Gas chromatography study of reagent degradation during chemical vapour deposition carbon nanotubes

The high temperature decomposition of three types of hydrocarbons, such as ethanol, camphor and cyclohexanol has been studied in order to find out the role played by the molecular structure during the formation of carbon nanotubes (CNTs) catalyzed by ferrocene. This investigation may allow identifying the properties required to the carbon precursor to obtain the highest CNT yield and quality. A gas chromatography mass spectrometry (GC-MS) technique was employed to monitor the evolution of the volatile cracking products resulting at 900°C in Ar atmosphere. The presence of ferrocene catalyst has showed negligible effect on the composition of the volatile products and the main decomposition molecule detected was benzene. Furthermore, the comparison of GC-MS results with SEM images and Raman spectra of the as-grown samples have suggested that the presence of benzene and its interaction with the iron clusters play a key role in the CNT formation only over the bare silicon wafer or quartz substrate.