From Graphite to Gold: How graphene gate-crashed the nano-carbon party and took over the dance floor.

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Posted
June 17, 2015
Author
Sam Findlay
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Graphene has amazing properties; a rare combination of strength, electrical conductivity and even compatibility with living cells.

These characteristics are seen in the nano-domain, and our challenge is to translate them to a larger scale, for practical applications. To do this, we need a holistic strategy, from source-to-system.

 

The source

Graphene, of course, is derived from graphite, and the source of the graphite determines the characteristics of our starting material.

 

Graphite can be naturally occurring (mined) or synthetically derived. Let’s focus on the naturally occurring graphite, and what’s important here is the purity of the material. Not just the purity of the graphite, but the nature of the additional materials that are inherently present.

 

Also important will be the flake size, since the dimensions of graphene sheets determine the properties that can be imported to other materials in hybrids and composites.

 

Our aim is to process the graphite to produce graphene that is amenable for use in actual products, whilst still retaining the valuable properties of the material itself. The way in which graphene is processed will determine our success or failure.

 

Scaling-up

The first step in the scaling-up process is to exfoliate the graphite into individual sheets. These sheets will consist mostly of carbon, with oxygen residues. Any soluble impurities can be moved at this point, and the sheets can be treated to remove oxygen (or this process can take place further down the line).

 

At some point, the sheets of graphene need to be integrated with another material, for use in an actual product. They can be processed as coatings for applications such as transparent electrodes – useful for touch screens and solar-driven devices.

 

The graphene sheets can also be introduced into polymers as reinforcing material to improve strength, whilst introducing electrical conductivity to allow electrical charge to transfer from one point to another. This can be useful in engineering materials, but effective integration will require clever chemistries.

 

Systems

The use of graphene as electrodes is all-the-buzz.

 

Applications include energy storage such as batteries and capacitors, energy conversion including solar cells and thermal energy harvesting, and for medical implantable bionics.

 

All of these applications require sophisticated electrode construction and seamless integration into the actual device. It appears that hybrid electrode materials will make the most of the graphene properties, for example, nitrogen provides significant enhancement to graphene in energy storage applications.

 

For medical bionic applications, graphene must be housed in an appropriate biocompatible structure such as silicone rubber. To make sure of graphene in nerve or muscle regeneration, more complex structures must be created.

 

The nano-carbon party

Graphene turned up to the nano-carbon party bang on time.

 

The material that took the research world by storm for a decade before graphene came on the scene, carbon nanotubes, is to thank for the development of many chemistries that were immediately applicable to its close relative, graphene.

 

These chemistries allow graphene to be integrated into structures such as fibres and composites, using fabrication options including spraying, dip-coating, dyeing of textiles, fibre production, knitting and 3D printing.

 

For a more detailed look at how Graphene is processed for use in useful applications, head over to our post on Bio Graphene, read our article published in Advanced Materials and watch our video – What is Graphene?

 

Find out more about Professor Gordon Wallace

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