Synthesis of High Purity Multiwalled and Singlewalled Carbon Nanotubes by Arc-discharge

The synthetic methods for high yield of multiwalled carbon nanotube (MWNT) and singlewalled carbon nanotube (SWNT) with high purity by arc discharge have been investigated. MWNTs were synthesized under different pressures of helium and the gas mixture of argon and hydrogen. Relatively high pressure of 300-400 torr was required for high yield MWNTs synthe-sis at low bias voltage of about 20 V and 55 A, whereas low pressure of about 100 torr was required for SWNTs. The intro-duction of hydrogen gases during the synthesis of MWNTs improved the yield and purity of the samples. The SWNTs were synthesized by the assistance of a small amount of mixture of transition metals, which played as a catalyst during the forma-tion process. The purity and yield of SWNTs were higher at a lower pressure and enhanced by mixing more components of the transition metals