A weak spot found in otherwise ultra-strong graphene -- the thinnest, strongest and least permeable material known to science -- could in fact be a boon and could lead to a revolution in fuel cell technology, researchers say.
Research at Britain's Manchester University led by Andre Geim -- who shared a Nobel Prize for the discovery of graphene -- has shown that the material is not quite as impermeable as previously though and will, in fact, allow protons to easily pass through it.
This quality could be utilized in the future to create graphene membranes that could "sieve" hydrogen gas directly out of the air to be used to generate electricity, the researchers say.
"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," says a co-researcher in Geim's study, Marcelo Lozada-Hidalgo.
Graphene, at a carbon atom thick, is 200 times as strong weight-for-weight as steel.
Its impermeability to atoms of any gas or liquid has made it a candidate for use in impermeable packaging and corrosion-proof coating.
Although even the smallest atoms cannot pass through graphene, Geim and his researchers suspected that protons -- hydrogen atoms that have been stripped of their electrons -- might find a way through.
Confirming that they could in fact do so means graphene could be used as proton-conducting membranes, considered a vital component in developing fuel cells, the researchers said in a report of their study published in the journal Nature.
Fuel cells and other hydrogen-based technologies require a barrier that only allow hydrogen protons to pass through, they point out.
A significant problem with existing fuel cells is that the fuels that allow them to convert chemical energy into electricity leak across their membranes, reducing the cell's efficiency by "poisoning" the chemical processes -- something the researchers say can be solved using graphene.
"When you know how it should work, it is a very simple setup," Lozada-Hidalgo says. "You put a hydrogen-containing gas on one side, apply small electric current and collect pure hydrogen on the other side. This hydrogen can then be burned in a fuel cell."
Although the scientists worked with very small membranes yielding tiny flows of hydrogen, the technology to make large graphene sheets exists, notes researcher Sheng Hu.
"Because graphene can be produced these days in square meter sheets, we hope that it will find its way to commercial fuel cells sooner rather than later," Hu says.
