Studies On Large-scale Synthesis For Carbon Nanotubes

The discovery of carbon nanotubes attracts many scientists attention due to they have unique mechanical , thermic, optical and electrical properties.Presently various synthesis methods have been developed for the production of nanotubes.But chemical vapor deposition(CVD) is still considered as the best method for producing carbon nanotubes on a large scale because the method has a simple equipment and low cost ,the reactive process is controlled easily , carbon nanotubes quality is good and the output is high.However, Purification and high-yield of carbon nanotubes are very important for applications using their excellent intrinsic properties.Current synthesis methods suffer from not only the production of impurities which must be removed through purification steps damaging carbon nanotubes, but also the problem of industrialization synthesis for carbon nanotubes.The paper has a general introduction in structure, character, growth mechanism and preparation.And a few effects on carbon nanotubes are discussed.At the same time,we are interested in developing new methods for synthesis of high-quality and clean carbon nanotubes by chemical vapor deposition (CVD).In this paper , carbon nanotubes were synthesized by the industry furnace instead of small study furnace using C₂H₂ as raw material with high yield of 150g/h. TEM and Raman spectrum show that the diameter of products is 20-30nm and carbon nanotubes have good quality.Then a systemic discussion about the effect of temperature, time ,flow rate of source gas and the technical parameters on the products was carried out.In this paper, high-quality and clean carbon nanotubes were synthesized by using the modularization catalyst instead of the dispersive catalyst.Carbon nanotubes were grown on the surface of the modularization catalyst and were separated from the catalyst. The structures of carbon nanotubes were characterization by TEM,XRD and Raman spectroscopy. Compared with the carbon nanotubes prepared by usingthe dispersive catalyst,the carbon nanotubes grown on the surface of the modularization catalyst are more pure ,less defects and have a higher degree of long range order.It is the most important that the high purity of the as-prepared carbon nanotubes allows us to omit the usual complex purification and damage to carbon nanotubes.