Density functional theory calculations were used to probe the chemical reactivity of graphene and single-wall carbon nanotubes with respect to small molecules (O2, H2, N2, C2H2, CO, CO2). It was found that there was a threshold carbon nanotube size below which C2H2 and CO became trapped in decorated hillock-like defects on the side-walls of carbon nanotubes. It was also found that O2, H2 and CO2 could etch isolated C adatoms and C adatom pairs. These processes played a role in the growth of carbon nanotubes and in the post-growth evolution of defects on carbon nanotubes during exposure to typical ambient gases.

Adsorbate-Induced Defect Formation and Annihilation on Graphene and Single-Walled Carbon Nanotubes. L.Tsetseris, S.T.Pantelides: Journal of Physical Chemistry B, 2009, 113[4], 941-4