Overview
Graphene is a two-dimensional solid consisting of hexagonally arranged intertwined carbon atoms. Perhaps it can best be imagined as a very small material similar to chicken-wire. In organic chemistry, the term aromatic refers to substances related to the benzene compound, which consists of a ring of six carbon atoms that are joined together, each with single hydrogen attached to it. However, graphene does not contain hydrogen; it is composed entirely of six-carbon rings. Graphene is the fundamental component of many natural and synthetic materials, such as graphite, charcoal, nanotubes, and fullerenes.
Etymology
“Graphene” is a combination of “graphite” and suffix -ene, named after Hanns-Peter Boehm, who in 1962 described carbon single-layer foils.
The term graphene first appeared in 1987 to describe single sheets of graphite as a constituent of intercalating graphite compounds (GICs); conceptually a GIC is an intercalant and graphene crystalline salt. Early mentions of carbon nanotubes, as well as epitaxial graphene and polycyclic aromatic hydrocarbons, have used the word.
Discovery/History
Graphene was first discovered by two Russian-born researchers at Manchester University, England, Andre Geim (1958-) and Konstantin Novoselov (1974-), in 2004. For their work, the two men received the Nobel Prize in Physics in 2010. Geim and Novoselov first isolated graphene by placing a strip of adhesive tape on top of a graphite piece and then removing the tape slowly. Single layers of carbon atoms — graphene layers — stuck to the tape as they did, from which they could be removed and studied later. The two physicists then determined how many physical properties the new material would have to have.
After its discovery in 2004, interest in graphene quickly grew. Not only have scientists learned much more about the physical properties of the substances, but they have also learned how to grow the material by synthetic means, rather than collecting it from products like graphite and charcoal.
Before the graphene monolayer was isolated in 2004, it was theoretically believed that, when separated, two-dimensional compounds could not exist because of thermal instability. Once graphene was isolated, however, it became clear that it was actually possible and it took some time for scientists to find out exactly how. After studying transmission electron microscopy of suspended graphene sheets, scientists believed that they found the reason to be due to slight rippling in the graphene, modifying the material structure.
▲(Collecting graphene with strips of tape, “Graphene.”[2])
Properties
Graphene excitement is in large measure based on its unusual physical properties. It is probably the most potent material ever discovered in the first place. As one Columbia University researcher has said, “It will take an elephant, perched on a knife, to crack the thickness of Saran Wrap across a layer of graphene.” Graphene is also an outstanding semiconductor, a substance that conducts electricity better than a non-conductor (like wood), but not as a conductor (like copper metal). As such, graphene has many potential applications in the field of electronics, where semiconductors are essential to a device’s operations. Graphene is therefore nearly entirely invisible to light. It absorbs just over two percent of the light that falls on it, which means that approximately 98 percent of the light passes through.
Applications
Electronics
A small transistor made by the Manchester researchers in 2008 that was only one atom thick and 10 atoms wide is an example of its use in electronic devices. This dimension of electronic devices can provide a response to the ongoing challenge that engineers face in making every smaller and smaller computer component. A transistor is an electronic solid-state device used to control the flow of an electric current. A typical transistor looks like a sandwich with one type of semiconductor as the bread slices and the second type as the filling.
▲(Transistor using graphene, “Transistor.” [1])
Graphene can also be used in storage systems for super-small files. For this reason, some researchers have already built super-miniature cable systems to connect graphene devices.
Plastics
Graphene may also be the key to plastics conduction development. Normally, plastics do not conduct an electrical current and are commonly used in electrical devices as an insulating material. But plastics’ flexibility makes them a promising material for specialist types of lightweight electrical devices. Embedding graphene in plastic can allow batteries and other electrical devices to be developed that do conduct electricity well but are flexible and lightweight. Other products may depend on combining two of the most important properties of graphene: Light transparency and electrical conductivity. For instance, solar cells that contain graphene units could be thinner, lighter, and more efficient in capturing and converting solar energy into electricity.
Thermal Management
Some of the future graphene-enabled thermal management applications include electronics, which could benefit greatly from the ability of graphene to dissipate heat and improve electronic operation. In micro- and nano-electronics heat is also a limiting factor for components that are smaller and more effective. Graphene and related materials with extraordinary thermal conductivity will also hold tremendous promise for this form of use. The heat conductivity of graphene can be used in many ways, including thermal interface materials (TIM), heat spreaders, thermal greases (thin layers usually between a heat source like a microprocessor and a heat sink), graphene-based nanocomposites, and more. (Applied in CPU cooling Systems)
In October 2018, Huawei revealed its Mate 20 X mobile, a gaming device that has implemented a heat-management graphene film cooling system. Now, Huawei has launched the smartphone Mate P30 Pro which also adopts a graphene film.
▲(Huawei Mate 20 X, “Graphene Applications.” [3])
Sensors
Graphene-based nanoelectronic devices were also investigated for use in DNA sensors (nucleobase and nucleotide detection), gas sensors (various gas detection), PH sensors, environmental contamination sensors, strain and pressure sensors, and more.
Graphene was developed in 2015 by researchers using epitaxial graphene on silicon carbide to create flexible biosensors. The sensors bind to 8-hydroxydeoxyguanosine (8-OHdG) and are able to bind selectively to the antibodies. It is common to associate the presence of 8-OHdG in blood, urine, and saliva with DNA damage. Elevated 8-OHdG levels have been linked to increased risk of multiple cancers. Owing to their special properties such as strength, bio-compatibility, and conductivity, graphene electrodes in the body remain considerably more durable than modern-day electrodes (of tungsten or silicon).
In June 2015, a partnership between Bosch, Germany’s tech giant, and scientists at the Max-Planck Institute for Solid State Science developed 100 times more sensitive graphene-based magnetic sensors than a silicon-based equivalent unit.
The US-based Graphene Frontier announced in August 2014 that it would raise $1.6 m to accelerate the production and manufacture of their graphene-functionalized GFET sensors. Their “six sensors” brand for highly sensitive chemical and biological sensors can be used to diagnose diseases unparalleled by traditional sensors with sensitivity and efficiency.
▲(Small sensor using graphene, “Graphene Applications.” [3])
Aerospace Applications
The Graphene Flagship revealed the GICE Spearhead Project — designing a graphene-based thermoelectric ice protection device aimed at advancing graphene development readiness in these applications.
When ice forms upon an aircraft’s wings, propellers, or other surfaces, the flight can be hindered seriously. This is prevented by thermoelectric ice protection systems, using an ultra-thin conductive coating layer to generate heat when current is applied. For this application, the GICE project will attempt to use graphene to improve existing technology.
[1] “Transistor.” UXL Encyclopedia of Science, edited by Amy Hackney Blackwell and Elizabeth Manar, 3rd ed., UXL, 2015. Gale In Context: Science, https://link.gale.com/apps/doc/CV2644300963/SCIC?u=nysl_li_schhs&sid=SCIC&xid=ccaab840. Accessed 6 Jan. 2020.
[2] “Graphene.” World of Chemistry, Gale, 2000. Gale In Context: Science, https://link.gale.com/apps/doc/CV2432500756/SCIC?u=nysl_li_schhs&sid=SCIC&xid=b21ebe21. Accessed 5 Jan. 2020.
[3] “Graphene Applications.” Graphene, www.graphene-info.com/graphene-applications.
[4] “Properties of Graphene.” Graphenea. https://www.graphenea.com/pages/graphene-properties#.XhM7k5Mza7o.
[5] “Graphene.” Wikipedia, Wikimedia Foundation, 14 June 2020, en.wikipedia.org/wiki/Graphene.
[6] Mogera, Umesha, and Giridhar U. Kulkarni. “A New Twist in Graphene Research: Twisted Graphene.” Carbon, Pergamon, 23 Sept. 2019,
[7] “Graphene – What Is It?” Graphenea, www.graphenea.com/pages/graphene.
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