21st coe seminar series #3 department of materials engineering the university of tokyo organizer:...
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21st COE Seminar Series #3Department of Materials Engineering
The University of Tokyo
Organizer: Prof. Toru H. OKABEhttp://okabe.iis.u-tokyo.ac.jp Tel: 03-5452-6314 For registration contact Ms. Miyako YUKIYOSHIE-mail: [email protected]
COE committee in Department of Materials Engineering
May 28, 2003 10:00-1st Conference Room, Institute of Industrial Science
（生産技術研究所第１会議室）
A Molten Salt Route for the Production of Carbon Nanotubes
by
Dr. George Z. Chen Department of Materials Science and Metallurgy, University of Cambridge
Pembroke Street, Cambridge CB2 3QZ, UKEmail: [email protected]
Tel: +44-(0)1223-762965 Fax: +44-(0)1223-334567
Soon after the discovery, carbon nanotubes (CNTs) attracted worldwide attention due to their unique quasi-molecular structures and remarkable material properties. The initial desired use of these conductive and strong nanotubes were in miniature devices, typically in the electrical and mechanical areas. However, recent development in research also shows a promising future for using these nanotubes in bulk quantities to enable much improved electron conduction in conventional polymers, energy conversion and storage, catalysis for targeted chemical processes and etc. In particular, it has been demonstrated that supercapacitors based on carbon nanotubes exhibit unprecedented high capacitance (high pulsed power) and long cycle life. This development is very welcomed by, for example, manufacturers of electric cars that are currently put on hold by the incapability of fuel cells and batteries to deliver power greater than 1 W/cm2 (electrolyte membrane). At present, carbon nanotubes are mainly produced, in the gas phase, by two methods: electric arc assisted carbon vaporisation, and catalytic decomposition of gaseous hydrocarbon at elevated temperatures. The former produces relatively defect free and hence straight CNTs, while the latter is featured by its flexibility in producing either bent CNTs in bulk quantities or aligned arrays standing on an appropriate substrate, both being much purer than the electric arc product. Nonetheless, the production cost of the two methods are far from being acceptable for bulk quantity use. In additional to the high energy input (electric arc method) or use of relatively expensive starting materials (catalytic method), the fact that the products from the two methods come out of the gas phase adds another hurdle to introduce further improvement. This presentation reviews a newly developed electrolytic method for the production of CNTs in molten salts. First discovered in the UK in mid 1990's, research in this method is gathering forces around the world. In particularly, it has been shown recently that, once being scaled up, the electrolytic method has the potential to significantly reduce the cost for the production of CNTs. Also included in this presentation are a historical view of the electrolytic method, the basic experimental set-up, characteristics of electrolytic CNTs and other carbon nano-materials, electrochemical studies of the process and a comparison of different formation mechanisms.