Scientists Build Graphene Trap For Hopping Protons

Chalk up another score for the fuel cell electric vehicle of the future, because US scientists have discovered a defect in graphene that lets protons — and only protons — “hop” through it. Graphene is an ultralight, ultrastrong material that is already being eyeballed for energy storage, and the new discovery could lead to the development of a new generation of fuel cell membranes.

Don’t run out to your local fuel cell EV dealer just yet, but US taxpayers can go ahead and give themselves a pat on the back. The new graphene discovery was mapped out using an ultra-powerful microscope at the Energy Department’s Oak Ridge National Laboratory.

Holy Hopping Protons, Batman!

Along with our sister site Gas2.org we’ve gone on and on (and on and on) about the many applications of graphene in clean technology, including electric vehicle batteries, but the fuel cell thing is a new one on us.

Apparently, it surprised the folks at ORNL, too. Although graphene is only one atom thick, it is incredibly strong, which is why we call it the nanomaterial of the new millennium. Until now, graphene was thought to be impermeable, limiting its use as a membrane.

The researchers found that defects in graphene act as highly selective molecular-scale “gates” that allow protons to “hop” through in “surprising numbers,” while keeping even the very smallest molecules out. That goes for you, too, hydrogen and helium.

The image above shows one such hopping proton in pink.

How To Trap A Hopping Proton

Speaking of group hugs, the ORNL project was a collaboration among 15 researchers in different fields including chemical vapor deposition techniques and electron microscopy.

To track the movement of the protons, the team fabricated a layer of graphene floating on a few molecules of water over silica glass.

This acted as a “trap for the hopping protons:”

Changes in the acidity of the aqueous solution on either side of the graphene layer revealed the covert gating mechanism in the material’s structure, which they were able to detect using a laser technique called second harmonic generation.

Second harmonic generation, btw, refers to an extremely sensitive technique for analyzing the chemical interface between two materials, without blowing either of them to bits.

You can read the whole study in Nature Communications under the title “Aqueous proton transfer across single-layer graphene.”

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Image Credit: Courtesy of Oak Ridge National Laboratory.