Polish co-authors of cheap graphene coating production method
PAP indywidualista.com / Grzegorz Krzyzewski 602861707
Researchers from the Institute of Physical Chemistry and Institut de Recherche Interdisciplinaire in Lille have developed an inexpensive method of producing graphene coatings. "The method is so simple that it can be performed in almost every laboratory" - reported the IPC PAS.
Cheap chemical method of production graphene layers has been developed in a joint project by teams from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw and Institut de Recherche Interdisciplinaire in Lille.
"The method is so simple to implement, that can be performed in almost every laboratory" - reported the IPC PAS in a release sent to PAP.
Graphene was discovered in 2004 by Andre Geim and Konstantin Novoselov, who stripped off layers of carbon from graphite with ordinary adhesive tape.
"If we consider industrial applications of graphene, we must find better controlled ways of producing it in large quantities, without having to use expensive, specialized equipment" - said Izabela Kaminska, PhD student at the IPC PAS. She conducted her experiments at Institut de Recherche Interdisciplinaire (IRI) in Lille.
Previous graphene production methods require expensive, specialized equipment and complex production procedures. "The only a bit more complex device used in the graphene coating production method developed by the IPC and the IRI is an ultrasonic cleaner, quite common in laboratories" - reads the IPC PAS release.
The unique structure of graphene is responsible for its unusual properties. Graphene is almost completely transparent, more than one hundred times stronger than steel and very flexible. It exhibits excellent thermal and electrical conductivity, so it is good material for use in electronics, for example, to make thin, flexible and durable displays and high speed processing systems. It is also suitable as a material for various types of biosensors.
The new manufacturing process of graphene layers begins with graphite, type of coal, the structure of which resembles a "sandwich" made of many layers of graphene. These layers are difficult to separate. The weakening of the interaction between them is possible by oxidation of graphite.
Resulting powder (graphite oxide) is then poured into water and placed in an ultrasonic cleaner. Ultrasound separates individual, oxidized graphene layers. The result is a colloid, a mixture containing a graphene oxide flakes.
"Graphene oxide flakes with monatomic thickness are a good starting point, but the problem are numerous functional groups that contain oxygen. They dramatically alter the physico-chemical properties of the material. Instead of a perfect conductor we have an insulator" - explained Kamińska.
In order to remove oxygen from graphene oxide flakes, the researchers used specific interactions occurring between carbon rings in graphene oxide and rings of the compound called trathiafulvalene (TTF).
"In practice, it was sufficient to mix trathiafulvalene with graphene oxide, and then put it in an ultrasonic cleaner. Interactions between the TTF rings and graphene oxide rings result in a reduction of graphene oxide to graphene, while TTF molecules oxidize" - described Kamińska.
As a result, graphene flakes settle on the electrode and form a smooth coating with a thickness of 100 to 500 nanometers, composed of tens to hundreds alternating layers of graphene and TTF molecules.
The publication describing the method was published in the prestigious journal Chemical Communications. Now scientists from the IPC PAS and IRI are working on further reduction of the graphene coating thickness.
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