Unveiling the Influence of Water Molecules for NF₃ Removal by the Reaction of NF₃ with OH: A DFT Study

The removal of nitrogen trifluoride (NF₃) is of significant importance in atmospheric chemistry, as NF₃ is an important anthropogenic greenhouse gas. However, the radical species OH and O(¹D) in atmospheric conditions are nonreactive towards NF₃. It is necessary to explore possible ways to remove NF₃ in atmosphere. Therefore, the participation of water molecules in the reaction of NF₃ with OH was discussed, as water is abundant in the atmosphere and can form very stable complexes due to its ability to act as both a hydrogen bond donor and acceptor. Systemic DFT calculations carried out at the CBS-QB3 and ωB97XD/aug-cc-pVTZ level of theory suggest that water molecules could affect the NF₃ + OH reaction as well. The energy barrier of the S_N2 mechanism was decreased by 8.52 kcal/mol and 10.58 kcal/mol with the assistance of H₂O and (H₂O)₂, respectively. Moreover, the presence of (H₂O)₂ not only reduced the energy barrier of the reaction, but also changed the product channels, i.e., formation of NF₂O + (H₂O)₂-HF instead of NF₂OH + (H₂O)₂-F. Therefore, the removal of NF₃ by reaction with OH is possible in the presence of water molecules. The results presented in this study should provide useful information on the atmospheric chemistry of NF₃.