Novel vapor phase reactions for the synthesis and modification of carbon nanotubes and inorganic nanowires

Several vapor phase methods have been developed for the preparation and modification of carbon nanotubes and inorganic nanowires. Thus, nebulized spray pyrolysis has been employed for the synthesis of carbon nanotubes and metal nanowires. Multi-walled carbon nanotubes (MWNTs) with fairly uniform diameters and aligned nanotube bundles have been obtained by nebulized spray pyrolysis using solutions of organometallics such as ferrocene in hydrocarbon solvents. Single-crystalline nanowires of zinc, cadmium, cobalt, and lead are obtained by the decomposition of metal acetates. By reacting acid-treated carbon nanotubes with vapors of metal halides, followed by reaction with water and calcination chemically-bonded oxide layers can be obtained on the nanotubes. A similar procedure has been employed to prepare chemically-bonded oxide layers on Al2O3, ZnO, and silicon nanowires by the reaction of the metal halides with the surface hydroxyl groups present on these nanowire surfaces.