Nanotubes materials

Hydrogen interaction with the carbon nanostructural materials (nanotubes, nanofibers, fullerenes C60 and C70 has been intensively studied over the last years. A developed surface of nanotubes and nanofibers induced a considerable applied interest aimed at hydrogen storage and reduced consumption of organic fuel in modem industry. For the academic studies, of interest is the nature of the hydrogen interaction with the carbon nanomaterials. 

Recently, considerable advances have been made in the production of a different class of nanoscopic carbon structures, namely, carbon nanotubes, which stimulated fundamental research exploring the structure-property relationship of these materials [227]. In their simplest form carbon nanotubes are composed of only a single cylindrieal graphene shell with a central hollow internal cavity. These structurally imiform cylinders are invariably sealed at both ends by bended carbon caps, which contain both five- and six-membered rings similar to the struetures of fullerenes. Based on their similarity with highly graphitized carbonaceous materials, nanotubes have low ehemieal reaetivity. Therefore, the chemistry of earbon nanotubes is mainly focused on opening reaetions at its... 

Since the discovery of carbon nanotubes in the early 1990s [273] there has been emerging interest in their applicability as catalyst supports for low-temperature PEMFCs. Recently, Lee et al. reviewed the area of Pt electrocatalyst preparation techniques using carbon nanotubes and nanofibers as supports [274]. Here, the emphasis will be on the impact of novel nanostructured carbon supports (ordered mesoporous materials, nanotubes, and nanofibers) on the electrocatalytic activity with respect to direct fuel cell anodes. 

The field of fullerene chemistry expanded in an unexpected direction in 1991 when Sumio lijima of the NEC Fundamental Research Laboratories in Japan discovered fibrous carbon clusters in one of his fullerene preparations This led within a short time to substances of the type portrayed in Figure 11 7 called single-walled nanotubes The best way to think about this material IS as a stretched fullerene Take a molecule of Ceo cut it in half and place a cylindrical tube of fused six membered carbon rings between the two halves... 

There are many applications for diamonds and related materials, e.g., diamondlike carbon films, and there are potential applications for Fullerenes and carbon nanotubes that have not yet been realised. However, the great majority of engineering carbons, including most of those described in this book, have graphitic microstructures or disordered graphitic microstructures. Also, most engineering carbon materials are derived firom organic precursors by heat-treatment in inert atmospheres (carbonisation). A selection of technically-... 

The structure-property relations of fullerenes, fullerene-derived solids, and carbon nanotubes are reviewed in the context of advanced technologies for carbon-hased materials. The synthesis, structure and electronic properties of fullerene solids are then considered, and modifications to their structure and properties through doping with various charge transfer agents are reviewed. Brief comments are included on potential applications of this unique family of new materials. 

As further research on fullerenes and carbon nanotubes materials is carried out, it is expected, because of the extreme properties exhibited by these carbon-based materials, that other interesting physics and chemistry will be discovered, and that promising applications will be found for fullerenes, carbon nanotubes and related materials. 

Chapter 1 contains a review of carbon materials, and emphasizes the stmeture and chemical bonding in the various forms of carbon, including the foui" allotropes diamond, graphite, carbynes, and the fullerenes. In addition, amorphous carbon and diamond fihns, carbon nanoparticles, and engineered carbons are discussed. The most recently discovered allotrope of carbon, i.e., the fullerenes, along with carbon nanotubes, are more fully discussed in Chapter 2, where their structure-property relations are reviewed in the context of advanced technologies for carbon based materials. The synthesis, structure, and properties of the fullerenes and... 

Harris has this to say on the breadth of appeal of nanotubes Carbon nanotubes have captured the imagination of physicists, chemists and materials scientists alike. Physicists have been attracted to their extraordinary electronic properties, chemists to their potential as nanotest-tubes and materials scientists to their amazing stiffness, strength and resilience . 

The other striking feature of nanotubes is their extreme stiffness and mechanical strength. Such tubes can be bent to small radii and eventually buckled into extreme shapes which in any other material would be irreversible, but here are still in the elastic domain. This phenomenon has been both imaged by electron microscopy and simulated by molecular dynamics by lijima et al. (1996). Brittle and ductile behaviour of nanotubes in tension is examined by simulation (because of the impossibility of testing directly) by Nardelli et al. (1998). Hopes of exploiting the remarkable strength of nanotubes may be defeated by the difficulty of joining them to each other and to any other material. 

In Fig. 13 is shown the 002 lattice images of an as-formed very thin VGCF. The innermost core diameter (ca. 20 nm as indicated by arrows) has two layers it is rather straight and appears to be the primary nanotube. The outer carbon layers, with diameters ca. 3-4 nm, are quite uniformly stacked parallel to the central core with 0.35 nm spacing. From the difference in structure as well as the special features in the mechanical strength (as in Fig. 7) it might appear possible that the two intrinsically different types of material... 

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