Carbon nanotubes: Synthesis, characterization, and applications

Carbon nanotubes (CNTs) are hexagonal rolled layers of graphene that form a cylindrical tubular structure. According to the number of these layers, CNTs can be classified as single walled or multiwalled, separated by small distances. The conductive nature of carbon nanotubes depends on the degree of graphene sheet twist, thus they can be a semiconductor or a metal. Due to the good electrical, thermal, and mechanical properties, carbon nanotubes have become good candidates for several applications such as drug delivery and sensors. Different methods are used to produce carbon nanotubes such as arc discharge and chemical vapor deposition. However, the properties of carbon nanotubes vary with the synthesis method.