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Posted: Aug 11, 2006
Towards multidimensional, multicomponent, and multifunctional nanomaterials
(Nanowerk Spotlight) With the recent development in nanoscience and nanotechnology, a large variety of single-component nanomaterials (such as carbon nanotubes, nanoparticles, and quantum dots) and devices have been reported. There is now a pressing need to integrate multicomponent nanoscale entities into multifunctional systems and to connect these nano-systems to the micro/macro-world. This connection from the nano world to the macro world has been one of the long-standing problems in nanotechnology and still remains a big challenge. A novel approach of growing aligned carbon nanotubes (CNTs) around microsized carbon fibers should provide a useful platform technology for the development of various multidimensional and multifunctional nanomaterials and devices.
Professor Liming Dai, Wright Brothers Institute Endowed Chair in Nanomaterials at Dayton University, together with postdoctor Dr. Liangti Qu from the Department of Chemical and Materials Engineering at Dayton, have successfully prepared multicomponent and multifunctional hybrid structures based on microsized carbon fibers sheathed with aligned/micropatterned CNTs and their derivatives. The so prepared carbon microfiber can be used as a microelectrode to connect the surrounding CNTs to the outside world.
SEM images of the pristine (a, b) and SiCl4-treated (c-h) carbon fibers before (a, c) and after (b, d-h) the growth of carbon nanotubes. (e, f) cross-sectional views after deliberately removal of some CNTs from one side of the carbon fiber along its length (e) and broken the aligned CNT sheathed carbon fiber (f), respectively. (g) an enlarged view of the square area shown in (e). (h) an enlarged view of the square area shown in (g). Scale bars: (a-f 5 µm; (g) 500 nm; (h) 200 nm. (Reprinted with permission from Wiley)
The researchers demonstrated that judicious modification of the carbon–fiber–supported aligned CNT with various functional substances leads to a class of novel multicomponent and multifunctional materials of practical significance.
Dai explains his current work to Nanowerk: "Carbon fibers have been used as carriers to assemble CNTs for designing and constructing certain high-performance filters, reinforced composites, and porous microelectrodes. In all these cases, however, nonaligned and nonpatterned CNTs were formed on the carbon fiber carries. In the present study, we have successfully grown aligned and micropatterned CNTs around carbon fiber carriers."
"The resultant microsized carbon fibers sheathed with aligned/micropatterned CNTs and their derivatives provide an effective means to connect nanoscale entities to the outside world, along with multidimensional and multicomponent nanomaterials with well-defined surface and interfacial structures for a wide range of potential applications" Dai says.
Examples of such multidimensional and multifunctional nanomaterials and devices could be methanol direct fuel cells, highly sensitive chemical and bio-sensors, and field emitters.