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Is hydrogen-economy 'go' after nanocomposite breakthrough?

By Martin Leggett - 14 Mar 2011 16:4:0 GMT
Is hydrogen-economy 'go' after nanocomposite breakthrough?

Harnessing the potential of hydrogen to power the economy, cleanly and efficiently, has been the dream of scientists for more than 3 decades. Hydrogen is limitlessly abundant, in water molecules, has a high energy density, and emits only water vapor when combusted.

Unfortunately it can also be dangerously explosive. But now a collaborative effort, involving the DOE and Berkeley Lab, has successfully produced a nanocomposite material capable of storing hydrogen safely - and at practical temperatures that have so far eluded other researchers.

First generation solutions to storing hydrogen, to be used in hydrogen-powered vehicles for instance, focused on compression and liquefaction. These could successfully pack a lot of hydrogen into a small space, but also required a lot of energy and technology to keep it there.

That made hydrogen-powered vehicles relatively costly and inefficient - and also prone to explosive risks in an accident.

The new generation of hydrogen storage solutions has tried getting round these problems by squeezing hydrogen into solid composite materials. Hydrogen has a very small atomic size (it is the smallest most basic of all the elements) and so can be packed quite tightly even into solids.

Most materials tried, however, have run into problems of storing adequate volumes at everyday temperatures - requiring extremes of cooling or heating.

Now the team at the Lawrence Berkeley's Molecular Foundry, in conjunction with Berkeley's Energy and Environmental Technologies Division, has successfully fabricated and tested a nanocomposite.

This is made of a Plexiglas-like polymer impregnated with nanoparticles of magnesium metal, and can rapidly absorb and discharge hydrogen. This happens without any of the chemical reactions required in other materials.

The new flexible hydrogen-storage material also works well at moderate temperatures, and so is a great candidate for hydrogen batteries and fuel cells. Jeff Urban, Deputy Director of the Inorganic Nanostructures Facility (a DOE science center at Berkley) said ''This work showcases our ability to design composite nanoscale materials that overcome fundamental thermodynamic and kinetic barriers to realize a materials combination that has been very elusive historically.'

The ability of the material to store hydrogen was confirmed using an advanced electron microscope, known as TEAM 0.5, developed by the National Center for Electron Microscopy.

Co-author of the paper, Christian Kisielowski, which will appear in the journal Nature Materials, said ''We confirmed the presence of hydrogen in this material through time-dependent spectroscopic investigations with the TEAM 0.5 microscope. This investigation suggests that even direct imaging of hydrogen columns in such materials can be attempted using the TEAM microscope.''