Copper Encapsulation of Multi-Walled Carbon Nanotubes

Properties of hollow carbon nanotubes (CNTs) could be modified by introducing foreign materials into the interior. Different materials used to fill CNTs include water molecules, DNA segments, metals and many others. Among CNTs filled with different materials, metal-filled CNTs show great potential in numerous applications, such as data storage nanotechnology, due to their small size. In addition, the carbon sheets of CNTs provide an effective layer against oxidation and therefore ensure long-term stability of the encapsulated metals. Since copper is a good electrical and thermal conductor and has a low binding energy to carbon, its encapsulation into CNTs would lead to many interesting practical applications. Typically, CNTs filled with Cu are useful for the fabrication of ultra-low resistance nanoscale electronic devices. Recently, bamboo-like tapered CNTs with only copper located at the tip region were also found to be useful for tube spot welding using current-induced Joule heating. The Cu impregnation in the hollow inner region of CNTs can be attained in situ during the CNT growth by incorporating metals or metal precursors along with the carbon source. The other fabrication method is to fill copper into the prepared CNTs by various means, such as electrodeposition, wet chemistry, capillary suction and plasma irradiation.