If you read of a material that was invisible to the eye, but hundreds of times stronger than steel, stretchable, flexible, and a superconductor of electricity, you might think it was an imaginary substance dreamed up by a science-fiction author.
However, such a material exists in our world: graphene. Graphene is allotrope of the element carbon — essentially, it is an extremely thin layer of graphite (the material in a pencil) that’s just one atom thick. As such, it is the thinnest material known to humans. At the same time, graphene is extraordinarily strong, transparent, flexible, impermeable to most gases and liquids, and an excellent conductor of heat and electricity. With these useful qualities, it’s not surprising that some refer to it as the “stem cell of the carbon world.”
Curiosity and persistence pay off
In 2010, Andre Geim shared a Nobel Prize in Physics with Konstantin Novoselov for their groundbreaking research into the creation, nature, and properties of graphene. The Nobel committee honored the physicists’ discovery of this form of carbon that has “exceptional properties” based in the operations of quantum physics.
Both scientists were born in the former Soviet Union, Geim in 1958 and Novoselov in 1974. Both immigrated to the United Kingdom, where they became professors and collaborators at the University of Manchester. The school is now home to the Graphene Engineering Innovation Centre.
Geim focuses on studying microscopically thin materials, and has gained renown for his quirky brilliance and his “curiosity-driven research.” In 2002, Geim asked a research student to produce a carbon layer that would be as thin as possible, and the two figured out a way to use Scotch tape to pull off ultra-thin filaments from a sample of graphite, the crystalline form of carbon used in pencils. Geim’s result was the first discovery of a two-dimensional material, a layer of carbon one atom thick. Beneath an atomic microscope, the substance appears as a honeycombed diagram of hexagons.
Previous researchers had believed it impossible to produce a stable one-atom-wide layer of material under room-temperature conditions, but Geim could see the graphene sample stabilizing under his microscope. Along with Novoselov, then his PhD student, Geim devoted the next few years to studying graphene virtually around the clock.
Their 2004 paper, “Electric Field Effect in Atomically Thin Carbon Films” was published in Science to widespread astonishment. Speaking to The New Yorker about this research, one executive from the Samsung Advanced Institute of Technology summed up the reaction from researchers: “It was as if science fiction had become reality.”
The Superman of materials
Geim and Novoselov uncovered a string of remarkable properties of the substance. Graphene can carry 1,000 times the amount of electricity as copper. Electrons travel across its single-layer, lattice-like structure almost completely without resistance, giving them astonishing speed and freedom of movement. In addition, graphene produces a notable “field effect,” which is also one of the distinguishing features of silicon. Scientists believe that graphene’s high degree of controllable conductivity could one day make it a replacement for silicon in the manufacture of computer chips.
Other scientists have built on this work, finding other properties of graphene that offer still more potentially world-changing uses.
Even before Geim and Novosolev earned their Nobel Prize, news media were hailing graphene as a “wonder material.” Although it is paper-light, it demonstrates a strength some 150 to 200 times as great as a comparable weight of steel. As bendy and flexible as a sample of rubber, graphene can stretch to more than double its own length. It is also extremely transparent, and appears to be impermeable to the actions of liquids and gases.
And it is even more electrically conductive than Geim and Novosolev originally realized. In terms of what electrical engineers call “mobility” — the speed at which a charge of electricity flows over a semiconductor’s surface — it can produce measurements 250 times those produced by silicon.
Although graphene is incredibly strong, in its polycrystalline form it has shown itself much more brittle than diamond, another very different allotrope of carbon. This remains a central problem facing researchers hoping to incorporate it into a variety of practical uses.
An adaptable — and ethical — replacement
By the year 2013, there were close to 8,500 individual patents relating to graphene worldwide. Graphene is also on many researchers’ lists as a leading carbon-based material that could replace scarce metals used in high-tech industries. Graphene could substitute for the gallium used in semiconductors, the germanium used in optical cable fibers, the indium used in electrodes, and the tantalum used in capacitors, among other applications.
It’s also important to note that many rare metals crucial to the manufacture of electronic devices are often sourced from conflict regions of the world, such as the Democratic Republic of the Congo. Finding alternatives could help reduce the violence and geopolitical problems associated with rare metal extraction in these areas.
From trash to treasure
Scientists at Rice University in Texas, LUT University in Finland, and other locations have recently used high-energy electrical pulses to transform plastics and other carbon-based waste products into graphene. These carbon-negative processes could open the door to an enormous change in the way we manufacture key products, and in the way we manage waste and environmental pollution.
A number of projects continue to investigate practical applications for graphene. These include its use in smartphones and other small electronics, possibly allowing them to be structured such a way that they could be folded and unfolded like paper, bending and shaping themselves around a wrist or arm. Graphene could become a highly efficient superconductor, replace silicon in photovoltaic cells, and act as a highly efficient mechanism for water filtration or distillation.
Biomedical research, and the manufacture of sensors and other medical devices, are other exciting possibilities. Graphene might also be capable of use as a sensor or drug-delivery device inside the human body. Some researchers are even looking at it in the form of a film that could act as a mosquito repellent.
From where things stand right now, in terms of these and other yet-unimagined uses, graphene offers a seemingly limitless world of potential.