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| Subatomic proton particles, as produced by this "Synergium" machine, can penetrate super material graphene, it has been discovered (AFP File) |
Scientists
said Wednesday they had found a chink in the impermeable armour of graphene,
the world's thinnest material, and one of the strongest.
The team said
they were surprised to see the super material known to repel all gases and
liquids, let through sub-atomic particles called protons.
And they
hailed the unexpected finding as a potential breakthrough for fuel cells -- a
non-polluting version of a traditional battery.
"The
discovery could revolutionise fuel cells and other hydrogen-based technologies
as they require a barrier that only allow protons -- hydrogen atoms stripped of
their electrons -- to pass through," said a statement from Manchester
University, whose researchers took part in the work.
Protons,
along with neutrons, make up the nuclei of atoms, the building blocks of
matter.
At just one
atom thick -- many times thinner than a human hair, graphene is stronger than
steel and acts as a barrier to even the smallest of atoms, hydrogen -- making
it a perfect ingredient for impermeable coatings and packaging materials.
Led by
physicist Andre Geim, awarded the Nobel in 2010 for his work on graphene, a
research team set out to test whether protons, like atoms and molecules, would
also be repelled by graphene.
They
"fully expected that protons would be blocked, as existing theory
predicted as little proton permeation as for hydrogen," said the statement
of the findings published in the journal Nature.
"Despite
the pessimistic prognosis, the researchers found that protons pass through the
ultra-thin crystals surprisingly easily, especially at elevated
temperatures..."
This made
graphene an excellent candidate for proton-conducting membranes key to efficient
fuel cell technology, said the statement.
Fuel cells,
a kind of battery used in some electric cars and backup power generators, for
example, use oxygen and hydrogen as a fuel and convert chemical energy into
electricity.
They
require membranes that allow protons to pass through, but not other particles.
"It
looks extremely simple and equally promising. Because graphene can be produced
these days in square metre sheets, we hope that it will find its way to
commercial fuel cells sooner rather than later," said study co-author
Sheng Hu.
Graphene
was aired as a theoretical substance in 1947. But for decades, physicists
thought it would be impossible to isolate, as such thin crystalline sheets were
bound to be unstable.
The problem
was resolved in 2004 by Geim and Konstantin Novoselov, who used ordinary sticky
tape to lift a layer from a piece of graphite.
That layer
was itself pulled apart using more tape, and the process repeated until just
the thinnest of layers remained -- a graphene sheet.
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