Adsorption of molecular oxygen on the walls of pristine and carbon-doped (5,5) boron nitride nanotubes: Spin-polarized density functional study

Abstract

We performed ab initio calculations to study the effect of molecular oxygen adsorption on the electronic properties of (5,5) pristine and carbon-doped boron nitride (BN) nanotube. The binding energies of oxygen molecules physisorbed at different sites were determined by considering both short- and long-range interactions. Spin-polarized calculation within the density functional theory yielded the triplet ground state for oxygen physisorbed on pure BN nanotube; the large energy gap between the unoccupied oxygen levels and the top of the valence band indicates the absence of hole doping. The introduction of substitutional carbon impurity increases the reactivity of BN nanotube toward molecular oxygen and stable ${\mathrm{O}}_{2}$ chemisorption states exist on both carbon-substituted nitrogen site $({\mathrm{C}}_{\mathrm{N}})$ and carbon-substituted boron site $({\mathrm{C}}_{\mathrm{B}})$ defect sites. Chemisorbed ${\mathrm{O}}_{2}$ on the ${\mathrm{C}}_{\mathrm{N}}$ defect is found to impart metallicity on the BN nanotube.