SYNTHESIS, CHARACTERIZATION, DECORATION AND FILLING OF CARBON NANOTUBES

Abstract

Carbon nanotubes (5-30 nm in diameter and 0.4-5 µm long) were synthesized by the arc-discharge method in a He atmosphere. The nonotube samples were oxidized by burning in air and by liquid-phase oxidation using KMnO4, HNO3 and a mixture of HNO3/H2SO4 as oxidants. We approached the decoration of these oxidized tubes from two angles. The first approach, involving metal deposition directly onto the oxidized tube surfaces, yielded nanotubes decorated with very fine particles of gold and nanoparticles of Pd/Pd oxides. Tubes filled with a Pd compound were also observed. The second method involved electroless plating on activated, oxidized carbon nanotubes. We studied two methods of activation - the two step sensitization/activation procedure and the single step activation procedure. Cu-decorated and Ni-decorated tubes were obtained employing the two-step procedure. We also observed that the age of the sensitizer was a crucial factor in determining the nature of the sensitized and activated tubes and the corresponding Cu deposits. The density of the active phase and Cu deposits peaked at around 3 days of sensitizer aging. Decoration employing the single step activation procedure yielded particularly intriguing results -carbon nanotubes densely decorated (coated) with Cu, Ni and Pd were obtained.