Pyrolytically prepared carbon from fluorine-GIC

Formation mechanism, crystallinity, porosity and chemical reactivity were studied on the carbon prepared by pyrolysis of single phase, stage-1 fluorine-graphite intercalation compound (fluorine-GIC; C_xF). The stage-1 C_2.5F directly decomposes to fluorocarbon gases and carbon above 650 K, without forming higher stage compounds. The pyrocarbon prepared from C_2.5F gives hkl diffraction peaks indicating graphite-like stacking order of graphene layers. This carbon possesses average crystallite sizes along the c- and a-axes (L_c and L_a) of about 5 and 50 nm, respectively. The specific surface area of the pyrocarbon (about 40 m² g⁻¹) is only twice as large as that of the original crystalline graphite. Chemical behavior of the pyrocarbon as an intercalation host for sodium and potassium is similar to that of crystalline graphite, but it is easily fluorinated by elemental fluorine even at 573 K to give poly(carbon monofluoride) [(CF)_n] probably due to the small crystallite size and the mesopores formed by formation/decomposition processes of C_2.5F.