FRONTIER RESEARCH
Making materials just one atom
thick
19 September 2016
by Aisling Irwin
A sophisticated ultra-high vacuum system lets researchers create tiny, perfect 2D materials. Image courtesy of Dr Manuela Garnica
Alonso
In Germany, Dr Manuela Garnica Alonso peers into a massive machine of shining steel that
sprouts wires, tubes, clusters of portholes, aluminium foil and industrial bolts.
The inside of the chamber is less than a trillionth of the air pressure in the surrounding lab. It also
contains a heater that can reach thousands of degrees and a microscope capable of imaging surfaces
down to the level of the atom.
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Dr Garnica’s goal is to create tiny but completely
perfect materials in just two dimensions.
See also
Sometimes she simply wants to prove that they can,
indeed, be coaxed into existence. Other times the goal
is to thoroughly understand their physics, and
sometimes she has also ‘decorated’ them with atoms
and molecules, just to see what happens.
Atom-scale sensors and
quantum bits – scaling the
possibilities of 2D tech
She is at the leading edge of an explosion in making
2D materials since a one-atom-thick layer of carbon
known as graphene was first isolated in 2004 by pulling
sticky tape across the surface of a pencil.
2D materials could expand
our understanding of gravity
– Prof. Kirill Bolotin
Tales of the second
dimension
Atom-thick solution to energy
storage conundrum
In a recent paper published in Nature Chemistry, Dr
Molecules rev up for world’s
Garnica, who is based at the Technical University of
tiniest race
Munich, and her colleagues report that they have
managed to make a new type of structure by fusing
other organic molecules to the edges of graphene – a
novel way of giving graphene interesting properties that could find applications in technology and
medicine.
‘It is the first time that it’s been proved that graphene can be functionalised by this method,’ said Dr
Garnica, who has been funded by the EU under the Marie Skłodowska-Curie Actions programme.
To make graphene, Dr Garnica heats a rod of graphite to thousands of degrees until a few atoms of
carbon gently lift away and lay themselves, in a single layer, on a crystal of silver.
She also wants to make a 2D layer of silicon carbide, highly anticipated amongst theorists as a
semiconductor that could rival silicon, the material that forms the basis for the electronic circuits we
use today.
She is simultaneously vaporising graphite and a wafer of silicon, in the hope that their atoms will nestle
together into a honeycomb lattice atop another crystal of silver.
The goal is to thoroughly understand 2D materials at an atomic level. That’s because, since graphene
was first discovered in Manchester, UK, 2D layered materials are giving engineers the tools they need
to create the highly efficient and flexible devices needed for a low-carbon world.
‘It is just one of hundreds, if not thousands of layered materials,’ explained Professor Jonathan
Coleman at Trinity College Dublin, Ireland, who has now created 25 different 2D materials – and he’s
still going.
Blender
He’s at the other end of the scale, making 2D materials using the laboratory equivalent of a kitchen
blender.
Prof. Coleman perfected his technique on graphene, dissolving graphite in soapy water and then
blending it.
The blades slice through the liquid with a shear
energy that slides graphite layers apart, and the
soapy water swiftly coats each flake, preventing
them from clumping back together.
Boron nitride, an effective insulator, was next. ‘It’s
the simplest after graphene,’ said Prof. Coleman.
Soon after came molybdenum disulphide, which as
it turns out can hold three to four times as much
electric charge as the graphite that is traditionally
used in lithium-ion batteries. He has also created a
2D version of nickel hydroxide, a catalyst which
could improve the quality of fuel cells, which make
electricity from hydrogen and oxygen.
‘Nanoscience
doesn’t have to be
complicated, it
doesn’t have to be
high tech.’
Prof. Jonathan Coleman,
Trinity College Dublin,
Ireland
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To his surprise, Prof. Coleman’s blender technique
has also managed to make phosphorene – one of
the potential high-flyers of the 2D world because,
like silicon carbide, it promises to be a semiconductor to rival silicon.
Although it is very unstable, he found that if he adds certain liquids to the mix they will protect the
sheets of phosphorene from chemicals that might react with it, leading to a substance that might be
useful in batteries and gas sensors.
‘Nanoscience doesn’t have to be complicated, it doesn’t have to be high tech,’ said Prof. Coleman, who
has been funded by the EU’s European Research Council.
‘It can be quite simple, and that’s actually really important.’
Prof. Coleman discussing graphene at TEDxBrussels.
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