might have wondered if people were confusing it with some kind of substance only found

in comic books. It's one atom thick, conducts electricity better than silver, conducts heat

better than diamond, and it's stronger than steel. It would take the focused force of

an elephant balancing on a pencil point to pierce through a piece of graphene as thick

as plastic wrap.

And yet, graphITE is made of the same stuff. And yeah, that crumbly stuff used to make

your pencil is a lot less impressive. So what's up? Graphene is made of carbon, and carbon

has only two naturally occurring crystalline structures; graphite, which is just stacks

and stacks of graphene piled on top of each other, and diamond, which is a network of

carbon atoms arranged into tetrahedrons one after the other. For being composed of entirely

the same element, those two things don't seem to have a lot in common. Diamond is clear,

graphite is black. Diamond is a nearly-perfect electrical insulator, while graphite is both

a great conductor of heat and electricity.

The differences between these substances all come down to the arrangement of their atoms.

Carbon has four outer electrons. In diamond, all four of those electrons bond to carbon

atoms around it, forming those tetrahedrons. This makes for an extremely rigid and strong

crystal. It's an insulator, because there are no electrons left over to carry a current,

and it's clear because light can't easily excite electrons that are tied up in such

stable bonds, which is where they'd otherwise be absorbed. Graphite, on the other hand,

is a crystalline form of carbon in which each atom is only bonded to three other carbon

atoms. Those atoms form a two-dimensional sheet of hexagons in which each atom has one

unpaired electron left over. And those electrons will go flying across the matrix of atoms

if you apply an electric current, allowing it to readily conduct electricity. They also

gobble up any photons coming their way, which is why graphite is black.

But while graphite is a great conductor, its natural form consists of layers of those sheets.

So if a current is applied to it, those free electrons have lots of different directions

they can go in, taking tangents up and down and left and right and so on. But if you strip

away just a single layer, forming graphene, then you have what amounts to an electron

super highway, a flat matrix of carbon atoms for that current to fly across. And those

sheets of carbon are pretty easy to separate because they're not molecularly bonded to

each other. That's why graphite is so soft. Instead, they're held together by Van Der

Waal's bonds, kind of a weak, electrostatic bond that's the same force that makes sticky

tape sticky. And in fact, graphene was only discovered in 2004 when two physicists at

the University of Manchester, Andre Geim and Konstantin Novoselov, decided to use sticky

tape to peel off thinner and thinner layers from a slab of graphite. Eventually, they

got a layer just one atom thick.

So that's what it is, but what is it good for? Because of its terrific conductive properties,

scientists are excited by the possibility of using graphene as the replacement for silicon

in microchips. Not only can electrons move faster across graphene, they're also subjected

to less noise. That means the electron can move from one side of the sheet to the other

in a straight line without detouring around a whole lot of atomic potholes. Scientists

think that graphene transistors could operate at frequencies of up to a thousand gigahertz.

That's ten times the maximum of silicon.

Another proposed use of graphene is in touch screens. The topmost layer of a touchscreen

has to be an excellent conductor of electricity, so the device can sense your fingertip. The

material we use now is indium tin oxide, but it's both rare and brittle. Even ground into

powder, graphene retains many of it's extraordinary properties, so it could replace graphite or

other forms of carbon in anything from car tires to double-A batteries to make them stronger

or more conductive.

The biggest problem with graphene though is how hard it is to make. I mean, peeing off

a tiny sheet at a time with sticky tape isn't really scaleable. We can grow graphene sheets

by hitting up a sheet of hydrocarbons like methane until the hydrogen separates, leaving

only the carbon behind, but the graphene we get from this is mostly low quality.

Basically, it's hard to create a one atom thick sheet of anything. And it's also really

hard to get a completely pure sample of anything, and here we're trying to do both. But then

again, the silicon industry faced the same purity problem fifty years ago, and we eventually

solved that problem with time and some money. So in some more time, and some more money,

I'm sure we'll do the same thing for graphene.

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