Christopher William Ince Jr. writes about a new insight into how nanotubes grow, which may lead to even more useful technological applications for these nanostructures: Physicists Zhifeng Ren and Hengzhi Wang of Boston College have discovered two initial stages of carbon nanotube growth previously obscured during the growth process. What the researches found is that carbon nanotube growth undergoes an initial phase in which newly grown tubes appear haphazardly arranged, followed by a second stage in which the tubes become more aligned. The third stage, and the one responsible for masking the initial two phases, is the stage in which the tubes are fully aligned. This stage of tube development is the one most used by researchers. Ren and Wang explain that the reason these initial two stages of carbon nanotube growth have been overlooked is due to the process used in plasma enhanced vapor deposition. During this process, the nanotubes are grown by the decomposition of gasses causing carbon atoms to accumulate on a catalyst particle. Each time plasma is applied to the catalyst, the previous stage is obscured, which the researchers say is the reason these two initial growth phases were not discovered sooner. Ren and Wang had used a thin catalyst layer in their research, which also made possible the discovery of these early phases. Because carbon nanotubes in these initial growth phases provide a larger surface area than in when they are in their fully-aligned stage, the researchers believe they may be useful for applications such as cooling integrated circuits used in electronics. Source: Hayward, E. (2011). Physicists at Boston College Discover Two Early Stages of Carbon Nanotube Growth. Boston College Office of News Public Affairs, 2011 Retrieved from http://www.bc.edu/offices/pubaf/news/2011_jun-aug/carbon_nanotube_growth.html
Posts Tagged ‘Carbon’
Boston College Researches Uncover Early Phases of Carbon Nanotube Growth
Posted in Nanotechnology 
Tags: boston, boston-college, Carbon, College, decomposition, early-stages, Nanotechnology, Process, public-affairs, Research, stage, such-as-cooling, tubes, william-ince 
Comments OffEdible Carbon Dioxide Sponge
A year ago, Northwestern University chemists published their recipe for a new class of nanostructures made of sugar, salt and alcohol. Now, the same team has discovered that the edible compounds can efficiently detect, capture and store carbon dioxide. And, the compounds themselves are carbon-neutral. The porous crystals — known as metal-organic frameworks ( MOF s) — are made from all-natural ingredients and are simple to prepare, giving them a huge advantage over other MOF s. Conventional MOF s, which also are effective at adsorbing carbon dioxide, are usually prepared from materials derived from crude oil and often incorporate toxic heavy metals. Other features of the Northwestern MOF s are they turn red when completely full of carbon dioxide, and the carbon capture process is reversible. “We are able to take molecules that are themselves sourced from atmospheric carbon, through photosynthesis, and use them to capture even more carbon dioxide,” said Ross S. Forgan, a co-author of the study. “By preparing our MOF s from naturally derived ingredients, we are not only making materials that are entirely nontoxic, but we are also cutting down on the carbon dioxide emissions associated with their manufacture.” The main component, gamma-cyclodextrin, is a naturally occurring biorenewable sugar molecule that is derived from cornstarch. The sugar molecules are held in place by metals taken from salts such as potassium benzoate or rubidium hydroxide, and it is the precise arrangement of the sugars in the crystals that is vital to their successful capture of carbon dioxide. “It turns out that a fairly unexpected event occurs when you put that many sugars next to each other in an alkaline environment — they start reacting with carbon dioxide in a process akin to carbon fixation, which is how sugars are made in the first place,” said Jeremiah J. Gassensmith, lead author of the paper. “The reaction leads to the carbon dioxide being tightly bound inside the crystals, but we can still recover it at a later date very simply.” The fact that the carbon dioxide reacts with the MOF , an unusual occurrence, led to a simple method of detecting when the crystals have reached full capacity. The researchers place an indicator molecule, which detects changes in pH by changing its color, inside each crystal. When the yellow crystals of the MOF s are full of carbon dioxide they turn red. The simplicity of the new MOF s, allied with their low cost and green credentials, have marked them as candidates for further commercialization. Ronald A. Smaldone, a co-author of the paper, added, “I think this is a remarkable demonstration of how simple chemistry can be successfully applied to relevant problems like carbon capture and sensor technology.” Read More Paper
Posted in Nanotechnology Tags: Carbon, Crystals, known-as-metal, Manufacture, mof, northwestern, Paper, Successful Comments OffElectric motor made from a single molecule (video)
Recent research progress with synthetic molecular machines continues with a news release from Tufts University reporting “ World’s smallest electric motor made from a single molecule “: Chemists at Tufts University’s School of Arts and Sciences have developed the world’s first single molecule electric motor, a development that may potentially create a new class of devices that could be used in applications ranging from medicine to engineering. In research published online September 4 in Nature Nanotechnology [ abstract ], the Tufts team reports an electric motor that measures a mere 1 nanometer across, groundbreaking work considering that the current world record is a 200 nanometer motor. A single strand of human hair is about 60,000 nanometers wide. According to E. Charles H. Sykes, Ph.D., associate professor of chemistry at Tufts and senior author on the paper, the team plans to submit the Tufts-built electric motor to Guinness World Records. “There has been significant progress in the construction of molecular motors powered by light and by chemical reactions, but this is the first time that electrically-driven molecular motors have been demonstrated, despite a few theoretical proposals,” says Sykes. “We have been able to show that you can provide electricity to a single molecule and get it to do something that is not just random.” … While there are foreseeable practical applications with this electric motor, breakthroughs would need to be made in the temperatures at which electric molecular motors operate. The motor spins much faster at higher temperatures, making it difficult to measure and control the rotation of the motor. “Once we have a better grasp on the temperatures necessary to make these motors function, there could be real-world application in some sensing and medical devices which involve tiny pipes. Friction of the fluid against the pipe walls increases at these small scales, and covering the wall with motors could help drive fluids along,” said Sykes. “Coupling molecular motion with electrical signals could also create miniature gears in nanoscale electrical circuits; these gears could be used in miniature delay lines, which are used in devices like cell phones.” The experiment was done at 5 K so that the molecular motion would be slow enough to permit the researchers to track the rotation of the molecule. The molecular motor is a molecule of butyl methyl sulfide adsorbed to a copper surface. The sulfur atom, with a one-carbon arm on one side and a four carbon arm on the opposite side, is the central pivot attached to the copper surface. Addition of electrons from a scanning tunneling microscope tip causes the molecule to rotate, and also supplies images of the molecule while it rotates. A BBC News article supplies additional comments from Dr Sykes, indicating he is considering more complex molecular machinery as well: “The next thing to do is to get the thing to do work that we can measure – to couple it to other molecules, lining them up next to one another so they’re like miniature cog-wheels, and then watch the rotation propagation down the chain,” he said. The coverage at PCMAG.COM includes a link to an excellent detailed Youtube Video produced by the Sykes Research Group .
Posted in Nanotechnology Tags: Carbon, construction, guinness-world, molecular nanotechnology, Nano, NANOTECH, Nanotechnology, Research, School, single-molecule, Video, youtube-video Comments OffCu@C composite nanotube array and its application as an enzyme-free glucose sensor
We report a novel hydrothermal method for the synthesis of a Cu@C nanotube array on a centimeter-scale substrate for the first time. In this hydrothermal reaction process, employing the carbon coated ZnO nanorod array as an inexpensive and partially sacrificial template, along with the ZnO dissolving in the alkaline atmosphere, the formed Cu particles deposit and grow on the carbon surface gradually. Importantly, the carbon shell of the template is not only essential to the preservation of the array configuration, but also makes a significant contribution to the final nanostructure. Such a method provides a morphology-reservation transformation when various shaped carbon-containing templates are adopted. Moreover, this designed Cu@C array has been demonstrated as an excellent electrode material for an enzyme-free glucose sensor in terms of sensitivity (1200 µA mM − 1 cm − 2 ) and significantly lower applied potential (−0.2 V). Our results present the first pr…
Posted in Nanotechnology Tags: alkaline, Carbon, carbon-coated, designed, glucose-sensor, hydrothermal, method-provides, preservation, results-present, Synthesis, template, the-synthesis Comments OffOptically Directed Assembly Of Materials
For many years, scientists have searched for ways to assemble nanoparticles into larger structures of any desired shape and form at will. This effect has been achieved in a new study by using a laser as if it were a magic wand, creating an assembled, continuous filament as the laser beam is moved around. “It’s possible that we could use this method to encapsulate pharmaceutical agents for new drug delivery systems or build cathodes with very large surface areas for use in batteries,” said Argonne biophysicist John Bahns, who led the invention of the technology. “It could potentially help us find better materials that could be used in everything from catalysts to semiconductors; the possibilities are endless.” Researchers at Argonne National Laboratory shined a low-power laser, similar in intensity to ones used in office laser pointers, into a solution of gold and carbon nanoparticles suspended in water. Unexpectedly, they found that the carbon nanoparticles decomposed or deformed to create a kind of “glue” that enabled the creation of long gold and carbon chains that assembled continuously wherever the laser was pointed. This new technique for materials design, known as “optically directed assembly” or ODA , could provide scientists and inventors with an uncharted route to new materials, technologies and even treatments for diseases. “It’s incredibly exciting to think about the vast world of technology that could result from people using ODA ,” said Liaohai Chen, who helped to develop the technology. “This is just the very beginning; we really don’t even know yet all the things that might be possible.” Read More Read More Paper
Posted in Nanotechnology Tags: Carbon, invention, laser, liaohai-chen, low-power-laser, Possibilities, Technology, uncharted-route, very-beginning Comments OffBulk synthesis, growth mechanism and properties of highly pure ultrafine boron nitride nanotubes with diameters of sub-10 nm
As a structural analogue of the carbon nanotube (CNT), the boron nitride nanotube (BNNT) has become one of the most intriguing non-carbon nanostructures. However, up to now the pre-existing restrictions/limitations of BNNT syntheses have made the progress in their research rather modest. This work presents a new route toward the synthesis of highly pure ultrafine BNNTs based on a modified boron oxide (BO) CVD method. A new effective precursor—a mixture of Li 2 O and B—has been proposed for the growth of thin, few-layer BNNTs in bulk amounts. The Li 2 O utilized as the precursor plays the crucial role for the present nanotube growth. The prepared BNNTs have average external diameters of sub-10 nm and lengths of up to tens of µm. Electron energy loss spectrometry and Raman spectroscopy demonstrate the ultimate phase purity of the ultrafine BNNTs. Property studies indicate that the ultrafine nanotubes are perfect electrical insulators exhibiting superb resistance t…
Posted in Nanotechnology Tags: Carbon, crucial, modified-boron, new-effective, Precursor, Present, Research, Synthesis, the-precursor, the-ultrafine, their-research, ultrafine, Work, work-presents Comments OffSPSU Nanoarchitecture Exhibition
The Architecture Gallery at Southern Polytechnic State University ( SPSU ), in Georgia, has just opened a one-month exhibition that features applications for smart materials and nanomaterials in architecture and design. The show focuses on the work of Decker Yeadon, an office in New York City that, for many years now, has been at the forefront of considering nanotech applications in architecture. In addition to a selection of short videos and an assortment of objects (including their nanoink, buckypapers, and artificial muscles), the exhibition presents a new 46 minute film by Jordan Alport and a massive electron microscope image of their carbon nanotube buckypaper. To complement the exhibition, both Decker and Yeadon delivered a lecture at SPSU , titled Nanoarchitecture .
Posted in Nanotechnology Tags: Architecture, Carbon, Decker, decker-yeadon, exhibition, forefront, Georgia, jordan-alport, NanoInk, short-videos, the-exhibition, the-forefront, their-carbon, Work Comments OffUltrahigh resolution focused electron beam induced processing: the effect of substrate thickness
It is often suggested that the growth in focused electron beam induced processing (FEBIP) is caused not only by primary electrons, but also (and even predominantly) by secondary electrons (SEs). If that is true, the growth rate for FEBIP can be changed by modifying the SE yield. Results from our Monte Carlo simulations show that the SE yield changes strongly with substrate thickness for thicknesses below the SE escape depth. However, our experimental results show that the growth rate is independent of the substrate thickness. Deposits with an average size of about 3 nm were written on 1 and 9 nm thick carbon substrates. The apparent contradiction between simulation and experiment is explained by simulating the SE emission from a carbon substrate with platinum deposits on the surface. It appears that the SE emission is dominated by the deposits rather than the carbon substrate, even for deposits as small as0.32 nm 3 .
Posted in Nanotechnology Tags: Carbon, deposits, growth, monte, often-suggested, substrate, the-substrate, yield-changes Comments OffGraphene For Solar Cell Electrodes
A promising approach for making solar cells that are inexpensive, lightweight and flexible is to use organic (carbon) compounds instead of expensive, highly purified silicon. But it has been hard to make electrodes that can carry the current to and from the cells using materials that can match the organic cells’ flexibility, transparency and low cost. The standard material used so far for these electrodes is indium-tin-oxide, or ITO . But indium is expensive and relatively rare, so the search has been on for a suitable replacement. Now, a team of MIT researchers has come up with a practical way of using a possible substitute made from inexpensive and ubiquitous carbon. The proposed material is graphene, a form of carbon in which the atoms form a flat sheet just one atom thick. Graphene is transparent, so that electrodes made from it can be applied to the transparent organic solar cells without blocking any of the incoming light. In addition, it is flexible, like the organic solar cells themselves, so it could be part of installations that require the panel to follow the contours of a structure, such as a patterned roof. ITO , by contrast, is stiff and brittle. The biggest problem with getting graphene to work as an electrode for organic solar cells has been getting the material to adhere to the panel. Graphene repels water, so typical procedures for producing an electrode on the surface by depositing the material from a solution won’t work. The team tried a variety of approaches to alter the surface properties of the cell or to use solutions other than water to deposit the carbon on the surface, but none of these performed well. But then they found that “doping” the surface with AuCl3 — that is, introducing a set of impurities into the surface — changed the way it behaved, and allowed the graphene to bond tightly. As a bonus, it turned out the doping also improved the material’s electrical conductivity. Read More Paper
Posted in Nanotechnology Tags: Carbon, changed-the-way, from-the-cells, highly-purified, Material, Organic, organic-solar, Panel, Search, Surface, the-surface, these-performed Comments OffCarbon Nanotube Touchscreens
Touchscreens contain rare and expensive elements, which is the reason why researchers at Fraunhofer are coming up with an alternative display made of low-priced renewable raw materials available all over the world. The researchers are presenting touchscreens that contain carbon nanotubes at the nano tech 2011 fair in Tokyo (Hall 5, Stand E-18-11) from February 16-18. Just touching it slightly with the tips of your fingers is enough. You can effortlessly write, navigate, open menu windows or rotate images on touchscreens. Within fractions of a second your touch is translated into control commands that a computer understands. At first glance, this technology borders on the miraculous, but in real life this mystery just is a wafer-thin electrode under the glass surface of the display made of indium-tin-oxide, ITO . ITO is nothing short of ideal for use in touchscreens because it is excellent at conducting slight currents and lets the colors of the display pass through unhindered. But, there is a little problem: there are very few deposits of indium anywhere in the world. In the long term, the manufacturers of electronic gadgets are afraid that they will be dependent upon the prices set by suppliers. This is the reason why indium is one of what people call “strategic metals.” Therefore, private industry is very interested in alternatives to ITO that are similarly efficient. The researchers at Fraunhofer have succeeded at coming up with a new material for electrodes that is on the same level as ITO and on top of it is much cheaper. Its main components are carbon nanotubes and low-cost polymers. This new electrode foil is composed of two layers. One is the carrier, a thin foil made of inexpensive polyethylenterephthalate PET used for making plastic bottles. Then a mixture of carbon-nanotubes and electrically conducting polymers is added that is applied to the PET as a solution and forms a thin film when it dries. In comparison to ITO , these combinations of plastics have not been particularly durable because humidity, pressure or UV light put a strain on the polymers. The layers became brittle and broke down. Only carbon nanotubes have made them stable. The carbon nanotubes harden on the PET to create a network where the electrically conducting polymers can be firmly anchored. That means that this layer is durable in the long run. Ivica Kolaric, project manager from Fraunhofer Institute for Manufacturing Engineering and Automation IPA , concedes that “the electrical resistance of our layer is somewhat greater than that of the ITO , but it’s easily enough for an application in electrical systems.” Its merits are unbeatable: carbon is not only low-cost and available all over the world. It is also a renewable resource that you can get from organic matter such as wood. Kolaric and his colleagues will be presenting their carbon touchdisplay at the 2011 nano tech fair. Since 2003 Fraunhofer researchers show their developments at the annual trade show. There are a whole series of implementations for the new technology. This foil is flexible and can be used in a variety of ways. Kolaric sums up by saying “we could even make photovoltaic foils out of it to line corrugated roofs or other uneven structures.” The researcher has already set up pilot production where the foil can be enhanced for a wide range of applications. Read More
Posted in Nanotechnology Tags: Carbon, Display, electrically, firmly-anchored, Fraunhofer, layer, Manufacturing, over-the-world, Reason, Tokyo, World Comments Off