Carbon nanotubes (CNTs) are tubular molecules of carbon with diameters measured in nanometers (nm). They were first discovered in 1991 by Sumio Iijima, a Japanese scientist working for NEC. CNTs have unique properties that make them attractive for use in a variety of applications, including electronics, optics, and structural materials.
The structure of a CNT is similar to that of a graphite molecule, consisting of hexagonal carbon atoms arranged in concentric circles around the tube axis. However, unlike graphite, which is an extended two-dimensional crystal, CNTs are rolled up into three-dimensional cylinders. This difference in structure gives rise to several interesting properties.
For example, CNTs are much stronger than other types of carbon molecules such as graphene or fullerenes. They also have extremely high electrical and thermal conductivity. These properties make CNTs suitable for use in electronic devices and circuits, where they can act as better substitutes for silicon or other materials currently used. In addition, CNTs can be used to create very strong and lightweight composite materials for use in aerospace and automotive applications.
While great progress has been made in the development of synthesis methods and applications for CNTs, there are still many challenges that need to be addressed before they can be widely used commercially. For example, it is difficult to control the size and shape of CNTs during synthesis; this limits their usefulness in certain applications such as semiconductor manufacturing where precise dimensions are required. Additionally, large quantities of impurities present in most synthetic samples degrade the performance of devices made from CNTs. Finally, the toxicology of CNTs is not well understood; more research is needed to assess their potential risks to human health before they can be widely adopted