Au-Decorated Ti₃C₂ MXene Sensor for Enhanced Detection of Gaseous Toxins (CO, COCl₂, H₂S, NH₃, NO₂): A DFT Study

The rising level of toxic gases in the environment poses a high demand for efficient gas sensing materials. MXenes, an emerging class of two-dimensional (2D) materials, have gained significant interest in this area for having an active-site rich structure, tunable surface properties, and remarkable stability. Herein, an extensive density functional theory (DFT) study is conducted to investigate the sensing properties of pristine and Au-functionalized Ti₃C₂ MXene for five toxic gas molecules: CO, COCl₂, H₂S, NH₃, and NO₂. Pristine Ti₃C₂ displays high affinity for CO, H₂S, and NH₃, as assessed by density of states and a large binding energy, resulting in the chemisorption of these gas molecules providing a relatively large recovery time. In contrast, Au-functionalized Ti₃C₂ is able to sense all five toxins which are physisorbed on it, as indicated by lower adsorption energy and faster recovery time. As an example, the adsorption energy computed for CO is -0.14 eV and the resulting recovery time 0.21 ns. These results reveal that Au-functionalized Ti₃C₂ can serve as a highly efficient material for toxic gas sensing, particularly CO.