Carbon onion growth enhanced by nitrogen incorporation

A mass of carbon onions have previously been successfully synthesized via catalytic decomposition of methane using nitrogen as a carrier gas over a Ni/Al catalyst. In this study, X-ray photoelectron spectroscopy characterization of the carbon onions shows that the as-grown carbon onions contained nitrogen and that the nitrogen concentration in the carbon onions increased with an increase in reaction time. When hydrogen is used as a carrier gas, it is found that no carbon onions are obtained. indicating that the carrier gas plays an important role in the synthesis of carbon onions and that there is an intimate relationship between carbon onion growth and nitrogen incorporation. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.