Abstract Submitted to the    NANOTUBE'04 Conference:

Selective synthesis of DWNTs in the arc discharge process [1] has been kinetically studied. Formation of hydrocarbons in the carbon arc in a H2/Ar atmosphere has been established by MS analysis that identified acetylene, ethylene, methane and traces of ethane in the gas sampled from the reactor. Most of the carbon is transferred from the anode through the gas phase to the metal catalyst particles as acetylene and polyynes C2nH2, the products of carbon hydrogenation in the arc gap area. The DWNT catalyst particle consumes amorphous carbon for the feedstock as well. It is shown that kinetics of DWNT formation is governed by the same hydrodynamic factor as for SWNTs: the rate of cooling the reaction mixture by the buffer gas. Arc synthesis of DWNTs in hydrogen atmosphere is a CVD process that grows one DWNT from an equal diameter catalytic metal particle. Diffusion of carbon through the bulk metal catalyst particle is the rate-limiting step of DWNT growth.

References:

1. J. Hutchison et al., Carbon 39, 761 (2001).