Carbon nanotubes prepared by catalytic decomposition of benzene over silica supported cobalt catalysts

Carbon nanostructures were prepared by catalytic decomposition of benzene on Co/SiO₂ catalysts at 873 K. As a function of particle size and reactive mixture, carbon filaments and nanotubes were obtained and various shapes observed such as straight, curved and helically-coiled nanotubes. Particularly, it was shown that the helically-coiled nanotubes do not present an ordered atomic structure as it was predicted theoretically. However, the active catalytic particle as well as the reactive environment may play an important role in the growth of such nanostructures.