Abstract
A theoretical study has been conducted 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 order 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 nanosheet was found to be weak, which leads a slight variation in its energy gap; therefore, a low sensitivity of this nanosheet toward the guanine molecule 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 which vary from −24.2 to −38.4 kcal mol−1, which are lower than those obtained for the NbBN cluster. Upon adsorption process, the energy gap of the NbBN cluster was greatly increased, which leads to a decrease in its electrical conductivity; thereby, it cannot be a suitable sensor for the detection of 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 possesses a great electronic sensitivity to the guanine molecule. Based on the transition state theory, the recovery time of the guanine desorption from the AuBN cluster was estimated of 27.6 s, reflecting that the Au-doped BN nanosheet could be employed as an appropriate nanosensor for the guanine molecule detection with a short recovery time.
Highlights
Small metal clusters dispersed over different supports have received great deal of interest in heterogeneous catalysis, due to their excellent catalytic properties in comparison with the bulk metal [1,2,3,4,5,6]
The results show that the HOMO-LUMO energy gap of the boron nitride (BN) nanosheet has been greatly decreased upon its doping with Nb and Au atoms, suggesting a great enhancement in its reactivity
The results indicate a strong adsorption of the guanine molecule over the surface of the NbBN cluster with adsorption energies which vary between – 36.7 and – 60.2 kcal mol− 1, indicating a great chemisorption process
Summary
Small metal clusters dispersed over different supports have received great deal of interest in heterogeneous catalysis, due to their excellent catalytic properties in comparison with the bulk metal [1,2,3,4,5,6] The reactivity of these nanocatalysts is largely influenced by the method of preparation, cluster size, geometry and the metal composition [7,8,9,10]. In the dehydrogenation of 2-octanol, the rhenium clusters supported on Al2O3 are found to be more active than those supported on SnO2, and the catalytic activity of the particles was multiplied by 5.2 when Al2O3 support was replaced by SnO2 [11] This difference in reactivity is strongly related to the nature of the interaction (strong or low) between the clusters and the surface of the support. The calculated specific activity (TOF) of the Rh/Gr nanocatalyst in the above reaction was found 2 times higher than that found for the Rh/Al2O3
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