Theoretical study of cyano radical adsorption on (6,0) zigzag single-walled carbon nanotube

The behavior of the cyano radical (center dot Ca parts per thousand N) adsorbed on the external surface of a (6,0) zigzag single-walled carbon nanotube was studied by using density functional calculations. Geometry optimizations were carried out at the B3LYP/6-31G* level of theory using the Gaussian 03 suite of programs. Our results show that the pristine carbon nanotubes can detect a center dot CN. The calculated binding energy of the center dot CN-attached (6,0) single-walled carbon nanotube indicates that the center dot CN can be best adsorbed at a carbon site in a C-down orientation (binding energy -356.5 kJ mol(-1)) and can thus be used in detection and storage of this species. The density of the state spectra, electron density plot, and HOMO and LUMO for the adsorbed species characterize it as a chemisorption process. The increase in global hardness, energy gap, and ionization potential because of the center dot CN functional group point to an increase of stability and decrease in reactivity and electrophilicity of the center dot CN-attached (6,0) CNT model. In addition, the Delta N value for the center dot CN/CNT complex is positive, indicating that the center dot CN acts as an electron acceptor.