Under construction: The fuel tank of the future
* 24 November 2008
* Magazine issue 2683. Subscribe and get 4 free issues.
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If the hydrogen economy is ever going to become reality, we will need a way to store the stuff without having to compress it to dangerously high pressures. The gas could then be fed to fuel cells to power the phones, laptops and automobiles of the future.
Just such a technique may now be coming together in a Dutch lab, in the shape of a material in which billions of carbon buckyballs are sandwiched between sheets of graphene - another form of carbon.
The US Department of Energy reckons that to be viable, hydrogen stores should hold at least 6 per cent by weight of the gas. Until now, materials designed to do the job have fallen well short of this target. Metal hydrides which bind loosely to hydrogen can hold only 2 per cent. So the race is on to develop a molecular matrix that can store more.
Last month, George Froudakis and his team at the University of Crete in Greece reported that computer simulations of a layer cake of graphene sheets connected by hollow carbon nanotubes (see right) indicate that it could store 6.1 per cent of its weight in hydrogen (Nano Letters, vol 8, p 3166).
Now Dimitrios Gournis of the University of Groningen in the Netherlands has started to make this exotic sandwich. So far he has created a 40-layer structure in which the sheets are separated by buckyballs, and is aiming to replace these with the nanotubes envisaged by Froudakis by the end of the year. The next step will be to fill the structures with hydrogen to see whether Froudakis's predictions hold true.