Building up Multiwall Carbon Nanotubes Nanostructures inside Millimetric Channels of Ceramic Monoliths

Multiwall carbon nanotubes were grown inside the millimetric channels of commercial ceramic materials, cordierite monoliths, using a modified catalytic chemical vapor deposition method. Fe(CO)₅ liquid catalyst precursor was introduced in gas phase at the same time as the acetylene carbon source to allow a more uniform distribution of carbon nanotubes on the substrate surface. Different techniques were used for the characterization of the obtained multiwall carbon nanotubes such as scanning and transmission electron microscopies, N₂ adsorption isotherms, Raman spectroscopy and thermogravimetric analysis. The results show that the surface of the ceramic monolith is progressively covered with multiwall carbon nanotubes reaching total coverage for longer times under reaction. The carbon nanotubes were built up with a tree-like morphology. So, firstly larger carbon nanotubes are formed as the tree trunks on the cordierite surface, followed by the growing on them of narrower and longer nanotubes suggesting the tree branches.