This is another bit of good news coming out of the labs. I am extremely optimistic regarding the future importance of graphene in technology development. What is there not to like about a substance that is hyper strong and able to handle the temperatures of all molten metals.
All other materials pale in comparison and I am sure that we will have grapheme as a working substrate for single layered metallic composites including superconductors and magnetic coolants.
2008 will surely be known as the year in which nanotechnology research reached full stride. Several labs have rushed into production their version of low cost solar cells. We are also due to see reports on some clever work involving surface structure management.
What most astonishes me is how the press has utterly missed the nanosolar story. The sheer size and the quality of corporate sponsorship is unprecedented. The fact that Nanosolar can announce a two million dollar tool able to produce the power capacity of a nuclear power plant in one year and they are shipping now has barely created a ripple.
We are entering one of the greatest five year technological transitions in human history. The starter gun was fired with $140 oil. The Global financial system was shaken out and soundly disciplined shortly thereafter.
We are now going to rebuild the global energy economy at breakneck speed. In five years we will all be driving electric autocarts because we have no choice. And North America will well on the way to energy self sufficiency.
This lab work is showing us the way to make large bits of graphene. This will surely be worked on intensely over the next two years in order to commercialize it. The second article gives us an excellent snap shot of the actual processes.
Researchers discover method for mass production of nanomaterial graphene process has already produced the largest graphene sample reported
Graphene is a perfect example of the wonders of nanotechnology, in which common substances are scaled down to an atomic level to uncover new and exciting possibilities.
Graphene is created when graphite — the mother form of all graphitic carbon, which is used to make the pigment that allows pencils to write on paper — is reduced down to a one-atom-thick sheet. Graphene is among the strongest materials known and has an attractive array of benefits. These sheets — single-layer graphene — have potential as electrodes for solar cells, for use in sensors, as the anode electrode material in lithium batteries and as efficient zero-band-gap semiconductors.
Research on graphene sheets has been restricted, though, due to the difficulty of creating single-layer samples for use in experiments. But in a study published online Nov. 9 in the journal Nature Nanotechnology, researchers from UCLA's California NanoSystems Institute (CNSI) propose a method which can produce graphene sheets in large quantities.
Led by Yang Yang, a professor of materials science and engineering at the UCLA Henry Samueli School of Engineering, and Richard Kaner, a UCLA professor of chemistry and biochemistry, the researchers developed a method of placing graphite oxide paper in a solution of pure hydrazine (a chemical compound of nitrogen and hydrogen), which reduces the graphite oxide paper into single-layer graphene.
Such methods have been studied by others, but this is the first reported instance of using hydrazine as the solvent. The graphene produced from the hydrazine solution is also a more efficient electrical conductor. Field-effect devices display output currents three orders of magnitude higher than previously reported using chemically produced graphene. Kaner and Kang's co-authors on the research were doctoral students Vincent Tung, from Yang's lab, and Matthew Allen, from Kaner's lab.
"We have discovered a route toward solution processing of large-scale graphene sheets," Tung said. "These breakthroughs represent the future of graphene nanoelectronic research."
The coverage of the graphene sheets can be controlled by altering the concentration and composition of the hydrazine solution. This hydrazine method also preserves the integrity of the sheets, producing the largest-area graphene sheet yet reported, 20 micrometers by 40 micrometers. A micrometer is one-millionth of a meter, while a nanometer is one billionth of a meter.
"These graphene sheets are by far the largest produced, and the method allows great control over deposition," Allen said. "Chemically converted graphene can now be studied in depth through a variety of electronic tests and microscopic techniques not previously possible."
"Interdisciplinary research of this sort is a benefit of collaborative institutes like the CNSI," said Kaner, who is also an associate director of the CNSI. "Graphene is a cutting-edge nanomaterial and one which has great potential to revolutionize electronics and many other fields."
There are two methods currently used for graphene production — the drawing method and the reduction method, each with its own drawbacks. In the drawing method, layers are peeled off of graphite crystals until one is produced that is only one-atom thick. When likely graphene suspects are identified from the peeled layers, they must be extensively studied to conclusively prove their identity. In the reduction method, silicon carbide is heated to high temperatures (1100° C) to reduce it to graphene. This process produces a small sample size and is unlikely to be compatible with fabrication techniques for most electronic applications.
"This technology (hydrazine reduction) utilizes a true solution process for graphene, which can dramatically simplify preparing electronic devices," said Yang, who is also faculty director of the Nano Renewable Energy Center at the CNSI. "It thus holds great promise for future large-area, flexible electronics."
The California NanoSystems Institute at UCLA is an integrated research center operating jointly at UCLA and the University of California, Santa Barbara, whose mission is to foster interdisciplinary collaborations for discoveries in nanosystems and nanotechnology; train the next generation of scientists, educators and technology leaders; and facilitate partnerships with industry, fueling economic development and promoting the social well-being of California, the United States and the world. The CNSI was established in 2000 with $100 million from the state of California and an additional $250 million in federal research grants and industry funding. At the institute, scientists in the areas of biology, chemistry, biochemistry, physics, mathematics, computational science and engineering are measuring, modifying and manipulating the building blocks of our world - atoms and molecules. These scientists benefit from an integrated laboratory culture enabling them to conduct dynamic research at the nanoscale, leading to significant breakthroughs in the areas of health, energy, the environment and information technology. For more information, visit www.cnsi.ucla.edu.
Rocket-fueled graphene production promises higher volume
By Todd Morton Published: November 12, 2008 - 08:22AM CT
Graphene has shown the great potential in the short time that it has been at the forefront of materials research. It's essentially an unrolled carbon nanotube, so graphene shares many of the unique electrical and physical properties that have made carbon nanotubes the poster child of materials research in the last decade. Production of graphene is still decidedly archaic, though.
Nobel Intent covered a decomposition technique that allowed for more accurate deposition. At the time, this was a "high volume" technique, but it provided nothing close to the volume needed for any industrial application or larger scale research effort. Recent research, published in Nature Nanomaterials, demonstrated a solution-based technique that has the promise of both large-scale production and bigger samples, which should open the door for more extensive characterization efforts.
When graphene was first discovered, the best method available for making it was simply taking graphite and peeling it apart with cellophane tape until you had a monolayer of graphene that you could transfer to a substrate (science at its finest, my friends). The arduous part came in determining just what exactly you had produced—scanning electron microscopy, which uses electrons instead of photons to resolve an image, would reveal candidate graphene sites, while atomic force microscopy (think of it as a record player that reads individual atoms instead of your worn out copy of Led Zeppelin III) would confirm a that it was, in fact, a perfectly flat single layer of carbon. To say that this method doesn't lend itself to large-scale production, or even large-scale laboratory work, would be an understatement.
Decomposition methods involving baking silicon carbide, which are also used to produce carbon nanotubes, often yield misshapen, mutant sheets of graphene, and demands high temperatures that rule out any sort of in-line processing with traditional electronics manufacturing equipment. It often yields materials that are less than a square micron, which rules out several characterization techniques that require a larger mass of material.
Researchers have continued working with hydrazine (a well-known rocket propellant), using it as a solvent for graphite oxide that can also strip off the oxygen, preparing the graphene for deposition. The resulting process could be controlled to make samples of graphene as large as 40 microns square, as well as smaller samples if required. The graphene was reasonably high quality, although testing revealed a lack of n-type semiconductor behavior might have resulted from residual hydroxyl groups left by the hydrazine.
Hydrazine processing eliminates several problems associated with using water as a solvent, such as agglomerations of graphene during drying. The dissolved graphene oxide could also be transferred to a less toxic solvent for deposition.
A truly bulk process, such as the solution process demonstrated in this research, is a big step towards making graphene devices a reality. A chemical process like this, although incredibly toxic, is much cheaper for a research institution to deal with than tying up expensive and specialized lithography equipment, which represented the previous state of the art for graphene production. Keep checking Nobel Intent, and we will continue to bring you news on studies of graphene's unique properties, and the efforts to produce it en masse.
Nature Nanomaterials, 2008. DOI: 10.1038/nnano.2008.329