Supermolecular self-assembly of graphene sheets: Formation of tube-in-tube nanostructures

Graphitic impurity nanoparticles were reorganized outside and inside of carbon nanotubes to produce novel tube-in-tube nanostructures. The graphitic nanoparticles were disintegrated into small graphene sheets by an intercalation-exfoliation process with nitric acid, during which the graphene sheets were simultaneously modified with carboxyl and hydroxyl groups at their edges. The modified graphene sheets were self-organized outside and inside of pristine carbon nanotubes in an acid-catalyzed esterification process, leading to an assembly of well-constructed tube-in-tube nanostructures.