Graphene

Following on from last month’s theme (subject material that is new to the guide) I thought this month I would concentrate on graphene.

Graphene crops up in topic 4, Chemical bonding and structure.

You may well have heard of graphene – it comes up from time to time in the media – but what is it?Rewind to 2004 and Andre Geim and his PhD. student Konstantin Novoselov. Location: The University of Manchester.

The experiment that led to its discovery was termed a “Friday evening experiment”. This was a term used to describe an “off beat, interest driven experiment and cunningly disguised the actual amount of work required to get any results.”¹

Ultimately, the Friday night experiment delivered the team a Nobel prize for their work.
There is a good BBC interview at:
http://news.bbc.co.uk/2/hi/programmes/click_online/9491789.stm– Although for many good reasons you may not be able to access this.
So what is graphene?
Firstly it is an allotrope of carbon with carbon atoms covalently bonded and densely packed together in an sp2 bonded hexagonal pattern (sounds familiar? Like graphite?)

However, graphene is a one atom thick and this opens up huge possibilities for the macromolecule that will be dealt with later.
Interestingly, it is the basic structural element of other carbon allotropes
[These allotropes being graphite, charcoal, carbon nanotubes and fullerenes.]

It can be thought of as an indefinitely large molecule that is strong, light, nearly transparent and an excellent conductor of heat and electricity (carbon atoms only form three covalent bonds with other carbons, freeing up an electron that can move and allow the material to conduct electricity – just like graphite).
Potentially it can be used in:
Biological engineering – with a high surface area graphene could potentially be used as a biosensor, being able to monitor haemoglobin or cholesterol.
Touchscreens – as the material is a conductor of electricity and almost transparent. Both of these properties are highly desirable when it comes to touchscreens.
Ultrafiltration – the ‘pore’ size (or the ‘hexagon’) acts as a natural filter. The molecule is held together by strong covalent bonds – so why can’t it be used to filter very small objects?
Photovoltaic cells – as an alternative to silicon.
(See http://www.graphenea.com/pages/graphene-uses-applications#.U1WDKPldWSo for more details).
However, currently only very small crystals have been made.
This raises questions such as:
• Can we truly predict its final applications?
• Are its physical and chemical properties the only determining factor of its success?
• And are there historical parallels? (did the Buckminster Fullerene fulfil its early potential?)
Some other sites that link into this are:
http://www.nobelprize.org/nobel_prizes/physics/laureates/2010/press.html
http://periodicvideos.com/videos/mv_graphene.htm
http://www.graphene.manchester.ac.uk/story/
Sources used:
¹ http://www.graphene.manchester.ac.uk/story/