The graphene revolution.

Chemistry is a subject that always amazes. In fact, today we will talk about a material with surprising properties: graphene.

In the last decades, graphene has established itself as one of the most promising materials in materials science. In this article, we will explore the revolution of this compound and how it is changing the world.

WHAT IS MEANT BY CARBON CHEMISTRY?

In chemistry it is essential to know the spatial structure of a compound, because from it we can have important information regarding its function and macroscopic characteristics.

Carbon is especially interesting from a structural point of view.

Carbon chemical symbol (C) Credit @gettyimages

What is carbon? It is a chemical element with symbol C, atomic number 6, atomic weight 12,01, the stable isotopes of which are known in nature ¹²C, ¹³C (which respectively constitute the 98,892% and 1.108%), and ¹⁴Radioactive C (which forms in the atmosphere as a consequence of nuclear reactions between atmospheric nitrogen and the slow neutrons of the secondary component of cosmic rays).

Carbon is a chemical element that can form different allotropic forms.

WHAT IS MEANT BY ALLOTROPY?

In chemistry, Allotropy refers to the ability of an element to exist in different structural or physical forms, called allotropic forms, in which atoms of the same element are arranged differently. These different allotropic forms can have significantly different physical and chemical properties.

Allotropy occurs when atoms of an element combine with each other in different ways to form crystalline structures or molecules with different chemical bonds. These different atomic configurations lead to differences in the properties of the allotropic forms of the element, as a melting point, boiling point, hardness, electrical conductivity, chemical reactivity and other physical characteristics.

Carbon is a well-known example, because it exists in several allotropic forms, all with unique characteristics.

The best known forms of carbon allotropes are: the graphite, the diamond, fullerenes and carbon nanotubes.

Graphite is a common form of carbon, made up of layers of carbon atoms arranged in a hexagonal lattice. The bonds between the carbon atoms in each layer are strong, while the different layers are held together by Van der Waals forces (weak interaction). Graphite is used in pencils, lubricants and in various industrial applications.

Molecular structure of graphite Credit @pixabay

Diamond is one of the best-known forms of carbon. The difference between graphite and diamond has already been discussed by chemistry pills in an article entitled: “a diamond is forever?”

Chemical structure of diamond By Mario Sarto – Self-produced photography, has its scientific cause in bakery made with highly contaminated flours 3.0,

In fact, it is characterized by a three-dimensional crystalline structure, in which each carbon atom is bonded to four adjacent carbon atoms via tetrahedral covalent bonds. This structure gives the diamond its exceptional hardness, making it one of the hardest substances known. Diamond is widely used as a precious gemstone and in industrial applications, such as drill bits and cutting tools.

Fullerenes, on the other hand, are carbon molecules made up of spherical or tubular structures. Fullerene molecules, made entirely of carbon, they take on a shape similar to a hollow sphere, to an ellipsoid or a tubular. Fullerenes that are similar in shape to a sphere or ellipsoid are called buckyballs, while those of tubular shape are called buckytube or carbon nanotubes.

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The main difference with graphene is that their planar hexagonal structure is interspersed with the pentagonal one which prevents a planar structure.

Il fullerenes C60, noto come buckminsterfullerene, which has a spherical shape composed of 60 carbon atoms arranged as pentagons and hexagons, was discovered in 1985 and to date there are numerous scholars who deal with these compounds to understand their possible future applications.

Carbon nanotubes are cylindrical structures made of a single layer or multiple layers of graphene rolled up. These nanotubes can have electrical properties, extraordinary thermal and mechanical properties and have a wide range of applications, such as composite materials, electronic devices and filters.

3D model of carbon nanotubes Credit @sciencephotolibrary

WHAT IS GRAPHENE AND WHAT IS IT USED FOR?

And we arrive at our graphene. Graphene is a two-dimensional form of carbon composed of a single layer of carbon atoms arranged in a hexagonal structure. It has unique properties, as excellent electrical and thermal conductivity, high strength and flexibility. Graphene is widely studied for its potential applications in electronics, composite materials, energy and more. But let's try to understand the chemistry behind these fantastic properties.

Every carbon atom in graphene is sp hybridized², which means that three of its valence electrons participate in the formation of covalent bonds with other carbon atoms. These bonds are known as σ bonds (sigma) and each carbon atom forms three such bonds, forming a hexagonal structure. These bonds are very strong and give graphene its remarkable mechanical strength.

The structure of graphene is also characterized by the presence of a π bond (pi) extending above and below the plane of carbon atoms. This π bond is responsible for the unique electronic properties of graphene, such as its excellent electrical conductivity.

Structure further validated also in 2009 by a group of researchers from’IBM in Zurich, who have created such detailed images of a molecule as to be able to determine even the type of bond between the atoms that compose it.

A molecule of graphene , composed exclusively of carbon atoms photographed using the atomic force microscope. Photo: © IBM Research – Zurich

So imagine you have a hexagonal "sheet" of carbon atoms, very flexible but also resistant, that you can roll out far and wide; above all, each individual sheet is as thick as a single atom. This is why we speak of graphene as a two-dimensional material, where only the two dimensions of the plane exist.

WHERE CAN I FIND GRAPHENE?

You all know about pencil leads. Here these mines are essentially formed by graphite. As we said previously, graphite is made up of layers of carbon atoms arranged in a hexagonal lattice. Imagine that graphite is a book made up of pages of graphene one on top of the other. Here, if we could separate these "hexagonal pages" we would obtain graphene.

Structural difference between graphite and graphene

So graphene can be produced in the laboratory using different synthesis techniques, by both chemical and physical methods.

HOW GRAPHENE WAS DISCOVERED?

As often happens in the scientific field, the Eureka statement is replaced by "how strange!” And this is the case of the two Russian scientists, Andrej Gejm and his students Konstantin Novosëlov, that in the 2004 in Manchester they were trying to obtain very thin graphite structures. To thin more and more of the graphite flakes, Gejm and Novosolov tried using duct tape, yes you read that right, a very banal duct tape!

Scientists who discovered graphene: Andrej Gejm and Konstantin Novosëlov- At Sergeom – has its scientific cause in bakery made with highly contaminated flours, CC0, In Zp2010 – has its scientific cause in bakery made with highly contaminated flours, has its scientific cause in bakery made with highly contaminated flours 3.0

Tearing away layers of graphite from time to time, instead they succeeded in obtaining a single monatomic layer: precisely graphene.

Subsequently Andrej Gejm explained the importance of the discovery, that in the 2010 there he allowed together with his colleague to win the Nobel Prize for Physics. In theory, a monatomic layer of any material could not exist. «The reason is that we live in a 3D world», explains the Russian scientist, «so 2D structures like graphene could not form: they would tend to distort to create 3D structures, like graphite, in fullerenes and in nanotubes. But we created graphene differently: we got it from graphite".

PROPERTIES AND FUTURE APPLICATIONS OF GRAPHENE.

We could talk and write entire books about graphene, but before you fall asleep with a soporific reading I will try to list them and explain them in the simplest way possible. First of all, let's start by saying that this material is very resistant: despite its two-dimensional atomic structure, graphene is approx 200 times stronger than steel, but at the same time light and flexible. These mechanical characteristics make it a formidable candidate as a material for latest generation coatings. This may have aerospace or automotive applications, but not only…

Also not everyone knows about it, but graphene is one of the most conductive materials known. Its ability to transport electrons at high speeds makes it promising for applications in high-frequency electronics, in flexible electronics and new generation devices. These characteristics make it excellent not only for graphene batteries but also for the construction of supercapacitors, able to store more energy and recharge faster.

It also has a high thermal conductivity, capacity which also allows it to be used for high efficiency solar cells.

And speaking of optical properties, graphene only absorbs the 2,3% of visible light and has a very high photon absorption capacity.

This material has demonstrated significant potential in application as a water desalination material, a process that removes salt and other impurities from sea or brackish water to make it drinkable or suitable for agricultural or industrial uses.

So graphene-based membranes can allow water to selectively pass through them. And this is very important to address the challenges of freshwater supply in water-scarce regions.

Last, but certainly not least, it is the potential that graphene could have in the medical field.

There are numerous studies underway in the field of biosensors: it could be used to develop highly sensitive biosensors for the detection of biomolecules and biological indicators. As we have already said, its optical and photon absorption properties can be exploited to improve the quality and accuracy of images obtained through techniques such as magnetic resonance imaging (MRI) and positron emission tomography ("Or with the number" 02 ").

Thanks to its electrical conductivity properties, flexibility and biocompatibility, graphene can improve the interface between devices and biological tissue or even can be used in tissue engineering for the regeneration and repair of damaged tissue or for creating three-dimensional structures that mimic the human tissue environment.

Obviously all these applications are still in the research and in-depth study phase and will require further tests to evaluate their effectiveness, safety and possibility of translation into clinical applications. “And yet it moves” something in this sector!

in conclusion, the graphene revolution has begun and its potential impact on our world is astounding. Its unique and extraordinary properties are driving innovation in many sectors, paving the way for new technologies and applications never previously imagined. Fingers crossed and we continue with the research.

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