A NOVEL FORM OF FILAMENTOUS GRAPHITE

CARBONACEOUS materials exist in many forms, with structures varying in the degree of structural order from diamond and hexagonal graphite to the less-ordered chars, soots and coals. Traditionally, graphite is produced from the less-ordered forms of carbon by exposing them to severe conditions of high temperature and pressure. Recently, there has been much interest in preparing highly ordered phases under relatively benign conditions. For example, diamond has been synthesized at low pressures1,2, and carbon deposition on transition-metal catalysts has been shown to produce highly graphitic phases in a variety of morphologies3,4. Here we show that disproportionation of carbon monoxide (2CO →C+CO2) catalysed by small iron-containing particles gives rise to a remarkably continuous stacking of fine graphitic layers on flat surfaces of the particles, producing carbon filaments with a ribbon-like morphology. Transmission electron microscopy reveals that stacking of the layers is not only very ordered but also unusual in being orientated perpendicular to the ribbon surface. These filaments may provide unique opportunities for studies of surface adsorption, catalysis and intercalation. © 1990 Nature Publishing Group.