Posted in | Graphene

Researchers Create Process for Synthesizing Pure Graphene

Formed deep within the earth, graphene has been proved to be stronger than steel, and thinner than a human hair. Some experts even refer to it as “the most amazing and versatile” material known to man.

UConn chemistry professor Doug Adamson has found an inexpensive way to manufacture the pristine form of this substance, which is stronger than steel and thinner than a human hair. (Peter Morenus/UConn Photo)

UConn Chemistry Professor Doug Adamson, a member of the Polymer Program in UConn’s Institute of Materials Science, has patented a one-of-a-kind method for exfoliating this amazing material in its pure (unoxidized) form, as well as manufacturing advanced graphene nanocomposites that could possibly have use in numerous applications.

If we view graphite like a deck of cards, then each card in the deck would be a sheet of graphene. Graphene is a two-dimensional crystal that is made up of a single layer of carbon atoms arranged in a hexagonal lattice. It is at least 100 times stronger than steel. Aerogels created using graphene are some of the lightest materials even known, and the graphene sheets are one of the thinnest, at just one atom thick – that is about one million times thinner than a human hair. Graphene is also even more electrically and thermally conductive than copper, with marginal electrical charge.

Owing to these exceptional qualities, graphene has been a popular topic among Academic Researchers and Industry Leaders since it was first isolated from graphite in 2004. Since then, the material has been featured in over 10,000 scholarly articles. However it is only Adamson who talked about a proprietary process for manufacturing graphene in its pure form.

What many are calling “graphene” is mostly really graphene oxide that has been thermally or chemically reduced. The oxygen in graphene oxide gives a kind of chemical handle that makes the graphene easier to manipulate, but incorporating it to pure graphene decreases the material’s thermal, mechanical and electrical properties in comparison to untouched graphene like the kind Adamson creates.

It also considerably increases the manufacturing cost of the material. Oxidizing graphite requires integrating costly hazardous chemicals, such as potassium peroxide and anhydrous sulfuric acid, followed by an extensive series of manipulations to isolate and cleanse the products, known as a chemistry workup. Adamson’s process does not require any extra steps or chemicals to create graphene in its pure form.

The innovation and technology behind our material is our ability to use a  thermodynamically driven approach to un-stack graphite into its constituent graphene sheets, and then arrange those sheets into a continuous, electrically conductive, three-dimensional structure. The simplicity of our approach is in stark contrast to current techniques used to exfoliate graphite that rely on aggressive oxidation or high-energy mixing or sonication – the application of sound energy to separate particles – for extended periods of time. As straightforward as our process is, no one else had reported it. We proved it works.

Doug Adamson, Chemistry Professor and a Member of the Polymer Program, UConn’s Institute of Materials Science

Shortly after the primary experiments by Graduate Student Steve Woltornist showed that something special was happening, Adamson was joined by longtime collaborator Andrey Dobrynin from the University of Akron, who has helped to comprehend the thermodynamics that drive the exfoliation. Their research has been published in the American Chemical Society’s peer-reviewed journal ACS Nano.

A distinguishing feature of graphene that looks like a hurdle to many – its insolubility – is at the center of Adamson’s discovery. As it does not dissolve in liquids, Adamson and his team place graphite at the interface of oil and water, where the graphene sheets impulsively spread to cover the interface and reduce the energy of the system. The graphene sheets are captured at the interface as individual, overlapping sheets, and can next be locked in place using a cross-linked plastic or polymer.

In 2010, Adamson started looking for ways to exfoliate graphene from graphite using a grant from the Air Force to synthesize thermally conductive composites. In 2012, he received funding from a National Science Foundation (NSF) Early-concept Grants for Exploratory Research (EAGER) award. After that he has also been awarded a $1.2 million grant from the NSF Designing Materials to Revolutionize and Engineer our Future program and $50,000 from UConn’s SPARK Technology Commercialization Fund program.

Dr. Adamson’s work speaks not only to the preeminence of UConn’s faculty, but also to the potential real-world applications of their research. The University is committed to programs like SPARK that enable faculty to think about the broader impact of their work and create products or services that will benefit society and the state’s economy.

Radenka Maric, Vice President for research, UConn and UConn Health

Graphene for Water Desalination

While stabilized graphene composite materials have countless potential uses in fields as diverse as electronics, aircrafts and biotechnology, Adamson chose to use his technology to enhance standard techniques for the desalination of brackish water. With his SPARK funding, he is building a device that uses his graphene nanocomposite materials to eliminate salt from water through a process called capacitive deionization, or CDI.

CDI depends on economical, high surface area, porous electrodes to eliminate salt from water. There are two cycles in the CDI procedure: an adsorption phase where the dissolved salt is eliminated from the water and a desorption phase where the adsorbed salts are discharged from the electrodes by either reversing or halting the charge on the electrodes.

Many materials have been used to develop the electrodes, but none have established to be a feasible material for large-scale commercialization. Adamson and his industry partners believe that his simple, economical and sturdy material could be the technology that finally takes CDI to market in a huge way.

“The product we are developing will be an inexpensive graphene material, with optimized performance as an electrode, that will be able to displace more expensive, less efficient materials currently used in CDI,” says Michael Reeve, one of Adamson’s partners and a veteran of a range of successful startups.

The team created a startup called 2D Material Technologies, and they have applied for a Small Business Innovation Research grant to pursue commercialization of Adamson’s technology. Ultimately, they hope to join UConn’s Technology Incubation Program to advance their model to market.

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