Adsorption of the Guanine Molecule Over the Pristine, Nb- and Au-doped Boron Nitride Nanosheets: A DFT Study

Abstract

A theoretical study has been performed onto the pristine, Nb- and Au-doped boron nitride (BN) nanosheets using DFT calculations with the B3LYP-D3 method in order to evaluate their stabilities and electronic properties. The interaction of the guanine molecule with these clusters was also examined in aim to determine their adsorption properties. The calculations show that the HOMO-LUMO energy gap (Eg) of the BN nanosheet was strongly decreased upon its doping with Nb and Au atoms, implying a strong enhancement in its surface reactivity. The interaction of the guanine with the BN sheet was found to be weak, which leads a slight variation in its energy gap, therefore a low sensitivity of this nanosheet toward the guanine was observed. The guanine adsorption over the NbBN cluster is very strong, and the calculated adsorptions energies are in the range of – 36.7 to – 60.2 kcal mol-1, suggesting a great chemical adsorption. For the AuBN cluster, the guanine molecule has been chemisorbed onto its surface with adsorption energies varying of – 24.2 to – 38.4 kcal mol-1, which are lower than those obtained for the NbBN cluster. Upon adsorption proceess, the energy gap of the NbBN cluster was greatly increased, which leads to a decrease in its electric conductivity, thereby it cannot be a suitable sensor for the guanine molecule. On the contrary, the energy gap of the AuBN cluster was reduced by the effect of the guanine adsorption on its surface, indicating an increase in its electrical conductivity, thus the AuBN cluster possess a great electronic sensitivity to the guanine molecule. Based on the transition state theory, the recovery time of the guanine from the AuBN cluster was estimated of 27.6 s, reflecting that the Au-doped BN nanosheet could be employed as an appropriate nanomaterial for the guanine molecule detection with a short recovery time.