Energetics of the oxidation and opening of a carbon nanotube

We apply first-principles calculations to study the opening of single-wall carbon nanotubes by oxidation. We show that an oxygen rim can stabilize the edge of the open tube. The sublimation of ${\mathrm{CO}}_2$ molecules from the rim with the subsequent closing of the tube changes from endothermic to exothermic as the tube radius increases, within the range of experimental feasible radii. We also obtain the energies for opening the tube at the cap and at the wall, the latter being significantly less favorable.