Growth of multi-walled carbon nanotubes by injection CVD using cyclopentadienyliron dicarbonyl dimer and cyclooctatetraene iron tricarbonyl

Preferential oriented multi-walled carbon nanotubes were prepared by injection chemical vapor deposition (CVD) using either cyclopentadienyliron dicarbonyl dimer or cyclooctatetraene iron tricarbonyl as the iron catalyst source. The catalyst precursors were dissolved in toluene as the carrier solvent for the injections. The concentration of the catalyst was found to influence both the growth (i.e., MWNT orientation) of the nanotubes, as well as the amount of iron in the deposited material. As deposited, the multi-walled carbon nanotubes contained as little as 2.8 wt.% of iron. The material was deposited onto tantalum foil and fused silica substrates. The nanotubes were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and thermogravimetric analysis. This synthetic route provides a simple and scalable method to deposit MWNTs with a low defect density, low metal content and a preferred orientation.