Saturday - Mar 23, 2019

What is Graphene?


In 2004, news started emerging of a unique substance which has grown to become a wonder that is now revolutionizing the science of matter. It was graphene, a two dimensional sheet that is formed when carbon bonds to three other carbon atoms. Normally when carbon bonds to four other atoms it forms diamond, which is what we are used to. So the difference between graphene and diamond lies in the number of atoms involved in the bonding. To get a picture of how this two dimensional sheet would like, think of a sheet of paper-it has two dimensions.

Graphene is considered the thinnest and lightest carbon compound that man has ever discovered, 100 times stronger than structural steel. It was produced for the first time in a lab in 2004 and it is a great conductor of both heat and electricity. It is actually better than silver and steel in conductivity. We might as well say that silicon is for once facing stiff competition in the optic and photonic industry.

In deeper terms, Graphene is a crystalline carbon allotrope structured in regular sp2 hexagonal bonds. These bonds are what make it stronger than the more regular metals we know. Both graphite and charcoal bear the basic structure of graphene and it is no wonder that they are both very light.

How Graphene came into being

Just like many other useful compounds that man stumbled upon, the discovery of Graphene was merely an accident. The first contact with Graphene was in 1859 by B.C. Brodie, a professor at the University of Oxford who had developed a lot of interest in Graphite. He had noticed that graphite was unique to other compounds in many ways and wanted to solve the puzzle of ‘why’. However, he faced a challenge in that graphite does not react even with the most potent oxidizers.

Nevertheless, Brodie used very strong reagents like potassium chlorate and steaming nitric acid. After heating the mixture, he noticed that his product had small flaky-like crystals. This was Graphene as it came to be named by latter scientists after a dormant period of 150 years. Brodie was never successful with his experiments since he could not come up with a safe and efficient way to oxidize graphite. The project stalled until 1957 when two scientists decided to continue solving Brodie’s puzzle.

The interest in Graphene was rekindled in 1957 by W. Hummers and R. Offeman. Building on Brodie’s experiments, these two scientists were able to safely and efficiently oxidize graphite. They used strong oxidizers like potassium permanganate, sodium nitrate and sulphuric acid. This method was efficient enough to produce an oxidation ratio of 2.1 carbon atoms to 1 oxygen atom. The successive scientists continued to use this method until 2004 when pure graphene was created in a lab by a team of scientists led by Andre Geim from the University of Manchester. The research is still on and the future will see more uses of this extraordinary carbon compound.

The unique properties of graphene

Graphene has many fascinating properties just like the single-dimension of carbon nanotubes (CNTs) we already know. The first notable property is the ability to conduct electricity. Electrons are able to move at high speed in graphene to an extent that this phenomenon can only be defined by the principle of relativity and not classical physics. What is abnormal about this conductivity is the fact that very minimal loss of energy occurs. In the future, graphene will be the undisputed nanoscale electronic conductor. With the amount of research going into graphene, better electronic days are just around the bend.

A lot of research has found graphene to possess extraordinary optical nonlinear characteristics. This is good news for optical connections and the almost zero-power photonic ICs (integrated circuits). Scientists have been able to use the one-atom compound to generate microwave photonic signals that can be converted into telecommunication waves. Thanks to this graphene property, a hybrid of graphene and silicon photonic chip that is power efficient, faster for modern and the future telecommunication has already been developed and tested. It is only about time that this creation hits the mass market and both optical and photonic fields are revolutionized.

The other outstanding property of graphene is its intrinsic strength. Thanks to the 0.142 Nm carbon bonds, this compound is the strongest ever (130 gigapascals as compared to 0.4 gigapascals of structural steel) in man’s history. In addition to this inherent strength, graphene is very elastic and can retain its original dimensions even after a rigorous strain.

Some of the applications that will use graphene

Graphene is a unique compound that is going to have a lot of use in the future. Some of the applications that will certainly take advantage of graphene's super properties include:

  • Solar cells: currently indium selenide is being used in solar cells. But it is expensive and gives low efficiency rates. Graphene will be much cheaper and efficient.
  • Cell phones will be integrated into our cloths, papers and house windows. The touch screen on smartphones will soon be made from graphene. These screens will be more sensitive to touch and hard to break even when smashed.
  • Disease diagnostic sensors: this will take advantage of large surface area and the presence of disease sensitive molecules in graphene.
  • Higher frequency transistors: electrons move at a higher speed in graphene than silicon. Scientists are busy developing ICs from graphene.

The future and challenges of graphene

Applications using graphene will hit the market and we will love them.  Silicon has been better but graphene will take its place thanks to its superior properties. However, the future of graphene is faced with a number of challenges.

The first challenge is informed by the way graphene is developed as a compound. Scientists are still using the Scotch Tape Technique to generate graphene. The first time this method was used, the quantities produced were considerable in that era. Today, the same method is being used with no improvement in the quantity of the product.

The other challenge lies in the one-atom structure of graphene. Anything done on this product is going to affect its properties. Researchers are yet to find ways that graphene can be gently handled without interfering with its delicate formula.

Challenges withstanding, there is every sign that graphene will soon disrupt the industry.  When and how is definitely a matter of time. What we know for fact is that there has been nothing stronger, thinner and more efficient as a conductor than graphene.