This photo of graphene on polydimethylsiloxane illustrating its transparency and flexibility. It was made in Dr. Rodney Ruoff's lab at The University of Texas at Austin, Department of Mechanical Engineering. Photo courtesy of Dr. Xuesong Li and Dr. Weiwei Cai.
Rodney Ruoff
Disclaimer: bold red type has been added to this article to make it easier to scan. The original articles did not emphasize the text in any way.
Professor Ruoff's lab has been informed that one of their papers, Synthesis and exfoliation of isocyanate-treated graphene oxide nanoplatelets (PDF), was one of the top-cited papers in the Elsevier, Inc. publication, Carbon. Having received 56 citations to date, the paper contributed to the 2008 Impact factor of 4.373. The publisher, Allyn Molina, wrote in a December email, "We want to finish by repeating our appreciation for your excellent contribution to Carbon. We hope that you will continue to consider the journal as the research outlet for your best work." Carbon is published by Elsevier, Inc. in New York City, New York.
We have produced several articles on graphene research and the work of Professor Rod Ruoff's research team. Readers may want to read the previous articles published on our site for detailed information on their ongoing research. The previous article links are provided on the right column.
Graphene on Polydimethylsiloxane
What is Graphene?
Graphene, an atom-thick layer of carbon atoms bonded to one another in a"chickenwire" arrangement of hexagons, holds great potential for nanoelectronics, including memory, logic, analog, opto-electronic devices and potentially many others. It also shows promise for electrical energy storage for supercapacitors and batteries, for use in composites, for thermal management, in chemical-biological sensing and as a new sensing material for ultra-sensitive pressure sensors.
Graphene has the possibility to be one of the most exciting and useful materials in future products, due to its unusual properties. To follow are excerpts from various papers by graphene researchers describing this promising material. Ruoff's team is researching ways to manufacture graphene in sheets large enough that it can be made commercially viable in applications such as the computer wafer manufacturing as a replacement material for silicon. They have made significant strides in bonding it to a variety of substrates in the past year.
Highlights from the frontlines of current Graphene Research
Materials Science: May 2009
Carbon Sheets an Atom Thick Give Rise to Graphene Dreams
Robert F. Service
...electrons in graphene don't behave like electrons in a standard metal. In the lattice of a typical metal, electrons feel the push and pull of surrounding charges as they move. As a result, moving electrons behave as if they have a different mass from their less mobile partners. When electrons move through graphene, however, they act as if their mass is zero-behavior that makes them look more like neutrinos streaking through space near the speed of light.
Close up of Ruoff's model made of ping pong balls representing a piece of graphene (a single-atom thick layer of carbon atoms) with ions (the ping balls) attached.
Interest in graphene, a novel material with amazing properties, continues to sweep through physics and chemistry labs worldwide. Graphene's carbon atoms are arranged in a chicken-wire pattern of hexagons, giving graphene a perfect crystalline order that makes it the strongest material ever made when yanked along the sheets, yet it flexes like plastic wrap. It's also an outstanding heat conductor. Electrons whiz through the sheets at rates far beyond those achieved in other materials. All these properties have made graphene a playground for researchers including theoretical and high-energy physicists, chemists, and computer-chip-device makers looking to lend graphene's exceptional properties to tomorrow's ultra-small gadgetry.
Half a decade after its arrival on the scene, graphene is showing staying power. Last year, researchers churned out some 1,500 papers on graphene. The number of Google searches on the topic rivals the number for carbon nanotubes, another hot topic with a 20-year head start.
Growing prospects
Most of the excitement right now focuses on using graphene to improve silicon-based computer chips, which form the backbone of a $260-billion-a-year industry.... But researchers are nearing the limits of conventional transistors, which rely on silicon as the semiconductor to ferry electrical charges in a channel between electrodes.
One strategy for further boosting the performance of transistors is to replace the silicon channel with a better conductor.
Up to this point, an even bigger hurdle has been manufacturing large-area graphene films, say Ruoff, Geim and others.... So, researchers around the globe have been racing to come up with other ways to grow large-scale graphene films at low cost.
Graphene on SiO2 wafer
In a paper posted online in Science on 7 May, Ruoff's team at UT, working with researchers at Texas Instruments in Dallas, reports using a similar technique to grow large-area graphene films on thin copper foils. Both the nickel and the copper growth techniques form highly pure graphene. But because copper normally forms larger grains that network themselves together in sheets, it makes larger regions of pristine graphene, Ruoff says.
From the journal Science.
Graphene research made their top-ten list of most important breakthroughs in 2009.
Much of graphene's fascination lies in the way it conducts electrons. Its near-perfect atomic order-a chicken wire-like lattice of carbon atoms- allows electrons to flow through it at ultrafast speeds. That property enables physicists to use it as a simple test bed for some of the unusual features of quantum mechanics. Last month, for example, separate research groups in New York and New Jersey confirmed that graphene's electrons exhibit the fractional quantum Hall effect, in which electrons act collectively as if they are particles with only a fraction of the charge of an electron. This behavior was spotted decades ago in some multilayer semiconductors but never before in such a simple material.
Simplicity reigned elsewhere as well. In May, researchers at the University of Texas, Austin, reported that they had made graphene films up to a centimeter square by growing them atop thin copper foils. A team at Cornell University modified their technique to grow graphene on silicon wafers. The two advances open the door for making large arrays of graphene-based electronic devices.
...In January, researchers at IBM reported building graphene transistors that can switch on and off 26 billion times per second, far outpacing conventional silicon devices. Researchers at the Massachusetts Institute of Technology chipped in with a graphene frequency multiplier for electronic signals, which could lead to new applications in communication and sensing. And elsewhere, researchers turned out everything from a graphene-based scale capable of weighing small molecules to a superfast graphene photodetector. Simple or not, researchers are making it look easy with graphene.
The Graphene Race is On
Graphene research is moving at breakneck speed. We will continue to post research updates from the University of Texas at Austin's Nanoscience and Technology Lab.
