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, O-2 and O-3 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, O-2 and O-3 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, O-2 and O-3 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. (C) 2009 Elsevier B.V. All rights reserved.