Arc discharge synthesis of carbon nanotubes: Comprehensive review

In quest to synthesize high quality carbon nanotubes in bulk, different routes have been proposed and established over the last two decades. Arc discharge is the oldest and among the best techniques to produce high quality carbon nanotubes. Though this synthesis technique has been explored for a long time, the nanotube growth mechanism is still unclear and the growth conditions lack strong correlation with the synthesized product. In this review, we attempt to present the mechanism of nanotube growth in arc discharge and the factors affecting its formation. In order to understand the physics of this mechanism, the effect of experimental parameters such as setup modification, power supply, arc current, catalyst, pressure, grain size, electrode geometry and temperature on size and yield of the nanotubes has been detailed. The variation in synthesis parameters employed in literature has been presented along with challenges and gaps that persist in the technique.