Purification and structural annealing of multiwalled carbon nanotubes at graphitization temperatures Original Research Article

In this work, we present a systematic study of the effects of graphitization on the structural perfection of multiwalled carbon nanotubes. High purity nanotubes were produced by a low temperature CVD method and subsequently annealed at temperatures between 1600 and 3000°C. The nanotubes were characterized for chemical purity, interlayer spacing, and defect healing. The graphitization procedure was found to remove residual metal catalyst in the nanotubes and reduce the wall defects as reflected in a reduced interlayer spacing between the graphene shells. Graphitization presents a low-cost, commercially viable method of purifying and ordering multiwall carbon nanotubes.