Arc process for preparation of Multi-Walled Carbon Nanotubes (MWNTs)

1 July 2007

A convenient and more appropriate method of preparing carbon nanotubes is by using an arc between high purity graphite electrodes at around 0.7 atmospheric pressure of helium. A high current in the range of 60-100 ampere and a potential drop of about 25 volts produces high yields of carbon nanotubes. The process is done in such a way so that the carbon electrodes (anode) get deposited at the cathode as carbon nanotubes with graphite nanoparticles.

Researchers have carried out the experiment in presence of various other gases such as He, Ar, methane and hydrogen. It has been observed that a few gases produce multi-walled carbon nanotubes of superior crystallinity. Various researchers are successful in producing large quantities of carbon nanotubes by using latest techniques such as plasma arc-jets after optimizing quenching between graphite anode and cooled copper cathode. If we use both graphite electrodes, we get the multi-walled carbon nanotubesas the main product along with fullerene.

A few researchers have also studied the arc discharge in liquid nitrogen and found that the process is able to produce high crystalline multi-walled carbon nanotubes. The electrode assembly chosen by the scientists is both anode and cathode as carbon rods and after immersing the electrode in liquid nitrogen an electric current of 80 A was passed between the electrodes kept at 1 mm apart. By this process the yield of multi-walled carbon nanotubes was reported very high and even in some cases the yield was up to 70 percent.

Although chemical vapor decomposition process, which is another noble process for manufacturing carbon nanotubes, the convenient arc process is widely studied by researchers. This process is very effective for producing both single wall carbon nanotubes and multiple wall carbon nanotubes.

Related Posts: