Imperfect Graphene Leads to Better Fuel Cells
Scientists have spent years trying to perfect the art of making the most efficient fuel cells, but what a recent study shows is that graphene naturally has a few tiny holes in it, and this imperfect nature can actually lead to better fuel cells.
"We found if you just dial the graphene back a little on perfection, you will get the membrane you want," chemist Franz M.Geiger, who led the research, said in a news release. "Everyone always strives to make really pristine graphene, but our data show if you want to get protons through, you need less perfect graphene."
Graphene - called graphite when stacked together and found in your everyday pencils - is a strong, transparent material that is great at conducting electricity, making it ideal in the production of electronics, such as batteries used in electric cars.
However, a major challenge when it comes to fuel cell technology in particular is efficiently separating protons from hydrogen. In a study of single-layer graphene and water, researchers from Northwestern University found that slightly defective graphene transports protons - and only protons - from one side of the graphene membrane to the other in just seconds. Compared to conventional membranes, this flawed method is much quicker and opens the doors to a new, simpler mechanism for fuel cell design.
Previous research has indicated that flawless graphene was the way to go, and that defects would cause the material to lose its highly conductive properties. However, now this new study shows that is not the case.
"Imagine an electric car that charges in the same time it takes to fill a car with gas," Geiger explained. "And better yet - imagine an electric car that uses hydrogen as fuel, not fossil fuels or ethanol, and not electricity from the power grid, to charge a battery. Our surprising discovery provides an electrochemical mechanism that could make these things possible one day."
To create the single-layer of graphene - the thinnest proton channel in the world at only one atom layer thick - Geiger's team removed a few carbon atoms from the normally pristine honeycomb structure. What they found was that the graphene formed significantly better. The protons can quickly slip through the imperfections in mere seconds, efficiently generating electricity.
With standard fuel cell membranes, which are hundreds of nanometers thick, proton selection normally takes minutes - that's much too long to put it to any practical use. But with this new method, researchers hope that a graphene membrane could lead to improved technologies, such as fast-charging batteries for transportation, wind or solar power plants.
"Our results will not make a fuel cell tomorrow, but it provides a mechanism for engineers to design a proton separation membrane that is far less complicated than what people had thought before," Geiger said. "All you need is slightly imperfect single-layer graphene."
The results were published in the journal Nature Communications.
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