Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. There are two main types of CNTs: multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs). MWCNTs have multiple layers of graphite sheets rolled up into concentric cylinders. They typically have diameters ranging from 2 to 100 nanometers and lengths up to several centimeters.
