Professor Yoshikazu Honma of Tokyo University of Science (Department of Physics, Faculty of Science), in joint research with Yoshihiro Kobayashi (Senior Researcher at NTT Basic Research Laboratories) and the Japan Science and Technology Agency, has succeeded in synthesizing high-quality monolayer carbon nanotubes using, as catalysts, various metals previously considered incapable of generating carbon nanotubes (such as gold, silver and copper) for the first time in the world.
With their characteristics of low weight, high intensity and good electrothermal conductivity, much is expected of carbon nanotubes as materials that will help form the infrastructure for next-generation industry, and research in the field has been thriving. Until now, however, much has been unknown about the mechanism whereby they are generated, and methods of synthesis are also a subject of ongoing research. This research achievement overturns conventional wisdom to show that carbon nanotubes can also be generated from any kind of metal. It is a discovery that is not only of fundamental importance to the mechanism of carbon nanotube generation, but can also be expected to lead to the establishment of a synthesis method with a high level of control using new catalysts. A more detailed discussion of this research can be found in the December 13 issue of "Nanoletters", a scientific journal published by the American Chemical Society. (Details due to be posted in advance on the journal's online version from November 24th.)
Method of synthesizing carbon nanotubes
The method of synthesizing carbon nanotubes considered closest to practical application today is that of generating carbon nanotubes through a high temperature reaction between gases of carbon compounds, such as ethanol and nanosize metal catalysts. In methods used until now, metal catalysts that could generate carbon nanotubes were restricted to ferrous metals (iron, cobalt and nickel). With these conventional metal catalysts, however, catalyst life was limited, and it was not only impossible to produce tubes of more than several mm in length, but also to control the diameter of the tube or the structure at atomic level. The structure of tubes at atomic level is complex, and since this determines the characteristics of the tube, free control of tube structure (including its length) has become a major issue with a view to practical application. This Research Group has been attempting to analyze the mechanism whereby carbon nanotubes are generated using an electron microscope. This time, they have succeeded in synthesizing high-quality monolayer carbon nanotubes for the first time in the world, using 8 new catalysts including gold, silver, copper and others that were previously thought impossible. They have achieved this by discovering a new method of activating catalyst particles and thus dramatically improving synthesis efficiency. With this diversification of catalysts, eyes now turn to the search for catalysts with longer life and the establishment of a synthesis method that will facilitate free control of tube structure in future. Meanwhile, the use of carbon nanotubes in various industrial sectors is expected to expand, such as their application superconducting devices after removing the magnetism of ferrous catalysts.
* This research was conducted as part of the research theme "The process of carbon nanotube growth and its development towards field observation and physical control" within JST Core Research for Evolutional Science and Technology (CREST). The research group was headed by Professor Yoshikazu Honma of the Department of Physics, Faculty of Science, Tokyo University of Science, and Yoshihiro Kobayashi, Senior Researcher at NTT Basic Research Laboratories.
- The journal's online version
- http://pubs.acs.org/journals/nalefd/index.html
- Honma Laboratory website
- http://www.tus.ac.jp/fac/kyouin/kyouin.php?b/honma