Uniform Large Diameter Carbon Nanotubes in Vertical Arrays from Premade Near-Monodisperse Nanoparticles

Despite the many processes developed for carbon nanotube synthesis, few if any of these control the carbon nanotube diameter and length simultaneously. Here, we report a process whereby we synthesize vertically aligned carbon nanotube arrays (VA-CNT) using water-assisted chemical vapor deposition from solution processed premade and near-monodisperse iron oxide nanoparticles. Utilizing a dendrimer-assisted iron oxide nanoparticle monolayer deposition technique, the synthesis of high quality VA-CNTs is observed with a surprising degree of walls uniformity and diameters that correlate closely with the catalyst particle size. Specifically, we utilize 8.3 and 15.4 nm nanoparticle sizes to grow uniform, large diameter VA-CNTs. We observe control of the VA-CNT diameter and number of walls based on the nanoparticle size, with the 8.3 nm nanoparticles growing over 90% four-walled CNTs. Additionally, there is a sparse population of VA-CNTs with large diameters and few walls that tend to flatten into nanostructures resembling paired-layer graphene nanoribbons.