Solar Powered Cars that Emit Water Instead of Carbon Emissions
By September 21st, 2009Monday, September 21, 2009 2:32 on
Materials science and engineering assistant professor Dane Morgan and Ph.D. student Edward (Ted) Holby are working to bring solar powered cars that will produces water instead of carbon emissions. They have created a computational model that could optimize an important component of fuel cells, making it possible for the technology to have a more widespread use. If the particle size of fuel cell catalyst is increased then the degradation can be reduced to a considerable amount, increasing the useful life time of fuel cell.
In the type of fuel cells Morgan is researching, called proton exchange membrane fuel cells, or PEMFCs, hydrogen is split into a proton and electron at one side of the fuel cell (the anode). The proton moves through the device while the electron is forced to travel in an external circuit, where it can perform useful work. At the other side of the fuel cell (the cathode), the protons, electrons and oxygen combine to form water, which is the only waste product.
Though the premise sounds straightforward, there are multiple hurdles to producing efficient fuel cells for widespread use. One of these hurdles is the catalyst added to aid the reaction between protons, electrons and oxygen at the cathode. Current fuel cells use platinum and platinum alloys as a catalyst. While platinum can withstand the corrosive fuel cell environment, it is expensive and not very abundant.
To maximize platinum use, researchers use catalysts made with platinum particles as small as two nanometers, which are approximately 10 atoms across. These tiny structures have a large surface area on which the fuel cell reaction occurs. However, platinum catalysts this small degrade very quickly.
Researchers have founded that if the particle size of a platinum catalyst is increased to four or five nanometers, which is approximately 20 atoms across, the level of degradation significantly decreases. This means the catalyst and the fuel cell as a whole can continue to function for much longer than if the particle size was only two or three nanometers.
The research into the fundamental physics of particle size will be useful as scientists extend their platinum studies to exploring platinum alloys, which can reduce platinum consumption when used as fuel cell catalysts. Morgan is beginning to research models to study size effects on the stability of platinum alloys, such as copper-platinum and cobalt-platinum catalysts.
[Original Source: AazoCleanTech]
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