As automakers ramp up their plans to put greener vehicles on the road, hydrogen storage has become a pivotal issue. Whereas it's been suggested that graphene could play an important role in retaining hydrogen for use in fuel cells and other technologies, a team of researchers at the National Institute of Standards and Technology (NIST) and the University of Pennsylvania in Philadelphia say they've found a way to configure graphene that enables it to hold 100 times more hydrogen molecules than a single layer of the carbon-based substance.
The trick is stacking oxidized graphene sheets atop one another "like the decks of a multilevel parking lot, connected by molecules that both link the layers to one another and maintain space between them," the researchers reported Thursday at the March meeting of the American Physical Society (APS) in Portland, Ore. They call the resulting configuration a "graphene-oxide framework."
The researchers claim that such a framework might be used not only to store hydrogen but to release it when it is needed, a fundamental requirement in fuel cell applications.
Research into graphene's hydrogen storage capabilities is gaining momentum. Kayvan Rafiee, a Rensselaer Polytechnic Institute Ph.D. candidate in mechanical engineering, won a $30,000 Lemelson–M.I.T. Student Prize earlier this month for his work developing a way to line a hydrogen vehicle's fuel tank with a one-atom-thick layer of graphene.
The challenges to making an automobile run on hydrogen are primarily those of hydrogen production, storage, distribution and energy conversion. From a technology perspective, storage is the most difficult of the four, Rafiee says. As a gas, hydrogen is a very low density material and difficult to store. "We need a cheap, porous material to store and release hydrogen at low pressure and at room temperature, and it needs to be a reversible process, for when the tank needs to be refilled," he says, adding that he and his colleagues are working on a business plan that will help them commercialize their work.