Carbon nanotubes synthesis methods

Owing to the many possible configurations applicable and several modifiable parameters, the arc method, which can be considered the traditional carbon nanotube synthesis method, has a greater possibility of being improved. 

J.P. Harmon and L.M. Clayton, Polymer/carbon nanotube composites, methods of use and methods of synthesis thereof, US Patent 7 399 794, assigned to University of South Florida (Tampa, FL), July 15, 2008. 

Our experiment has demonstrated the possibility of the carbon nanotubes synthesis by low temperature (substrate temperature was 500°C) vapor deposition method from the ethanol vapor. Field emission samples were produced with different catalyst distribution on the substrate surface. 

The synthesis processes for the nanotubes have been continuously refined in the recent years and today, a number of methods are available to synthesize both single and multiwalled carbon nanotubes. These methods include high temperature evaporation using arc-discharge (28-30), laser ablation (31), chemical vapor deposition etc. (32-34). 

Other technological aspects of carbon nanotube synthesis currently under scrutiny include study of the growth mechanism [67,71], attempts to control the diameter [72-74], processes which yield very long CNTs [70,75], optimization of the catalyst composition [76], and improvements in purity [77]. A major area of focus is the production of CNTs at selected sites on a substrate (micropatterning) [78-81]. Other synthetic methods investigated have been (i) a solvothermal route, in which reactants are heated in solution in a sealed autoclave [82,83] (ii) a solid-state metathesis process [84] (iii) a hydrothermal process which produces MWNTs from amorphous carbon [85] and (iv) low-temperature processes [59]. 

In the field of carbon nanotubes synthesis, widely studied for the moment, the one-step sol-gel method is examined as a way to prepare bimetallic catalysts leading to a high productivity in single-walled carbon nanotubes (SWNTs). For example, Su et al. [145] prepared a Fe-Mo/AljOj aerogel (dried in supercritical COj) and Mehn et al. [133] prepared a Fe-Mo/AljOj cryogel (freeze-dried) both with a good activity in SWNTs synthesis. 

Prasek J, et al. Methods for carbon nanotubes synthesis-review. Journal of Materials Chemistry 2011 21 15872-84. http //dx.doi.org/10.1039/cIjm12254a. 

Prasek, J., Drbohlavova, J., Chomoucka, J., Hubalek, J., Jasek, O., Adam, V., Kizek, R., 2011. Methods for carbon nanotubes synthesis—review.. Mater. Chem. 21, 15872—15884. 

Nasibulin, A.G., Moisala, A., Brown, D.P., Jiang, H., and Kauppinen, E.I. (2005). A novel aerosol method for single walled carbon nanotube synthesis. Chem Phys Lett 402 227-232. 

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... 

Xin and co-workers modified the alkaline EG synthesis method by heating the metal hydroxides or oxides colloidal particles in EG or EG/water mixture in the presence of carbon supports, for preparing various metal and alloy nanoclusters supported on carbon [20-24]. It was found that the ratio of water to EG in the reaction media was a key factor influencing the average size and size distribution of metal nanoparticles supported on the carbon supports. As shown in Table 2, in the preparation of multiwalled carbon nanotube-supported Pt catalysts... 

Liu J, Czerw R, Carroll DL (2005a) Large-scale synthesis of highly aligned nitrogen doped carbon nanotubes by injection chemical vapor deposition methods. Journal of Materials Research 20 538-543. 

Depending on the synthesis procedure (see Section 1.4) and purification methods (Section 1.6.1), the structure of synthesized carbon nanotubes may include a range of defects (see Chapter 4). 

Carbon nanotubes comprise a very promising material for various applications and especially as an active component in composites and hybrids as will be documented in the other chapters of this book. Harnessing these nanoscopic assets in a macroscopic material would maximize CNTs potential and applicability. The choice of synthesis technique and purification method, which define size, type, properties, quality and purity of CNTs as well as their processability, is crucial for their implementation into composites and hybrids. 

Since the synthesis of carbon nanotubes by Iijima [1, 2], a lot of investigations have been made on this kind of novel material [3-16]. Carbon nanotubes can be conventionally synthesized with several methods [17, 18], Recently, catalytic synthesis method has been developed to prepare carbon nanotubes on Co/Si02 [19, 20]. Hemadi et al. first extended the catalytic synthesis to the use of zeolites (NaY, HY and ZSM-5) as catalyst supports to synthesize carbon nanotubes [21]. 

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