Wet-chemical assembly of carbon tube-in-tube nanostructures

The regular and well-organized tube-in-tube carbon nanotubes (TTCNT) with both two- and threefold tubular structures have been successfully assembled by a wet-chemical reorganization of the carbonaceous impurities around and inside pristine nanotubes. The multiple channels and surfaces of the TTCNTs are readily accessible for guest materials such as iron oxides and allow the casting of nanotube-based host-guest heterostructures. SEM images were taken using a Hitach S-4000 scanning electron microscope with a field emission gun operated at a 15 kV accelerating voltage. The samples were prepared by placing one drop of alcohol suspension on a silicon substrate for SEM analyses or on a carbon-film supported copper grid for TEM analyses. The results show that the wet-chemical method yields TTCNTs at low cost and on a large scale and also provides a great opportunity for fundamental properties and potential applications.