Sol–gel preparation of catalyst particles on substrates for hot-filament CVD nanotube deposition

Carbon nanotubes (CNTs) were grown by hot-filament chemical vapour deposition and iron was the catalyst. The aim of this research was to produce aligned CNTs attached to a substrate.For a homogeneous distribution of the catalyst particles on substrate plates various sol–gel mixtures were used containing iron nitrate and tetrabutyltitanate forming an inorganic network. The produced gels were spin-coated on the substrates and after drying a temperature treatment between 650 and 800 °C was applied. For comparison iron nitrate was dissolved in ethanol and spin-casted on the substrate.Parameter variation during hot-filament CVD growth resulted in the formation of different types of nanotubes and also sectors of aligned CNTs were observed. The nanotube types were: double-wall CNTs, multiwall CNTs, bamboo-type CNTs and fishbone carbon nanofibers.