Geography | Insight | 13.....
GRAPHANE: THE POTENTIAL OF GRAPHENE’S YOUNGER BROTHER Shihaab Nawab Many of may have heard of the material Graphene: the material made of carbon that has been hailed as a ‘wonder material’ by some due to its various properties. For those who don’t know what it is, I’ll briefly explain: Graphene is an allotrope of carbon. Allotropes are different physical forms of an element, meaning that whilst they may all contain the same element, in this case carbon, they have different molecular structures. Other allotropes of carbon include diamond and graphite. Graphene has a very similar structure to graphite, meaning that it is comprised of carbon in a honeycomb-like structure. But unlike graphite, graphene is only a single layer thick. This makes it an extremely lightweight material, whilst staying strong and flexible, due to it being held together purely by covalent bonds. As well as this, it has an extremely low resistivity, as its electrons can move very freely throughout the structure, making it one of the best electrical conductors at room temperature known to man. It is these properties that make it show great promise for use in semiconductors in place of elements such as silicon in microchips and other electrical applications. However, graphene’s ability to conduct electricity can actually pose a problem: it conducts it almost too well. This means that
it is extremely difficult to make components such as transistors out of graphene as once it starts conducting, it is virtually impossible to ‘switch off’, meaning that they can’t really be used in circuits safely or effectively as of yet. In the search for a solution to this problem, scientists have managed to create another carbon based material: graphane. Graphane is a material which has exactly the same structure as graphene, except both sides of the carbon sheet have had hydrogen added to them (through a process known as hydrogenation). These hydrogen atoms bond to the free electrons in the graphene sheet, preventing them from moving freely throughout the structure. This means that whilst it completely loses the conductivity that graphene has, it retains the strength and lightweight nature of its older brother. This opens up a wide range of potential applications for a material like this. A very important one is its potential use in graphene based circuits. In circuits, graphene is used in very small strips, made by taking a sheet of graphene and then burning off large amounts of excess graphene until they are in the desired shape. Hydrogenating these excess areas to produce graphane provides a less wasteful alternative whilst achieving the same result, as electricity can conduct along
the graphene strips, without the risk of conducting along the graphane areas. Graphane itself also has potential for conducting electricity. Researchers at Rice University, Texas have discovered that by strategically removing hydrogen atoms from the graphane sheet it gains semi-conductive properties which are far more useful in circuits and semiconductors than pure graphene as it has fewer free-moving electrons, giving it potential to act as a substitute for silicon in such applications. These applications are only the beginning. Graphane is a relatively recent discovery, and so little research has gone into its full capabilities and its potential applications, though many see the potential it has as both an insulator and a semiconductor. Aside from its conductivity, scientists are also starting to look at how its strength and small mass can be used, as graphane is said to be as much as 1000 times stronger than steel. The discovery of graphane has also raised questions about other modifications to graphene, such as what would happen if we were to replace the hydrogen in graphane with an element like fluorine. There is so much more to learn about graphane before we can widely use it to its full effectiveness. Will we ever see it become widely used in our lifetimes? Only time will tell.