Ab initiostudy of benzene adsorption on carbon nanotubes

The adsorption of a benzene molecule on carbon nanotubes (CNTs) with various diameters and chiral angles is investigated within the ab initio framework. The physisorption of such an organic molecule is an example of noncovalent functionalization involving $\ensuremath{\pi}$-stacking interactions and corresponding to a weak binding energy. Our calculations show that for small diameter tubes, the most favorable adsorption site is one type of $\mathrm{C}\mathrm{C}$ bond. The disparities between the inequivalent bonds of a CNT are discussed in terms of the $\ensuremath{\pi}$ orbital axis vector misalignment. Moreover, the curvature and the chirality effect on benzene adsorption are analyzed, showing that large diameter nanotubes are the most reactive ones.