Graphene is being explored, among many other uses, as a replacement material for silicon in photonic devices to expand the wavelength range of operation and to improve performance. Another area where graphene potentially could replace silicon and could have a huge impact is as light-absorbing material in solar cells. Although it has been well known that graphene has very attractive properties for photovoltaic applications - tunable bandgap and large optical absorptivity - these advantages could not be exploited so far due to the problem of fabricating solution-processable, stable, and large enough, size-controllable graphene structures useful for charge collection in solar cells. Graphene quantum dots might offer a solution to these fabrication problems.
Few technologies on the near-term horizon offer as much potential for game-changing results as do carbon nanotube products. But in an age where the state-of-the-art in global defense, transportation and energy depend on meaningful advancement and delivery of novel materials, it is critical to view scalability to be as important as product performance itself. To date, few nanotechnology manufacturers have solved this scaling problem - choosing instead to focus most of their resources on research and advances in material science. Materials without a meaningful path to volume delivery will remain just that; novel inventions with very little practical value. Instead, addressing the issue of scaled production is the central challenge for today's nanotechnology firms.
It has been known for several years that carbon nanotubes would heat, ignite and luminesce upon exposure to certain types of electromagnetic radiation, including laser light. However, no one expected any form of fullerenes to do the same thing. Until now. A team at the University of Florida has discovered that functionalized fullerenes heat, ignite, glow and transform into other carbon nanostructures such as carbon nanotubes upon exposure to low-intensity laser light. This is the first time these findings have been published. A possible explanation for the optical heating and ignition phenomena that have been observed is a distortion of the symmetrical cage structure of the fullerenes.
Some scientists believe that, with the increased mass production of engineered nanoparticles like carbon nanotubes, there is a realistic chance for these particles to interact with water, soil and air, and subsequently enter the food chain. However, understanding the behavior and impacts of nanomaterials in the environment and in human health is a daunting task. Nevertheless, a general understanding about nanotoxicity is slowly emerging as the body of research on cytotoxicity, genotoxicity, and ecotoxicity of nanomaterials grows. In our Spotlight today we take a look at new biophysical research - a parallel study of carbon-nanoparticle uptake by plant and mammalian cells - that contributes to the general picture of the fundamental behaviors of nanoparticles in both biological and ecological systems.
Surface energy is ubiquitous in nature and it plays an important role in many scientific areas such as for instance surface physics, biophysics, surface chemistry, or catalysis. So far it has been impractical to consider utilizing surface energy as an energy source because there are few molecules or atoms involved in the surface interaction and the density of surface energy is low. However, due to the lower power consumption requirements of nanotechnology devices and the higher specific surface area for nanomaterials it appears attractive to use surface energy at the nanoscale. Researchers in China have now demonstrated that an effective design of single-walled carbon nanotubes can be used to convert the surface energy of liquids into electricity.
Among various nanomaterial candidates for water treatment, metal oxides have been widely used as removal agents for various heavy metal ions and their removal capacity was found to be relatively reliable. The removal mechanism for heavy metal ions is thought to be the formation of a strong bond between metal ions and metal oxide surfaces. This strong complexation is advantageous for complete removal of heavy metal ions but it presents a drawback if one wants to design a reusable agent by reviving the reaction site for heavy metal ions. Precisely because the removal mechanism is based on the strong complex formation between metal ions and oxide surfaces, recycling of these removal agents has proved to be difficult. Offering a potential solution, researchers have demonstrated a recyclable removal agent for heavy metal ions by fabricating a core-in-shell structure based on a core of carbon nanotubes and an iron oxide microcapsule structure.
Materials engineers are keen to exploit the outstanding mechanical properties of carbon nanotubes for applications in fibers, composites, fabrics and other larger-scale structures and devices. The ability to fabricate continuous, multifunctional yarns represents an important step in this direction. The development of a continuous, weavable multilayered CNT yarn with superior mechanical, structural, surface, and electrical properties would open the way for a wide range of structural and functional applications, including composites, intelligent fabrics, catalyst supports, and sensors. Researchers in China now demonstrate the fabrication of a novel continuous yarn of CNTs with a multiple-layer structure by a CVD spinning process. The yarn consists of multiple monolayers of CNTs concentrically assembled in seamless tubules along the yarn axis.
Carbon nanotubes are 'strange' nanostructures in a sense that they have both high mechanical strength and extreme flexibility. Deforming a carbon nanotube into any shape would not easily break the structure, and it recovers to original morphology in perfect manner. Researchers in China are exploiting this phenomenon by making CNT sponges consisting of a large amount of interconnected nanotubes, thus showing a combination of useful properties such as high porosity, super elasticity, robustness, and little weight. The nanotube sponges not only show exciting properties as a porous material but they also are very promising to be used practically in a short time. The production method is simple and scalable, the cost is low, and the sponges can find immediate use in many fields related to water purification.