that can ride any terrain and never break, or batteries with lifetimes ten times as long as current models as practical applications for graphene technology. The potential is there, but it is now up to those on the forefront of materials science to leverage these discoveries in the progression of mankind. CONTACT SCOTT GLADSTONE AT SCOTT.W.GLADSTONE.15@DARTMOUTH.EDU References
Image courtesy of Stan Zurek from Maxwell Technologies retrieved from http://en.wikipedia.org/wiki/File:Supercapacitors_chart.svg (accessed 10 May 2012)
Figure 3: Comparison of energy density and power output in batteries and capacitors.
carries electrical currents. However, indium tin oxide is expensive and, as some iPhone and other touch-screen gadget users have experienced firsthand, is likely to shatter or crack upon impact (4). Replacing indium tin oxide with graphene-based compounds could allow for flexible, paper-thin computers and television screens. One researcher proposes the following scenario: “Imagine reading your Daily Mail on a sheet of electronic paper. Tapping a button on the corner could instantly update the contents or move to the next page. Once you’ve finished reading the paper, it could be folded up and used afresh tomorrow,” (4). Samsung has been one of the biggest investors in graphene research, and has already developed a 25-inch flexible touch screen that uses graphene. Companies like IBM and Nokia have followed suit. IBM recently created a 150-gigahertz (GHz) transistor; in comparison, the fastest comparable silicon device runs at about 40 GHz (3). Even though graphene-based technology is beginning to emerge, scientists are faced with a fair share of problems. One of the biggest issues for graphene researchers is the fact that graphene has no “band gap,” meaning that its conductive ability can’t be switched “on and off,” like that of silicon (2). For now, silicon and graphene operate in different domains, but as Nobel Prize winner professor Geim states, “It is a dream,” (3). There is good reason to believe that graphene research will be well worth the struggle. Most recently, researchers at the University of Manchester showed that 8
graphene is impermeable to everything but water. It is the perfect water filter. In an experiment, the researchers filled a metal container with a variety of liquids and gases and then covered it with a film of graphene oxide. Their most sensitive equipment was unable to register any molecules leaving the container except water vapor–even helium gas, a molecule that is particularly small and notoriously tricky to work with, was kept at bay (8). Dr. Rahul Nair, leader of this research project, claims that this ability is due to the fact that, “graphene oxide sheets arrange in such a way that between them there is room for exactly one layer of water molecules. If another atom or molecule tries the same trick, it finds that graphene capillaries either shrink in low humidity or get clogged with water molecules,” (8). It is hard to understate the importance of graphene oxide’s potential as an ideal filter, as it could quickly and inexpensively replenish rapidly decreasing clean water supplies. More powerful than a steel beam, tougher than a diamond, a better conductor than copper and the best water filter possible– these are but a few of what Nobel Prize winners Geim and Novoselov claim to be a “cornucopia of new physical and potential applications” of graphene (1). The potential uses of graphene are innumerable, and run the gamut from supercomputers that process at over 300 GHz to super-distilled vodka with zero percent water. Some have gone so far as to suggest iPhones that users can roll up and tuck behind their ears like a pencil, car tires
1. A.K. Geim, K.S. Novoselov, The rise of graphene. Nature Materials 6, 183-191 (2007). 2. M.J. Allen, V.C. Tung, R.B. Kaner, Honeycomb carbon: a review of graphene. Chem. Rev. 1, 132-145 (2010). 3. A. Hudson, Is graphene a miracle material? BBC News (2011). Available at http://news.bbc.co.uk/2/hi/ programmes/click_online/9491789.stm (May 2011). 4. D. Derbyshire, The wonder stuff that could change the world: graphene is so strong a sheet of it as thin as clingfilm could support an elephant. Daily Mail, Science & Tech (2010). Available at http:// www.dailymail.co.uk/sciencetech/article-2045825/ Graphene-strong-sheet-clingfilm-support-elephant. html (October 2011). 5. Graphene – the best electrical conductor known to man. AZOM (2008). Available at http://www.azom. com/news.aspx?newsID=11679 (March 2008). 6. G.E. Moore, Cramming more components onto integrated circuits. Electronics. 8, 4-7 (1965). 7. Graphene capacitors to increase power efficiency. Times of India (2012). Available at http://articles. timesofindia.indiatimes.com/2012-03-20/ infrastructure/31214537_1_graphene-capacitorselectrodes (March 2012). 8. S. Anthony, Graphene: the perfect water filter. ExtremeTech (2012). Available at http://www. extremetech.com/extreme/115909-graphene-theperfect-water-filter (January 2012).
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