By Aida Rafat

23 May 2016 - 14:55

'Every person who's ever drawn with a pencil has created graphene' Photo (c) Vladimer Shioshvili, licensed under CC BY-SA 2.0 and adapted from the original.
'Every person who's ever drawn with a pencil has created graphene' Photo ©

Vladimer Shioshvili, licensed under CC BY-SA 2.0 and adapted from the original.

Imagine a material that is stronger than steel, more transparent than glass, and thinner than a human hair. Hint: it's not kryptonite. Aida Rafat, an assistant engineer at ConocoPhillips who won the Qatar final of our international science communication competition FameLab, explains.

What is graphene?

It's the most extraordinary material that, in theory, should be science fiction. It has countless applications and phenomenal properties, and has got scientists very excited.

This two-dimensional wonder substance comes from a simple source. Graphene is the basic building block of graphite, a fundamental form of carbon and an abundant mineral. Graphite is made of thousands of layers of graphene that are stacked on top of each other. We're familiar with it as pencil lead. So technically, every person who's ever drawn a line with a pencil has made graphene.

How did scientists discover it?

By accident. And it was all thanks to sticky tape. Back in 2004, two researchers from the University of Manchester, Andre Geim and Kostantin Novoselov, were working in the lab. They were investigating the electrical properties of graphite, and decided to use adhesive tape to see if they could peel off thinner flakes. They continued to peel off more and more layers from the original cleaved flake of graphite, until they realised that they had ended up with a layer that was a single atom thick. What they had created was graphene, and they later won the 2010 Nobel Prize in physics for their discovery.

What makes graphene so special? 

Graphene has amazing and unique mechanical, electrical, thermal and optical properties.

First, it's strong. People used to think that two-dimensional materials would just fall apart. But in fact, graphene is the strongest material that has ever been tested: about 200 times stronger than steel. A hammock made of one square meter of graphene would support the weight of a chunky four-kilo cat, but would weigh only as much as one of the cat's whiskers at 0.77 mg (about 100,000 times lighter than one square metre of paper).

Second, despite its tremendous strength, graphene retains flexibility and elasticity. You can bend it, and it's transparent: both very important features in electronics, as it means that you could use it to make bendable, transparent touch screens for computers and mobile devices.

Third, it conducts electricity brilliantly. In fact, electrons move faster through graphene than through any other tested material. Scientists can 'dope' graphene by chemically adding or removing electrons to it. The more electrons added to it, the more current it can produce. 'Doped' graphene could be even better at conducting electricity than copper.

Fourth, graphene is super-impermeable, so even the tiniest molecules like helium can't get into it. This could be a very important feature, as it would allow us to use graphene to separate liquid and gas.

What is different about the structure of graphene?

Graphene has a very unique structure, like a honeycomb lattice of carbon atoms. What's unusual is how these atoms interact with each other.

A carbon atom has six electrons, of which four sit at its outer shell, ready to bond with other atoms to form molecules. But in graphene, only three of these electrons tightly bond to the neighbouring atoms, creating an extremely strong and tight bond. The fourth electron remains unbonded. These unbonded electrons behave very differently from usual. They act like particles of light, or photons, and actually move at the speed of light above the graphene sheet, giving graphene its phenomenal electrical properties.

What does graphene look like?

We can't see graphene with the naked eye. It is the thinnest material ever discovered. A sheet of graphene is 1,000 times thinner than a human hair. In fact, the scientists who discovered it were only able to see the graphene flakes because they had placed them on a wafer of silicon oxide. If they had used another material, they might not have even seen it.

Is graphene already being used for anything?

Many big companies, such as IBM and Samsung, are closely investigating graphene. One of the main challenges facing the electronics industry right now is that we're pushing the limits of silicon transistors (which amplify and conduct electrical signals). In other words, how can we make smaller and smaller silicon transistors, so companies can produce thinner, yet more powerful smart phones, tablets and computers?

The problem is that we have already reached the limit of what we can do with silicon transistors. We just can't make them any smaller. However, with graphene, there is great potential to go further, and even to make transparent touch screens and electronics.

It's not just computers. One of the current commercial applications to incorporate graphene is a tennis racket from a company called HEAD. The racket seems to be much more powerful and much lighter – two essential things to have in an ideal tennis racket!

What else could graphene be used for in the future?

The transport industry could mix graphene with an existing composite material, to make stronger, lighter aircraft and cars. Because of its impermeability, graphene would also make an excellent coating material to resist corrosion.

Put a coat of graphene on plastic, and you have an electrically conductive plastic. Or an electronics company could take advantage of graphene's flexibility and use it to make a tablet that you could fold like a newspaper, or a tiny smart phone that you could stick to your t-shirt.

Graphene can dramatically improve the lifetime of a traditional lithium battery, shrinking the charging time significantly. It can be used to store solar energy, or to make supercapacitors (giant batteries used in electric cars and lifts).

Scientists are also talking about using graphene filters for desalination, to turn seawater into drinking water, and as a drug delivery system for cancer treatment.

Is graphene patented?

Graphene patenting is one of the most hotly debated topics in science. Graphene itself cannot be patented, as it's derived from carbon - a naturally occurring material. What's more, scientists have known about graphene since the 20th century, they just didn't know how to isolate it.

However, many organisations have patented graphene devices and processes to produce graphene. I don't know whether the two scientists who discovered graphene became rich as a result. But they did become extremely famous, and won the Nobel Prize. Their scientific paper about the groundbreaking discovery of graphene was eventually published in Science, and the paper itself was listed in the top 100 most cited papers of all time. This is an achievement every scientific researcher dreams about.

Aida Rafat is Assitant Engineer at ConocoPhillips. You can watch her compete in the international FameLab finals on 8-9 June 2016. 

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