Surface-bound chemical vapour deposition of carbon nanotubes: In situ study of catalyst activation

We combine in situ X-ray photoelectron spectroscopy and ex situ electron and Raman spectroscopy to study chemical interactions of SiO2-supported Fe catalyst films during C2H2 exposure in the 400–600 °C temperature range. Carbon nanotubes nucleate at C2H2 pressures below 10−6 mbar, which allows a time-resolved recording of core level spectra. We find a rapid transition from an initial chemisorbed carbon on metallic Fe catalyst nanoparticles to a sp2 graphitic carbon network. Pre-treating the Fe catalyst film by H2 sputtering influences the initial catalyst de-wetting and increases carbon nanotube yield.