Mössbauer Study of Catalytically Grown Carbon Nanotube

The valence states of iron in iron catalysts, hydrogen reduced catalysts, and catalytically grown carbon nanotubes are determined by Mössbauer spectra, respectively. The results show that the iron exists as Fe, FeO, and α-Fe₂O₃ in hydrogen reduced catalysts, whereas it exists as Fe-C alloy, FeO, and α-Fe₂O₃ in the catalysts encapsulated in carbon nanotube. It is postulated that Fe in hydrogen reduced catalysts plays the main role in the formation of catalytically grown carbon nanotube.