Dec 13, 2007
Nitride nanocrystals for fuel cell catalysts
A new type of nanocrystal electrocatalyst for fuel cells has been developed by scientists in China and the US. The non-noble chromium nitride material might be a real alternative to expensive platinum in years to come.
Polymer electrolyte membrane fuel cells (PEMFCs) have a high energy-conversion efficiency, which makes them promising for applications in transport. They are thought to be the best type of fuel cell to eventually replace the gasoline and diesel internal combustion engine. Although platinum is widely used as the catalyst in PEMFCs, because it is very active, this noble metal is expensive – something that is holding back the wider use of PEMFCs today.
Now, Huamin Zhang of the Chinese Academy of Sciences in Dalian and colleagues have put forward a possible alternative to this noble metal. While the catalytic activity of chromium nitride (CrN) nanocrystals is still somewhat lower than that of platinum, it is a non-noble material. If compared to other such materials being investigated for PEMFCs, it does have a comparatively better activity, says Zhang.
"This work is the first report of the material as a fuel cell catalyst," he told nanotechweb.org. "Further optimization in the preparation of CrN could enhance its activity, making it a truly cost-effective alternative to platinum."
Zhang and co-workers tested the electrochemical activity of their catalysts by trying them out in a single fuel cell. They found that the material showed platinum-like catalytic activity and was stable in a PEMFC at temperatures of up to 80 °C.
The researchers hope to significantly improve their material within three years. They will do this by optimizing its chemical composition and the way that the catalyst is prepared. They will also develop a membrane electrode assembly manufacturing process to further enhance the activity of the catalyst.
When this is done, the material might be readily available on the market because it is easy and cheap to make, says Zhang.
The results were presented in Appl. Phys. Lett..
About the author
Belle Dumé is contributing editor at nanotechweb.org