A recently discovered form of carbon graphite – the material in pencil lead – has turned out to have a completely unexpected property which could revolutionise the development of green energy and electric cars.

Researchers have discovered that graphene allows positively charged hydrogen atoms or protons to pass through it despite being completely impermeable to all other gases, including hydrogen itself.

The implications of the discovery are immense as it could dramatically increase the efficiency of fuel cells, which generate electricity directly from hydrogen, the scientists said.

The breakthrough raises the prospect of extracting hydrogen fuel from air and burning it as a carbon-free source of energy in a fuel cell to produce electricity and water with no damaging waste products.

“In the atmosphere there is a certain amount of hydrogen and this hydrogen will end up on the other side [of graphene] in a reservoir. Then you can use this hydrogen-collected reservoir to burn it in the same fuel cell and make electricity,” said Professor Sir Andrei Geim of Manchester Univeristy.

Ever since its discovery 10 years ago, graphene has astonished scientists. It is the thinnest known material, a million times thinner than human hair, yet more than 200 times stronger than steel, as well as being the world’s best conductor of electricity.

Until now, being permeable to protons was not considered a practical possibility, but an international team of scientists led by Sir Andre, who shares the 2010 Nobel Prize for his work on graphene, has shown that the one-atom thick crystal acts like a chemical filter. It allows the free passage of protons but forms an impenetrable barrier to other atoms and molecules.

“There have been three or four scientific papers before about the theoretical predictions for how easy or how hard it would be for a proton to go through graphene and these calculations give numbers that take billions and billions of years for a proton to go through this same membrane,” Sir Andrei said.

“It’s just so dense an electronic field it just doesn’t let anything through. But it’s a question of numbers, no more than that. This makes a difference between billions of years and a reasonable time for permeation. There is no magic,” he said.

Click HERE to view full-size graphic

The study, published in the journal Nature, shows that graphene and a similar single-atom-thick material called boron nitride allowed the build-up of protons on one side of a membrane, yet prevented anything else from crossing over into a collecting chamber.

In their scientific paper, the researchers speculate that there could be many applications in the field of hydrogen fuel cells and in technology for collecting hydrogen gas from the atmosphere, which would open up a new source of clean energy.

“It’s really the very first paper on the subject so what we’re doing is really to introduce the material for other experts to think about it,” Sir Andrei said.

What could graphene be used for Show all 8 1 /8 What could graphene be used for What could graphene be used for Sensitive medical sensors Graphene, strands of DNA, and fluorescent molecules sensitive to particular diseases can be combined to create sensors that diagnose diseases with sensitivity down to a single atom Creative Commons What could graphene be used for Green cars Graphene is incredibly conductive as well as relatively stable and strong with enormous surface area. It has a potential to be the ideal electrode material, which could enhance electric batteries, hydrogen fuel cells, and 'ultracapacitors' for green cars Getty What could graphene be used for Better transport Graphene is a reallystrong and lightweight material. It mixes well with all sorts of plastics such as epoxy to make composites which have enormous strength-to-weight ratios. It can be used to produce things such as wind turbine blades. These composites could also be used in creation of safer transport, where they replace metals in the manufacture of aircraft and cars, making them lighter and more fuel-efficient Creative Commons What could graphene be used for Flexible displays The graphene products can be used in production of electronic paper, bendable personal communications devices and flexible touch screen displays Creative Commons What could graphene be used for Ultrafast computing Most of computers and electronic devices are built by stacking silicon semiconductors and other elements on top of one another. By using graphene in a single layer formation researchers expect to get much faster performance out of tiny, nano-scale transistors such as a microchip used in a hearing aid Rex What could graphene be used for Artificial retinas Graphene could in future be used to make artificial retinas as it conducts electrical signals really well and is also chemically sensitive, as well as being flexible and strong in the same time Creative Commons What could graphene be used for Cheaper solar power Graphene could be used to make solar cells out of carbon instead of more costly materials. That would lower the costs of solar power and simplify the manufacturing process, making clean energy more affordable Creative Commons What could graphene be used for Explosives detection Graphene's chemical sensitivity could also make the material effective at detecting explosives. Sensors coated with graphene can detect the presence of low levels of vapors from chemicals used in explosives, such as ammonia Getty

“It was difficult not to speculate. If you can pump protons from a hydrogen-containing gas into a chamber that doesn’t contain anything, you start thinking how you can exploit this?” he said.

“One of the possibilities we can imagine, however futuristic, which has to be emphasised because everything has been shown on a small scale, is applying a small electric current across the membrane and pushing hydrogen though the graphene or boron nitride membrane,” he explained.

“Essentially you pump your fuel from the atmosphere and get electricity out of this fuel, in principle. Before this paper, this wouldn’t even be speculation; it would be science fiction. At least our paper provides a guidance and proof that this kind of device is possible and doesn’t contradict to any known laws of nature,” Sir Andre added.

Graphene: potential uses

Graphene is tough, about 200 times stronger than steel, yet incredibly light. It is considered the first two-dimensional material because it forms sheets of crystal that are just one atom thick.

It is also an excellent conductor of electricity, so is useful for anything involving electronics, such as bendable mobile phones and cameras, and wearable electrical devices attached to clothing.

Water purification is among graphene’s potential global uses (Getty) (Getty Images)

Medical applications include its possible use as a material for delivering drugs to damaged sites within the body, which could open new avenues for treating patients with brain conditions such as Parkinson’s disease or cancer.

Graphene is also being developed as a new material for membranes involved in separating liquids. It could be used to purify water in the developing world or to create more efficient desalination plants.

Scientists also believe that graphene’s high strength and low weight can be harnessed in the making of new composite materials and polymers for the transport industry, making travel safer and more fuel efficient.