About graphene
What is Graphene? It is a single layer of carbon atoms arranged in a hexagonal lattice. Graphene was first isolated in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester, and they were awarded the Nobel Prize in Physics in 2010 for their work.
Graphene is a truly remarkable material with several exceptional properties, including:
High electrical conductivity: Graphene is an excellent conductor of electricity, with conductivity about 100 times greater than that of copper. This means that graphene can be used to create highly efficient transistors and other electronic devices. The carbon atoms in graphene are all bonded to each other through sp2 bonds, sharing three electrons. This leaves one electron free to move throughout the material, resulting in high electrical conductivity. With graphene, a moiré pattern can be formed by the overlap of two graphene layers at a small angle. The pattern is then visible as a pattern of dark and light lines or stripes. The size and shape of the pattern depend on the angle between the two layers and the distance between them. These patterns can be used to investigate a wide range of graphene properties, such as electrical conductivity, mechanical properties, and optical properties. They are also used to develop new graphene-based materials and devices.
High thermal conductivity: Graphene is also an excellent conductor of heat, with a thermal conductivity about 5 times greater than that of copper. This means that graphene can be used to create highly efficient heat dissipators and thermal interface materials, as exemplified by the following:
Thermal management: Graphene can be used to provide highly efficient heat dissipation in electronic devices and other applications.
Energy storage: Graphene can be used to create supercapacitors that can store more energy than traditional supercapacitors.
Sensors: Graphene can be used to create sensors that are highly sensitive to a wide range of stimuli.
Composites: Graphene can be added to other materials to make them stronger, lighter, and more thermally conductive.
Biomedical devices: Graphene can be used to create biomedical devices such as implants and sensors.
High mechanical strength: Graphene is the strongest material known, with a tensile strength of 130 GPa, approximately 200 times greater than that of steel. This means that graphene can be used to create very strong and lightweight composites. This can be applied in aerospace, construction, and other industries. Graphene can also be used to create protective coatings that are highly resistant to damage. For example, this can be applied in the automotive industry, construction, and other industries. Due to its biocompatibility, graphene can also be used to create medical devices that are both strong and lightweight. This can be applied in implants, prosthetics, and other medical devices.
High flexibility: Graphene is also highly flexible and can be stretched up to 20% of its original length without breaking. This means that graphene can be used to create highly flexible electronic devices and composites.
High transparency: Graphene is also highly transparent, with a transmission of approximately 97%. This means that graphene can be used to create highly transparent electronic devices and composites.
In addition to these exceptional properties, graphene also has several other potential benefits, including:
Chemical inertness: Graphene is chemically inert, which means it is not easily corroded or damaged by chemicals. This makes graphene a promising material for use in various applications where corrosion resistance is important.
Biocompatibility: Graphene is biocompatible, meaning it is not toxic to living cells. This makes graphene a promising material for use in biomedical applications, such as implants and sensors.
Scalability: Graphene can be produced in large quantities, making it a scalable material for industrial applications.
The theoretical background of graphene can be traced back to the early 1960s when P.R. Wallace first predicted that a two-dimensional layer of carbon atoms would be a high electrical conductivity semiconductor. However, it was not until the early 2000s that graphene was actually isolated and characterized.
Graphene was first isolated in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester. They used a tape method to isolate graphene from graphite by repeatedly peeling off layers. The tape method is a simple but labor-intensive way to isolate graphene, resulting in graphene membranes with a high number of defects. These defects can affect the properties of graphene, such as electrical conductivity, mechanical strength, and optical properties. Some of the most common defects in graphene include:
Folds: Folds can be caused by various factors such as mechanical damage, chemical treatment, and exposure to high temperatures. Folds can reduce the electrical conductivity and mechanical strength of graphene.
Holes: Holes can be caused by various factors such as mechanical damage, chemical treatment, and exposure to high temperatures. Holes can reduce the electrical conductivity and mechanical strength of graphene.
Contamination: Contamination can be caused by various factors such as exposure to air, water, and other chemicals. Contamination can reduce the electrical conductivity and mechanical strength of graphene.
More or fewer layers: Graphene can also exist in the form of multilayer membranes, which have lower electrical conductivity and mechanical strength compared to monolayers.
In recent years, several new methods have been developed to isolate graphene. These methods result in graphene membranes with lower defect density, improving the properties of graphene. One of the most promising new methods is the chemical vapor deposition (CVD) process. The CVD process involves the formation of graphene on a substrate by reacting carbon monoxide with hydrogen at high temperature and pressure. The CVD process leads to graphene membranes with very low defect density, resulting in much better graphene properties than membranes isolated using the tape method.
The flash method is a new process for making graphene. Graphite is rapidly heated to a high temperature, causing the layers of graphene to separate and rise as a gas. The gas is then cooled, causing the layers of graphene to come together and form graphene. This is a very promising method as it is highly efficient and leads to graphene of very high quality.
The exceptional properties and potential benefits of graphene make it a highly promising material for a wide range of applications. As research on graphene continues, we can expect even more innovative and groundbreaking applications of this amazing material in the coming years. Many of the possibilities of graphene have not even been invented or imagined yet.
