Graphene

Graphen

Graphene visible

Nobelpriset i fysik 2010

Nobel Prize 2010-Press Conference KVA-DSC 8009

Carbon hybrid orbitals - from s+px,py,pz to sp²+pz

Graphene is a single layer (monolayer) of carbon atoms, tightly bound in a hexagonal honeycomb lattice. It is the basic structural element of other allotropes of carbon, such as graphite, carbon nanotubes, and fullerenes. It can also be considered as an indefinitely large aromatic molecule, the ultimate case of the family of flat polycyclic aromatic hydrocarbons.

Graphene has many extraordinary properties. It is about 200 times stronger than the strongest steel, conducts heat and electricity with great efficiency, and is nearly transparent. Researchers have identified the potential of graphene in various applications including semiconductors, energy generation, batteries, sensors, and medicine.

Properties

Graphene is the thinnest compound known to man at one atom thick, the lightest material known (with 1 square meter weighing around 0.77 milligrams), and also incredibly strong - approximately 200 times stronger than steel. With a tensile strength of 130 GPa (gigapascals), graphene is the strongest material ever tested. It conducts electricity much better than copper, is a perfect thermal conductor, and is impermeable to gases.

Despite its strength, graphene is very flexible and can be stretched up to 25% of its original length. Its high electron mobility is 100 times greater than that of silicon, which makes it a potential material for the electronics industry, especially for the development of fast, efficient semiconductors, transistors, and flexible displays.

Synthesis

Graphene can be produced by several methods. The most common include mechanical exfoliation, chemical vapor deposition (CVD), and chemical reduction of graphene oxide. Mechanical exfoliation, often referred to as the "Scotch tape" method, involves peeling layers off graphite to obtain layers of graphene. CVD growth of graphene on metal substrates like copper or nickel involves depositing gaseous reactants that form graphene on the substrate surface. Chemical reduction of graphene oxide is another method where graphene oxide is reduced to graphene by removing oxygen-containing groups.

Applications

The unique properties of graphene make it suitable for a wide range of applications:

- In electronics, graphene is used to develop faster, more efficient semiconductors and transistors. It is also being explored for use in flexible displays, touchscreens, and solar cells.

- Graphene's strength and flexibility are utilized in the development of new materials that are super strong yet lightweight, potentially revolutionizing the fields of construction, aerospace, and automotive industries.

- In energy storage and conversion, graphene is used to enhance the capacity and charge rates of batteries and supercapacitors. It is also being explored for use in fuel cells.

- The material's high surface area and conductivity make it an ideal candidate for various sensor applications, including those in biomedical research, environmental monitoring, and defense.

- In medicine, graphene is being studied for drug delivery, biomedical imaging, and as a material for developing bionic devices that can interface with biological tissues.

Challenges and Future Directions

While graphene has the potential to revolutionize many industries, there are still challenges to be overcome, particularly in terms of large-scale production and integration into existing technologies. The development of cost-effective and efficient methods for producing high-quality graphene is an area of ongoing research. Additionally, understanding the environmental and health impacts of graphene is crucial as its applications become more widespread.

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