doping strengthens the interactions between the material surface and SO₂ molecules. Electronic structure estimates suggest significant charge transfer and band structure modifications throughout the adsorption process. The density of electronic states in the ZnO-MoTe₂ combination exhibits significant variation, indicating that the chemical adsorption of SO₂ is predominant. Additionally, the TiO₂-doped system shows a selective adsorption tendency for acidic gases such as HF. The comparison of total electron density and differential charge density distributions demonstrates that the charge redistribution at the interface, generated by doping, is the crucial factor enhancing gas adsorption performance. This work reveals, at the atomic scale, the mechanism by which metal oxide doping modulates the gas-sensing properties of MoTe₂, providing a theoretical foundation for developing highly selective gas sensors for detecting CF₃SO₂F decomposition products.