Non-destructive purification of multi-walled carbon nanotubes produced by catalyzed CVD

A three-step purification process of multi-walled carbon nanotubes (MWNTs) produced by catalytic CVD method with Ni-Mg-O as catalysts is described. In the former two-step process, 3 M HNO3 and 5 M HCl treatment are effective to remove metal and metal oxide. With thermogravimetric analysis (TGA), the burning temperature of MWNTs in air was determined and 510 degreesC was chosen to be optimum temperature to eliminate non-nanotube carbon materials for the third step purification of MWNTs. By this way, larger than 96 wt.% purity of MWNTs is obtained without damage. (C) 2002 Elsevier Science B.V. All rights reserved.