Functionalization of individual multi-wall carbon nanotubes during irradiation and annealing

Multi-walled carbon nanotubes were subjucted to irradiation of argon ions and electron and consequent annealing in inert ambient. Transmission electron microscopy and X-ray photoelectron spectroscopy have been used to study the structure tranformation and chemical conditions of nanotubes. It is shown that irradiation with argon ions and electrons leads to the formation of defects in the structure of carbon nanotubes and a change in the interlayer distance in the walls of nanotubes. Also the fixation of functional oxygen-containing groups on their surface is observed. Annealing of irradiated nanotubes in an inert atmosphere leads to a partial restoration of the structure of MWCNT. In this case, upon irradiation with argon ions, the nanotube structure is restored, and the oxygen concentration decreases. After the annealing of MWCNT irradiated with electrons, multi-vacancy defects are observed on the outer graphene layers. These large defects are the attachment points for functional groups containing a carbon-oxygen double bond (C = O). Binding energies and optimized geometry for various configurations of vacancy clusters in the graphene plane were obtained using calculations performed within the framework of the density functional theory.