What is Graphene?
Graphene is and
allotrope of carbon. Carbon the basis of life, fossil fuels and some of its
structures form some of the strongest compounds in the universe such as
diamond. Graphene has exactly the same structure and bonding as graphite,
however it differs in one key aspect. Graphite is made up of several layers
that are held together by a weak intermolecular force called Van Der Waals
forces whereas graphene has only one layer. The bonding is exactly the same as
graphite; each carbon atom is covalently bonded to 3 other carbon atoms to form
a hexagonal lattice. How to Make Graphene
Graphene is made by using a process called mechanical
exfoliation which, this may sound crazy but, literally involves using adhesive
tape to remove layers off a graphite block and slowly as the block becomes
thinner and thinner until you are left with a single layer which is graphene,
however to remove the flakes off the tape they dissolved the tape in acetone
and after a couple of other processes, the single layer graphene sheet was
sedimented on a silicon wafer. There are a few other methods such as epitaxial
growth on silicon carbide and metal substrates. Growing graphene on silicon
carbide involves heating it to temperatures over 1100°C and on the surface of the
carbide a sheet of graphene will form on the surface of the carbide. It is a
similar process when using metal substrates. There are also several other
methods such as the reduction of graphite or carbon dioxide or even cutting
open nanotubes.
What is So Special about Graphene?
Since testing with graphene has begun scientists have be discovering several unusual properties that it has. Graphene has been shown to be more than 200 times stronger than steel and has a tensile modulus of 1 TPa which is equivalent to 150,000,000 pounds per square inch, whereas steel has a tensile modulus of 104,400 pounds per square inch. Graphene is also a lot lighter, harder, stronger and more flexible than steel and is also much more cost effective and it is also eco-friendly. It is a perfect material to be used in manufacture of planes and other vehicles; it is much lighter and stronger than most of the materials used at the moment, such as steel, aluminium and fibre glass. It is much more cost effective because it will save fuel because of its weight and also it will create less pollution and therefore will be cheaper to run; also it is much more ecologically sustainable.
Another astonishing property of graphene is that it has no band gap which means that it can absorb light with any frequency, this is a very useful property when trying to create photovoltaic cells also known as solar cells, this is also a very helpful in out fight against global warming and finding a more sustainable fuel source.
Graphene has another very intriguing property due to its
hexagonal lattice. It can conduct electron at room temperature with almost no
resistance this is because its mean free path is bigger than its dimensions.
This is very similar to superconductivity however at room temperature.
Graphene has some other physical properties such as it is transparent however if you put it on a completely blank piece then you can just about see it, astonishingly this means that you can see a single layer of atoms. Also it is rather elastic and can stretch up to 20% of its original length.
Graphene has broken both the records for thermal and electrical conductivity. It is a 1,000,000 times more conductive than copper and conducts electricity in the limit of no electrons; it carries electricity with more precision and efficiency than any other material ever discovered. Also diamond is a very good conductor of thermal energy however graphene has been proven to be a better conduct of heat than diamond and now
holds the record for the best heat conductor.
And finally, graphene is impermeable, not even a helium atom can pass through its lattice and so is very good at containing even gasses, and when these gasses get caught in its lattice they change its electrical properties, this makes it perfect for creating sensors to detect even the smallest gas leaks.
What can it Be Used For?
Graphene is an amazing material with amazing properties but what are its uses? As I have already mentioned graphene could be used in sensors and be used to find dangerous molecules. It can also be used to create better solar cells and stronger wind turbines and this will lead to a more green way of living. Also because of the strength and light weight of graphene, it can be used to make stronger and lighter implants such as the hip or shoulder. And because of it electrical properties it could possibly be used to create super capacitors and in high powered electronic devices, and will be a very useful tool in advancing touchscreen and TV technology. IBM has already made a 100GHz transistor out of graphene and has promised a 1THz processor soon.
Graphene is a very useful material with several possible uses and will become very common in some of the technology we use every day, this is one material that you will be seeing a lot of in coming years.
