Aerosol-assisted chemical vapour deposition synthesis of multi-wall carbon nanotubes: III. Towards upscaling

We report the optimisation of the experimental variables for the synthesis of large-area (90 cm2), mm-thick carpets of vertically aligned multi-wall carbon nanotubes (MWCNTs) using the aerosol-assisted chemical vapour deposition technique. The effect of the reactor size, temperature, time and the flow rate of the carrier gas on the catalytic conversion rate of the precursor, composition of the atmosphere of the reactor and various properties of MWCNTs such as the mass, length, outer diameter, defect density, oxidation resistance and residual catalyst concentration was investigated. By increasing the volume of the reactor from around 0.2 to 8.5 L, the mass of synthesised MWCNTs and the efficiency of the precursor were increased fivefold (up to 14 g/h.) and twice (up to 88%), respectively. Free-standing and on-substrate carpets of MWCNTs could withstand normal handling without falling apart, making them suitable for characterisations and applications from nano to macro scales. The synthesis recipe also improved the production rate of nitrogen-containing MWCNTs by an order of magnitude.