FLUORINATION OF CARBON NANOTUBES

Carbon nanotubes were prepared by thermal decomposition of acetylene o ver silica-supported cobalt catalysts. Subsequent chemical treatments with concentrated hydrofluoric acid and dilute nitric acid, respective ly, eliminated the silica substrate and the remaining catalyst. The co mplete removal of cobalt was very difficult due to encapsulation of pa rt of it in the shells, but a graphitization at 2800 degrees C elimina ted the rest of cobalt and the structural defects. The reactivity of c arbon nanotubes with fluorine was studied and compared to that of grap hite. Important modification of the nanotubes structure was observed a fter reaction at high temperature as against the behaviour observed du ring reaction at room temperature. Compounds were analysed by means of transmission electron microscopy, X-ray diffraction and Fourier trans form infrared spectroscopy. (C) 1997 Elsevier Science Ltd.