Control of the single-wall carbon nanotube mean diameter in sulphur promoted aerosol-assisted chemical vapour deposition

The influence of gas flow on nanotube diameter during the synthesis of high-purity, very long single-wall carbon nanotubes (SWCNT) via aerosol-assisted chemical vapour deposition is reported. The sample morphology, nanotube yield, defect concentration and amount of carbonaceous impurities, as well as the mean diameter and the diameter distribution of the SWCNTs were analysed by combined scanning- and transmission electron microscopy, Fourier Transform Raman spectroscopy and optical absorption spectroscopy. The results show that by using a solution of ferrocene and sulphur in m-xylene the addition of sulphur as a promoter was found to enhance the SWCNT growth and to increase the yield. A reduction of the mean diameter and a change in the diameter distribution are observed when the total gas flow is increased.