Graphene research shows multiple uses

Russian physicists, Andre Geim and Konstantin Novoselov, won the 2010 Nobel Prize for their work with graphene, a lattice of carbon only one atom thick and “virtually two-dimensional.” Graphene has a large spherical molecular shape which gives it superior electrical and heat conductivity; the shape of the molecules are relatively closed off, meaning it doesn’t react chemically with many substances.

“It’s the thinnest material you can get,” Geim said in an article by Stefanie Blendis from CNN from Oct. 6. “It’s only one atom thick. A tiny amount can cover a huge area, so one gram could cover a whole football pitch. It’s the strongest material we are aware of because you can’t slice it any further. Of course, we know that atoms can be divided into elementary particles, but you can’t get any material that is thinner than one atom, or it wouldn’t count as a material anymore.”

These properties make the uses for graphene virtually limitless. There are already plans to create longer lasting batteries, more efficient solar panels, thinner electronic devices and sponges for industrial oil cleanup.

Inserting graphene into plastics could reinforce them as well as make them conductive. Since graphene is transparent, it could pave the way for more intuitive touch screens and a more shatter resistant cell phone screen. Eventually, it could completely replace silicone chips in electronic devices.

Vikas Berry, assistant professor of chemical engineering, has been researching graphene at K-State. He had the chance to discuss his research with Geim and received a five year, $400,000 National Science Foundation CAREER Award to pursue his research.

He focuses mainly on the biological applications of graphene, like the DNA sensors and bacteria transistors he built for earlier projects. He also developed a graphene cloak that covers bacteria under a high vacuum electron microscope, leading to clearer images and water retention in the slide material that more accurately illustrate the sizes of living bacteria. Currently, he and his research team study the possible use of graphene in molecular machines.

Phong Nguyen, doctoral candidate in chemical engineering, tethered actuating molecules, the catalysts for starting a molecular machine and then recorded the results. By identifying which substances react the most to graphene, the composition of electronic batteries could be changed.

They’ve found that graphene responds more sensitively than other substances to changes in the atmosphere. When graphene dots are placed next to each other on a hydroscopic microfiber, they can give readings through electron tunneling on changes in local humidity.

“These devices are unique because, unlike most humidity sensors, these are more responsive in vacuum,” Berry said. “For example, these devices can be incorporated into space shuttles, where low humidity measurements are required. These sensors might also be able to detect trace amounts of water on Mars, which has 1/100th of the Earth’s atmospheric pressure. This is because the device measures humidity at a much higher resolution in vacuum.”

The research team is also looking into changing the substance on which they place the dots.

“If you replace this polymer with a polymer that is responsive to other stimuli, you can make a different kind of sensor,” Berry said. “I envision this project to have a broad impact on sensing.”

The research results from Berry and his team appear in a recent issue of Nano Letters in an article titled “Electron-tunneling modulation in percolating-network of graphene quantum dots: fabrication, phenomenological understanding, and humidity/pressure sensing applications,” and the journal Small in an article titled “Covalent functionalization of dipole-modulating molecules on trilayer graphene: an avenue for graphene-interfaced molecular machines.”

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