Formation of nitrogen doped carbon during arc-discharge of carbon rods in the presence of pyrrole

When the are vaporization of carbon rods in a helium atmosphere is conducted in the presence of small amounts of pyrrole, not only does one form nitrogen-doped fullerenes, but also the surface of the carbon rods becomes coated with a layer of a nitrogen-doped carbon. X-ray diffraction indicates d spacing expansion, and x-ray photoelectron spectroscopy confirms that nitrogen doping has occurred at a level of 2.3%. N-1s spectra reveal a nonuniformity in the distribution of nitrogen atoms relative to carbon. These data are consistent with a model in which substitution of nitrogen occurs at the domain boundaries of the graphitic particles. A consequence of this doping is a twofold increase in the electrical conductivity of the carbon. The x-ray photoemission results indicate that N incorporation induces a shift of the valence band toward the Fermi level. (C) 1996 American Institute of Physics.