Mar 11, 2010
Catalyst pre-treatment produces isolated CNT bundles
Catalysts play a key role in the growth of carbon nanotubes. The microwave plasma-assisted chemical vapor deposition (MPACVD) method is now commonly used for directional and conformal growth of carbon nanotubes (CNTs) on substrates.
Reporting their results in the journal Nanotechnology, researchers in France have investigated the effect of H2 plasma pre-treatment on the diameter and density of iron-catalyst nanoparticles for different iron-layer thicknesses in order to grow isolated bundles of CNTs. The formation of isolated bundles of CNTs opens up an interesting perspective in terms of chemical functionalization efficiency because the bundles are not aggregated.
Atomic force microscopy shows first that as plasma power density increases, the diameter of the iron nanoparticles decreases, which is due to increasing gas dissociation giving more ion bombardment energy. Second, the data reveal that the diameter of nanoparticles decreases with catalyst thickness.
The growth of CNTs was carried out under different CH4 concentrations for different iron-film thicknesses. Transmission electron microscopy and Raman spectroscopy show that the synthesized CNTs are of good quality and have an outer diameter between 5 and 10 nm.
Full details are available in the journal Nanotechnology.
About the author
The work was performed at the Institut Jean Lamour, a joint laboratory of CNRS and Nancy University, France. Dr Badreddine Assouar is a research scientist at CNRS and he is accredited to supervise research. Currently his main research interests include nanotechnologic process development, phononic crystals and condensed materials. Prof. Jamal Bougdira is a professor at Nancy University. Dr Manuel Dossot is an associate professor at Nancy University. Dr Sandra Rizk is a postdoctoral researcher at Nancy University.