US Patent 7309404 - Arc discharge CNT manufacture using charcoal electrodes

http://www.freepatentsonline.com/7309404.html

The three main methods of carbon nanotube manufacture are laser ablation, CVD, and arc discharge. The arc discharge method forms carbon nanotubes via the application of a direct current discharge between graphite electrodes in a reduced pressure, inert gas atmosphere. This patent from Fuji Xerox teaches using charcoal in place of the graphite for cheaper cost production. Claim 1 reads:

1. A manufacturing method for a carbon nanotube, comprising: applying a voltage between two electrodes whose tips are opposed to each other; generating discharge plasma in a discharge area between the two electrodes; and using an electrode made of a porous carbonaceous material, wherein said porous carbonaceous material is charcoal as at least one of the two electrodes whose tips are opposed to each other.