CVD growth of single-walled carbon nanotubes using size-controlled nanoparticle catalyst

We investigated single-walled carbon nanotube (SWNT) growth using a novel Fe3O4 nanoparticle catalyst synthesized with a simple organic chemistry process. We characterized the structure of the grown SWNTs through scanning electron microscopy (SEM), atomic force microscopy (AFM) and microscopic Raman spectroscopy. Discrete nanoparticles with a uniform diameter of ∼4 nm could be deposited on Si substrates with a thermal oxide layer by spin-coating with a nanoparticle solution. Nanoparticles prepared under optimum conditions remained discrete and uniform without aggregation even after chemical vapor deposition (CVD) process and their diameters were reduced to ∼1.7 nm due to decomposition reactions during CVD. These nanoparticles were found to have remarkable catalytic activity in the CVD growth of the SWNTs. SWNTs with diameters of around 1 nm were produced from the reduced nanoparticle catalyst. The diameters of the grown SWNTs were closely correlated with those of the catalytic nanoparticles and tended to be slightly smaller than the particle size.