A single compound can be the source of carbon atoms and an iron catalyst needed to make carbon nanotubes
Bulk quantities of single-walled carbon nanotubes (SWNTs) can be made by the well-known high-pressure carbon monoxide disproportionation process (HiPco). This method produces SWNTs by flowing a gaseous mixture of carbon monoxide and a small amount of an iron catalyst through a reactor at high temperature.
Now, researchers at the Leibniz-Institut fér Festkörper- und Werkstoffforschung Dresden in Germany and the Universitat Autonoma de Barcelona in Spain have shown that a single compound can serve as the carbon source as well as the catalyst. Amelia Barreiro and co-workers1 flowed a mixture of gaseous argon and ferrocene — a chemical compound composed of an iron atom sandwiched between two five-membered carbon rings — through a heated reactor. At temperatures exceeding 500 °C, ferrocene spontaneously decomposed into iron clusters and reactive carbon fragments. The metal clusters acted as nucleating agents onto which the carbon atoms grew into SWNTs.
Electron microscopy images showed the samples were mainly long bundles of SWNT with diameters between 20–30 nm. Further characterization using spectroscopic methods confirmed that the material was very similar to those made using the standard HiPco procedure.
Barreiro, A. et al. J. Phys. Chem. B (2006). 10.1021/jp0636571