Authors: C. Paukner, K.K.K. Koziol
Affilation: University of Cambridge, United Kingdom
Pages: 21 - 24
Keywords: single wall CNTs, CNT fiber, Raman, TEM
We report a new strategy towards the control of carbon nanotube (CNT) structure and continuous fiber formation using a floating catalyst direct spinning CVD process. In the procedures used to date, a sulphur promoter precursor is added to significantly enhance the rate of CNT formation in the floating catalyst synthesis. Within the reaction zone, the rapidly grown nanotubes self-assemble into bundles, followed by their continuous spinning into fibers, yarns, films or tapes. Our latest findings demonstrate a catalyst control strategy in the floating catalyst system, where the CNT formation process is independent of the presence of a promoter but leads to successful spinning of the macroscopic carbon nanotube assemblies with specific morphology, high purity (Raman D/G 0.03) and very narrow diameter range (0.8-2.5 nm). This can be achieved by the control of catalyst precursor decomposition and subsequent formation of homogeneous nano-sized catalyst particles. The effects of varied precursor decomposition temperature on the morphology of CNTs were determined by comprehensive characterization using SEM, TEM, TGA and Raman spectroscopy. Their combination revealed that the different CNT species in the samples as well as the presence of other impurities depends strongly on the pyrolysis temperature of the precursors used.