Liquid-Phase Deposition of Aligned Carbon Nanotubes Using Cobalt Catalyst

Abstract

We have recently developed a novel catalytic method for synthesizing a wide variety of carbon nanomaterials in the organic liquid. The method enabled us to realize a simple, rapid, and high-purity growth of carbon nanotubes (CNTs) in alcohol liquids. In this study, cobalt (Co) was used as a catalyst metal. In order to control the structure of carbon nanomaterials, we investigated the relationship between the growth conditions and the grown materials. Scanning electron microscopy (SEM) observation revealed that the morphology of the grown carbon nanomaterials strongly depended on the reaction temperature. Under the reaction temperature in the range from 873 to 973 K, fibriform deposits were mainly obtained. Transmission electron microscopy (TEM) revealed that the fibriform deposits were CNTs. The amount of the supported Co catalyst affected the fine tubular structure of the CNTs. We found that the existence of the reaction temperature of 873 K during the reaction time was essential for growing a fibriform structure in this study. The longer duration time for the reaction temperature of 1127 K resulted in a higher crystal quality for CNTs. We also demonstrated that the Co catalyst thermal oxidation at 1173 K resulted in the growth of aligned CNTs with the higher density.