Synthesis of single-walled carbon nanotubes by low-frequency bipolar pulsed arc discharge method

• SWNTs have been synthesized by bipolar pulsed arc discharge.
• A newly developed bipolar pulsed current circuit with constant pulse duration has been used for the arc discharge.
• The input current and power is effectively controlled, and the arc discharge is quite stable.
• This method can utilize all the sublimated carbon for producing SWNTs with no cathode deposit.
• SWNTs obtained from this new arc discharge have good quality compared with those obtained by the DC arc discharge method.

The effective synthesis of single-walled carbon nanotubes (SWNTs) by low-frequency bipolar pulsed arc discharge method using a newly developed bipolar pulsed current circuit with constant current and constant pulse duration is reported. In this method, there is no cathode deposit, which means that all the sublimated carbon becomes soot containing single-walled nanotubes. The soot production rate of the bipolar pulsed arc discharge method is compared with those of the DC, the AC, and the unipolar pulsed arc discharge methods. It is found that the soot production rate increases with increasing frequency whereas the quality of the produced SWNTs remains almost the same. The nanostructures of the synthesized SWNTs are characterized by a TEM and Raman spectroscopy.