Ab Initio Study of Hydrogen Interaction with Defective BC2N Nanotubes

The spin polarized density functional theory is used to investigate the incorporation of hydrogen adatoms and the interaction between molecular H-2 with antisites and vacancies in both zigzag (4,0) and armchair (3,3) BC2N nanotubes. We find that the presence of antisites and vacancies increases the binding energy of hydrogen adatoms on the tube surface. In the most stable antisites (C-B, C-N, N-CI and B-CII), the hydrogen adatoms bind preferentially on carbon atoms of the defective site (C-B, and C-N) or closer to it (N-CI and B-CII). For a single adsorbed H, the calculated binding energies show that the H adsorption on a carbon vacancy (V-CII) is the most stable site with a binding energy of -4.23 eV. The adsorption of a second H atom near the previous one is an exothermic process compared to of a single H-2 molecule physisorbed on the nanotube surface.