Carbon nanotubes growth methods

Yamamoto K, Koga Y, Fujiwara S, Kubota M. New method of carbon nanotube growth by ion beam irradiation. Appl Phys Lett 1996 69 4174-5. 

Whereas multi-wall carbon nanotubes require no catalyst for their growth, either by the laser vaporization or carbon arc methods, catalyst species are necessary for the growth of the single-wall nanotubes [156], while two different catalyst species seem to be needed to efficiently synthesize arrays of single wall carbon nanotubes by either the laser vaporization or arc methods. The detailed mechanisms responsible for the growth of carbon nanotubes are not yet well understood. Variations in the most probable diameter and the width of the diameter distribution is sensitively controlled by the composition of the catalyst, the growth temperature and other growth conditions. 

The direct linking of carbon nanotubes to graphite and the continuity in synthesis, structure and properties between carbon nanotubes and vapor grown carbon fibers is reviewed by the present leaders of this area, Professor M. Endo, H. Kroto, and co-workers. Further insight into the growth mechanism is presented in the article by Colbert and Smalley. New synthesis methods leading to enhanced production... 

Electron irradiation (100 keV) of the sample, heated to 800°C, yields MWCNTs (20-100 nm in length) attached to the surface. Such nanotube growth does not take place if natural graphite, carbon nanoparticles or PTFE are subjected to electron irradiation. The result implies that the material may be a unique precursor for CNTs and may constitute a new preparation method. 

An alternative route to obtain NbS2-sheathed carbon nanotubes (CNT) has been proposed by Zhu et al. [71] with this sonochemical method. In this study, CNTs act as templates to produce the uniform and well-crystallized bS2 nanotubes and the formation of such nanotubes has been explained by means of multi-point nuclei site growth mechanism. 

The methods of preparation discussed above do not involve any template and the nanoparticles of the oxide or the trisulfide act as nucleation centers for tube growth. Recently, CNTs have been used as templates to grow MoS2, WS2 and NbS2 coated carbon nanotubes, some of which contain 1-2 layers of the chalcogenide at the exterior. " The CNTs were coated with the metal oxide or its precursor and treated in a H2S/H2/N2 atmosphere at elevated temperatures to convert the oxide to the sulfide However, the CNT core was not removed in the nanostructures (Fig. IS). 

A. Loiseau, X. Blase, J.C. Charlier, P. Gadelle, C. Journet, C. Laurent and A. Peigney, Synthesis methods and growth mechanisms, in Understanding Carbon Nanotubes. From Basics to Application, Lecture Notes in Physics 677, Springer, 2006. 

Lee, C. J., et al. (2002), Large-scale production of aligned carbon nanotubes by the vapor phase growth method, Chem. Phys. Lett., 359(1-2), 109-114. 

The arc method of production was vastly improved after these original observations, and numerous other production methods were developed [96-99], including methods which primarily promoted the growth of single wall carbon nanotubes (SWNTs) [99-101]. As implied by the name, SWNTs are nanotubes which consist of only one layer of carbon atoms. 

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