Novel experiments with carbon nanotubes: opening, filling, closing and functionalizing nanotubes

Abstract

Carbon nanotubes have been opened using a variety of oxidants including $HF/BF_3$ and $O_sO_4$ at room temperature. The opened nanotubes have been filled with metals such as Ag, Au, Pd and Pt by simple chemical means. The opened nanotubes, containing a high concentration of acidic functional groups, get covered or closed by reaction with reagents such as ethylene glycol. The opened nanotubes can also be closed by treatment with benzene vapour in a reducing atmosphere of argon and hydrogen at high temperatures. Refluxing carbon nanotubes in a $H_2SO_4–HNO_3$ mixture results in a clear colourless solution, which on removal of the solvent and excess acid gives a white solid containing functionalized nanotubes. Neutralization of the acidic solution by alkali results in the precipitation of a brown solid containing nanotubes.