'Nano-chocolates' that store hydrogen
Innovative ideas for the energy carrier of the future

Date:
December 27, 2021
Source:
Deutsches Elektronen-Synchrotron DESY
Summary:
An innovative approach could turn nanoparticles into simple storage
devices for hydrogen. The concept uses nanoparticles made of the
precious metal palladium.



FULL STORY ==========================================================================
An innovative approach could turn nanoparticles into simple reservoirs
for storing hydrogen. The highly volatile gas is considered a promising
energy carrier for the future, which could provide climate-friendly
fuels for airplanes, ships and lorries, for example, as well as allowing climate-friendly steel and cement production -- depending on how the
hydrogen gas is generated.

However, storing hydrogen is costly: either the gas has to be kept in pressurised tanks, at up to 700 bar, or it must be liquified, which
means cooling it down to minus 253 degrees Celsius. Both procedures
consume additional energy.


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A team led by DESY's Andreas Stierle has laid the foundations for an alternative method: storing hydrogen in tiny nanoparticles made of the
precious metal palladium, just 1.2 nanometres in diameter. The fact
that palladium can absorb hydrogen like a sponge has been known for
some time. "However, until now getting the hydrogen out of the material
again has posed a problem," Stierle explains. "That's why we are trying palladium particles that are only about one nanometre across." A nanometre
is a millionth of a millimetre.

To ensure that the tiny particles are sufficiently sturdy, they
are stabilised by a core made of the rare precious metal iridium. In
addition, they are attached to a graphene support, an extremely thin
layer of carbon. "We are able to attach the palladium particles to
the graphene at intervals of just two and a half nanometres," reports
Stierle, who is the head of the DESY NanoLab. "This results in a regular, periodic structure." The team, which also includes researchers from
the Universities of Cologne and Hamburg, published its findings in the
American Chemical Society (ACS) journal ACS Nano.

DESY's X-ray source PETRA III was used to observe what happens when
the palladium particles come into contact with hydrogen: essentially,
the hydrogen sticks to the nanoparticles' surfaces, with hardly any of
it penetrating inside. The nanoparticles can be pictured as resembling chocolates: an iridium nut at the centre, enveloped in a layer of
palladium, rather than marzipan, and chocolate-coated on the outside
by the hydrogen. All it takes to recover the stored hydrogen is for a
small amount of heat to be added; the hydrogen is rapidly released from
the surface of the particles, because the gas molecules don't have to
push their way out from inside the cluster.

"Next, we want to find out what storage densities can be achieved using
this new method," says Stierle. However, some challenges still need to
be overcome before proceeding to practical applications. For example,
other forms of carbon structures might be a more suitable carrier than
graphene -- the experts are considering using carbon sponges, containing
tiny pores. Substantial amounts of the palladium nanoparticles should
fit inside these.

========================================================================== Story Source: Materials provided by
Deutsches_Elektronen-Synchrotron_DESY. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Dirk Franz, Ulrike Schro"der, Roman Shayduk, Bjo"rn Arndt,
Heshmat Noei,
Vedran Vonk, Thomas Michely, Andreas Stierle. Hydrogen Solubility
and Atomic Structure of Graphene Supported Pd Nanoclusters. ACS
Nano, 2021; 15 (10): 15771 DOI: 10.1021/acsnano.1c01997 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211227154330.htm

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