Showing Spotlights 97 - 104 of 304 in category Carbon Nanotubes (newest first):
Catalytic dehydrogenation of ethylbenzene is one of the most important processes in the chemical industry world-wide. Styrene, for instance, is commonly produced using this process. The annual production of some 20 million metric tonnes of styrene is an important precursor in the plastics industry. Being able to develop a new metal-free, energy-saving, and efficient catalyst for alkane dehydrogenation would have a significant positive impact on the environment. Coke formation during the current industrial process is the main disadvantage of the metal-based catalysts now used. Steam is used as a protection agent to avoid coking and thus keep the catalysts active. The steam generation consumes massive amounts of energy. This is simply solved by using carbon as catalyst material. Even without steam, the catalyst is free from coke formation and shows long time stability. Researchers have now developed a new process for the dehydrogenation of ethylbenzene, using nanodiamonds as catalyst, that is oxygen-free and steam-free.
Oct 18th, 2010
Gold-based nanostructures and carbon nanotubes have been successfully applied for photoacoustic imaging and photothermal treatment of tumors. Medical researchers believe that such nanoparticle-mediated, image-guided cancer therapy has tremendous promise for increasing the efficacy of cancer treatment while reducing toxic side effects traditionally associated with treatment. Working with a different carbon nanomaterial, researchers now have been able to show that polyhydroxy fullerenes can be utilized for the same purposes. The minute size and biocompatibility of polyhydroxy fullerenes make them particularly attractive for biomedical applications - they are water-soluble, biodegradable, antioxidant, and rapidly excreted.
Sep 29th, 2010
Progress towards SWCNT-based technology has commenced slowly even though the remarkable potential has been realized soon after their discovery in 1991. A first major drawback is related to the characterization of functionalized SWCNTs. Since carbon nanotubes are intrinsically insoluble in common organic solvents and water, their surface needs to be modified by covalent or noncovalent functionalization in order to increase their poor processeability. Accordingly, the successful derivatization needs to be analyzed, usually by cumulating evidence from a variety of independent spectroscopic and microscopic techniques. However, it is exactly this diversity that renders nanotube characterization highly challenging, as no standard protocol for the precise analysis has yet been established. Taken as individual methods, every characterization technique has its own limitations and restrictions so that the precise analysis can only be achieved by combining the information from the different techniques. Researchers in Germany have presented significant progress towards reaching this goal by describing a readily accessible and low-cost methodology towards correlating spectroscopic and microscopic information by the aid of the optical visualization of one dimensional nano-scaled objects such as SWCNTs.
Sep 10th, 2010
Electron pumps are devices that can transfer a certain number of electrons during each pumping cycle. Besides being of fundamental interest to physicists, single-electron pumps have a potential for practical application in metrology, acting as an accurate frequency-current converter. The general goal of this field is to build a current standard based on the electrical charge of a single electron in order to achieve high accuracy for current measurement. A device called single-electron transistor (SET) can confine charges down to single electron level and hence is applicable for quantized current generation. Attempts to generate quantized current in nanotubes have been made with various methods over the past few years, but were not very successful in obtaining a high degree of current quantization. A research team in Germany has now demonstrated the feasibility of using a single molecule - in this case, a single-walled carbon nanotube - for the generation of quantized electric current.
Sep 9th, 2010
Single-walled carbon nanotube (SWCNT) based thin film transistors (TFTs) could be at the core of next-generation flexible electronics - displays, electronic circuits, sensors, memory chips, and other applications that are transitioning from rigid substrates, such as silicon and glass, to flexible substrates. What's holding back commercial applications is that industrial-type manufacturing of large scale SWCNT-based nanoelectronic devices isn't practical yet because controlling the morphology of single-walled carbon nanotubes is still causing headaches for materials engineers. In an effort to develop a new and effective solution process of isolated SWCNTs, researchers in Japan have now demonstrated a novel solution process to fabricate high-performance TFTs of individual SWCNTs using DNA.
Sep 7th, 2010
Supercapacitors, also called electric double layer capacitors (EDLC), store energy in two closely spaced layers with opposing charges and offer fast charge/discharge rates and the ability to sustain millions of cycles. It is frequently stated that supercapacitors bridge the gap between batteries and electrolytic ('conventional') capacitors, but contemporary devices have a lower specific energy than Li-ion batteries and are orders of magnitude slower than electrolytic capacitors. A research team has now shown that by moving from porous carbon with a network of pores inside particles as electrode material to exposed surfaces of nanostructured carbon onions of 6-7 nm diameter, it is possible to reach the discharge rate (power) of electrolytic capacitors, but with volumetric capacitance about four orders of magnitude higher. Moreover, observed discharge rates up to 200 V/second are about three orders of magnitude higher than conventional supercapacitors.
Aug 19th, 2010
Bullet-proof vests are basically made from high stiffness and toughness, woven or laminated, polymeric fibers stacked in a number of layers. Upon impact of the striking bullet, the fabric material absorbs the energy by stretching of the fibers and the stiff fibers ensure that the load is dispersed over a large area throughout the material. Carbon nanotube is an ideal candidate material for bulletproof vests due to its unique combination of exceptionally high elastic modulus and high yield strain. If one compares these values with those for other fibers suitable for ballistic applications, the enormous potential of CNTs as a candidate material for bullet-proof armor system is quite evident.
Aug 6th, 2010
Previous studies have revealed that single-walled carbon nanotubes (SWCNTs) strongly absorb light, especially in the near-infrared region, and convert it into heat. There even has been a report that fluffy SWCNTs can burst into flames when exposed to a camera flash, which means the local temperature has reached 600-700C. This effect has already been used to develop effective CNT-based cancer killers or extremely dark materials. In a new twist, researchers in China have now discovered that SWCNT buckypapers have a large Seebeck coefficient, indicating a strong capability to convert heat into electricity. Based on this, they have designed an opto-electronic power source which converts the incident light into electricity. While this has been discussed as a theoretical mechanism, the team at Tsinghua University in Beijing has actually fabricated an integrated device that outputs a macroscopic voltage, moving forward towards practical applications.
Jul 29th, 2010