Influence of the Support on the Structural Characteristics of Carbon Nanofibers Produced from the Metal-Catalyzed Decomposition of Ethylene

Abstract

The notion of using support materials to achieve high dispersions of metal particles has been extended to the synthesis of carbon nanofibers from the catalyzed decomposition of ethylene. By using this approach it has been possible to generate nanofibers whose widths are dictated by the dimensions of the supported metal particles. In addition, the support may alter the state of the bulk and/or the surface of the catalyst particle through metal−support interactions, and the impact of this effect is manifested by modifications in the structural characteristics of the nanofiber deposits. In an attempt to gain a clearer insight into the influence of metal−support interaction on the growth characteristics of GNF, three metals, Fe, Ni, and Co that are known to be active catalysts for this process were impregnated onto silica, graphite, and well-characterized graphite nanofiber supports. Characterization of the solid carbon products was performed by a variety of approaches including high-resolution transmission electron microscopy (HRTEM), gas-phase analysis, and thermal-programmed oxidation (TPO). The goal of this study was to correlate each nanofiber product with the behavior of the specific metal/support precursor system. The advantages of using selected support materials to control the morphologies and sizes of nanofibers is presented.