The C2N surface as a highly selective sensor for the detection of nitrogen iodide from a mixture of NX3 (X = Cl, Br, I) explosives

Explosives are quite toxic and destructive; therefore, it is necessary to not only detect them but also remove them. The adsorption behavior of NX3 analytes (NCl3, NBr3 and NI3) over the microporous C2N surface was evaluated by DFT calculations. The nature of interactions between NX3 and C2N was characterized by adsorption energy, NCI, QTAIM, SAPT0, NBO, EDD and FMO analysis. The interaction energies of NX3 with C2N are in the range of −10.85 to −16.31 kcal mol−1 and follow the order of NCl3@C2N > NBr3@C2N > NI3@C2N, respectively. The 3D isosurfaces and 2D-RGD graph of NCI analysis qualitatively confirmed the existence of halogen bonding interactions among the studied systems. Halogen bonding was quantified by SAPT0 component energy analysis. The SAPT0 results revealed that ΔEdisp (56.75%) is the dominant contributor towards interaction energy, whereas contributions from ΔEelst and ΔEind are 29.41% and 14.34%, respectively. The QTAIM analysis also confirmed the presence of halogen bonding between atoms of NX3 and C2N surface. EDD analysis also validated NCI, QTAIM and NBO analysis. FMO analysis revealed that the adsorption of NI3 on the C2N surface caused the highest change in the EHOMO–LUMO gap (from 5.71 to 4.15 eV), and resulted in high sensitivity and selectivity of the C2N surface towards NI3, as compared to other analytes. It is worth mentioning that in all complexes, a significant difference in the EHOMO–LUMO gap was seen when electronic transitions occurred from the analyte to the C2N surface.