Redox Chemistry of Carbon Nanotubes

Carbon nanotubes can act both as electron donor or acceptor and consequently exhibit an abundant redox chemistry. Still oxidizing reactions mainly take place at the tubes ends and at defects. The direct oxidation of carbon atoms in an intact side wall, on the other hand, rarely ever occurs. It would require much 

The oxidation of nanotubes can be reversed by the reaction with reductants Uke NaBH4 or Na2S204. Provided the samples are more or less homogeneous, the redox reaction can be monitored by absorption spectroscopy, which enables the performance of redox titrations. 

The reactivity of some oxidizing agents, for example, sulfuric acid, can even be enhanced by simultaneous ultrasonication. This technique reduces the reaction times required and facilitates the cutting of the tubes. 

Compared to small graphene fragments or amorphous material, the nanotubes stand the oxidation mostly undamaged. The only considerable exceptions are the 

Supercritical water as well may bear oxidizing effect under suitable conditions. The reaction can also serve to purify nanotube samples as these are less reactive than the impurities present The removal of catalyst particles and amorphous carbon material is achieved this way. 

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Zheng M, Diner BA (2004) Solution redox chemistry of carbon nanotubes. J Am Chem Soc 126 15490-15494... 

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