STRUCTURAL AND CHEMICAL CHARACTERIZATION OF N-DOPED NANOCARBONS

Fullerene blacks with 0.7-4.5 at% of nitrogen incorporated into their carbon framework were produced by feeding N-2 gas into the center of a carbon arc through a hollow graphite electrode. The formation of tolu ene-soluble fullerenes is effectively suppressed under these condition s. Optical emission spectroscopy of the are plasma revealed the presen ce of N atoms and CN radicals. Chemical composition and stability of t he N-doped fullerene blacks were examined and compared to their N-free counterparts produced in pure helium atmosphere by X-ray photoelectro n spectroscopy(XPS), electron energy loss spectroscopy and temperature -programmed oxidation with mass-spectrometric detection of the product gases. The nitrogen content was not diminished when N-doped fullerene black was heated to 500 degrees C in an in situ XPS experiment. Graph itic onions could be formed From n-doped fullerene black by intense el ectron irradiation in the electron microscope without loss of the nitr ogen content. Structural and morphological properties were studied by powder X-ray diffraction, high-resolution transmission electron micros copy and the determination of BET (Brunauen Emme Teller) specific surf ace areas. The performance of N-doped and undoped fullerene blacks in the removal of ionic contaminants from water was examined in a dynamic adsorption scheme using diammonium chromate(VI) as a test compound. ( C) 1998 Published by Elsevier Science Ltd. All rights reserved.