Optimisation of the arc-discharge production of multi-walled carbon nanotubes

The effect of varying current density and pressure during are generation on the yield and purity of multi-walled nanotube-containing carbon soot has been studied in this work. Various soots were produced and characterised qualitatively using transmission electron microscopy and quantitatively using electron paramagnetic resonance and thermogravimetric analysis. It was found that both yield and purity increase as current density and pressure are increased to the limit of our experimental investigations, i.e. 195 A/cm(2) and 500 Torr of helium. Under these conditions a yield of 24 mg/min soot containing 48% by mass nanotubes was obtained. (C) 2002 Elsevier Science Ltd. All rights reserved.