Full to the brim with hydrogen: Porous form of magnesium borohydride can store hydrogen

September 29, 2011
Full to the brim with hydrogen: Porous form of magnesium borohydride can store hydrogen

(PhysOrg.com) -- Hydrogen could be one of the most important fuels in a new energy economy based on renewable resources. However, no ideal hydrogen storage material has yet been found. A team led by Yaroslav Filinchuk at the Université Catholique de Louvain, Belgium, and Torben R. Jensen at the University of Aarhus in Denmark has now introduced a new highly porous form of magnesium borohydride in the journal Angewandte Chemie. This material can store hydrogen in two ways: chemically bound and physically adsorbed.

The perfect must store hydrogen efficiently and securely in a small volume, and should release it on demand. It must be rapidly refillable under mild conditions, while being as light and inexpensive as possible. One approach to this is solid-state storage. In such systems, hydrogen can be chemically bound, as in borohydride compounds, or it can be adsorbed as a molecule into a nanoporous material, as in some metal–organic frameworks.

The researchers have now found a material that can do both. It is a new, highly porous form of magnesium borohydride—the first light-metal hydride that is porous like a metal–organic framework and is capable of storing molecular hydrogen.

Magnesium borohydride (Mg(BH4)2) is one of the most promising for chemical because it releases hydrogen at relatively low temperatures and can hold a high proportion by weight (about 15 %) of hydrogen. Two forms of this compound, α and β, were previously known. The researchers have now made a third form, designated the γ form. Its pore volume comprises about 33 % of the structure, and its channels are wide enough to take up and store small gas molecules, such as nitrogen, dichloromethane, and most importantly hydrogen.

Interestingly, under high pressure this material converts into a nested, non-porous framework with a density that is nearly 80 % higher. This makes the δ form the second densest in hydrogen content and more than twice as dense as liquid hydrogen. Furthermore, this conversion results in a 44 % reduction in volume, which is the largest contraction yet observed for a hydride.

“A combination of the chemical (through covalent bonding) and physical (through adsorption in the pores) storage of hydrogen seems to be difficult in practical applications,” explains Filinchuk. “However, this research has a broader impact, as it reveals a new class of hydride-based porous solids for storage and separation of various gases.”

Explore further: Adsorbent materials for hydrogen storage

More information: Yaroslav Filinchuk, Porous and Dense Magnesium Borohydride Frameworks: Synthesis, Stability, and Reversible Absorption of Guest Species, Angewandte Chemie International Edition, dx.doi.org/10.1002/anie.201100675

Related Stories

Adsorbent materials for hydrogen storage

June 27, 2005

A research team from the Public University of Navarra has started a study of the design and development of absorbent materials that enable the storage of hydrogen, a clean fuel that can be used as an alternative to those ...

New form of compound stimulates research on hydrogen storage

December 3, 2007

Research on hydrogen-fueled cars may be one step closer to application thanks to a new form of hydride discovered by scientists at the ESRF. The material, lithium borohydride, is a promising energy storage system: it contains ...

Hydrogen storage in nanoparticles works

March 31, 2008

Dutch chemist Kees Baldé has demonstrated that hydrogen can be efficiently stored in nanoparticles. This allows hydrogen storage to be more easily used in mobile applications. Baldé discovered that 30 nanometre particles ...

On the way to hydrogen storage?

April 19, 2011

(PhysOrg.com) -- The car of the future could be propelled by a fuel cell powered with hydrogen. But what will the fuel tank look like? Hydrogen gas is not only explosive but also very space-consuming. Storage in the form ...

Baking powder for environmentally friendly hydrogen storage

June 14, 2011

(PhysOrg.com) -- Hydrogen is under consideration as a promising energy carrier for a future sustainable energy economy. However, practicable solutions for the easy and safe storage of hydrogen are still being sought. Despite ...

Recommended for you

Moonlighting molecules: Finding new uses for old enzymes

November 27, 2015

A collaboration between the University of Cambridge and MedImmune, the global biologics research and development arm of AstraZeneca, has led researchers to identify a potentially significant new application for a well-known ...

A new form of real gold, almost as light as air

November 25, 2015

Researchers at ETH Zurich have created a new type of foam made of real gold. It is the lightest form ever produced of the precious metal: a thousand times lighter than its conventional form and yet it is nearly impossible ...

Getting under the skin of a medieval mystery

November 23, 2015

A simple PVC eraser has helped an international team of scientists led by bioarchaeologists at the University of York to resolve the mystery surrounding the tissue-thin parchment used by medieval scribes to produce the first ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Oct 04, 2011
Porous sounds the way to go for this as the hydrogen will be able to enter and exit easily. It would be sensitive to water and oxygen though. Are there also metal-hydrocarbon combinations that can make a cage structures?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.