title: Effect of iron concentration on the growth of carbon nanotubes on clay surface.
abstract: The successful growth of carbon nanotubes (CNTs) on montmorillonite (MMT) precursors treated with different concentrations of ferric nitrate at 50 °C (MMT(Fe)-50) and 100 °C (MMT(Fe)-100) was achieved via the in situ chemical vapor deposition (CVD) of acetylene. The as-obtained MMT-CNTs composites were characterized using X-ray diffraction, inductively coupled plasma emission spectrometry, scanning electron microscopy, and transmission electron microscopy. All Fe(3+) ions were intercalated into the MMT interlayers at either 50 or 100 °C in the case of [Fe(3+)]/[clay] = 1. However, the iron content in MMT(Fe)-100 increased rapidly with the amount of ferric nitrate added, whereas the iron content in MMT(Fe)-50 did not exhibit significant changes. On the other hand, the physical and chemical adsorption of Fe(3+) onto the MMT surface was believed to be responsible for the great diversity of iron contents in MMT(Fe)-50 and MMT(Fe)-100 at the same [Fe(3+)]/[clay] ratios. Moreover, the CNT yield showed variation similar to the iron content because the CNTs yield depends primarily on the amount of catalyst available. The CNTs embedded onto MMT(Fe)-100 exhibited narrower diameter distributions than those on the MMT(Fe)-50 precursors, with more CNTs with diameters less than 50 nm on the former. It is suggested that a porous structure with many pores formed by iron species and MMT laminas is related to the morphology and structure of CNTs embedded on the surface of MMT.
authors.affiliation: Key Laboratory of Macromolecule Synthesis and Functionalization, Ministry of Education, Department of Polymer Science and Engineering, Zhejiang University, Hanghzou, China.
authors.forename: Fu
authors.initials: F
authors.lastname: Huakang
authors.forename: Du
authors.initials: D
authors.lastname: Miao
authors.forename: Zheng
authors.initials: Z
authors.lastname: Qiang