Structures, stabilities and electronic properties of carbon monoxide adsorbed and embedded boron nitride nanotubes with different lengths

The boron nitrides as excellent sensors are adopted to detect some harmful gases. The adsorption sites and lengths of the boron nitrides are very important to improve the adsorption capacity. The structures, stabilities and electronic properties of the COB_mN_m and CO@B_mN_m ($m=48$, 96 and 144) nanotubes with different lengths have been investigated by using density functional theory. The longer B_mN_m, COB_mN_m and CO@B_mN_m clusters are more stable. The adsorption of the CO molecules at the ends of B_mN_m nanotubes competes with the insertion of the CO molecules in the B_mN_m nanotubes. The COB_mN_m clusters exhibit higher chemical reactivity than the CO@B_mN_m clusters. The lengths of the B_mN_m nanotubes have little effect on the chemical reactivity of the nanotubes. The charge transfer amounts of the O atoms increase while those of the C atoms of the COB_mN_m and CO@B_mN_m clusters are almost the same with the increase of cluster lengths. The CO molecules lose fewer electrons ($0.174|\mathrm{\text{e}}|$, $0.164|\mathrm{\text{e}}|$, $0.158|\mathrm{\text{e}}|$) to the B_mN_m nanotubes of the COB_mN_m clusters while the CO molecules obtain fewer electrons ($-0.028|\mathrm{\text{e}}|$, $-0.045|\mathrm{\text{e}}|$, $-0.045|\mathrm{\text{e}}|$) from the B_mN_m nanotubes of the CO@B_mN_m clusters.