Imperfectly-formed graphene could pave the way for better and more efficient fuel cells

Imperfectly-Formed Graphene To Create More Efficient Fuel Cells-1

Who knew that a substance, so minute as to be completely invisible to the human eye, could solve half of the world’s problems? From being hailed as the world’s strongest material to being a game-changer in the fields of medicine, electronics and energy development, graphene still continues its glorious career as a wonder material. What is more, scientists now believe that even defective graphene is quite precious. Thanks to its naturally-formed imperfections, this atomic-scale allotrope of carbon has been found to allow swift passage of protons; a property that could eventually lead to better and more efficient fuel cells.

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As some might already know, graphene is a two-dimensional lattice of carbon atoms, which are in turn arranged in a honeycomb pattern. In case of improperly-formed graphene, however, the missing carbon atoms actually create gaps in the otherwise perfectly-uniform structure. Now coming to proton exchange membrane (PEM) fuel cells, one of the major drawbacks of the available technology is the lengthy process of isolating protons from hydrogen. In general, a polymer electrolyte membrane allows hydrogen ions (i.e. protons) to pass, while being impermeable to electrons. As these membranes are several hundred nanometres in thickness, the entire process of proton selection takes quite a long time to complete.

Graphene, on the other hand, is a lot thinner. Being a single-atom-thick layer, it could easily replace traditional fuel cell membranes. However in its flawless form, graphene is impervious to protons at room temperature. In an unexpected chain of events, scientists have discovered that when exposed to water, the gaps present in defective graphene actually allow protons to flow through them. Unlike conventional polymer electrolyte membranes, the two-dimensional graphene accomplishes the task of channelling the protons, from one of its sides to the other, in seconds. Talking about the research, whose findings were recently published in the Nature Communications journal, a professor of chemistry and a team member, Franz M. Geiger said:

We found if you just dial the graphene back a little on perfection, you will get the membrane you want. Everyone always strives to make really pristine graphene, but our data show if you want to get protons through, you need less perfect graphene.

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According to the group, the imperfections in the single graphene layer actually create what is currently being deemed as the world’s thinnest proton exchange membrane. Based on their observations, which were carefully recorded using computer simulations, advanced imaging techniques and lasers, the researchers concluded that in the presence of water, improperly-built graphene becomes permeable to protons. Only a handful of these gaps, per square-micron area of a sheet of graphene, has been found to be sufficient to set off the process. Geiger said:

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. All you need is slightly imperfect single-layer graphene.

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The team believes that the breakthrough could help engineers design better and more efficient fuel cells. Speaking about its potential applications, Geiger was reported saying:

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.

The project was the outcome of a research consortium including Northwestern University, Pennsylvania State University, the University of Minnesota, the University of Virginia and a few other institutions.

Via: Northwestern University / Nature Communications

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