Graphene could store hydrogen safely in fuel cell applications
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Graphene now appears to be a promising base material for capturing hydrogen, according to recent research undertaken by the US National Institute of Standards and Technology (NIST) and the University of Pennsylvania. The findings suggest stacks of graphene layers could potentially store hydrogen safely for use in fuel cells and other applications.
The researchers say that, if oxidized graphene sheets are stacked and connected by molecules that not only link the layers, but also maintain space between them, the resulting graphene-oxide framework (GOF) can accumulate hydrogen in greater quantities.
NIST theorist Taner Yildirim said: "What we have found so far indicates that GOFs can hold at least a hundred times more hydrogen molecules than ordinary graphene oxide. The easy synthesis, low cost and non toxicity of graphene make this material a promising candidate for gas storage applications."
The GOFs can retain 1% of their weight in hydrogen at a temperature of 77K and ordinary atmospheric pressure – comparable to the 1.2% that metal organic frameworks can hold.
The researchers also discovered that, although a GOF can absorb hydrogen, it does not take in significant amounts at below 50K. Moreover, it does not release any hydrogen below this 'blocking temperature'. This, says the team, suggests that GOFs might be used not only to store hydrogen, but also to release it when it is needed, a fundamental requirement in fuel cell applications.
