Growth of Carbon Nanofibers and Nanotubes

Huang, H., Kajiura, H., Murakami, Y., Ata, M. - Metal sulphide catalyzed growth of carbon nanofibers and nanotubes . Carbon 41 (2003) 579-625 Takikama, H., Kusano, O., Sakakibara, T. - Graphite cathode spot produces carbon nanotubes in arc discharge , Appl. Phys. 32 (1999) 2433-2437 Maser, W. K., Munoz, E., Benito, A. M., Martinez, M. T., de la Puente, G. R, Maniette, Y., Anglaret, E., Sauvajol, J. L. - Production of high density single walled nanotube material by a simple laser ablation method , Chem. Phys. Lett. 292 (1998) 587-593... 

As reported elsewhere [22], similar to those found on other catalysts, the forms of carbon materials deposited on Fe-loading zeolite molecular sieves are carbon nanotube, carbon nanofiber and amorphous carbon. One obvious phenomenon of the carbon nanotubes formed on Fe/NaY or Fe/SiHMS catalysts is that almost all tips of these tubes are open, indicating the interaction between catalyst particles and supports is strong [23]. On the other hand, the optimal formation time of carbon nanotubes on Fe/SiHMS is longer than that on Fe/NaY. However, the size of carbon nanotubes is easily adjusted and the growth direction of carbon nanotubes on the former is more oriented than on the latter. 

Another idea is to deposit on the electrode surface carbon nanofibers (nanotubes) by PECVD and then decorating them by sputtered platinum nanoclusters. Generally, three consecutive plasma deposition steps are carried out to this end the sputtering of a catalyst used to initiate the growth of the carbon nanofibers (e.g. Fe, Ni, Co), the creation of the nanofibers by PECVD from a mixture of precursors (e.g. CH4/H2, CH4/N2) and the sputtering of platinum. The plasma produced systems consisting of carbon nanofibers with a diameter of... 

Four different aryldiazonium salts have been used to functionalize SWCNTs through electrochemical reduction. By XPS and Raman diffusion measurements, the growth of aryl chains on the sidewalls of the nanotubes was observed [178]. Electrically addressable biomolecular functionalization of SWCNT electrodes and vertically aligned carbon nanofiber electrodes with DNA was achieved by elec-trochemically addressing (reduction) of nitrophenyl substituted nanotubes and nanofibers. Subsequently, the resulting amino functions were covalently linked to DNA forming an array of DNA-CNT hybrid nanostructures (Scheme 1.28) [179],... 

Like small amphiphile nanotubes [14], block copolymer nanotubes should have potential applications in controlled deUvery and release [97,98], in encapsulation [99], and in nanoelectronics [100] etc. Although there have been reports on laboratory use of block copolymer nanofibers as vehicles for drug delivery [101], as scaffolds for cell growth [88,102], as precursors for ceramic magnetic nanowires [103,104], and as precursors for carbon nanofibers [105,106[, practical applications of block copolymer nanotubes have not been reported. This is probably due to the difficulty in making such structures. Their preparation from the self-assembly of block copolymers and interests from industry will likely change the scenery of nanotube appUca-tions in the futme. 

The researchers observed a series of nanoprotrusions from spikes to blocks oriented perpendicular to the fiber axis. The mechanism for this process was similar to the crystallization mechanism of CNT growth from a surface. Carbon nanostructures from electrospun carbon nanofibers with iron and palladium nanoparticles were grown, respectively. In a later work, the type of carbon dictated the morphology of the resulting nanostructure. Toluene as the carbon source yielded straight nanotubes, pyridine gave coiled and Y-shaped nanotubes, and chlorobenzene formed nanoribbons. Figure 8.4 displays a variety of carbon nanostructures from rods to Y-shaped protrusions. 

As we discuss there are various methods to produce carbon nanofibers or carbon nanotubes, for example, vapor growth [89], arc dischaige, laser ablation and chemical vapor deposition [28, 89]. However, these are very expensive processes owing to the low product yield and expensive equipment. Preparation carbon nanofiber by electrospinning of proper precursors is preferred because of its lower cost and more output [90]. 

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