Ultra-strong graphene's weak spot could be key to fuel cells

[December 02, 2014]  By Kate Kelland
 
 LONDON (Reuters) - In a discovery that experts say could revolutionize fuel cell technology, scientists in Britain have found that graphene, the world's thinnest, strongest and most impermeable material, can allow protons to pass through it.

The researchers, led by the Nobel prize winner and discoverer of graphene Andre Geim of Manchester University, said their finding also raised the possibility that, in future, graphene membranes could be used to "sieve" hydrogen gas from the atmosphere to then generate electricity.

"We are very excited about this result because it opens a whole new area of promising applications for graphene in clean energy harvesting and hydrogen-based technologies," said Geim's co-researcher on the study, Marcelo Lozada-Hidalgo.

Graphene, the thinnest material on earth at just one atom thick, and 200 times stronger than steel, was first isolated in 2004 by Geim and fellow researchers, who were awarded a Nobel Prize in 2010 for their work.

It is renowned for being impermeable to all gases and liquids, giving it the potential for a range of uses such as corrosion-proof coatings, impermeable packaging and even super-thin condoms.

Knowing that graphene is impermeable to even the smallest of atoms, hydrogen, Geim's team decided to test whether protons, or hydrogen atoms stripped of their electrons, were also repelled. Their work was published in the journal Nature.

Against expectations, they found the protons could pass through the ultra-strong material fairly easily, especially at raised temperatures and if the graphene films were covered with nanoparticles such as platinum, which acted as a catalyst.

Geim and Lozada-Hidalgo, explaining their finding in a telephone briefing for reporters, said this meant graphene could in future be used in proton-conducting membranes, a crucial component of fuel cell technology.

Fuel cells, used in some modern cars, use oxygen and hydrogen as fuel and convert the input chemical energy into electricity. But a major problem is that the fuels leak across the existing proton membranes, "poisoning" the process and reducing the cells' efficiency -- something Geim said could be overcome using graphene.

The team also found that graphene membranes could be used to extract hydrogen from the atmosphere, suggesting the possibility of combining them with fuel cells to make mobile electric generators powered just by the tiny amounts of hydrogen in the air.

"Essentially, you pump your fuel from the atmosphere and get electricity out of it," Geim said. "Our (study) provides proof that this kind of device is possible."

(Reporting by Kate Kelland; Editing by Kevin Liffey)

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