Breakthrough could make hydrogen vehicles more feasible

Science Notes: Less platinum generates more promise for fuel cells' potential

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Only a few of the roughly one billion cars and trucks on global roads run on hydrogen. This could change after a breakthrough achieved by researchers at the University of Copenhagen, a new catalyst that can be used to produce cheaper and far more sustainable hydrogen powered vehicles.

Hydrogen has held potential as an alternative fuel for vehicles for years. It is attractive because the process exhausts only water. The challenge has been to make hydrogen fuel cells that don’t rely on a large amount of platinum to serve as a catalyst in their fuel cells. About 50 grams has been needed per hydrogen-powered vehicle. Typically, vehicles only need about five grams of this rare and precious material. Indeed, only 100 tonnes of platinum are mined annually, in South Africa.

Researchers at the University of Copenhagen’s Department of Chemistry have developed a catalyst that doesn’t require such a large quantity of platinum.

“We have developed a catalyst which, in the laboratory, only needs a fraction of the amount of platinum that current hydrogen fuel cells for cars do. We are approaching the same amount of platinum as needed for a conventional vehicle. At the same time, the new catalyst is much more stable than the catalysts deployed in today’s hydrogen powered vehicles,” said Professor Matthias Arenz from the Department of Chemistry.

Sustainable technologies are often challenged by the limited availability of the rare materials that make them possible, which in turn, limits scalability. Due to this current limitation, it is impossible to simply replace the world’s vehicles with hydrogen models overnight.

“The new catalyst can make it possible to roll out hydrogen vehicles on a vastly greater scale than could have ever been achieved in the past,” said Professor Jan Rossmeisl, center leader of the Center for High Entropy Alloy Catalysis at UCPH’s Department of Chemistry.

The new catalyst improves fuel cells significantly, by making it possible to produce more horsepower per gram of platinum. This in turn, makes the production of hydrogen fuel cell vehicles more sustainable.

Because only the surface of a catalyst is active, as many platinum atoms as possible are needed to coat it. A catalyst must also be durable. Herein lies the conflict. To gain as much surface area as possible, today’s catalysts are based on platinum-nano-particles that are coated over carbon. Unfortunately, carbon makes catalysts unstable. The new catalyst is distinguished by being carbon-free. Instead of nano-particles, the researchers have developed a network of nanowires characterized by an abundance of surface area and high durability.

“With this breakthrough, the notion of hydrogen vehicles becoming commonplace has become more realistic. It allows them to become cheaper, more sustainable and more durable,” said Rossmeisl.

The research results have been published in Nature Materials.

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