Mike Jones
WRIT 340
Illumin Article
12 April 2013
From Scotch Tape to Electric Cars: Graphene, the Wonder Material
Although its properties have been hypothesized for years, graphene has only recently been isolated in
forms large enough to enable experiments to be conducted. These experiments have revealed that
graphene, comprised of carbon atoms arranged in repeated hexagonal rings, possesses some of the
amazing properties that had been anticipated. These properties, including strength and conductivity,
may enable graphene to be implemented in a wide array of fields, hopefully with much success.
Multimedia Suggestions: Source [2]. It is a video that explores Ric Kaner’s research to create a graphene
supercapacitor, and can be found on vimeo[dot]com.
Mike Jones is a sophomore studying Chemical Engineering with a Biochemical emphasis. He is a tutor at
the Viterbi Academic Resource Center and is involved with his fraternity.
Introduction
Every day, students all across the world pick up their pencils and drag these sticks of carbon
graphite across their papers, creating drawings, essays, and the occasional love note. With the naked
eye, we merely see the creation of metallic gray lines, but what is happening on the molecular scale? In
fact, when the graphite is pressed and dragged against the surface of the paper, small sheets of carbon
atoms flake off and adhere to the paper. One single sheet of these carbon flakes is called graphene,
whose extraordinary properties just might revolutionize the world of electronic devices.
History
When we think of pure carbon, three materials traditionally come to mind: diamond, coal, and
graphite. These materials are called allotropes, or different structural arrangements of the same atom,
and are made possible by carbon’s desire to form four bonds. Diamond contains carbon in a very rigid
3-dimensional crystal lattice, coal contains carbon in random, or amorphous, arrangements, and
graphite contains carbon atoms linked together in repeating hexagonal rings that form sheets stacked
on top of one another, as seen in figure 1. To put the size of each layer in perspective, there are 3
million layers for every millimeter of thickness of graphite [1].
Fig 1. A model showing layers of
graphite split apart to reveal the
hexagonally linked carbon atoms.
Web Elements
For many years, it had been theorized that a single layer of graphite would have very interesting
electrical properties, but isolating a sheet large enough to conduct tests proved difficult. Eventually,
Andre Geim and Konstantine Novoselov, two scientists from Manchester University, applied a small
chunk of graphite to a piece of Scotch tape and found that, after sticking and unsticking the tape to and
from the graphite chunk a few times, they could isolate relatively large single layers of graphite. They
deposited these layers, an example of which is depicted in figure 2, onto oxidized silicon, ran some tests,
and the world of graphene research was born. Geim and Konstantine won the 2010 Nobel Prize in
Physics both for the significance of their own experiments as well as for igniting a wave of graphene
research across the globe.
Fig 2. A model of a large sheet of
graphene, emphasizing its near 2dimensionality.
Jannik Meyer/Science vol 324, 15 May 2009
Properties
This wave revealed just how unique graphene truly is. Graphene is essentially a 2-dimensional
material, as the thickness of a carbon atom is absolutely minuscule compared to the area of even a very
small sheet. This means that graphene has a very high surface area, 2630 m2/gram [2], and is nearly
transparent, absorbing only 2.3% of any visible spectrum light shining at it [1]. However, it is also
extremely strong, given the very stable nature of the repeating carbon hexagon rings. It boasts a 2dimensional breaking strength of 42 Newtons per meter, which is 100 times greater than that of a
hypothetical steel sheet similar in dimension to graphene [1]. Figure 3 puts this strength into
perspective.
Fig 3. A hypothetical 1m2 graphene
hammock would be able to support a
4kg cat, yet weigh about as much as one
of the cat’s whiskers and be nearly
invisible [8].
Graphene is also a very good conductor, despite it being a nonmetal. Linear electrical conductance is
the reciprocal of linear electrical resistance, which is measured in Ωcm, or ohm*centimeters, and linear
thermal conductance is measured in Wm-1K-1, or watts per meter per Kelvin. Graphene conducts
electricity at 0.96x10^6 Ω-1 cm-1,which is approximately 50% better than copper [1], and conducts heat
at 5000 Wm-1K-1, which outperforms any other known material [3].
Applications
Graphene’s special properties – conductivity, surface area, transparency, and strength – have
launched it to the forefront of many application-based research initiatives. One field in which graphene
could have a large impact is that of biomedicine, which has taken specific interest in graphene oxide, a
form of graphene that contains oxygen atoms and other oxygen-containing groups. For biomedical
purposes, graphene oxide performs as a framework onto which different “accessory” compounds can be
attached in order to carry out various tasks, which include delivering compounds to certain cells of the
body. When folic acid and sulfonic acid are attached to graphene oxide, it delivers doxorubicin and
camptothecin in order to target and kill human breast cancer cells. When a compound called
polyethenimine is attached, graphene oxide can condense and transport DNA and RNA, possibly treating
diseases involving genetic defects like cystic fibrosis or Parkinson’s disease. Graphene oxide can even
function as a nanoscale biosensor to detect various molecules in the body, and can provide a
“scaffolding” on which new tissues can be grown [2]. These are just a few of the roles for graphene that
biomedical scientists are exploring.
However, whatever splash graphene may make in the biomedical realm, it is a proverbial drop in
the bucket compared to the impact it could have on the future of electronic devices. Currently, circuits,
motors, screens, or anything else in an electronic device that needs energy is powered by either a
battery or a capacitor. A battery, such as the lithium-ion type in a cellular or smartphone, uses an
electrochemical reaction to create electric power [4], whereas a capacitor, such as those in radio tuning
circuits, delivers energy by storing electrons between two oppositely charged plates and then releasing
them [5]. Currently, batteries have a high capacity for energy, but long charge times, and capacitors
have very quick charge times, but very low energy capacities. With its remarkable electrical properties,
graphene seeks to combine the best of both into what is called a supercapacitor—a capacitor that has
the energy capacity of a battery, but the charge time of a capacitor. The graphene supercapacitor is still
in the research phase, and many variations are being tested, including one that uses hybridized ribbons
of vanadium oxide and graphene. This Rice University-developed material can reach full charge in a
mere twenty seconds, and after 1,000 charge and discharge cycles, can still be charged to 90% of its
original capacity [6]. UCLA chemistry professor Ric Kaner has worked with pure graphene, layering it
with simple plastic and electrolytes to create a capacitor that can store the same amount of energy as a
traditional battery, but can go through a discharge-charge cycle one hundred to one thousand times
faster [7].
Impact on the Future
Imagine that when the warning appears on a laptop indicating 5% battery life remaining, the
owner could plug the laptop into an outlet for a mere five minutes and the laptop’s graphene
supercapacitor would be fully charged. This would undoubtedly increase the convenience of many
people’s lives. However, implementing the same technology into the transportation sector, however,
could be revolutionary. Electric family cars, taxis, buses, and possibly even electric semi-trucks could
fully recharge during a one hour lunch break instead of the current commitment of eight to nine hours
overnight [8]. It is by no means an immediate reality, but graphene has the potential to serve as the
foundation for the transportation, electronic device, pharmaceutical, and materials science sectors, as
seen in figure 4. And perhaps, graphene could revolutionize fields we have not yet considered.
Limitations
Unfortunately, this graphene-embedded future may not be realized for quite some time. As
with any engineered chemical product, graphene is bounded by three primary parameters: cost,
production scale, and quality of the product. And, unfortunately, there is no production method
currently available that can fulfill all three parameters, which is impeding the widespread
implementation of graphene. In addition to the various fields of application, figure 4 also portrays the
pros and cons of various graphene production methods.
CKMNT
Fig 4: The current methods of producing graphene sheets and their respective pros, cons, and
applications.
Conclusion
There is no debate over just how extraordinary graphene is. It is the first 2-dimensional material
to be heavily studied, boasting transparency, strength, and conductivity, and despite the limitations that
may exist currently, the applications of graphene in biomedicine, electronics, and other fields are
promising enough to push forward with any and all research and industrial initiatives. It wouldn’t be the
first material for which scientists and engineers needed to overcome significant obstacles in its
development, and like many others graphene could be well worth the effort.
[1] “The Nobel Prize in Physics 2010: Background Information.” Nobel Prize. [On-line]. [29 Mar 2013]
[2] H Shen, et al. (2012). Biomedical applications of graphene. Theranostics. pp.283–94.
[3] “The Nobel Prize in Physics 2010: Information for the Public.” Nobel Prize. Internet. [29 Mar 2013].
[4] Brain, Marshall, Charles W. Bryant, and Clint Pumphrey. "How Batteries Work." HowStuffWorks.
Internet. [1 Apr. 2013].
[5] Brain, Marshall, and Charles W. Bryant. "How Capacitors Work." HowStuffWorks. Internet. [1 Apr.
2013].
[6] Mike Williams. "Hybrid Ribbons a Gift for Powerful Batteries." Rice University News. [Internet]. [2
Apr. 2013].
[7] Jennifer Marcus. “Researchers Develop Graphene Supercapacitor Holding Promise for Portable
Electronics." UCLA Engineering. Internet. [1 Apr. 2013].
[8] “Fuel Economy.” Internet: http://www.fueleconomy.gov [02 Apr. 2013].
[9] Brian G. Davis, Director, “The Super Supercapacitor”. [Video]. Focus Forward Films. [21 Oct. 2012].