Carbon

Multiwalled carbon nanotubes
Multiwalled carbon nanotubes are another allotrope of carbon discovered after C60. They have a relatively small radial dimension, with the outer diameter of the tube generally ranging from a few nanometers to tens of nanometers, and the inner diameter is even smaller, with some being only about 1nm. Its length is generally at the micrometer level, and the ratio of length to diameter is very large, reaching 103 to 106. Therefore, carbon nanotubes are regarded as a typical one-dimensional nanomaterial. Since their discovery by humans, carbon nanotubes have been hailed as the materials of the future and have been one of the cutting-edge fields in international science in recent years.