An atomically thin membrane with microscopically small holes may prove to be the basis for future hydrogen fuel cells, water filtering and desalination membranes, according to a group of 15 theorists and experimentalists, including three theoretical researchers from Penn State University.

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One of the largest challenges in fuel technology is successfully separating protons from hydrogen. A team of researchers found that slightly imperfect graphene shuttles exclusively protons from one side of the material in a matter of seconds. The demonstrated speed and selectivity is far superior to what has been seen in the past.

The team, led by Franz Geiger of Northwestern University tested the possibility of using graphene, the robust single atomic layer carbon, as a separation membrane in water and found that naturally occurring defects -- essentially a few missing carbon atoms -- allowed hydrogen protons to cross the barrier at unprecedented speeds.

While many researchers strive to make graphene defect-free to exploit its superior electronic properties, Geiger's team found that graphene required the vacancies to create water channels through the membrane. Computer simulations carried out at Penn State and the University of Minnesota showed the protons were shuttled across the barrier via hydroxyl-terminated atomic defects, that is, by oxygen hydrogen groups linked at the defect.

"Imagine an electric car that charges in the same time it takes to fill a car with gas. 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," said Geiger.

The research team looked at graphene exposed to water and found the protons were moving through the graphene. Using laser techniques, imaging methods and computer simulations, the scientists found naturally-occurring flaws in the material triggered a "chemical merry-go-round" in which protons on one side of the graphene were quickly shuttled through the material.

The team found that removing only a few carbon atoms caused others to become highly reactive, jumpstarting the proton shuttling process.

The new study was published in Nature Communications.

TagsImperfect Graphene Improves Fuel Cell Design, Graphene, fuel cell, protons, Hydrogen, carbon atoms, Carbon, Atoms, hydrogen fuel cells