Diameter controlled growth of single-walled carbon nanotubes from SiO 2 nanoparticles

Abstract

A rational approach is reported for the growth of single-walled carbon nanotubes (SWCNTs) with controlled diameters using SiO 2 nanoparticles in a chemical vapor deposition system. The SiO 2 nanoparticles with different sizes were prepared by thermal oxidation of 3-aminopropyltriethoxysilane (APTES) with different number of layers which were assembled on Si substrates. It was found that the size of SiO 2 nanoparticles increased with the number of assembled APTES layers. Using these SiO 2 nanoparticles as nucleation centers, the diameter distribution of as-grown SWCNTs were correlated with the size of SiO 2 particles. In addition, both the classical longitudinal optical or transverse optical bands of SiC in in situ Raman spectra during the whole growth process and the Si 2p peak of SiC in the X-ray photoelectron spectra were not observed, suggesting that the carbon sources did not react with the SiO 2 nanoparticles during the growth. Comparing to vapor–liquid–solid mechanism for metallic catalysts, vapor–solid mechanism is proposed which results in a lower growth rate when using SiO 2 nanoparticles as nucleation centers.