Pathways for oxygen adsorption on single-wall carbon nanotubes

Effects of oxygen adsorption on the structural and transport properties of single wall carbon nanotubes (SWCN’s) are investigated in detail using ab initio and generalized tight-binding molecular-dynamics methods. We find that the oxygen-SWCN interaction depends strongly on the spin configuration which, in turn, specifies oxygen’s adsorption pathway. In the case of a single oxygen, the most stable adsorption site is one in which the O atom sits on a C-C bridge, breaking the underlying C-C bond. For the ${\mathrm{O}}_2$ molecule, the adsorption geometry is found to depend sensitively on the curvature of the nanotube. Our calculations also show that the transport properties of nanotubes are significantly affected by the presence of oxygen.