- We totally take pencils for granted.
This writing right here, it only works
because of a unique chemical phenomenon happening
inside the pencil lead.
And that phenomenon could hold the key
to the future of electronics, medicine,
space travel, energy storage, and more,
but only if we can actually get past the hype
and harness it appropriately.
(upbeat percussive music)
(simple bright music)
The graphite in pencil lead,
which you probably know isn't actually elemental lead
at all, is just the right chemical structure
to leave some of itself behind
as a mark on the paper.
Graphite is composed of layers of carbon.
Within each individual layer,
each carbon atom is tightly bound
to three other carbon atoms in a honeycomb pattern.
Each layer is a single sheet of graphene,
and there are only very weak Van der Waals interactions
between the layers.
This means they can easily slide relative
to one another due to those weak interactions.
So as you run the pencil tip across paper,
layers of graphene are left behind.
And you might know
that graphite isn't the only carbon structure
that we commonly find uses for.
Diamonds are also composed of pure carbon atoms,
but in a different pattern that looks like.
This 3D carbon structure is way stronger
than graphite in all directions,
with each carbon equally strongly bonded
to four other carbons in a tetrahedral structure.
Running a diamond
across paper isn't gonna leave little chunks
of diamond behind, thankfully.
In fact, diamond is the strongest substance known
and is often used in really intense drill bits.
But writing and drilling aren't
the only things we're trying
to use unique carbon structures for.
For decades, scientists have wondered
if we could make new carbon structures
or configurations that could be used
in everything from building better superconductors
to really precise drug delivery
to brain computer interfaces.
But it's been decades.
We were promised graphene batteries
and buckyball-based medicines by now.
In fact, a 1991 popular science article teased
that carbon structures called buckyballs
could bring us lightweight batteries,
powerful rocket fuels,
and infinite possibilities of plastics.
Put those three things together
and you know what you get?
A jet pack. Where's my jet pack?
So how close are we actually
to tiny carbon structures running our world?
I am tired of driving.
I would like my eco-friendly jet pack now, please.
(engine roaring)
So if you're familiar with any weird carbon structure,
it's probably the buckyball.
First described in 1985,
buckyballs, or buckminsterfullerene,
are clusters of 60 carbon atoms shaped like a soccer ball
with 12 pentagonal faces and 20 hexagonal faces.
The scientists who first created them were interested
in learning about how carbon chains formed in space.
So to try and replicate some
of those interstellar conditions,
they vaporized graphite with lasers
and then allowed it to quickly cool in a stream of helium.
You know, as you do when you're looking
for carbon space dust.
When the carbon dust cleared,
what was left behind were little carbon clusters
or buckyballs.
Also, a side tangent here
that the last paragraph of the paper
that described this is an absolute eye-roll.
They named the compound after Buckminster Fuller,
an architect who designed a lot of geodesic domes,
but then in their own paper, they say,
"We are disturbed at the number of letters
and syllables in the rather fanciful,
but highly appropriate name."
And they suggest other names like ballene,
spherene, soccerene, or carbosoccer,
which are all terrible.
In the end, they say they preferred
to let this issue of nomenclature be settled by consensus.
And apparently, we, the consensus, settled on buckyballs.
The scientists speculated that buckyballs formed
under the violent conditions found in space.
Things like UV radiation, harsh vacuums,
and super cold temperatures might be plentiful out
in the universe.
They also thought that these buckyballs could help play
a role in explaining how early life formed
in the early Earth 'cause,
you know, space conditions, early Earth, chemistry.
And a few things about buckyballs made
the scientific community interested
in their useful potential,
like amazing batteries or jet packs.
First, buckyballs are a relatively simple structure,
and they're hollow.
Early studies show that scientists could place
other molecules into those hollow cores,
which might make them useful for storing
or delivering things like medicine.
They're also made up of just one common element, carbon,
which can make creating them easier
than more complex compounds.
Scientists had a number of ideas
of how they might be useful in everything
from lubricants to rocket fuel and superconductors
to even, at one point, an anti-HIV drug.
Buckyballs were 1991's molecule of the year,
with Science Magazine proclaiming
that the new structure unleashes
tantalizing new experimental and theoretical ideas,
and that improving life through science is a path
that would see all citizens
of the world holding hands like the carbon atoms
in C60, and like them, welcoming any newcomer,
no matter how different his or her skills or challenges.
♪ It's the real thing ♪
♪ Coke is what the world wants today ♪
- (sighs) They were really excited about buckyballs.
The '90s were weird.
But the actual applications of buckyballs
and similar spherical compounds
have been slow to materialize.
There's lots of really fascinating research
into their potential applications.
Coatings containing buckyballs have been proposed
as machine lubricants,
and other spherical carbon structures
with slightly different numbers of carbons have been tried
as drug delivery vehicles.
But most of these applications are still
in the development stage decades later.
We've been almost there for a long time now.
But research on buckyballs led
to another potentially useful carbon structure,
carbon nanotubes.
(engine roaring)
So if you imagine taking a sheet of graphene
and folding it up into a cylinder,
(simple bright music)
you would get a carbon nanotube.
It's a nanotube 'cause it's like a, it's a tiny tube.
This is not to scale.
To make a nanotube,
scientists coat a silicon wafer
in metal catalysts like iron or nickel.
They put them into a furnace with carbon-containing gases.
Rings of carbon start to form on the catalyst,
determining the diameter of the tube.
As more and more carbons are added,
the tube grows longer and longer,
and the catalyst particles rise up off the wafer.
They'll keep on growing
until the catalyst particle is covered
in carbon and deactivated.
Carbon nanotubes are typically
about one nanometer in diameter,
80 to 100,000 times thinner than a human hair.
Discovered in the early '90s,
they too were thought to hold a lot of scientific promise.
Nanotubes are tiny, hollow wires made up of only carbon,
with every atom on the surface of the tube.
They have a really high tensile strength,
meaning they can resist being broken when stretched,
as well as a high elasticity,
meaning they'll easily return to their original shape
if bent or stretched.
They also have some pretty cool electronic properties.
Carbon nanotubes can act either
as conductors or semiconductors,
materials with properties
between those of insulators and conductors.
Fascinatingly, that depends
on the chirality of the nanotube:
whether the hexagons are oriented this way,
or if they were oriented in the opposite direction.
Semiconductors are incredibly useful in tiny computer chips,
which are in everything from watches
to phones to cars to computers.
Carbon nanotube semiconductors might be helpful
in building tiny electronics and mechanics
that are faster and require less power
than the silicon semiconductors we use today.
But producing, aligning, and building computer chips
with these tiny tubes can be difficult.
They need to be perfectly aligned like bundles
of dry spaghetti, which is incredibly hard to do
when you think about the fact you're working
with something only one nanometer wide.
Despite this, carbon nanotubes are actually used
in some products today.
In fact, several thousand tons of them are made
and sold each year.
Some are used in water filtration products,
while others are used as electrodes
in batteries and capacitors.
And they can be made into strong frames
for things like bikes and tennis rackets.
If you know anyone who rides a fancy bike,
they've absolutely told you
about their carbon fiber bike frame.
You know they have. Are you that person?
Unfortunately, like buckyballs,
nanotubes are still most often talked about
for the applications that they could have
rather than what they are doing right now.
They're useful, but they're not yet powering my phone,
or my watch, or my jet pack.
(engine roaring)
Now, if we wanna look
at the next big potential carbon innovation,
we actually have to go back to the graphene sheets
from our pencils.
There are lots of groups working
on making single-layer sheets of graphene.
And while it was first successfully accomplished in 2004,
it's taken a bit for the production
to get to a stage where we can do it efficiently enough
for graphene to make a potentially useful product.
The current best strategy of making graphene sheets is
to use something called chemical vapor deposition.
Like the nanotubes,
it involves a thin substrate layer coated
in some kind of catalyst inserted into a furnace.
A carrier gas like methane is added to the furnace as well.
The high heat decomposes the methane into carbon,
and the carbon deposits onto the catalyst layer.
With just the right conditions,
you can get a single atomic layer of graphene.
Or, believe it or not,
you can make small quantities of it using tape as well.
If I put this piece of graphite right
in the middle of this tape, press it together,
and then pull it apart,
I've pulled a few layers of graphene off
of that big original chunk.
And now I can do that again
and again and again to get down
to thinner and thinner sheets.
Scientists discovered this method
of making graphite sheets in 2004.
And in 2014, another group found
that you could actually do this using the sheer forces
in a big mixer to exfoliate layers
of graphene off of graphite.
You can even do this in your own home blender.
But I refuse because I love my morning smoothies,
and I will not sacrifice my blender for this.
Like nanotubes, there are also a lot of people interested
in using graphene for its electrical properties.
Electrons can really quickly travel
through the orbital shells of the carbon atoms
in graphene, making it a great conductor.
In fact, one of the best conductors.
Electrons can zip through these graphene sheets faster
than any other known material at room temperature.
We can actually demonstrate this conductivity
with just a pencil and some paper.
If I take this multimeter,
I can actually measure how well electrons flow
through a square of graphite drawn on the graph paper.
What we're measuring here is the resistance
that electrons feel as they pass through the graphite.
And it's very low.
There are a few big areas
where graphene could actually be useful.
And one is renewable energy,
where scientists hope to use graphene in batteries,
fuel cells, and other energy storage methods.
Its flexibility and thinness
and great conductivity have a lot of groups hoping
that it could replace silicon in all kinds of electronics.
There's also a lot of work looking at using graphene
in biomedical applications.
Things like embedded sensors under the skin
to track blood sugar or heart rate,
or biointerfacing in the brain,
allowing people with diseases that leave them unable
to control their muscles the ability
to communicate with the outside world.
And other groups are already using it
to make conductive ink or filtration
and separation membranes,
or fancy new displays and screens
to make our everyday lives better.
There is, however, a problem with graphene.
If you're flowing electrons through it,
it's really hard to get them to stop flowing through it.
You need something called a band gap
to turn the flow of electricity off,
and this has been really hard to engineer into graphene.
But a couple of groups have figured out a way
to do this by using not one sheet of graphene,
but two, putting them together, and twisting them.
If you take two sheets of graphene
and then stack them and then twist them super slightly,
just 1.1 degrees, you can turn the graphene sandwich
from a conductor, which allows electrons
to easily flow from one atom to the next,
into an insulator, which restricts the flow of electrons,
and then into a superconductor,
which is a conductor on metaphorical steroids,
passing electrons along with basically no resistance.
Now, they've labeled this field twistronics.
And like soccerene, twistronics.
Come on, chemists. Your naming is not great.
When the two sheets of graphene are twisted
at that incredibly, very precise 1.1 degree angle,
they form a moire pattern.
That is the pattern that forms
when you shift two grids over one another,
like this animation that I'm gonna make the animator make.
You get alternating spots of dark and light.
The overlapping dark areas allow atoms
to act together like super atoms,
which is what allows the electrons
to flow between them so quickly.
It's like the electrons are moving around the same atom
rather than having to hop between atoms.
Unfortunately, to get this superconductivity,
you have to chill the structures down almost all the way
to absolute zero.
Eh.
Cold temperatures are pretty common for superconductors,
but it means they're not actually gonna be used
in our phones or computer screens or anything anytime soon.
And that is super frustrating
because if we could find a way
to economically manufacture and chill these devices,
they could be useful for things like quantum computing
or for ultrasensitive detectors.
One group showed that they could detect a single photon
of far infrared light with this stuff.
A single photon. One.
One photon. That is incredibly cool.
And of course, scientists have continued
to build these materials out,
moving from bilayers of graphene
to twisted trilayer graphene sandwiches,
which show even more robust superconductivity.
So this is the thing, then,
that's gonna make my jet pack real.
This is it, right?
Well, like buckyballs and nanotubes,
a lot of the stuff is still just really new.
Graphene is used in some phones
as a heat dissipating layer,
and the makers of some fancy audio equipment tote 5
to 10 layer sheets of graphene as strong,
yet flexible additions to diaphragms inside earbuds.
Graphene is also used in wearable sensor prototypes,
and its thinness means it could have applications
in all kinds of wearable tech
as sensors, batteries, and conductors.
It just feels like we are right
on the cusp of the electronics on our wrists
and in our pockets being full of graphene,
but we're still not quite there yet.
But this play bar has not hit the end yet.
There are still weirder,
potentially world-changing carbon structures out there
that we can talk about.
So let's do that.
I would need way more pieces to make this next structure,
so we're gonna have to go to an image.
Scientists have recently made a single layer
of buckyballs all bonded together
that looks a little something like this.
This material could be really interesting
because it's made up of conductive graphene
and insulating buckyballs,
meaning it could be used as a semiconductor
in some new electronic devices.
But how do you actually make something like this?
You can't just stick some buckyballs together
with really teeny-tiny tweezers.
So first, the scientists made buckyballs,
and then they heated the pre-made buckyballs up
with magnesium powder.
So the buckyballs all stuck to each other,
and their negative charges repelled the magnesiums,
creating interspersed sheets of buckyballs and magnesium.
The researchers then swapped the magnesium ions out
for a bucky ion and then were able
to peel the layers apart.
Though, actually, the peeling was described
as manual shaking in the article,
which sounds way more fun.
The result was single layers
of honeycombed buckyballs that were described
by one article as coming apart like layers of bubble wraps.
You can imagine that each one of these little bubbles
is a buckyball all stuck together in a hexagonal pattern.
And then once they had those bucky ions in there,
they were able to just pull those layers apart
and peel them off one by one,
giving you a sheet of buckyballs.
But like the structures before it,
they're still investigating the properties
of this new material,
and they're not 100% sure what it'll be used for yet.
This sounds pretty similar
to basically everything we've talked about so far.
It's a lot of potential,
but not a lot of change in my world right now.
So how close are we actually
to a graphene and carbon-structure-powered future?
How do we get out of this repeating pattern of excitement
and then, honestly, disappointment?
Well, one of the experts I talked to told me
that this time, really, we are close.
Electronic ink, conductive glues,
and electromagnetic shielding using
these structures are already happening.
And the next big thing that companies are tackling
are energy storage technologies using carbon structures
because we all know we need better ways
to store energy right now.
A recent McKenzie report is a little more sedate,
suggesting that while graphene will help
to enhance the current technology
that we've already got over the next 5 to 10 years,
it'll be probably 10 to 25 years
before graphene replaces silicon in our devices,
and 25 plus years before we get the promised technologies
of the future.
So maybe no jet packs quite yet.
But I'll take a better battery.