Graphitized carbon nanofibers are prepared from 2-propanol at 673 K by spray pyrolysis in which dc high voltage is applied to the spray nozzle. A mixture of helical and straight carbon nanofibers is observed, and their diameters are ca. 100 -300nm. The resultant carbon nanofibers after acid-and heat-treatment show large capacity of around 310 mAh g^-1 and high reversibility with little hysteresis after the 2nd cycle in insertion/extraction reactions of lithium-ion, while a large irreversible capacity of 365 mAh g^-1 is observed at potentials below 0.9 V in the 1st cycle.

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The present authors developed a new method to prepare carbon nanotubes (CNT), whereby fine core-shell polymer particles are elongated by melt-spinning and then stabilized and carbonized. However, after its removal, no trace of the core polymer can be found in the resultant CNT. This behavior is investigated by TG-Mass spectroscopy. The shell polymer is thermally decomposed into small chemical fragments and disordered loose residue. The former are released through the latter, together with small fragments formed from the core polymer at nearly the same temperature range. After the removal of the core polymer, the shell residue is gradually rearranged into a dense carbon with increasing temperature. No trace of the core polymer remains in the resultant CNT.

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The feasibility of preparing double-layered nanotubes consisting of an inner carbon layer and outer silicon carbide layer was explored. Fine particles consisting of a poly (methyl methacrylate) core and polyacrylonitrile shell were coated with polycarbosilane by spray-drying. The resulting particles were buried in PVA fibers and elongated mechanically. After the removal of PVA, the particles were stabilized and finally heated at 1000°C in an inert atmosphere. Nanotubes were rarely observed. A nanotube showed a diameter of ca. 100 nm, wall thickness of 30 nm and composition (by weight) of 9.8% Si, 69.5% C and 20.7% O. The feasibility was confirmed by the composition and the structure of particles prepared by spray-drying.

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Application of electric current on many carbon nanotubes (CNTs) was carried out. An aggregated single-wall CNTs whose bulk density was about 1.4 g/cm³ changed into a rigid substance by electric current of about 500 A/cm² for 5 min. An increase of electric conductivity, an increase of rigidity, a Raman spectroscopy and microscope observations of the substance indicated the generation of new carbon-carbon bonds among many CNTs.

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A new centrifugal spinning apparatus with the maximum rotation speed of 6000 rpm and the highest temperature of 300°C was developed. In particular the apparatus is characterized by a mesh heather of thin nichrome belt with many line pores, which makes possible to spin immediately after polymer fuses by heating. This apparatus is useful for the preparation of carbon nanotubes and carbon nanofibers by using polymer blend technique.

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Intensive studies on a catalytic chemical vapor deposition method (CCVD) for producing carbon nanotubes has been carried out because this technique exhibits both controllability and scalability. In this paper, we, first, describe historical review on the selective synthesis of single-or multi-walled carbon nanotubes, and then report recent advance in the fabrication of high-purity double walled carbon nanotubes buckypaper through the right combination of a CCVD and an optimized purification process.

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Carbon nanotubes are one of the most promising materials because of their unique structure and electric properties. To apply them, it is important to produce nanotubes in high quantity and high purity. Various synthesizing methods have been established and they are now in progress. In this article, we focus on an arc discharge, which is traditional and is good method to produce in high quantity. We review from a history of the arc discharge to novel methods to produce nanotubes.

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Carbon nanotubes (CNTs) have single- or multi-cylindrical graphene structures that possess diameters of a few nanometers, while the length can be up to a few micrometers. Single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) possess a high tensile strength and ultra-light weight, and have excellent chemical and thermal stability. They also possess semiconducting and metallic conductive properties. These anomalous features have led to many proposed applications in the biomedical field, including biosensors, drug and vaccine delivery. However, CNTs could have unusual toxicological properties, in that they share intermediate morphological characteristics of both fibers and nanoparticles. This review presents the cytotoxicity and biocompatibility of CNTs. Finally, we report the activation of the human acute monocytic leukemia cell line THP-1 in vitro and the response in subcutaneous tissue in vivo to MWCNTs of different lengths.

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