Design gas sensor based on transition metal doped graphene like nanosheets: A quantum chemical study

Recently, sensitive sensors capable of detecting toxic gasses have been considered to be of paramount importance in different industries. The adhesion of different molecules of different gasses NX3 (X = F, Cl, and Br) onto pure graphene like nanosheets (PGr) and Ti-doped Gr (TGr) was investigated through DFT calculations to understand possibility of using TGr as a gas sensor. Different adhesion sites and orientations were considered for the different gas molecules mentioned above. After determining the configuration with most stability, the NCI analyses were performed to compute the adhesion energy with van der Waals interactions. Furthermore, to understand the adhesion behaviors, the electronic attributes like highest occupied molecular orbital (HOMO)- lowest unoccupied molecular orbital (LUMO) electron density and charge transport were explored. Based on the results, the molecules of different gasses had a weak adhesion on PGr and the adhesion energies were low. However, there was an increase in the adhesion energy of these molecules on the TGr. With an adhesion energy of 0.896 eV, the sensitivity of the NF3 to the TGr was high because the orbital hybridization was strong and the charge transport was high. Moreover, the sensitivity of the TGr became more due to its higher electrical conductance, making it suitable for the detection of NX3 gasses.