Production of carbon nanotubes by CO2-laser evaporation of various carbonaceous feedstock materials

In this paper we report on the production of single-wall carbon nanotubes (SWNT) by the laser-ablation technique using graphite, pitch and coke as carbonaceous feedstock materials. Using a continuous-wave CO2-laser a wide range of experimental conditions have been studied by systematically varying the nature and the concentration of the metal catalyst, the type and pressure of the buffer-gas as well as the laser conditions. Employing graphite as a precursor material, the experimental parameters have been optimized in order to synthesize high-density SWNT material. On the other hand, using pitch and coke as carbonaceous feedstock materials can lead to the formation of SWNT. However, the amount of SWNT material obtained is much lower than in the case of graphite. We qualitatively analyse the whole synthesis process and show that the formation of SWNT is closely related to the use of an appropriate feedstock material as well as to favourable local temperature conditions experienced by the evaporated species.