Development of innovative approach to hydrogen storage

An innovative method transforms nanoparticles into simple reservoirs for storing hydrogen.

Development of innovative approach to hydrogen storage
The palladium nanoparticles (green) are stabilized by a core of iridium (red). Hydrogen can accumulate on their surface as a kind of chocolate icing – and can be released again when heated. Image credit: DESY, Andreas Stierle.

The highly volatile gas is a hopeful energy carrier for the future, which can offer climate-friendly fuels for, for example, trucks, ships and aircraft and enable climate-friendly steel and cement production.

However, storing hydrogen is expensive: either the gas must be stored in pressurized tanks, at up to 700 bar, or liquefied. This involves cooling to -253 ° C. Both procedures add extra energy.

Research led by DESY’s Andreas Stierle has laid the foundation for an alternative technique: storing hydrogen in small nanoparticles made from the valuable metal palladium, only 1.2 nm in diameter. The fact that palladium can absorb hydrogen like a sponge has been well known for some time.

However, until now it has been a problem to get the hydrogen out of the material again. Tos why we try palladium particles that are only about a nanometer across.

Andreas Stierle, Leader, NanoLab, Deutsches Elektronen Synchrotron

To guarantee that the small particles are sufficiently robust, they are stabilized by a core made of the rare useful metal iridium, and are attached to a graphene support – an extremely thin layer of carbon.

We are able to attach the palladium particles to the graph at intervals of only two and a half nanometers. This results in a regular, periodic structure.

Andreas Stierle, Leader, NanoLab, Deutsches Elektronen Synchrotron

The team also includes researchers from the universities of Cologne and Hamburg and has published its research results in the journal American Chemical Society (ACS) ACS Nano.

DESY’s X-ray source PETRA III was used to observe what happens when the palladium particles come in contact with hydrogen: Basically, the hydrogen fits into the surfaces of the nanoparticles, where almost none of it penetrates.

The nanoparticles could be depicted as resembling chocolate: an iridium nut in the center, enclosed in a layer of palladium instead of marzipan, and chocolate coated on the outside of the hydrogen.

All one has to do to recover the stored hydrogen is that a small amount of heat is added; the hydrogen is rapidly discharged from the surface of the particles as the gas molecules do not have to exit from inside the cluster.

Next, we want to find out what stock densities can be achieved with this new method.

Andreas Stierle, Leader, NanoLab, Deutsches Elektronen Synchrotron

But there are few challenges that should be overcome before moving on to practical applications. For example, other types of carbon structures may be a more suitable support compared to graphene. The experts considered using carbon sponges, consisting of small pores, where significant amounts of the palladium nanoparticles must fit.

Journal reference:

Franz, D., et al. (2021) Hydrogen solubility and atomic structure of graphene-supported Pd nanoclusters. ACS Nano.


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