The Gas-Sensing Properties of Ag-/Au-Modified Ti₃C₂T_x (T=O, F, OH) Monolayers for HCHO and C₆H₆ Gases

Based on density functional theory calculations, this study analyzed the gas-sensing performance of Ti₃C₂T_x (T=O, F, OH) monolayers modified with precious metal atoms (Ag and Au) for HCHO and C₆H₆ gas molecules. Firstly, stable structures of Ag- and Au-single-atom doped Ti₃C₂T_x (T=O, F, OH) surfaces were constructed and then HCHO and C₆H₆ gas molecules were set to approach the modified structures at different initial positions. The most stable adsorption structure was selected for further analysis of the adsorption energy, adsorption distance, charge transfer, charge deformation density, total density of states, and partial density of states. The results show that the Ag and Au modifications improved the adsorption performance of Ti₃C₂O₂ for HCHO and C₆H₆. In comparison, the effect of the Au modification was better than that of Ag. For Ti₃C₂F₂, the Ag and Au doping modifications did not significantly change the adsorption effects for HCHO and C₆H₆. However, the Ag and Au doping modifications decreased the adsorption of Ti₃C₂(OH)₂ for HCHO, while there was no significant change in the gas adsorption for C₆H₆. The above results serve as a theoretical foundation for the design of new sensors for HCHO and C₆H₆.