What is Graphene?
Dubbed “the supermaterial of the future” by researchers, graphene is an allotrope (form) of carbon which comprises a one atom thick layer of carbon atoms arranged in a hexagonal honeycomb-like structure. Simply put, graphene is a single layer of graphite, the same material we use in pencils to write with .
Whereas the other carbon allotropes, diamond and graphite, have a three-dimensional crystal lattice structure, graphene’s crystalline structure is two-dimensional . It is this unique structure that gives graphene the thermal, mechanical, and electrical properties that has researchers and manufactures so excited.
- Being only one atom thick, graphene is one of the thinnest materials in the world, being 0.34 nanometers (1 nm = 10^-7 cm) thick. In comparison, paper’s thickness is around 100 000 nm.
- Graphene is also visible to the naked eye, absorbing 2.3% of white light, large amount for a 2D material .
- It is incredibly light weighing only 0.77 mg/m2. One gram of the material can cover an entire soccer field .
- Graphene is one of the strongest materials discovered, it having a tensile strength 200x stronger than that of the A36 steel, a common structural steel used in the US. Despite that, graphene is surprisingly brittle, and will crack in similar conditions to that of ceramic material .
- Graphene has an extremely high electrical conductivity. Its high electrical current density, the rate at which current travels through a cross-sectional area, is million times of that of copper .
- When combined with praseodymium cerium copper oxide, or arranged in a pair at an angle of 1.1° and cooled to 1.7° above absolute zero, graphene has been observed to act as a superconductor, a material that conducts electricity with no resistance .
History of Graphene
While graphene has only recently been isolated and categorized, researchers have been discussing it for over half a century. The theory of graphene was first explored in 1947 by a Canadian physicist by the name of P.R. Wallace as he was studying the properties of graphite. Unable to obtain data on graphite, Wallace instead theorized a two-dimensional analog of graphite, graphene, which he could use to extrapolate data .
It was not until 2004, however, that we were able to isolate graphene. Andre Giem and Konstantin Novoselov at the University of Manchester finally obtained a sample of graphene through the use of a common household material, scotch tape. The method they used was simple. The two would apply tape to a piece of graphite and then peel it off, drawing a layer of the graphite in the process. They would then repeat the same process on the peeled off graphite, making thinner and thinner layers until they obtained the one atom thick graphene. The pair published a paper, “Electric Field Effect in Atomically Thin Carbon Films”, on their findings in the Science journal, and in 2010 received a Nobel Prize in Physics for their efforts .
What can graphene be used for?
Given graphene’s unique properties, it can be used in a variety of different industries ranging from technology all the way to medicine. Here are some of the most prominent uses of graphene that have been explored:
Graphene’s flexibility, durability, and transparency make it ideal for use in portable electronics. Incorporating graphene into the touchscreen of devices allows them to be substantially more durable than the current glass screens and could allow for further development of foldable electronics .
Today, several companies, mostly producers of sporting goods, have released products that have incorporated graphene into their design. One prominent example would be Dassi, a British bike manufacturer. In 2017, Dassi began offering the “Interceptor” to consumers, the world’s first graphene bike. The bike frame, retailing at approximately $10,437 Canadian, is 30% lighter than traditional carbon frames with a weight of only 750g unpainted .
Graphene’s high conductivity and transparency also gives it great potential for use in solar cells. Currently, solar cells are composed of silicon which release one current-driving electron for each photon that it absorbs. In comparison, graphene will produce several current-driving electrons for each photon it absorbs. Solar cells composed of graphene are said to have a 60% efficiency compared to the 25% efficiency seen by silicon solar cells .
Graphene has also begun to see use in battery technology as well. In 2017, Samsung began development on incorporating graphene into its lithium ion batteries for smartphones through the use of a graphene ball coating. This new battery is said to have a 45% increase in capacity while having a charging speed five times faster than the current lithium-ion battery. It would only take 12 minutes for the battery to fully charge .
Due to its high conductivity, researchers have also begun to explore using graphene in semiconductors. Results from the US Department of Energy have shown that graphene can conduct electricity faster than a current silicon chip even when being five times thicker. Generally, polymers will conduct charge more efficiently the thinner it is .
Graphene’s property of being impermeable to nearly all gasses and liquids except for water makes it an intriguing material for filtration. In 2013, Lockheed Martin began developing membranes constructed with graphene under the name of Perforene. According to the company, these new filters will reduce energy usage in the desalination process by 20% and will be available in 2020 .
One of the major hurdles for graphene that has prevented it from playing a larger part in our lives is that it is extremely difficult to produce in industrial quantities. Current production methods are only able to produce graphene sheets in small quantities at a time.
The main methods of producing graphene are mechanical exfoliation (peeling away layers similar to what Giem and Novoselov did), and chemical vapour deposition (CVD). CVD involves putting a carbon-based gas, usually methane, into a reaction chamber with heated copper at the bottom. When the gas comes into contact with the copper, a reaction occurs between the two, and a film of graphene is deposited onto the surface .
While graphene certainly has the potential to revolutionize our world, it is important to not get too carried away. It may take several years before graphene starts to play an important role in our daily lives. For example, synthetic plastic was first derived in 1907, and it was not until World War II that the industry really began to take off .
With that being said, many researchers across the world are continually working on developing methods to efficiently produce graphene and discover uses for this ‘supermaterial’. Just last year in 2018, engineers at MIT developed a new continuous manufacturing process for graphene that produces long strips of material that they believe can be scaled up for industrial use . Graphene is still in the early stages of its development, but the possibilities it offers are truly extraordinary.
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