Ab initio study of the size-dependent effect on the covalent functionalization of single walled carbon nanotubes with hydroxyl, amine and carboxyl groups.

We have investigated the sidewall functionalization of several (n, 0) zigzag Single Wall Carbon Nanotubes (SWNTs) by the hydroxyl, amine and carboxyl groups with n varying from 5 to 23 by using ab initio calculations. The results show that the stability of the OH, NH2 and COOH groups depends on the size of carbon nanotubes. The binding energies and structural properties have been determined and discussed.