Parametric analysis of chirality families and diameter distributions in single-wall carbon nanotube production by the floating catalyst method

We report a detailed parametric analysis of the production of single-wall carbon nanotubes (SWCNTs) by the floating catalyst method in a vertical furnace using an alcohol precursor. From a combined study of Raman and absorption spectroscopies and transmission electron microscopy, we have developed a semi-quantitative way of estimating the diameter and chiral family distribution of the SWCNTs produced. This approach shows that increased residence times and higher concentrations of metal catalyst in the precursor solution (i.e. ferrocene in ethanol) increase the diameter of the tubes produced. Increasing growth temperatures result in the formation of both larger and small diameter SWCNTs, in contrast to previous reports of increasing diameter with temperature. Varying these parameters could be effective in tailoring the size distribution of the SWCNTs to meet the needs of specific applications. Also evidence is presented to show the absence of red shifting of the Raman radial breathing modes, expected due to bundling, of the metallic tubes.