Realistic Applications of Cnts

Engineering Department, Cambridge University, Cambridge CB2 1PZ, UK E-mail: [email protected] Carbon nanotubes (CNTs) are a fascinating subject for curiosity-driven research. But will they give rise to commercially viable applications? CNTs are rolled up sheets of sp2 bonded graphite with no surface broken bonds. Their possible applications1,2 arise from the remarkable properties of single-walled nanotubes (SWNTs) such as the highest Young’s modulus, highest thermal conductivity, ballistic electron transport, and high aspect ratio structure. To date, development of nanotube-based products has been delayed by a lack of availability of quantities of material and lack of control of their growth. Supplies of multi-walled nanotubes (MWNTs) or nanofibers have been available from Hyperion Catalysis International, but under constraint and only as preformed composites. The supply situation is now improving with several firms producing on a larger scale, such as CNI, Showa Denko, Thomas Swan, and Nanocyl. Now is, therefore, a good time to look at applications from a more business view. A key point for a new product to find a market is that it should have either a unique function not previously existing, or it should have a high (x10) performance advantage to displace an existing product in its market. A second point is that while SWNTs may be the most interesting form of nanotube, they have limitations, so one should really consider the most appropriate form of sp2 carbon for the job in question, whether it is SWNTs, MWNTs, nanofibers, or a nanostructured carbon. We shall consider applications in four broad areas; composites, field emission, electronics, and electrochemistry.