Engineers in Australia have demonstrated that hydrogen can be released
and reabsorbed from a promising storage material, overcoming a major hurdle to
its use as an alternative fuel source.
For the first time, engineers in
Australia have demonstrated that hydrogen can be released and reabsorbed from a
promising storage material, overcoming a major hurdle to its use as an
alternative fuel source.
Considered a major a fuel of the
future, hydrogen could be used to power buildings, portable electronics, and
vehicles – but this application hinges on practical storage technology.
Lightweight compounds known as
borohydrides (including lithium and sodium compounds) are known to be effective
storage materials but it was believed that once the energy was released it could
not be reabsorbed. This critical limitation made sodium borohydride an oft
overlooked chemical compound for energy storage.
In a paper published recently in
the journal ACS Nano, researchers from the Materials Energy Research Laboratory
in nanoscale (MERLin) at the University of New South Wales (UNSW) synthesized
nanoparticles out of sodium borohydride and encased these inside nickel shells.
“No one has ever tried to
synthesize these particles at the nanoscale because they thought it was too
difficult, and couldn’t be done. We’re the first to do so, and demonstrate that
energy in the form of hydrogen can be stored with sodium borohydride at
practical temperatures and pressures,” said senior author Dr. Kondo-Francois
Aguey-Zinsou.
In this study, the researchers
observed remarkable improvements in the thermodynamic and kinetic properties of
their unique “core-shell” nanostructures. This means the chemical reactions
needed to absorb and release hydrogen occurred faster than previously studied
materials, and at significantly reduced temperatures – making possible
application far more practical.
In its bulk form, sodium
borohydride requires temperatures above 550 °C just to release hydrogen. Even
on the nanoscale the improvements were minimal. But with their core-shell
nanostructure, the researchers saw initial energy release happening at just 50
°C, and significant release at 350 °C.
“By controlling the size and
architecture of these structures we can tune their properties and make them
reversible – this means they can release and reabsorb hydrogen,” said
Aguey-Zinsou.
“We now have a way to tap into
all these borohydride materials, which are particularly exciting for
application on vehicles because of their high hydrogen storage capacity.”
The paper can be downloaded at: Christian ML et al. (2012) A
Core-Shell Strategy Leading to High Reversible Hydrogen Storage Capacity for
NaBH4.
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Source: UNSW.
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