The fascinating material graphene is naturally filled with honeycomb-like holes, but new research suggests fewer holes could create a proton-selective membrane that could be used to improve fuel cells.
One of the largest challenges in fuel technology is successfully separating protons from hydrogen, Northwestern University reported. 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.
"Imagine an electric car that charges in the same time it takes to fill a car with gas," said chemist Franz M. Geiger, who led the research. "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."
Protons are relatively large in the atomic world, and researchers do not believe they would be able to pass through a layer of perfect graphene at room temperature.
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.
"Everyone always strives to make really pristine graphene, but our data show if you want to get protons through, you need less perfect graphene," Geiger said.
The team found that removing only a few carbon atoms caused others to become highly reactive, jumpstarting the proton shuttling process.
"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 findings were published in a recent edition of the journal Nature Communication.
