New Route to Graphite Flakes and Films: Pyrolysis of Aromatic and Heteroaromatic Compounds under Dehydrogenation Conditions

Highly conducting carbon flakes and films are prepared in high yield from the pyrolysis of benzene, biphenyl, naphthalene, and pyrazine, by heating the parent compound in a vapor stream in the presence of a dehydrogenating agent at 800-900 degrees C. Pyrolysis at these temperatures normally produces carbons in powder form, but the simple addition of halogen vapor easily provides flakes of thicknesses up to 20 mu m and lengths up to 1 cm on a side. If chlorinated or brominated benzenes are used, films and flakes are obtained even in the absence of any added halogen vapor. Quartz substrates and walls can also be coated with thin or thick films in this manner. The flakes and films are metallike in appearance and have a conductivity of about 200-300 S cm(-1) at room temperature. By heat treatment to 2600 degrees C, graphitic order is improved and the conductivity rises to approximate to 10000-15000 S cm(-1).