Aerosol-assisted chemical vapour deposition synthesis of multi-wall carbon nanotubes: I. Mapping the reactor

We report a study of aerosol-assisted chemical vapour deposition (ACVD) technique for the large scale production of carbon nanotubes (CNTs) by investigating the reasons behind the variation and inhomogeneity of the morphologies and quality of CNTs alongside the reactor. Our approach in understanding the system is to simplify it by dividing the reactor into sections and then to characterise the CNTs zone by zone using transmission and scanning electron microscopy, Raman spectroscopy and thermogravimetric analysis in order to identify their level of graphitisation, diameter distribution, catalyst content, growth rate and oxidation resistance in relation to their position in the reactor. Moreover, we established a gallery of electron micrographs depicting different morphologies of CNTs and identified the regions where multi-wall, double-wall, and single-wall nanotubes were produced. We conclude that any attempt to scale up the production of uniform CNTs by ACVD should first aim to homogenise the temperature and catalyst concentration throughout the reactor.