Hybrid carbon nanotube material allows ultrafast nonlinear optical switching

Researchers in Singapore told Nanowerk how they developed a very simple technique to fabricate a hybrid nanomaterial system comprising of ZnO nanobeads anchored onto the cylindrical body of CNTs.
"In our humble opinion" Professor Chorng-Haur Sow from the National University of Singapore says, "our results shed light on opportunities for integrating CNTs with functional oxide nanoparticles cost-effectively for future nanodevices."
Sow and his colleagues report their work, titled "Multiwalled Carbon Nanotubes Beaded with ZnO Nanoparticles for Ultrafast Nonlinear Optical Switching" in the March 2, 2006 online edition of Advanced Materials. In their paper, the researchers detail the simple fabrication technique and characterizations of the hybrid nanomaterial system.
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The two important building blocks in nanotechnology, ZnO nanoparticles and CNTs, have rarely been assembled as hybrid structures.
CNTs have been used as templates or scaffolds for the hybrid assembly of nanoparticles. Because of their great hardness and toughness, CNTs keep their morphology and structure even at high nanoparticle loadings. Using different methods, many types of metal and semiconductor nanoparticles have been assembled on CNTs. Recently, CNTs beaded with a variety of nanoparticles have been reported. More importantly, some of these beaded CNT hybrid systems exhibit unique properties.
ZnO, on the other hand, has received widespread attention because of its excellent performance in electronics, optics, and photonics systems due to its importance as a wide-bandgap semiconductor with a large exciton binding energy.
Sow explains to Nanowerk: "From the point of view of potential application, we found that this hybrid nanomaterial demonstrated nonlinear ultrafast optical response and the absorption is tunable by the amount of ZnO coating.
"Such behavior reflects the intriguing interplay between the properties of ZnO and CNTs in this hybrid system."
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He adds: "Such integration could induce lots of novel or optimized properties. We feel that more experiments involving such hybrid nanomaterial can be carried out since they can be fabricated with ease. In addition, the feasibility of a simple and economical method for the fabrication of such hybrid nanomaterials system would be very attractive to the future application of nano hybrids."
By Michael Berger, Copyright 2006 Nanowerk LLC