Nano-tubes

Fig. 18. One-dimensional energy dispersion relations for (a) armchair (5,5) nanotubes, (b) zigzag (9,0) nanotubes, and (c) zigzag (10,0) nano tubes. The energy bands with a symmetry arc non-degenerate, while the e-bands are doubly degenerate at a general wave vector k [169,175,176].

The newest addition to the forms of elemental carbon is the nanotube. A carbon nanotube is a long cylinder of carbon atoms, connected together in much the same way as in a fullerene. Both the diameter and the length of carbon nano-tubes can vary. Properties of nanotubes, such as their ability to conduct electrical charge, change dramatically with the dimensions of the tube. Carbon nanotubes are under intensive study. For example, a carbon nanotube laid down on a silicon chip forms a molecular transistor. Such devices may eventually lead to further miniaturization of the chips that are at the heart of modem computers. 

This process of filament growth is closely related to the synthesis of single walled carbon nano-tubes. Here the aim is to selectively produce a single layer of carbon in a tube that is as long as possible. Owing to their extreme mechanical strength and interesting electronic behavior these materials have recently attracted substantial interest in materials science. 

Several studies have been dedicated to the application of amine-modified carbon nano tubes (CNTs) as solid sorbents for C02 separation [65-69]. Industrial grade CNTs have been functionalized with tetraethylenepentamine (TEPA) by Liu et al. [65], and the effects of amine loadings on the C02 uptake, heat of adsorption, and adsorbent regenerability were investi-... 

Bahome, M., Jewell, L., Hildebrandt, D., Glasser, D., and Coville, N. J. 2005. Fischer-Tropsch synthesis over iron catalysts supported on carbon nano tubes. Applied Catalysis A General 287 60-67. 

The ID electronic energy bands for carbon nanotubes [170,171, 172, 173, 174] are related to bands calculated for the 2D graphene honeycomb sheet used to form the nanotube. These calculations show that about 1/3 of the nano tubes are metallic and 2/3 are semiconducting, depending on the nanotube diameter di and chiral angle 6. It can be shown that metallic conduction in a (ra, m) carbon nanotube is achieved when... 

ID Ti02 nanostructures, e.g. nanorods, nanowires and nanofibres, nano tubes and nanopillars. 2D Titania nanostructures, e.g. columnar-type films, ordered arrays of nanotubes or nano-rods/-wires, nanobowl array, nanomembranes (called also nano-hole array) and nanosponge, and Ti-based ordered mesoporous matrices are instead not discussed, because it will be review in a consecutive paper. 

Single walled carbon nano tubes (SWNTs), 22 720... 

It has been pointed out however that further innovative steps are needed before single nano-tubes devices with adequate reproducibility can be made. A paper by Zhang et al. (2006) indicates parallel research lines intended to develop the various complementary aspects of nano-sciences and their applications. They observed that metallic and semi-conducting carbon nano-tubes generally coexist in as grown... 

Levitsky IA, Kanelos PT, Woodbury DS, Euler WB (2006). Photoactuation from a carbon nano-tube-nafion bilayer composite. J. Phys. Chem. B. 110 9421-9425. 

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