Synthesis and analysis of aligned multi-walled carbon nanotubes by chemical vapour deposition

Abstract

The present work reports on the development of self-standing tubular geometry of aligned multi-walled carbon nanotubes (AMWCNTs) with uniform diameter and high surface area. The synthesis involves catalytic chemical vapour deposition of methane in nitrogen atmosphere. The colloidal dispersion of Fe-Mo/MgO with ferrocene-benzene was used as the catalyst. A new catalyst fabrication method based on sol gel precursor technique was adapted which resulted in the formation of AMWCNTs. They had outer diameter in the range of 4-6 nm (average diameter 5.1 nm) and walls comprised of 3-6 graphenes. The effect of various parameters such as growth temperature, ferrocene concentration, flow rate of nitrogen gas, the pumping rate of sol gel precursor and carbon feed stock were studied. The product was analysed using high resolution transmission electron microscopy (HRTEM), scanning electron microscopy and Raman spectroscopy. The high ratio of IG/ID of Raman analysis indicates that the synthesised AMWCNTs have low defect levels in atomic carbon structures and is in accordance with HRTEM observations.