Graphene creates advantages, limitations for experiments
Army veterans wear this material in artificial retina. Professional tennis players find it in their tennis rackets. And it may be the secret to quantum computers.
Graphene is the “material of superlatives,” according to a Nature article, although it’s essentially a two-dimensional sheet of graphite. Graphene’s beehive-shaped molecular structure gives it strength and pliability as well as the ability to conduct heat and electricity efficiently.
Graphene is about 200 times stronger than steel but much thinner. It is practically impermeable to gases and conducts less heat as the temperature increases, which allows it to withstand high heat. Also, graphene is composed of carbon, the fourth-most abundant element in Earth’s atmosphere.
According to physics graduate student Yujin Cho, graphene’s most important property is transparency. Cho worked with a group of researchers to build the world’s thinnest light bulb from graphene at UT-Austin. According to Cho, graphene’s transparency, along with its durability, yields numerous possibilities for faster electronic devices and nanoscale light experiments.
“It’s also super strong. The material is good enough and stronger than iron, so some people make jokes about how you can make a tennis racket out of graphene,” Cho said. “But the racket will definitely be super expensive.”
High quality graphene is an expensive material because manufacturers cannot currently produce graphene in mass quantities.
Traditionally, researchers produce graphene through the “Scotch Tape” method, in which they use sticky tape to peel off layers of graphite until only a layer with the thickness of one atom is left, but this arduous process produces only small amounts of graphene.
Richard Piner, research associate in the Texas Materials Institute, said the thinness of graphene presents various issues in mass production, such as the amplification of small impurities.
In his past research, Piner worked on microscopes that were sensitive to friction. The graphene impurities created friction in an otherwise smooth sheet of graphene, even though they would not present many problems in three-dimensional materials, such as ceramics.
“Anything insignificant in 3-D will kill you in 2-D,” Piner said. “For [pure] graphene, oxygen is death.”
Graphene reacts instantly with oxygen to form graphite oxide, which is the most common form of graphene. Scientists can effectively synthesize pure graphene on a large scale by chemical reduction or by removing the oxygen in graphite oxide.
The complications of mass production for graphene also include the lack of a band gap, according to the journal Nature. On a molecular level, the band gap is the minimum amount of energy required for an electron to break free. Once it does, the electron can participate in conduction.
Due to the absence of a band gap, the electrons in graphene flow continuously, causing graphene to act more like a metal than a semiconductor. Unlike metals, semiconductors have on/off switches. The band gap prevents scientists from controlling electron flow and using graphene in transistors, a key component of electronic devices.
Graphene presents potential for a vast number of electronic and medical applications, including cars, buildings and cancer research. Piner said graphene, if perfected, can be used to build a quantum computer that can theoretically calculate all possible solutions at once at an infinitely faster computer speed.
However, according to many researchers, including Piner, the limitations still need to be overcome to take full advantage of this carbon material.
“That’s the thing about graphene. It’ll be really useful for things like quantum computing and electronics,” Piner said. “But it needs to be really perfect, and that whole other level of chemistry is going to be really difficult.”