A computational study on the effect of local curvature on the adsorption of oxygen on single-walled carbon nanotubes

We investigated the effect of local curvature on the adsorption of oxygen on single-walled carbon nanotubes based on density functional theory calculations with van der Waals corrections. The results showed that as the curvature increases, the interaction of the nanotubes with oxygen increases as well. An oxygen atom was strongly chemisorbed on the bridge site of the nanotubes accompanied by a significant transfer of charge from the surface to the oxygen atom. Larger curvature enhanced both the adsorption energy and charge transfer due to the greater strain on the carbon atoms that led to a better interaction with oxygen. The oxygen molecule was physisorbed on the nanotubes with the interaction arising mostly from the long-range van der Waals interactions. The adsorption energy was also enhanced by greater curvature. The results were compared with the flat graphene sheet to confirm the effects of surface curvature.