Computational Screening of Ti3C2TX MXene by Controlling the Functionalized Catalyst for NH3 Gas Sensor

First‐principles calculations are used to research the adsorption behavior of ammonia on Ti 3 C 2 O 2 , Ti 3 C 2 F 2 , Ti 3 C 2 H 2 , Ti 3 C 2 S 2 , and Ti 3 C 2 Cl 2 . Herein, a total of four special adsorption sites α , β , γ , and δ are considered. The adsorption energy, charge transfer, and electronic properties of the gas‐adsorption system are calculated, and the better adsorption sites and adsorption functional groups of ammonia on Ti 3 C 2 T X with different functional groups are studied. The results show that the best adsorption positions of ammonia on Ti 3 C 2 O 2 , Ti 3 C 2 F 2 , Ti 3 C 2 H 2 , Ti 3 C 2 S 2 , and Ti 3 C 2 Cl 2 are all α position. According to the analysis of differential charge density, adsorption energy, and charge transfer of ammonia molecules, the adsorption strength of ammonia molecules on Ti 3 C 2 surfaces modified with different functional groups is Ti 3 C 2 H 2 > Ti 3 C 2 O 2 > Ti 3 C 2 F 2 > Ti 3 C 2 S 2 > Ti 3 C 2 Cl 2 . The ammonia molecule adsorbs on the surface of Ti 3 C 2 H 2 exhibits the strongest adsorption energy (−0.787 eV), but the −H group is more likely to break and form other groups. Therefore, the Ti 3 C 2 surface modified by −O group is more suitable for ammonia detection.