Brazil has the largest graphene reserves in the world.
What is Graphene?
Graphene is the thinnest material in the world. It consists of a two-dimensional layer of carbon atoms arranged in hexagonal structures, the height of which is equivalent to that of an atom. This material can be produced by extracting surface layers of graphite, an abundant mineral on Earth and one of the most common allotropes of carbon.
The chemical bonds formed between carbon atoms and the thickness of graphene make this element record-breaking in some physical properties, such as mechanical resistance, thermal and electrical conductivity. These characteristics make graphene one of the most promising materials and can be used in a wide variety of applications.
What makes graphene special?
Graphene has incredible physical properties that make it a material with diverse technological applications. Know some properties that make this allotrope so special.
Graphene is the strongest material ever known, being able to withstand pressures of up to 130 gigapascals (130,109 Pa). Such resistance stems from the strong chemical bonds formed between its carbon atoms. Materials widely used in civil construction, such as steel, support 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 quite elastic and therefore returns to its original size relatively easily.
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, such as hydrogen gas. 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 suffering detours or collisions. Due to the hexagonal structure of 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, around 10-6 Ω.m, lower than the resistivity of silver, the best known metallic conductor.
Despite being a layer of carbons with the height of a single atom, graphene is visible to the naked eye, as it allows the passage of 97% to 98% of incident light. 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 body, capable of absorbing almost all the radiation incident on it.
Due to its electronic properties, graphene is an excellent thermal conductor. This material is able to dissipate heat faster than any other material known. Furthermore, some studies suggest that its melting temperature is 4125 K, about 3851°C.
Who discovered graphene?
Stable, two-dimensional graphene was accidentally discovered in 2004 by Russian physicists André Geim and Konstantin Novoselov. This discovery guaranteed the researchers the Nobel Prize in Physics in 2010. The existence of this allotrope of carbon, however, had been known since the 1930s.
What is the price of graphene?
The price of graphene is still high due to its complex means of obtaining it. The most current techniques that allow the production of pure and thin layers of this material work with vapor deposition on metallic substrates, such as copper sheets.
Currently, a sheet of graphene measuring 5.08 cm by 2.54 cm, about 12.9 cm², can cost up to $275: an average of $21 per square centimeter. However, factors such as impurities and asymmetries can drastically reduce this price.
Another way of obtaining graphene is from graphite: with 1 kg of graphite, which costs around 1 dollar, it is possible to produce up to 150 g of graphene, whose value exceeds 15 thousand dollars¹.
Where do we find graphene?
Despite being an allotrope of carbon, like graphite and diamond, graphene is not found in nature in its two-dimensional configuration, that is, containing only one atom in height.
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 electric current and the most resistant material ever known. Thus, in nature, the occurrence of multilayer graphene is privileged, 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 repeat along a two-dimensional plane, only one atom high.
What can you do with graphene?
Graphene is one of the most promising materials known. 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), more resistant touch screens, more efficient transistors, supercapacitors, heat sinks and cell phone superbatteries are some examples of technologies possible through the application of graphene. Recently, a student at the University of California State showed that, by subjecting a graphene disc to an electric charge for two seconds, it is possible to keep an LED on for up to 5 minutes.
Graphene in Brazil
Brazil is in the technological race in search of cheaper and more efficient methods for the production of graphene. According to a report produced in 2012 by the National Department of Mineral Production (DNPM), in a few years, the graphene market should be one of the most profitable in the world, with the potential to reach up to 1 trillion dollars in 10 years. In addition, Brazil has the largest graphene reserves in the world.