Posts Tagged ‘Rice University’

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Graphene euphoria, heat sinks, diamonds, and Rice University’s Ajayan Group

Wednesday, May 29th, 2013

Pulickel Ajayan, at Rice University (Texas), must have one of the most active laboratories in the US where nanotechnology-based research and announcements about it are concerned and I imagine it’s an exciting place to work. Whoever wrote the May 28, 2013 Rice University news release on EurekAlert seems to have caught some of the Ajayan Group’s excitement,

What may be the ultimate heat sink is only possible because of yet another astounding capability of graphene. The one-atom-thick form of carbon can act as a go-between that allows vertically aligned carbon nanotubes to grow on nearly anything.

That includes diamonds. A diamond film/graphene/nanotube structure was one result of new research carried out by scientists at Rice University and the Honda Research Institute USA, reported today in Nature’s online journal Scientific Reports.

The heart of the research is the revelation that when graphene is used as a middleman, surfaces considered unusable as substrates for carbon nanotube growth now have the potential to do so. Diamond happens to be a good example, according to Rice materials scientist Pulickel Ajayan and Honda chief scientist Avetik Harutyunyan.

Here’s an image the team has provided,

Rice University and the Honda Research Institute use single-layer graphene to grow forests of nanotubes on virtually anything. The image shows freestanding carbon nanotubes on graphene that has been lifted off of a quartz substrate. One hybrid material created by the labs combines three allotropes of carbon – graphene, nanotubes and diamond – into a superior material for thermal management. (Credit: Honda Research Institute)

Rice University and the Honda Research Institute use single-layer graphene to grow forests of nanotubes on virtually anything. The image shows freestanding carbon nanotubes on graphene that has been lifted off of a quartz substrate. One hybrid material created by the labs combines three allotropes of carbon – graphene, nanotubes and diamond – into a superior material for thermal management. (Credit: Honda Research Institute)

The news release provides more information about the diamond-carbon nanotube-graphene hybrid material,

Diamond conducts heat very well, five times better than copper. But its available surface area is very low. By its very nature, one-atom-thick graphene is all surface area. The same could be said of carbon nanotubes, which are basically rolled-up tubes of graphene. A vertically aligned forest of carbon nanotubes grown on diamond would disperse heat like a traditional heat sink, but with millions of fins. Such an ultrathin array could save space in small microprocessor-based devices.

“Further work along these lines could produce such structures as patterned nanotube arrays on diamond that could be utilized in electronic devices,” Ajayan said. Graphene and metallic nanotubes are also highly conductive; in combination with metallic substrates, they may also have uses in advanced electronics, he said.

To test their ideas, the Honda team grew various types of graphene on copper foil by standard chemical vapor deposition. They then transferred the tiny graphene sheets to diamond, quartz and other metals for further study by the Rice team.

They found that only single-layer graphene worked well, and sheets with ripples or wrinkles worked best. The defects appeared to capture and hold the airborne iron-based catalyst particles from which the nanotubes grow. The researchers think graphene facilitates nanotube growth by keeping the catalyst particles from clumping.

Ajayan thinks the extreme thinness of graphene does the trick. In a previous study, the Rice lab found graphene shows materials coated with graphene can get wet, but the graphene provides protection against oxidation. “That might be one of the big things about graphene, that you can have a noninvasive coating that keeps the property of the substrate but adds value,” he said. “Here it allows the catalytic activity but stops the catalyst from aggregating.”

Testing found that the graphene layer remains intact between the nanotube forest and the diamond or other substrate. On a metallic substrate like copper, the entire hybrid is highly conductive.

Such seamless integration through the graphene interface would provide low-contact resistance between current collectors and the active materials of electrochemical cells, a remarkable step toward building high-power energy devices, said Rice research scientist and co-author Leela Mohana Reddy Arava.

Here’s a link to and a citation for the paper,

Graphene as an atomically thin interface for growth of vertically aligned carbon nanotubes by Rahul Rao, Gugang Chen, Leela Mohana Reddy Arava, Kaushik Kalaga, Masahiro Ishigami, Tony F. Heinz, Pulickel M. Ajayan, & Avetik R. Harutyunyan. Scientific Reports 3, Article number: 1891 doi:10.1038/srep01891 Published 28 May 2013

Scientific Reports, a Nature publication, provides open access to its papers.

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Cow blood declumps (stabilizes) gold nanoparticles in a solution

Tuesday, May 14th, 2013

Rice University (Texas, US) researchers have discovered a means of stabilizing gold nanoparticles in a variety of solutions including one of the harshest, salt solutions. From the May 14, 2013 news item on Nanowerk (Note: A link has been removed),

A protein from cow blood has the remarkable ability to keep gold nanoparticles from clumping in a solution. The discovery could lead to improved biomedical applications and contribute to projects that use nanoparticles in harsh environments.

Bovine serum albumin (BSA) forms a protein “corona” around gold nanoparticles that keeps them from aggregating, particularly in high-salt environments like seawater. The new research by the Rice University labs of chemists Stephan Link and Christy Landes was published by the American Chemical Society journal ACS Sustainable Chemistry and Engineering (“Adsorption of a Protein Monolayer via Hydrophobic Interactions Prevents Nanoparticle Aggregation under Harsh Environmental Conditions”).

The May 13, 2012 Rice University news release by Mike Williams, which originated the news item, describes the researchers and the nature of their work,

Link’s primary interest is in the plasmonic properties of nanoparticles. Landes’ work incorporates protein binding and molecular transport. The BSA research combines their unique talents with those of Sergio Dominguez-Medina, a graduate student in Link’s lab who studied to be a physicist at Monterrey Tech and was drawn to this interdisciplinary project during an undergraduate fellowship at Link’s Rice lab.

“Initially, we wanted to look at nanoparticles in solution with something they would encounter frequently in blood: serum albumin,” Landes said. “In our first experiments, Sergio reported the very efficient, reasonably fast and irreversible binding the moment he put nanoparticles into a solution that contained serum albumin.”

“It turned out the salt is actually driving this binding,” Dominguez-Medina said.

Without BSA, gold nanoparticles in a salty solution quickly aggregate and fall to the bottom. “That by itself is undesirable for biomedical or industrial applications, because it could lead to toxicity issues,” he said. “The nanoparticles get more hydrophobic because in the presence of salts, the excess charges on the surface (which discourage clumping) are actually removed.” But if BSA is present, the proteins are drawn to the nanoparticles faster than the particles are drawn to each other.

“Once the protein is bound, it gives a super protection against any type of salt-induced aggregation. We think this could be used for the stabilization of nanoparticles in environments where, right now, it hasn’t been achieved,” Dominguez-Medina said.

He said the discovery also offers the possibility that nanoparticles might be made more compatible for treating humans by using a patient’s own albumin. “Albumin is really easy to purify and the process is well-established,” he said.

Here’s a little more about the plasmonics of the situation and how this discovery about cow blood protein might apply in biomedical and other applications (from the news release),

The ability of gold nanoparticles to absorb and redirect light is at the heart of several breakthrough technologies being developed at Rice and elsewhere. Most notable are a nanoparticle-based cancer treatment now in human testing that was developed by Professor Naomi Halas and former Rice colleague Jennifer West, and Halas’ project to convert solar energy directly into steam for sanitation and water purification.

“The only way nanoparticles exhibit their really nice optical properties in very specific optical frequencies is if they’re separated,” Landes said.

The key words in Landes comment is ‘separated’ (from the news release),

Because pure gold nanoparticles are so hydrophobic, they naturally clump together in a solution unless chemically treated. “A lot of industrial effort goes into keeping stuff off of surfaces, like contact lenses and ship hulls,” she said. “That involves chemically altering the surfaces to prevent unwanted adsorption, or in the case of nanoparticles, unwanted aggregation.”

Protecting the surface is costly, Link said. “But we found we could take nanoparticles prepared in the cheapest way, with a sodium citrate coating that stabilizes the particles by electrostatic repulsion, and add BSA, which coats the particles and makes them really stable.”

Adding the BSA seems logical when one of the scientists explains the reasoning (from the news release),

Albumin is the most common protein in blood, and the bovine version shares 98 percent of its amino acid sequence with human serum albumin. “One of its main purposes, biologically, is to take things that aren’t water-soluble, bind to them and make them soluble,” Landes said. “When you combine it with gold nanoparticles, BSA trades places with the cheap citrate, which isn’t a good protective layer, to form the monolayer corona, which is very strong and protective.”

Aside from obvious biomedical applications (e.g. implants and joint replacements), there are desalination and fuel cell applications (from the news release),

Seawater is the very definition of a harsh environment, Landes said. “One of the problems with desalination applications and, similarly, with fuel cells, is that saline or acidic conditions are very corrosive,” she said. “That’s why you have to use platinum electrodes in fuel cells – not because they’re better than cheaper materials at catalysis, but because they don’t corrode in a harsh environment.” She sees promise for BSA-treated gold nanoparticles in both applications.

The researchers have other plans as well (from the news release),

The researchers are now looking at how well gold nanoparticles retain their albumin corona with repeated use. “Gold is expensive,” Landes said. “But the beauty of it is that if you can reuse it, it only costs you once.”

They also want to use spectroscopy to see how the binding mechanism works in real time, Link said. “We want to study what’s happening at the interface of nanoparticles and biologically relevant media” that may eventually include DNA, RNA and drugs for delivery to cells, he said.

Link plans to see how BSA can be used in combination with gold nanorods. Because nanorods’ plasmonic properties can be tuned, “we can get them into the biological window, which is near-infrared light,” he said. Near-IR from lasers is used to activate, by heating, Halas’ and West’s cancer-killing nanoshells. Nanorods may also offer ways to combine BSA and other useful proteins by coating the tips and sides separately.

For interested parties, here’s a link to and a citation for the published paper,

Adsorption of a Protein Monolayer via Hydrophobic Interactions Prevents Nanoparticle Aggregation under Harsh Environmental Conditions by Sergio Dominguez-Medina, Jan Blankenburg, Jana Olson, Christy F. Landes, and Stephan Link. ACS Sustainable Chem. Eng., Article ASAP DOI: 10.1021/sc400042h
Publication Date (Web): April 3, 2013
Copyright © 2013 American Chemical Society

Unusually for the American Chemical Society (ACS), this paper appears to be open access; I was able to access the full HTML version today, May 14, 2013 at 10:10 am PDT.

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PGClear and remediating soil contaminated by chlorinated compounds

Thursday, April 18th, 2013

The story twists and turns a bit and some of the details are a little indistinct but it seems there’s new technology, PGClear, has been developed for cleaning up water and soil. From the Apr. 16, 2013 news item on Nanowerk,

Researchers from Rice University [Texas], DuPont Central Research and Development and Stanford University [California] have announced a full-scale field test of an innovative process that gently but quickly destroys some of the world’s most pervasive and problematic pollutants. The technology, called PGClear, originated from basic scientific research at Rice during a 10-year, federally funded initiative to use nanotechnology to clean the environment.

PGClear uses a combination of palladium and gold metal to break down hazardous compounds like vinyl chloride, trichloroethene (TCE) and chloroform into nontoxic byproducts.

“Chlorinated compounds were widely used as solvents for many decades, and they are common groundwater contaminants the world over,” said Rice’s Michael Wong, professor of chemical and biomolecular engineering and the lead researcher on the PGClear project. “These compounds are also extremely difficult to treat inexpensively with conventional technology. My lab began its work to solve this problem more than a decade ago.”

The Apr. 15, 2013 Rice University news release, which originated the news item, provides more detail about Wong’s work and how it came to be applied to remediation of chlorine-based contaminants (Note: Links have been removed),

Wong began working on the catalytic remediation technology shortly after arriving at Rice in 2001, the same year Rice won a grant from the National Science Foundation for the Center for Biological and Environmental Nanotechnology (CBEN). CBEN, a 10-year, $25 million effort, was the world’s first academic research center dedicated to studying the interaction of nanomaterials with living organisms and ecosystems. CBEN was one of the first six U.S. academic research centers funded by the National Nanotechnology Initiative.

“Prior research had shown that palladium was an effective catalyst for breaking down TCE, but palladium is expensive, so it was thought to be impractical,” Wong said. “At CBEN, we used nanotechnology to design particles in which every atom of palladium was used to catalyze the reaction. We also found that adding a tiny bit of gold enhanced the reaction.”

DuPont contacted Wong about the award-winning research in 2007 and proposed developing a scalable process to use the palladium-gold catalysts to treat other chlorinated pollutants like chloroform and vinyl chloride. With additional support from the World Gold Council in London, researchers from Rice and DuPont worked to refine the catalyst and the process. They also worked with the South African mineral research organization MINTEK, which produced the catalytic pellets for the first PGClear unit. Gold and palladium make up only about 1 percent of material in each of the purple-black pellets.

Rice has supplied a video of the researchers discussing their work with palladium-gold pellets,

Here’s the plan for the unit that will be used by Dupont (from the Rice University news release),

The first large-scale PGClear unit, which is designed to treat groundwater contaminated with chloroform, is scheduled for installation at a DuPont site in Louisville, Ky., in June [2013?]. The 6-by-8-foot unit contains valves and pipes that will carry groundwater to a series of tubes that each contain thousands of pellets of palladium-gold (PG) catalyst. The pellets, which are about the size of a grain of rice, spur a chemical reaction that breaks down chloroform into nontoxic methane and chloride salt. [emphasis mine]

“The palladium-gold catalyst has so far performed well for remediating groundwater samples collected at DuPont,” said Brad Nave, director of the DuPont Remediation Project. “While the project is not yet full-scale, our next step will subject the technology to the rigors of real-world field conditions. Rice, Stanford and DuPont have been working on the details of the field pilot for several years, and we’re looking forward to a successful test.”

While it’s good to note that the pollutants are broken down into nontoxic materials, it would have been interesting to find out what happens to the pellets over time (presumably they become less effective and need to be replaced with new pellets while the old ones are disposed of) and to find out how the groundwater is being captured for purification.

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Rice U and the US National Institute of Standards and Technology settle into armchairs, the carbon nanotube kind

Wednesday, February 6th, 2013

An armchair carbon nanotube is amongst the most desirable of carbon nanotubes. You’ll have to look carefully to see the resemblance to an armchair,

Armchair carbon nanotubes, so named for the arrangement of atoms that make their ends look like armchairs, are the most desirable among nanotube researchers for their superior electrical properties. Image by Erik Hároz [downloaded from http://news.rice.edu/2013/02/05/essential-armchair-reading-for-nanotube-researchers-2/]

Armchair carbon nanotubes, so named for the arrangement of atoms that make their ends look like armchairs, are the most desirable among nanotube researchers for their superior electrical properties. Image by Erik Hároz [downloaded from http://news.rice.edu/2013/02/05/essential-armchair-reading-for-nanotube-researchers-2/]

The Feb. 6, 2013 news item on phys.org about the armchair carbon nanotubes notes that this latest research is an early outcome from a recently announced (Oct. 2012) partnership between Rice University and the US National Institute of Standards and Technology (NIST). Trom the news item (Note: Links have been removed),

The first fruits of a cooperative venture between scientists at Rice University and the National Institute of Standards and Technology (NIST) have appeared in a paper that brings together a wealth of information for those who wish to use the unique properties of metallic carbon nanotubes.

The feature article published recently in the Royal Society of Chemistry journal Nanoscale gathers research about the separation and fundamental characteristics of armchair carbon nanotubes, which have been of particular interest to researchers trying to tune their electronic and optical properties.

The Rice University Feb. 5, 2013 news release by Mike Williams, which originated the news item, describe s the process the scientists undertook,

This paper, said Rice physicist Junichiro Kono, provides scientists a valuable resource for detailed information about metallic carbon nanotubes, especially armchair nanotubes. “Basically, we summarized all our recent findings as well as all information we could find in the literature about metallic nanotubes, along with detailed accounts of preparation methods for metal-enriched nanotube samples, to show the community just how much we now understand about these one-dimensional metals,” he said.

As part of the lengthy work, the team compiled and published tables of essential statistics, including optical properties, for a variety of metallic nanotubes. “We provide fundamental theoretical backgrounds and then show very detailed experimental results on unique properties of metallic nanotubes,” Kono said. “This paper summarizes what kind of aspects are understood, and what is not, about fundamental optical processes in nanotubes and will make it easier for researchers to identify their spectroscopic features and transition energies.”

For this of us who are less well versed on armchair carbon nanotubes and their electronic and optical properties, the news releases provides some information (Note: Links have been removed),

Nanotubes come in many flavors, depending on their chirality. Chirality is a characteristic akin to the angles at which a flat sheet of paper might align when wrapped into a tube. Cut the tube in half and the atoms at the open edge would line up in the shape of an armchair, a zigzag or some variant. Even though their raw material is identical – chicken-wire-like hexagons of carbon – the chirality makes all the difference in how nanotubes transmit electricity.

Armchairs are the most coveted because they have no band gap; electrons flow through without resistance. Cables made with armchair nanotubes have the potential to move electricity over great distances with virtually no loss. That makes them the gold standard as the basic element of armchair quantum wire. The ongoing development of this very strong, lightweight, high-capacity cable could improve further the record properties of multifunctional carbon nanotube fibers that are being developed by the group of Rice Professor Matteo Pasquali.

For the project-specific work the scientists performed (Note: Links have been removed),

The new work led by Kono and Robert Hauge, a distinguished faculty fellow in chemistry at Rice, along with scientists at NIST and Los Alamos National Laboratory, looks beyond the armchair’s established electrical properties to further detail their potential for electronic, sensing, optical and photonic devices.

“Of course, to get there, we need really good samples,” Kono said. “Many applications will rely on our ability to separate carbon nanotubes and then assemble macroscopically ordered structures consisting of single-chirality nanotubes. Nobody can do that at this point.”

When a batch of nanotubes comes out of a furnace, it’s a jumble of types. That makes detailed analysis of their characteristics — let alone their practical use — a challenge.

But techniques developed in recent years at Rice and by NIST scientist Ming Zheng to purify metallic nanotubes are beginning to change that. Rice graduate student Erik Hároz said recent experiments established “unambiguous evidence” that a process he and Kono are using called density gradient ultracentrifugation can enrich ensemble samples of armchairs. Taking things further, Zheng’s method of DNA-based ion-exchange chromatography provides very small samples of ultrapure armchair nanotubes of a single chirality.

You can read more about the work at phys.org or at Rice University using the links already provided. For those who’d like to read the research,

Fundamental optical processes in armchair carbon nanotubes by Erik H. Hároz ,  Juan G. Duque,  Xiaomin Tu ,  Ming Zheng ,  Angela R. Hight Walker ,  Robert H. Hauge ,  Stephen K. Doorn and Junichiro Kono. Nanoscale, 2013,5, 1411-1439 DOI: 10.1039/C2NR32769D First published on the web 04 Jan 2013

This article is behind a paywall of sorts.  RSC (Royal Society of Chemistry) Publishing (which publishes Nanoscale) has an open access policy but there are various options, from the RSC Publishing’s Open Access Policy webpage,

RSC Open Access statement

Open Access is the term given to making electronic versions of articles accessible to readers, without any subscription or ‘access side’ fees.

RSC supports Open Access models which seek to ensure that scholarly publishing activities operate in a long term sustainable way.

  • Our fundamental goal is to advance the chemical sciences, through the effective dissemination of high quality research content
  • We seek to maximise the dissemination of the research that we publish
  • We support any and all sustainable and fair models of access. We believe that the integrity and archiving of scholarly content must be maintained throughout
  • We support ‘Gold’* Open Access and encourage funding to be made available to support authors during any transition from reader to author side payments
  • We support the author’s ability to choose where they publish their work to the benefit of the advancement of science. We do not wish authors to be discriminated against if they are unable to pay author-side fees
  • We seek to work closely with other parties, including funders and government agencies, to achieve the above goals

RSC Publishing provides authors with the option to make their article Open Access, through payment of a fee on acceptance. Authors following the traditional route still have deposition options – details are on the ‘Deposition and Licence to Publish’ page of the website.

*There are several types of Open Access:

  • Gold Open Access: Publication costs are covered by an ‘Article Processing Fees’ being paid by authors upon acceptance. The final ‘article of record’ is made available to all, immediately, without any barriers to access
  • Green Open Access: A version of the paper (often the author’s manuscript) is made available via a subject or institutional repository. An embargo period is often involved, typically 6-24 months. No payment is made, and publishers should strive to recoup their investment through traditional sales during the embargo period
  • Delayed Open Access: The final version of the paper is made available by the publisher after an embargo period (e.g. publisher deposit the paper in PubMed after 12 months)

It would seem the option for this article is ‘Delayed Open Access’.

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Prima donna of nanomaterials (carbon nanotubes) tamed by scientists at Rice University (Texas, US), Teijin Armid (Dutch/Japanese company), and Technion Institute (based in Israel)

Friday, January 11th, 2013

The big news is that a multinational team has managed to spin carbon nanotubes (after 10 years of work) into threads that look like black cotton and display both the properties of metal wires and of carbon fibers. Here’s more from the Jan. 10, 2013 news item on ScienceDaily,

“We finally have a nanotube fiber with properties that don’t exist in any other material,” said lead researcher Matteo Pasquali, professor of chemical and biomolecular engineering and chemistry at Rice. “It looks like black cotton thread but behaves like both metal wires and strong carbon fibers.”

The research team includes academic, government and industrial scientists from Rice; Teijin Aramid’s headquarters in Arnhem, the Netherlands; the Technion-Israel Institute of Technology in Haifa, Israel; and the Air Force Research Laboratory (AFRL) in Dayton, Ohio.

The Jan. 10, 2013 Rice University news release on EurekAlert, which originated the news item, describes some of the problems presented when trying to produce carbon nanotube fiber at an industrial scale,

The phenomenal properties of carbon nanotubes have enthralled scientists from the moment of their discovery in 1991. The hollow tubes of pure carbon, which are nearly as wide as a strand of DNA, are about 100 times stronger than steel at one-sixth the weight. Nanotubes’ conductive properties — for both electricity and heat — rival the best metal conductors. They also can serve as light-activated semiconductors, drug-delivery devices and even sponges to soak up oil.

Unfortunately, carbon nanotubes are also the prima donna of nanomaterials [emphasis mine]; they are difficult to work with, despite their exquisite potential. For starters, finding the means to produce bulk quantities of nanotubes took almost a decade. Scientists also learned early on that there were several dozen types of nanotubes — each with unique material and electrical properties; and engineers have yet to find a way to produce just one type. Instead, all production methods yield a hodgepodge of types, often in hairball-like clumps.

Creating large-scale objects from these clumps of nanotubes has been a challenge. A threadlike fiber that is less than one-quarter the thickness of a human hair will contain tens of millions of nanotubes packed side by side. Ideally, these nanotubes will be perfectly aligned — like pencils in a box — and tightly packed. Some labs have explored means of growing such fibers whole, but the production rates for these “solid-state” fibers have proven quite slow compared with fiber-production methods that rely on a chemical process called “wet spinning.” In this process, clumps of raw nanotubes are dissolved in a liquid and squirted through tiny holes to form long strands.

Thank you to the writer of the Rice University news release for giving me the phrase “prima donna of nanomaterials.”

The news release goes on to describe the years of work and collaboration needed to arrive at this point,

Shortly after arriving at Rice in 2000, Pasquali began studying CNT wet-spinning methods with the late Richard Smalley, a nanotechnology pioneer and the namesake of Rice’s Smalley Institute for Nanoscale Science and Technology. In 2003, two years before his untimely death, Smalley worked with Pasquali and colleagues to create the first pure nanotube fibers. The work established an industrially relevant wet-spinning process for nanotubes that was analogous to the methods used to create high-performance aramid fibers — like Teijin’s Twaron — which are used in bulletproof vests and other products. But the process needed to be refined. The fibers weren’t very strong or conductive, due partly to gaps and misalignment of the millions of nanotubes inside them.

“Achieving very high packing and alignment of the carbon nanotubes in the fibers is critical,” said study co-author Yeshayahu Talmon, director of Technion’s Russell Berrie Nanotechnology Institute, who began collaborating with Pasquali about five years ago.

The next big breakthrough came in 2009, when Talmon, Pasquali and colleagues discovered the first true solvent for nanotubes — chlorosulfonic acid. For the first time, scientists had a way to create highly concentrated solutions of nanotubes, a development that led to improved alignment and packing.

“Until that time, no one thought that spinning out of chlorosulfonic acid was possible because it reacts with water,” Pasquali said. “A graduate student in my lab, Natnael Bahabtu, found simple ways to show that CNT fibers could be spun from chlorosulfonic acid solutions. That was critical for this new process.”

Pasquali said other labs had found that the strength and conductivity of spun fibers could also be improved if the starting material — the clumps of raw nanotubes — contained long nanotubes with few atomic defects. In 2010, Pasquali and Talmon began experimenting with nanotubes from different suppliers and working with AFRL scientists to measure the precise electrical and thermal properties of the improved fibers.

During the same period, Otto [Marcin Otto, Business Development Manager at Teijin Aramid] was evaluating methods that different research centers had proposed for making CNT fibers. He envisaged combining Pasquali’s discoveries, Teijin Aramid’s know-how and the use of long CNTs to further the development of high performance CNT fibers. In 2010, Teijin Aramid set up and funded a project with Rice, and the company’s fiber-spinning experts have collaborated with Rice scientists throughout the project.

“The Teijin scientific and technical help led to immediate improvements in strength and conductivity,” Pasquali said.

Study co-author Junichiro Kono, a Rice professor of electrical and computer engineering, said, “The research showed that the electrical conductivity of the fibers could be tuned and optimized with techniques that were applied after initial production. This led to the highest conductivity ever reported for a macroscopic CNT fiber.”

The fibers reported in Science have about 10 times the tensile strength and electrical and thermal conductivity of the best previously reported wet-spun CNT fibers, Pasquali said. The specific electrical conductivity of the new fibers is on par with copper, gold and aluminum wires, but the new material has advantages over metal wires.

Here’s an explanatory video the researchers have provided,

A more commercial perspective is covered in the Teijin Armid Jan. 11, 2013 news release (Note: A link has been removed),

“Our carbon nanotube fibers combine high thermal and electrical conductivity, like that seen in metals, with the flexibility, robust handling and strength of textile fibers”, explained Marcin Otto, Business Development Manager at Teijin Aramid. “With that novel combination of properties it is possible to use CNT fibers in many applications in the aerospace, automotive, medical and (smart) clothing industries.”

Teijin’s cooperation and involvement was crucial to the project. Twaron technology enabled improved performance, and an industrially scalable production method. That makes it possible to find applications for CNT fibers in a range of commercial or industrial products. “This research and ongoing tests offer us a glimpse into the potential future possibilities of this new fiber. For example, we have been very excited by the interest of innovative medical doctors and scientists exploring the possibilities to use CNT fiber in surgical operations and other applications in the medical field”, says Marcin Otto. Teijin Aramid expects to replace the copper in data cables and light power cables used in the aerospace and automotive industries, to make aircraft and high end cars lighter and more robust at the same time. Other applications could include integrating light weight electronic components, such as antennas, into composites, or replacing cooling systems in electronics where the high thermal conductivity of carbon nanotube fiber can help to dissipate heat.

Teijin Aramid is currently trialing samples of CNT fiber on a small scale with the most active prospective customers. Building up a robust supply chain is high on the project team’s list of priorities. As well as their carbon fiber, aramid fiber and polyethylene tape, this new carbon nanotube fiber is expected to allow Teijin to offer customers an even broader portfolio of high performance materials.

Teijin Group (which is headquartered in Japan) has been mentioned here before notably in a July 19, 2010 posting about a textile inspired by a butterfly’s wing (Morphotex) which, sadly, is no longer being produced as noted in a more recent April 12, 2012 posting about Teijin’s then new fiber ‘Nanofront™’ for use in sports socks.

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Graphene and radioactive waste

Tuesday, January 8th, 2013

In fact, the material in question is graphene oxide and researchers at Rice University (Texas) and Lomonosov Moscow State University have found that it can rapidly remove radioactive material from water  From the Jan. 8, 2013 news item on ScienceDaily,

A collaborative effort by the Rice lab of chemist James Tour and the Moscow lab of chemist Stepan Kalmykov determined that microscopic, atom-thick flakes of graphene oxide bind quickly to natural and human-made radionuclides and condense them into solids. The flakes are soluble in liquids and easily produced in bulk.

The Rice University Jan. 8, 2013 news release, which originated the news item, was written by Mike Williams and provides additional insight and quotes from the researchers (Note: Links have been removed),

The discovery, Tour said, could be a boon in the cleanup of contaminated sites like the Fukushima nuclear plants damaged by the 2011 earthquake and tsunami. It could also cut the cost of hydraulic fracturing (“fracking”) for oil and gas recovery and help reboot American mining of rare earth metals, he said.

Graphene oxide’s large surface area defines its capacity to adsorb toxins, Kalmykov said. “So the high retention properties are not surprising to us,” he said. “What is astonishing is the very fast kinetics of sorption, which is key.”

“In the probabilistic world of chemical reactions where scarce stuff (low concentrations) infrequently bumps into something with which it can react, there is a greater likelihood that the ‘magic’ will happen with graphene oxide than with a big old hunk of bentonite,” said Steven Winston, a former vice president of Lockheed Martin and Parsons Engineering and an expert in nuclear power and remediation who is working with the researchers. “In short, fast is good.”

Here’s how it works (from the news release; Note: Links have been removed),

The researchers focused on removing radioactive isotopes of the actinides  and lanthanides  – the 30 rare earth elements in the periodic table – from liquids, rather than solids or gases. “Though they don’t really like water all that much, they can and do hide out there,” Winston said. “From a human health and environment point of view, that’s where they’re least welcome.”

Naturally occurring radionuclides are also unwelcome in fracking fluids that bring them to the surface in drilling operations, Tour said. “When groundwater comes out of a well and it’s radioactive above a certain level, they can’t put it back into the ground,” he said. “It’s too hot. Companies have to ship contaminated water to repository sites around the country at very large expense.” The ability to quickly filter out contaminants on-site would save a great deal of money, he said.

He sees even greater potential benefits for the mining industry. Environmental requirements have “essentially shut down U.S. mining of rare earth metals, which are needed for cell phones,” Tour said. “China owns the market because they’re not subject to the same environmental standards. So if this technology offers the chance to revive mining here, it could be huge.”

Tour said that capturing radionuclides does not make them less radioactive, just easier to handle. “Where you have huge pools of radioactive material, like at Fukushima, you add graphene oxide and get back a solid material from what were just ions in a solution,” he said. “Then you can skim it off and burn it. Graphene oxide burns very rapidly and leaves a cake of radioactive material you can then reuse.”

The low cost and biodegradable qualities of graphene oxide should make it appropriate for use in permeable reactive barriers, a fairly new technology for in situ groundwater remediation, he said.

Romanchuk, Slesarev, Kalmykov and Tour are co-authors of the paper with Dmitry Kosynkin, a former postdoctoral researcher at Rice, now with Saudi Aramco. Kalmykov is radiochemistry division head and a professor at Lomonosov Moscow State University. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science at Rice.

Here’s a ‘before’ shot of solution with graphene oxide and an ‘after’ shot where radionuclides have been added and begun to clump,

A new method for removing radioactive material from solutions is the result of collaboration between Rice University and Lomonosov Moscow State University. The vial at left holds microscopic particles of graphene oxide in a solution. At right, graphene oxide is added to simulated nuclear waste, which quickly clumps for easy removal. Image by Anna Yu. Romanchuk/Lomonosov Moscow State University

A new method for removing radioactive material from solutions is the result of collaboration between Rice University and Lomonosov Moscow State University. The vial at left holds microscopic particles of graphene oxide in a solution. At right, graphene oxide is added to simulated nuclear waste, which quickly clumps for easy removal. Image by Anna Yu. Romanchuk/Lomonosov Moscow State University

As noted in the ScienceDaily news item, the research has been published in the Royal Society’s Physical Chemistry Chemical Physics journal,

Anna Yu. Romanchuk, Alexander Slesarev, Stepan N. Kalmykov, Dmitry Kosynkin, James M Tour. Graphene Oxide for Effective Radionuclide Removal. Physical Chemistry Chemical Physics, 2012; DOI: 10.1039/C2CP44593J

This article is behind a paywall.

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Mad about Madder in lithium-ion batteries

Wednesday, December 12th, 2012

It hasn’t happened yet but it looks like the future might hold greener lithium-ion (Li-ion) batteries. According to the Dec. 11, 2012 news release on EurekAlert,

Scientists at Rice University and the City College of New York have discovered that the madder plant, aka Rubia tinctorum, is a good source of purpurin, an organic dye that can be turned into a highly effective, natural cathode for lithium-ion batteries. The plant has been used since ancient times to create dye for fabrics.

…

The goal, according to lead author Arava Leela Mohana Reddy, a research scientist in the Rice lab of materials scientist Pulickel Ajayan, is to create environmentally friendly batteries that solve many of the problems with lithium-ion batteries in use today.

Purpurin, left, extracted from madder root, center, is chemically lithiated, right, for use as an organic cathode in batteries. The material was developed as a less expensive, easier-to-recycle alternative to cobalt oxide cathodes now used in lithium-ion batteries. Credit: Ajayan Lab/Rice University

The Dec. 11, 2012 Rice University news release by Mike Williams, the origin for the one on EurekAlert, describes why the researchers are so interested in a more environmentally-friendly cathode,

While lithium-ion batteries have become standard in conventional electronics since their commercial introduction in 1991, the rechargeable units remain costly to manufacture, Reddy said. “They’re not environmentally friendly. They use cathodes of lithium cobalt oxide, which are very expensive. You have to mine the cobalt metal and manufacture the cathodes in a high-temperature environment. There are a lot of costs.

“And then, recycling is a big issue,” he said. “In 2010, almost 10 billion lithium-ion batteries had to be recycled, which uses a lot of energy. Extracting cobalt from the batteries is an expensive process.”

Reddy and his colleagues came across purpurin while testing a number of organic molecules for their ability to electrochemically interact with lithium and found purpurin most amenable to binding lithium ions. With the addition of 20 percent carbon to add conductivity, the team built a half-battery cell with a capacity of 90 milliamp hours per gram after 50 charge/discharge cycles. The cathodes can be made at room temperature, he said.

“It’s a new mechanism we are proposing with this paper, and the chemistry is really simple,” Reddy said. He suggested agricultural waste may be a source of purpurin, as may other suitable molecules, which makes the process even more economical.

Innovation in the battery space is needed to satisfy future demands and counter environmental issues like waste management, “and hence we are quite fascinated by the ability to develop alternative electrode technologies to replace conventional inorganic materials in lithium-ion batteries,” said Ajayan, Rice’s Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science and of chemistry.

“We’re interested in developing value-added chemicals, products and materials from renewable feedstocks as a sustainable technology platform,” said co-lead author George John, a professor of chemistry at the City College of New York-CUNY and an expert on bio-based materials and green chemistry. “The point has been to understand the chemistry between lithium ions and the organic molecules. Now that we have that proper understanding, we can tap other molecules and improve capacity.”

For anyone who’s interested, you can read the researchers’ article (open access),

Lithium storage mechanisms in purpurin based organic lithium ion battery electrodes by Arava Leela Mohana Reddy,  Subbiah Nagarajan, Porramate Chumyim, Sanketh R. Gowda, Padmanava Pradhan, Swapnil R. Jadhav, Madan Dubey,  George John & Pulickel M. Ajayan in Scientific Reports 2 Article number: 960 doi:10.1038/srep00960

You might also want to check out Dexter Johnson’s Nov. 26, 2012 posting (on Nanoclast, an IEEE [Institute of Electrical and Electronics Engineers] blog)where he mentions a technical deficiency (recharging becomes increasingly difficult) with the current Li-ion batteries in the context of his description of a new imaging technique.

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James’ bond (Rice University research team creates graphene/nanotube hybrid)

Wednesday, November 28th, 2012

I have to give credit to Mike Williams’ Nov. 27, 2012 Rice University news release for the “James’ bond” phrase used to describe this graphene/nanotube hybrid,

A seamless graphene/nanotube hybrid created at Rice University may be the best electrode interface material possible for many energy storage and electronics applications.

Led by Rice chemist James Tour, researchers have successfully grown forests of carbon nanotubes that rise quickly from sheets of graphene to astounding lengths of up to 120 microns, according to a paper published today by Nature Communications. A house on an average plot with the same aspect ratio would rise into space.

Seven-atom rings (in red) at the transition from graphene to nanotube make this new hybrid material a seamless conductor. The hybrid may be the best electrode interface material possible for many energy storage and electronics applications. Image courtesy of the Tour Group

The Rice hybrid combines two-dimensional graphene, which is a sheet of carbon one atom thick, and nanotubes into a seamless three-dimensional structure. The bonds between them are covalent, which means adjacent carbon atoms share electrons in a highly stable configuration. The nanotubes aren’t merely sitting on the graphene sheet; they become a part of it.

“Many people have tried to attach nanotubes to a metal electrode and it’s never gone very well because they get a little electronic barrier right at the interface,” Tour said. “By growing graphene on metal (in this case copper) and then growing nanotubes from the graphene, the electrical contact between the nanotubes and the metal electrode is ohmic. That means electrons see no difference, because it’s all one seamless material.

…

In the new work, the team grew a specialized odako that retained the iron catalyst and aluminum oxide buffer but put them on top of a layer of graphene grown separately on a copper substrate. The copper stayed to serve as an excellent current collector for the three-dimensional hybrids that were grown within minutes to controllable lengths of up to 120 microns.

Electron microscope images showed the one-, two- and three-walled nanotubes firmly embedded in the graphene, and electrical testing showed no resistance to the flow of current at the junction.

“The performance we see in this study is as good as the best carbon-based supercapacitors that have ever been made,” Tour said. “We’re not really a supercapacitor lab, and still we were able to match the performance because of the quality of the electrode. It’s really remarkable, and it all harkens back to that unique interface.”

Here’s the citation and a link for the article,

A seamless three-dimensional carbon nanotube graphene hybrid material by Yu Zhu, Lei Li, Chenguang Zhang, Gilberto Casillas,  Zhengzong Sun, Zheng Yan, Gedeng Ruan, Zhiwei Peng, Abdul-Rahman O. Raji, Carter Kittrell, Robert H. Hauge & James M. Tour in Nature Communications 3, Article number:1225 doi:10.1038/ncomms2234 Published 27 November 2012

This article is behind a paywall.

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NASA, nano, and the race to space

Tuesday, October 16th, 2012

“NASA’s Relationship with Nanotechnology: Past, Present and Future Challenges” has just been published by Rice University’s (located in Texas) Baker Institute for Public Policy. The paper claims that the US National  Aeronautics and Space Administration(NASA) needs to invest more money in nanotechnology research or risk being eclipsed by other countries in the ‘race to space’.

The Oct. 16, 2012 news release from Rice University provides more information,

The paper sheds light on a broad field that holds tremendous potential for improving space flight by reducing the weight of spacecraft and developing smaller and more accurate sensors.

This area of research, however, saw a dramatic cutback from 2004 to 2007, when NASA reduced annual nanotechnology R&D expenditures from $47 million to $20 million. NASA is the only U.S. federal agency to scale back investment in this area, the authors found, and it’s part of an overall funding trend at NASA. From 2003 to 2010, while the total federal science research budget remained steady between $60 billion and $65 billion (in constant 2012 dollars), NASA’s research appropriations decreased more than 75 percent, from $6.62 billion to $1.55 billion.

…

“The United States currently lacks a national space policy that ensures the continuity of research and programs that build on existing capabilities to explore space, and that has defined steps for human and robotic exploration of low-Earth orbit, the moon and Mars,” Matthews said [Kirstin Matthews, one of researchers and a co-author]. “With Congress and the president wrestling over the budget each year, it is vital that NASA present a clear plan for science and technology R&D that is linked to all aspects of the agency. This includes connecting R&D, with nanotechnology as a lead area, to applications related to the agency’s missions.”

H/T to R&D magazine where I first saw the news item which led me to the Rice University news release and paper.

I have read the paper, which was written by the research team of  Baker Institute science and technology policy fellow Kirstin Matthews, current Rice graduate student Kenneth Evans and former graduate students Padraig Moloney and Brent Carey, and found that much of the reasoning is based on the notion that nanotechnology research is fundamental to wining the ‘space race’. Strikingly, there is very little attempt to explain or justify this reasoning. It’s a little disconcerting and reminds me of joining a conversation that’s been in progress for some time and where the context has been long established  leaving the new participant struggling to catch up and in the position of asking ‘dumb’ questions. For example, how important is leading the ‘race to space’?

In general, this paper seems to reflect a fairly high level of anxiety about US scientific superiority (from the news release),

The authors said that to effectively engage in new technology R&D, NASA should strengthen its research capacity and expertise by encouraging high-risk, high-reward projects to help support and shape the future of U.S. space exploration

“Failure to make these changes, especially in a political climate of flat or reduced funding, poses substantial risk that the United States will lose its leadership role in space to other countries — most notably China, Germany, France, Japan and Israel — that make more effective use of their R&D investments,” Matthews said.

I sometimes think the current US interest in space exploration is a way of harkening back to the glory days of the 1960s where US scientific superiority was unassailable. Much of this superiority was based on the US successfully beating Russia in a race to place ‘a man on the moon’.

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DAVinCI lets Rice University researchers visualize their data big time

Friday, July 13th, 2012

The July 13, 2012 news item on physorg.com presents an extraordinary picture (Note: I have removed a link),

The 200-inch wall (measured diagonally) lets users display and analyze images of all types, from atoms to galaxies. This studio is expected to help researchers in Earth science, biomedicine, engineering, art, architecture and other fields gain extraordinarily clear pictures of their data sets, be they bacteria or bridges.

“I can take my 3-D seismic images,  project them here and walk around inside them,” said Alan Levander, Rice’s Carey Croneis Professor of Earth Science and principal investigator of the Data Analysis and Visualization Cyberinfrastructure (DAVinCI) project. “With a tracking device in my hand, I can go through and choose the features that I want to look at.” The DAVinCI project adds to Rice’s extensive supercomputing resources, which also include Blue Gene/P, among the 500 most powerful supercomputers in the United States.

The news item originated in a July 12, 2012 Rice University news release by Mike Williams,

The futuristic wall of 50-inch high-resolution projection monitors supports two- and three-dimensional visualization needs at extremely high resolution and clarity, Odegard [Jan Odegard, executive director of Rice’s Ken Kennedy Institute for Information Technology] said. Backed by custom graphics engines, the wall allows data to be displayed in three dimensions using modern active stereo shutter glasses, often seen in home 3-D TV systems but far more sophisticated than glasses used at a 3-D movie theater.

The shutters are linked wirelessly to the graphic engines so that, in effect, only one eye is open at a time, and it matches the left or right images displayed on the screen. But this all happens very fast, at a frame rate of 120 times a second, so users see no flicker in their images.

Erik Engquist, manager of the lab who joined Rice last year, has been demonstrating the system with geological, molecular and other 3-D data that float in front of the screen and allow viewers to see details that might be invisible on flat images, no matter how big. The system has two other advantages over standard 3-D displays. The 32-megapixel screen can track researchers with an infrared system (also tied into the glasses) and allows them to walk around inside an image. Researchers can also interact with the data by turning them this way and that in midair to get a different perspective and interpret the data quantitatively.

“If you have a 10-dimensional data space — which is not uncommon — you can’t visualize it in 10 dimensions, but you can visualize any three at a time,” Levander said. “You can walk through complicated multidimensional space looking at what are called ‘hypercubes.’ You can interact with them and look for correlations in complex systems.”

Engquist, an applied mathematician, said the 16 projection monitors were chosen for their display brilliance and their narrow borders that leave only a thin strip of black between individual screens. “It’s far less intrusive than if we had used regular TV monitors, which have a large bezel,” he said. “If the images have a black background, you barely see the lines; in fact, after a while you don’t really notice them, since your focus will be on the data.”

Here’s a video about DAVinCI produced by Rice University,

The official opening for this project is Sept. 5, 2012 but researchers are already working with this new equipment (or playing with a fabulous new toy which brings to mind the Star Trek holodeck). Rice University has made an online technical manual, Getting Started on DAVinCI available. You need to be familiar with the Linux operating system and comfortable with writing short scripts (i.e., have rudimentary programming skills).

 

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