Graphene is a material produced from graphite. Its incredible physical properties make it a material with several technological applications.
Graphene is a material composed of a thin layer of graphite, and since its discovery, it has attracted the attention of scientists and the technology industry due to its unique properties and potential applications.
But why is this material so revolutionary?
1. Graphene is the most conductive material in the world
One of the characteristics that promises to change the tech industry is graphene’s high conductivity.
Electrons move through graphene with virtually no resistance. This makes it transport electricity more quickly, efficiently, and accurately than any other material.
The University of California has already proven that it is possible to create graphene cell phone batteries that charge in just 5 seconds and that can last for an entire week.
2. Graphene is one atom thick
According to Rive University in Texas, even though graphene is only one atom thick – the thinnest material known – it is still visible.
Graphene is incredibly transparent, absorbing only 2.3% of the light, however, if you place it on top of a sheet of paper, you will be able to see it.
3. Graphene is 200 times stronger than steel
Despite being thin and light, graphene is an extremely strong material – it is the strongest material known to exist, surpassing even diamond.
Just to give you an idea, a graphene sheet of 1 square meter weighs only 0.0077 grams, however, it is capable of supporting the weight of up to 4 kilograms.
4. Flexibility, transparency and impermeability
Even though it is very rigid, graphene has great elasticity, stretching up to 25% of its length.
According to Dr. Ponomarenko, one of the scientists studying this material, graphene is also the most impermeable material ever discovered, and even atoms of helium (the second smallest element) cannot pass through it.
5. Graphene is a two-dimensional material
The characteristics of graphene are very different from graphite, which is the three-dimensional version of carbon, and studying graphene helps us to predict how other materials would behave in a two-dimensional way.
However, the most intriguing was the way that physicists Andre Geim and Konstantin Novoselov arrived at this two-dimensional shape in an experiment in 2004.
They used a tape to peel off a layer of graphite from a piece of pure graphite. They repeated this several times, removing several layers, until it was only one atom thick.
Now that you know why this material has the potential to revolutionize the technologies of the future, check out some frequently asked questions about graphene.
Who discovered graphene?
Stable, two-dimensional graphene was discovered accidentally in 2004 by Russian physicists Andre Geim and Konstantin Novoselov. This discovery earned them, in 2010, the Nobel Prize in Physics. The existence of this carbon allotrope, however, has been known since 1930.
How much does it cost?
The price of graphene is still high because it is difficult to produce it in significant amounts. Current techniques that allow the production of pure and thin layers of this material work with the deposition of steam on metallic substrates, such as copper sheets.
Currently, a 5.08 cm by 2.54 cm graphene sheet, about 12.9 cm², can cost up to 275 dollars: an average of 21 dollars per square centimeter. However, factors such as impurities and asymmetries can drastically reduce this price.
Another way to obtain graphene is from graphite: with 1 kilogram of graphite, which costs around 1 dollar, it is possible to produce up to 150 grams of graphene, whose value exceeds 15 thousand dollars.
Where can we find it?
Despite being an allotrope of carbon, like graphite and diamond, graphene can’t be found in nature in its two-dimensional configuration, that is, containing only one atom in thickness.
In its two-dimensional form, graphene has its chemical stability drastically reduced, despite acquiring physical and chemical properties that make it an excellent conductor of heat and electricity and the most resistant material known.
For this reason, in nature, the occurrence of multilayer graphene is more common, which is much less interesting for technological applications.
What is the composition of graphene?
Graphene is composed of carbon atoms linked in hexagonal crystalline structures through sp2 bonds. These bonds are repeated along a two-dimensional plane, only one atom high.
What can we do with graphene?
Graphene is one of the most promising materials today. Its technological applications are vast and are limited to the production capacity of this material on large scales.
Devices such as foldable LED screens, photovoltaic cells (solar panels), tougher touch screens, more efficient transistors, supercapacitors, heat sinks, and cellphone super batteries are some examples of technologies possible through the application of graphene.
Recently, a student at the California State University, showed that, by charging a graphene disk for two seconds, it is possible to keep an LED on for up to 5 minutes.
Graphene is the most resistant material known to exist, being able to withstand pressures of up to 130 gigapascals (130,109 Pa).
Such resistance stems from the strong chemical bonds between its carbon atoms. Materials widely used in civil construction, such as steel, withstand only a third of this pressure.
Another interesting property of graphene is its high Young’s modulus, indicating that, in addition to being resistant, this material is very elastic and, therefore, returns to its original size with relative ease.
The small areas of each carbon hexagon are responsible for the high impermeability of graphene, which can be used as a small net capable of holding gases that leak very easily from their containers.
In addition to being extremely resistant, graphene is very light: its density is 0.77 g/m², about a thousand times lighter than a sheet of paper.
Electrons can propagate in graphene almost freely without deviating or colliding. Due to the hexagonal structure of the carbon bonds, electrons move within these thin layers at relativistic speeds, close to the speed of light.
At room temperature, the electrical resistivity of graphene is the lowest we know, about 10-6 Ω.m, less than the resistivity of silver, the best-known metallic conductor.
Despite being a layer of carbons with a thickness of a single atom, graphene is visible to the naked eye, since it allows 97% to 98% of the incident light to pass through.
This optical behavior arises from the relativistic properties of electrons in graphene. This implies that, by stacking several sheets of graphene, it is possible to produce a perfectly black object, capable of absorbing almost all the radiation incident on it.
Because of its electronic properties, graphene is an excellent thermal conductor. This material is capable of dissipating heat faster than any other known material. In addition, some studies suggest that its melting temperature is 4125 K, about 3851°C.