Probing the electronic sensitivity of BN and carbon nanotubes to carbonyl sulfide: A theoretical study

Density functional theory calculations were employed to investigate the electronic and structural behavior of a pristine boron nitride nanotube (BNNT) and a single-walled carbon nanotube (CNT) toward carbonyl sulfide (COS) gas adsorption. It was found that when a COS molecule is adsorbed on the CNT, an energy of about 6.0 kcal/mol is released and the HOMO-LUMO gap of CNT is decreased by about 38.7%. Thus, the electrical conductivity of the CNT is significantly increased, indicating that the CNT can produce an electronic noise at the presence of COS molecules. The recovery time for the COS desorption from the surface of CNT is calculated to be very short (~ 0.24 μs). Also, our finding and the literature review indicated that the CNT can selectively detect the COS gas among different ones including H2, H2CO, H2S, O2, etc. Compared to the CNT, the BNNT shows a higher reactivity toward the COS, but its electronic properties are insensitive to this gas. The adsorption energy of COS on the BNNT was calculated to be about 11.3 kcal/mol.