No abstract

We report a new strategy towards the control of carbon nanotube (CNT) structure and continuous fibre 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 fibres, yarns, films or tapes. In this paper we 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.

We have studied the influence of different carbon precursors (methane, ethanol and toluene) on the type, diameter and chiral angle distributions of carbon nanotubes (CNTs) grown with the floating catalyst technique in a horizontal gas-flow reactor. Using electron diffraction to study their atomic structures, we found that ethanol and toluene precursors gave high single-wall CNT yields (92% and 89% respectively), with narrow diameter distributions: 1.1 nm to 1.7 nm (ethanol); 1.3 nm to 2.1 nm (toluene), with a propensity for armchair-type chiral angles. In contrast, methane-grown CNTs gave high double-wall CNT yields (75%) with broader diameter populations: 1.2 to 4.6 nm (inner CNT) and 2.2 to 5.3 nm (outer CNT) with a more uniform spread of chiral angles, but weakly peaked around 15 to 20 degrees. These observations agree with known growth models. However, double-wall CNTs grown with toluene showed an unusually narrow interlayer spacing of 0.286 ± 0.003 nm with suggestions of large, 20° to 25°, differences between inner and outer CNT chiral angles. Methane gave a large interlayer spacing (0.385 ± 0.002 nm) with suggestions of small 5° to 10° inter-tube chirality correlations.

Abstract

We present the fabrication of lipid nanoscaffolds inside carbon nanotube arrays by employing the nanostructural self-assembly of lipid molecules. The nanoscaffolds are finely tunable into model biomembrane-like architectures (planar), soft nanochannels (cylindrical) or 3-dimensionally ordered continuous bilayer structures (cubic). Carbon nanotube arrays hosting the above nanoscaffolds are formed by packing of highly oriented multiwalled carbon nanotubes which facilitate the alignment of lipid nanostructures without requiring an external force. Furthermore, the lipid nanoscaffolds can be created under both dry and hydrated conditions. We show their direct application in reconstitution of egg proteins. Such nanoscaffolds find enormous potential in bio- and nano-technological fields.