Influence of carbon structure of the anode on the synthesis of single-walled carbon nanotubes in a carbon arc plasma

Arc plasma evaporation of carbon electrodes doped with various catalysts is one of the most effective methods of single-walled carbon nanotube fabrication. It was found that the reaction yield is strongly influenced not only by the appropriate choice of the catalyst(s), but also by the type of carbon material used for electrode fabrication. Several different carbon powders i.e. graphite powders, glassy carbon and coke, have been tested in order to establish which parameters (primary particle size, granulation, density or conductivity of the electrode) affected the outcome of the reaction the most. The highest yield of single-walled nanotubes was found for anodes fabricated from graphite powders, whilst the electrodes made from glassy carbon or coke yielded significantly smaller amounts of nanotubes. The reaction zone where carbon radicals nucleate (close to the arc gap) was probed by optical absorption spectroscopy. The estimated temperature distributions and contents of C2 radicals did not depend on the anode characteristics.