Exploring graphene’s nearly endless uses

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April 23, 2015

11:59 PM

It is about 100 times stronger than steel, conducts heat and electricity with great efficiency and is nearly transparent. Graphene seems like an impossibly advanced material, yet it is already at most of our fingertips — literally. Stacks of graphene sheets make up the graphite we use every day when we use pencils. Graphite-based writing works through a property of graphene: the sheets have fantastically strong lateral bonds but extremely weak ones between each sheet. As we press graphite to paper, the sheets slip apart, leaving lines of broken graphite that become words, drawings or bubbles on a scantron. This application of carbon-based material is an essential component of our everyday lives, to be sure, but scientists are rapidly discovering the exciting industrial potential that lies within the sheets. Professor Hannes Schniepp’s lab in the applied science department is developing methods of harnessing the awesome strength of graphene’s two-dimensional carbon bonds to reinforce much larger structures and materials.

Graphene is an allotrope of carbon, which simply means it is one of many “flavors” that are possible for carbon to exist in with respect to how it is “mixed” together with itself. Each “flavor” denotes a particular set of properties and qualitative differences. Other allotropes of carbon include diamond, glassy carbon and the intriguing buckminsterfullerene. Graphene is a standout flavor for a few key reasons that have huge industrial implications. As mentioned previously, graphene is a wildly efficient conductor of electricity, which gives it the potential to usurp silicon as the dominant material for microprocessors in microchips. Conductivity combined with a two dimensional structure also makes graphene an excellent candidate for use in technological screens: on laptops, cell phones, televisions, et cetera.

So, as Schniepp describes, graphene in the form we encounter on a regular basis, graphite, isn’t very impressive: it breaks easily and is not strong enough to build a viable structure with. Graphene is most useful in its purest form: as atom-thick sheets. Producing this form of carbon isn’t the hard part. As mentioned, there are trace amounts of graphene on any paper that has been written on with pencil. The challenge is making graphene en masse, in large enough quantities that would allow us to employ graphene structurally like we do iron, brass or silicon. The other confounding factor that Schniepp describes is that “you can make it, and then the problem is finding it. You can’t see something that is only an atom thick.”

Schniepp was researching graphene even before it was first described in scientific literature by Andre Geim in 2004. He began his work with graphene as a post-doc at Princeton in a lab that was independently exploring the material Geim described in his paper, placing Schniepp at the forefront of the graphene paradigm that has since exploded in the materials science field. Schniepp remarked on this trajectory: “It’s been great to be on some of these first papers that are cited thousands and thousands of times, on the other hand … the best people from everywhere just jumped on this, so actually it’s a pretty rough battlefield.”

Geim’s groundbreaking discovery was simply a matter of pressing scotch tape to a strategically shaped block of graphite and physically stripping off a bit of graphene. Schniepp’s lab is more interested in producing large amounts of graphene at a time, so they’ve developed a different approach. “We don’t mechanically peel the sheets off, we do it chemically, which makes it at a larger scale, you can make grams or kilograms of graphene,” he said. This means treating the sheets with tremendously robust acid. “The acid goes between the sheets, weakens some of the inter-sheet bonds, and then you heat it, and then the sheets pop apart like popcorn.”

The acids employed in this procedure are the “nastiest you can imagine,” and they compromise a bit of the electrical conductivity of the sheets in the process. This is why Schniepp’s lab explores mainly structural applications of this material; their mass-produced graphene can’t match the electrical potential of pure graphene, but its structural integrity remains largely intact. Right now, Schniepp and his team are focusing on creating plastics that are enriched with graphene. Super-strong plastic and graphene composites could be applied in any number of ways in many industries: Essentially, any product that needs to be strong and lightweight could benefit from advances in our understanding of graphene functionality in plastic. Think aerospace, automotive or security applications in particular. The immediate challenge is to avoid the between-sheet slipping that occurs in pencil graphite.

To address this, the lab is working on ways to give chemical traction to the sheets’ surfaces, so that the bits of incorporated graphene are wholly integrated and homogeneously distributed in the plastic composite.

“If they stick, if they don’t stick, if they slip, what plastic works, how we have to mix the plastic: those are all the questions we’re trying to answer… making something stronger is always best,” says Schniepp.

The applied sciences department encompassing Schniepp’s lab, as well as neuroscience, computer science, computational biology, robotics and laser spectroscopy labs, is explicitly graduate-student focused: it is the largest PhD granting department on campus and it does not offer an undergraduate major. However, Schniepp has become increasingly involved in the undergraduate experience, offering lab positions to several undergraduates and participating in freshman advising. He described how this is one of the highlights of working at the College of William and Mary, and he enjoys introducing students to careers in materials science research.

“I like to give students unsolved problems,” Schniepp said. “In a few cases, we’re able to do world-class, cutting edge research with an undergraduate student.”

Outside of the lab, Schniepp instructs an applied science course, APSC 201, Introduction to Materials Science, a relatively new course at the College that has maxed out at registration every time it has been offered.

“We’re bringing this research we’re doing to the classroom,” says Schniepp. “It’s important for me that undergrads know that they can be a part of this PhD level research.”

Graphene is not the only material Shniepp’s lab is concerned with; they also conduct research on a diverse collection of nanomaterials, including synthetic “spider silk,” self-organizing surfactant molecules, and improved surface materials for medical implants, to name a few. For more information on these and other projects, look to the lab’s page listed here: http://as.wm.edu/schniepp/research.html

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  • Carly Martin