Different electronic sensitivity of BN and AlN nanoclusters to SO2 gas: DFT studies

Abstract

Density functional theory calculations are used to investigate the electronic and structural behavior of a pristine Al12N12 and B12N12 nanoclusters to sulfur dioxide (SO2) gas adsorption. It is found that the SO2 molecule prefers to be adsorbed on the XN (X = B or Al) bonds with the Gibbs free energy change of −58.6 and −12.2 kcal/mol on the Al12N12 and B12N12 nanoclusters at room temperature, respectively. When a SO2 molecule is adsorbed on the BN cluster, a new state appears through the HOMO-LUMO gap of the cluster which significantly reduces the gap (by about 29.8%). Thus, the electrical conductivity of the B12N12 is meaningfully increased, indicating that it can produce an electronic noise at the presence of SO2 molecules and can be used in chemical sensors. The recovery time for the SO2 desorption from the surface of BN cluster is calculated to be very short (∼0.96 m). We find that the electrical conductivity of the cluster much more increases by increasing the gas coverage and a larger electronic signal can be obtained at high concentrations. The Al12N12 shows a higher reactivity to the SO2, but its electronic properties are insensitive to this gas.