How does adhesive tape win a Nobel Prize?
Sometimes Nobel Prize winning science requires the world’s most powerful particle accelerator, fastest supercomputer or strongest telescope. In 2010, all the winners really needed was an office supply store stocked with adhesive tape and pencils. Using these simple tools, they were able to isolate graphene for the first time, a super-material that could be used to make ultra strong and light materials, revolutionize electronics and build better solar cells.
It had long been theorized that it should be possible to create sheets of carbon atoms only one atom thick, and that they would have some pretty amazing properties. Since then, scientists had been trying to isolate these sheets, known as graphene. Many methods had been tried, but for years nothing worked. Some scientists were starting to think that such sheets were too thin and delicate to exist at all. Then in 2004, the Russian physicists Andre Geim and Konstantin Novoselov working at the University of Manchester in the United Kingdom were the first to isolate the elusive material using only adhesive tape and the lead of pencils. Six years later, they won Nobel Prizes for their work.
To really understand what graphene is and why scientists are so keen on manufacturing it, it’s important to first understand what it’s made of.
Carbon is an amazing element. It does everything from heat your house to bind together the building blocks of life. Pure carbon can take on many different forms depending on its molecular structure. Coal is one kind of pure carbon, so is diamond, so is the graphite in a pencil and so is graphene.
What separates a gem of diamond and a hunk of coal. The difference arises in how the atoms are organized in the molecules of each material. In coal, the atoms are kind of splayed all over the place, not really forming any kind of ordered structure. Atoms in a diamond on the other hand are very ordered, forming intricate lattice at the molecular level.
Graphite is different still; it’s made up of many layers of sheets of carbon atoms that each form a hexagon pattern. Imagine sheets of chicken wire, where each individual wire is like a molecular bond between two atoms. Every place where wires intersect is an atom. Graphite would be like millions of those sheets piled on top of each other. One single millimeter of graphite is made up of about three million of these layers.
These layers aren’t strongly bound to one another, and it’s easy to get them to flake off. This is what happens when a pencil writes on a piece of paper, layers of graphite flake off and stick to the paper.
What Geim and Novoselov did was use adhesive tape to peel off a single layer of this sheet of carbon atoms. Starting out, the team used nothing more than ordinary adhesive tape, just like what you can get at any office supply store, and blocks of the same kind graphite used in pencils. They stuck a piece of tape to the graphite and pulled it off; it’s known as the micromechanical cleavage method. The first time they tried, they pulled off hundreds of layers of carbon still stuck together. However after repeatedly sticking more tape to what they originally pulled off, they gradually whittled it down to a single layer, the long sought after graphene molecule that scientists had been trying to isolate for years!
In order to confirm that they had in fact isolated an elusive graphene molecule Geim and Novoselov placed a flake on a slide of oxidized silicon and put it under a microscope. Peering through the eyepiece, the team was able to see the telltale color pattern that proved they had a pure single sheet of graphene on their hands.
Geim has always devoted some of his time to exploring fun and unconventional science. In 2000 he won the Nobel Prize’s tongue-in-cheek cousin, the Ig Nobel prize, for levitating a living frog in a magnetic field. He also developed a kind of tape that mimics the way a gecko’s feet stick to surfaces.
So why are scientists so gaga over graphene? What can it really do? A better question to ask might be what can’t it do? Its unique molecular structure makes it stronger than steel but still flexible, as transparent as glass, as good as copper at conducting electricity and able to conduct heat as well. If even a small amount is combined with plastic, the plastic could start to conduct electricity. If infused into construction materials, graphene could increase the physical strength of an object without adding any extra weight. Because graphene is clear and can conduct electricity, researchers are looking for ways to turn it into the next generation of solar cells.
Much of these applications are so far just speculation. Geim and Novoselov only first isolated the material in 2004, but since then research into graphene has become one of the fastest growing areas of physics research. A major breakthrough happened in 2007 when Geim and Novoselov showed that a transistor made of graphene can perform at least as well as one made of silicon, a tantalizing hint at a future where carbon could replace silicon to shrink electronics even further. Though Geim and Novoselov only had tiny flakes of graphene to work with, technicians now are working to industrialize its production on a much wider scale. Companies have been able to produce rolls of graphene sheets two feet wide, and the work continues to further produce it as a whole.