**Author details**

**Figure 16.** Raman spectrum showing the most characteristic features of CNTs produced by arc discharge method in

Carbon nanotubes (CNTs), a new structure of carbon element, are composed of graphen sheets rolled into closed concentric cylinders with diameter of the order of nanometers and length of micrometers. CNTs are attracted significant attention because of their unique physical and mechanical properties. These properties have been the engines of the rapid de‐ velopment in scientific studies in numerous applications such as in fuel cell and electrocata‐

Three methods, laser, arc discharge and chemical vapor deposition are used to synthesize CNTs. The laser method is also known as the laser-furnace method. The quantities CNTs in this method are large but this technique is not economically advantageous, since the process demanded considerable power. The chemical vapor deposition is another method for pro‐

the walls of the CNTs frequently contain many defects. Traditional arc discharge requires a complicated vacuum and heat exchange system. The yields of the laser and traditional arc discharge methods are very low (mg/h). From the application perspective, researchers are

Arc discharge in liquid media is a new method of synthesizing CNTs developed recently. All that is required is a dc power supply and an open vessel full of liquid nitrogen, deion‐

C in large quantities, but

lyst, nanobiosensors, gas adsorptions and membrane separation [82-88].

ducing CNTs. It could produce CNTs at temperatures above 700 0

continuously trying to devise improved methods for CNTs fabrication.

liquid followed by acid treatment [62].

70 Syntheses and Applications of Carbon Nanotubes and Their Composites

**6. Conclusion**

Mohsen Jahanshahi\* and Asieh Dehghani Kiadehi

\*Address all correspondence to: mjahan@nit.ac.ir

Nanotechnology Research Institute and Faculty of Chemical Engineering Babol University of Technology, Babol,, Iran
