Figure 1.
Effective mass of the obtained multi-walled carbon nanotubes after purification as a function of the catalyst composition Fe1-xMx with M = Co (■) and Ni (●). The TEM images show representative carbon nanotubes obtained for (a) x = 0 mol%, (b) x = 25 mol%, (c) x = 33 mol% and (d) x = 50 mol% Fe1-xCox catalyst.