There is now a way to build fuel cells that produce as much electricity as current models, but require much less of the precious metal platinum, which means hydrogen-powered cars are one step closer to hitting the street.
As a replacement for a combustion engine, fuel cells are better for the climate and for the environment. One reason is because fuel cells use the fuel much more efficiently and because they emit no smoke, no smog, nor CO2.
Unfortunately fuel cells have a technical limitation. They only work if they contain the metal platinum which is less common and more costly than gold. This has been a big obstacle to the development of the energy efficient power generators.
“A marked reduction in platinum needed is certainly realistic,” said Matthias Arenz, associate professor in the Department of Chemistry at the University of Copenhagen. “And that will be a huge financial advantage.”
In collaboration with researchers from the Technical University München and the Max Planck Institute for Iron Research in Düsseldorf Arenz built and tested a number of catalysts, the devices at the heart of a fuel cell. He is confident his discovery can show the way for economically viable fuel cell production.
“In the lab we have shown, that we can generate the same amount of electricity with just a fifth of the platinum,” he said. “We don’t expect to do quite that well in an everyday situation, but a marked reduction in platinum need is certainly realistic. And that will be a huge financial advantage.”
The precious metal platinum is one of the rarest elements on earth. Most of it is in South Africa, where they mine 80 percent of world production while Russia extracts another ten percent. This means the metal is strategically important.
In 2012 ,world production of platinum was 179 metric tons. By comparison gold production was 2.700 tons. And while the cost of platinum in 2010 was $1.60 per Troy Ounce gold sold at $1.30 for a Troy Ounce.
Fuel cells produce electricity from hydrogen and oxygen in a catalytic reaction which platinum helps keep going. The greatest effect comes from flowing gasses over a sheet or film of platinum, but that requires large amounts of the costly element. Instead, modern fuel cells consist of particles, or little granules, of platinum. Arenz’ group showed these granules could end up placed more efficiently and could then get more productivity.
When tested in the laboratory, catalysts bought on the market today will produce around one Ampere for every milligram of metal. The Arenz group developed a fuel cell catalyst that got eight Amperes per milligram of platinum. Their initial instinct was that they got a bigger power yield, because they had used smaller granules of platinum. But careful measurement revealed something much more surprising.
The key factor leading to platinum savings ended up discovered by accident. They had produced a number of catalysts with varying sizes of platinum particles. By chance on a few of the sample catalysts the particles ended up very tightly packed and as it turned out, the packing of the particles was much more significant than the size. An effect the researchers called the “Particle Proximity Effect.”
Next step will be to develop a chemical method to produce tightly packed catalysts on an industrial scale. Arenz has a few ideas for that as well, so he and his group have started applying for grants.