DFT study on the chemical sensing properties of BN nanocage toward formaldehyde.

It has been previously shown that the toxic formaldehyde gas (HCO) cannot be detected by pristine BCN, carbon, and BN nanotubes, BC nanosheet and graphene. Herein, density functional theory calculations were employed to investigate the electronic and structural behavior of a pristine BN nanocluster toward HCO molecules. It was found that [4,6] BN bonds of the nanocluster are the most favorable sites for the HCO adsorption, compared to the [4,8], and [6,8] ones. When an HCO molecule is adsorbed on a [4,6] BN bond, an energy of about 16.40kcal/mol is released and the HOMO-LUMO gap of the cluster is decreased from 6.45 to 2.98eV. Thus, the electrical conductivity of the cluster is significantly increased, indicating that it can produce an electronic noise at the presence of HCO molecules. Increasing the number of adsorbed HCO molecules, the electrical conductivity more increases. The recovery time for the HCO from the surface of BN is calculated to be very short (∼1.02s). Also, the UV-vis spectrum shows that the λ of the BN shows a large redshift upon the adsorption process and transfers from the UV to the visible region.