Applications of carbon nanotubes

Carbon nanotubes (CNTs) are graphitic carbon materials which are formed as hollow nanotubes under certain synthesis conditions. They are classified as single-walled CNTs (SWCNTs), double-walled CNTs (DWCNTs), and multiwalled CNTs (MWCNTs), based on their wall numbers. CNTs are extensively employed as carbon nanomaterials in numerous applications due to their exceptional optical, electrical, and mechanical characteristics. They are utilized in photocatalysts, catalysts, adsorbents, membranes, sensors, conductive coatings, batteries, supercapacitors, hydrogen storage devices, solar cells, and fuel cells. Likewise, they are applied in biomedicine as extremely sensitive biosensors (for sensing glucose, choline, and hydrogen peroxide) and drug delivery systems (particularly in cancer treatments). CNTs exhibit other outstanding properties such as open, meso −/macroporous structures, large specific surface areas, high resistance against acidic and alkaline corrosions, high mechanical and thermal (in inert gas) stabilities, controllable porosity, and possibility of the surface modification allowing changing their hydrophobic characteristics. Such features make them appropriate support materials for photocatalysts and catalysts employed in diverse reactions. In this chapter, it has been aimed to overview the recent progresses achieved on diverse applications of CNTs in photocatalysts, catalysts, adsorbents, membranes, sensors, conductive coatings, batteries, supercapacitors, hydrogen storage devices, solar cells, fuel cells, as well as their biomedical applications.