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Method Devised for Inexpensive Graphene Production

Izabela Kaminska holding a model of graphene molecules (Institute of Physical Chemistry)

Izabela Kaminska holding a model of graphene molecules (Institute of Physical Chemistry)

Researchers from Poland, France, and India have developed a process for producing the high-performance material graphene using common laboratory equipment. The team led by the Institute of Physical Chemistry (translation provided by EurekAlert) of the Polish Academy of Sciences in Warsaw, published a description of that process earlier this year in the journal Chemical Communications; paid subscription required.

Graphene is a two dimensional material composed of hexagonal carbon rings, one atom in thickness, that resembles a honeycomb. It is a good conductor of electricity and heat, and among the strongest and thinnest materials ever measured. Potential uses of graphene include composite materials, flexible touchscreens, pollution sensors, and biomedical sensors. Andre Geim and Kostya Novoselov of University of Manchester in the U.K. received the Nobel Prize in physics in 2010 for their work demonstrating the properties of graphene.

Current methods for producing graphene involve depositing crystalline layers on a metallic or silicon carbide substrate, or using chemical or vapor deposition processes. All of these approaches require expensive and specialized equipment, as well as complex manufacturing procedures.

The team that included participants from the Interdisciplinary Research Institute in Lille, France — where the experiments were carried out — and North East Institute of Science and Technology in Dispur, India, started with the common material graphite, which when oxidized using an ordinary ultrasound cleaner often found in labs, produced flakes of graphene oxide.

Graphene oxide was a step in the right direction, but the researchers still had to remove the oxygen-containing elements in the compound. The problem, with this intermediate material, as described by first author Izabela Kaminska (pictured at top), was that it “changed dramatically the physico-chemical properties of the material. Instead of an excellent conductor we had… an insulator.”

To remove the oxygen from the graphene oxide flakes, the team mixed the graphene oxide with a carbon-sulphur compound called tertathiafulvalene (TTF), again with an ultrasound cleaner. The interactions between the graphene oxide and TTF resulted in a reduction of graphene oxide to graphene with a simultaneous oxidation of the TTF molecules, leaving graphene flakes with TTF molecules inserted between them.

When the resulting solution was spread on electrodes and dried, graphene flakes formed into a smooth coating with controllable thickness from 100 to 500 nanometers, composed of a few dozen to a few hundred alternate graphene sheets and TTF molecules. The researchers removed the remaining TTF with an aqueous iron-chlorine-oxygen solution.

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