Density functional theory study of atomic oxygen, O2 and O3 adsorptions on the H-capped (5,0) single-walled carbon nanotube

Behavior of atomic oxygen, O2 and O3 molecules adsorbed on external surface of H-capped (5,0) single-walled carbon nanotube is studied using density functional calculations. Geometry optimizations were carried out at B3LYP/6-31G* level of theory using Gaussian 98 suites of program. Binding energies corresponding to chemical adsorption of atomic oxygen, O2 and O3 molecules are obtained to be in the range 65–250 kcal/mol. An oxygen atom is found to bind to the outside surface of the nanotubes to give stable epoxide-like and ether structures. Of these, the most stable is the epoxide, with calculated adsorption energy of 68.014 kcal/mol. Calculated chemical shielding, electric filed gradient tensors and their relative orientation at the sites of carbons reveal that atomic oxygen, O2 and O3 adsorptions have a dramatic effect on the electronic structure of single-walled carbon nanotubes (SWCNTs). Moreover, total density of states calculations show a significant difference in the density of states at the Fermi level for the two sites of (O–CNT) system.