Large-scale synthesis of multi-wall nanotubes

A technique which has the ability to obtain a reliable quantitative of multi-wall nanotubes (MWNT) with the output of 15kg per hour has been developed by Tsinghua faculty recently. Professor Wei Fei from the department of chemical engineering pointed out that the method is suitable for achieving a "large-scale production" of carbon nanotuhes.

Nanfeng Chemical Group co-operates with Tsinghua University by establishing an R&D center for the industrialization of the MWNT.

The fascinating electrical and mechanical properties of single-walled carbon nanotubes (SWNT) have opened a great number of potential applications for these unique materials. However, the high costs of the current production methods and the difficulty in making them available for large-scale manufacture can slow down the process of bringing this technology to commercial production. To develop a cost-effective operation for the manufacture of SWNT a drastic change in the production scale is necessary.

Following the original arc-discharge method, other synthesis methods have been investigated, including laser ablation, plasma discharge, and catalytic decomposition of carbon-containing gaseous compounds. The catalytic method for production of nanotubes has been known for a long time, but this method typically results in production of multi-wall nanotubes (MWNT).

Carbon nanotubes are fullerene-related structures, which consist of graphene cylinders closed at either end with caps containing pentagonal rings. They were discovered in 1991 by the Japanese electron microscopist Sumio Iijima who was studying the material deposited on the cathode during the arc-evaporation synthesis of fullerenes. He found that the central core of the cathodic deposit contained a variety of closed graphitic structures including nanoparticles and nanotubes, of a type which had never previously been observed. A short time later, Thomas Ebbesen and Pulickel Ajayan, from Iijima's lab, showed how nanotubes could be produced in bulk quantities by varying the arc-evaporation conditions. This paved the way to an explosion of research into the physical and chemical properties of carbon nanotubes in laboratories all over the world.


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