Graphite Electrodes Containing Nanometer-Sized Metal Particles and Their Use in the Synthesis of Single-Walled Carbon Nanotube Composites

Abstract

Composite graphite/metal(0) electrodes were prepared by the absorbtion of organic solutions of metal carbonyls or aqueous solutions of metal salts into high-purity porous graphite rods. The metal carbonyls were converted to the CO-free metal(0) species by heating the composites under an atmosphere of N2 and then under reduced pressure at 1000 °C. The metal-salt-containing graphite rods were heated under an atmosphere of H2 at 1000 °C to reduce the salts to the corresponding metal(0) species. This procedure permitted dispersion of metal(0) throughout the graphite rod with average metal particle sizes in the range 6.2−11.6 nm by transmission electron microscopy (TEM) analysis. Metals used were Ag, Co, Cu, Fe, La, Ni, and Pt. The composite graphite/metal(0) electrodes were vaporized in a plasma discharge apparatus under a helium atmosphere. The Co, Fe, Ni, and Pt all catalyzed single-walled nanotubule (bucky tube) growth. The soot material from the Co, Fe, and Ni-containing rods had a foam-rubber-like texture. All the metal-containing soots, except for the La-derived material, could be press molded into pellets, without the use of a binder. Data from the trace remaining ligand analyses, powder X-ray diffraction, TEM, conductivity measurements, and surface area analyses are presented. The properties of the arc-derived soots prepared by this method are compared to the soots prepared by standard cored rod/metal(0) methods.