Graphene: Sketching Out A New World, by Dr David Horsell
On 28th February a group of Westholme’s keenest physicists attended a lecture at Liverpool University. Led by Dr Horsell, the talk explored the different uses of graphene (a relative of graphite) and why scientists are getting so excited about this substance.
Year 13 physics student, Nila Murali’s report:
The talk began by listing the different kinds of substances that are made up of carbon atoms in 3 of the 4 dimensions; 0D (fullerene), 1D (nanotube), 3D (diamond, graphite). Since each of the dimensions except 2D have been filled, it was presumed that the missing substance would fit into this space. And surprise surprise, a Nobel Prize was won by Andre Geim and Konstantin Novoselov for discovering the 2D material graphene in 2010.
The experiment they used was explained to us relatively simply by Dr Horsell, as he illustrated that by drawing on a piece of paper, sticking a strip of sellotape to the marks and removing it – we could just about simulate the very same discovery that the dynamic duo themselves had made. Graphene is basically a layer of carbon atoms that are only one atom thick; scientists thought that it couldn’t exist because it would just collapse on itself each time it formed. However, graphene has proved to be an immensely useful substance. It is the only 2D conducting membrane in nature. It’s optically transparent, strong (C=C bonds), flexible and impermeable (even gases can’t get through!).
So, now that scientists know about this lovely stuff – how can they make more of it? Many synthetic processes have been tried and tested to create graphene; Chemical Vapour Disposition, Liquid Phase Exfoliation, Epitaxial Growth (and many more large, complicated words) – but none provided pure, defect-free graphene. The best ingredient for that is naturally occuring graphite.
This was all pretty impressive. But, we thought, what can we actually do with this miraculous membrane? Dr Horsell went on to explain a great many uses for it – in solar cells, in rapid DNA sequencing, and even in futuristic fuel cells where it’s combined with hydrogen to form yet another exotic substance: graphane, which is a good insulator and is also a useful high density storage medium. Another interesting use for graphene is as a substitute for the indium tinoxide used in LCD screens. When indium is used, the screens become like ceramic, and break relatively easily. With graphene, because of its flexibility, this is not a problem. We were told of a future containing inventions like wristband phones and newspapers that you can scrunch up in your pocket and whip out completely wrinkle-free.
But at this point things got really interesting. Our lecturer turned off the power point screen, and flicked on an old-fashioned over-head projector (see physics lab stock) with a tupperware box stationed underneath. He told us that he was going to show us an experiment, and that he should be careful because it was connected to a 5000V supply (we could tell this was going to be good). He was demonstrating the use of graphene as a transistor that would turn the conduction of electricity on and off. Water was poured into the box, with a small cap representing an electron. To our great amusement, the experiment failed, and after several mild shocks and adamant cries of “it worked this morning!”, Dr Horsell surrendered. However, he promises us that graphene transistors are in fact profitable devices.