Diamonds are fuel cells' best friends
Researchers at UC Davis have used nanocrystals made of diamond-like cubic zirconia to develop cooler fuel cells. Even if hydrogen fuel cells have been touted as clean energy sources, current fuel cells have to run at high temperatures of up to 1,000 °C. This new technology will allow fuel cells to run at much lower temperatures, between 50 and 100 °C. Obviously, this could lead to a widespread use of fuel cells, which could become a realistic alternative power source for vehicles. The researchers have applied for a patent for their technology, but don't tell when fuel cells based on their work are about to appear.
This invention has been done by a team led by Zuhair Munir, professor of chemical engineering and materials science, Umberto Anselmi-Tamburini and Sangtae Kim, an assistant professor in the same department.
Here is how UC Davis describes the invention. The researchers "invented a method to make oxides such as cubic zirconia (zirconium oxide) with extremely small grain sizes, on the order of 15 nanometers. A nanometer is one-billionth of a meter, or the size of a few atoms. At that scale, the crystals conduct electricity very well, through the movement of protons. The material could be used in fuel cells that are based on chemical oxides."
In "Cubic zirconia could make more cost effective fuel cells," Lucian Dorneanu provides a good perspective on the future use of this technology (Softpedia, July 10, 2007). "Since all fuel cells are based on oxides, this new material could be used to increase their efficiency and to reduce the costs, by reducing the needed temperature and replacing precious platinum. Fuel cells are very useful as power sources in remote locations, such as spacecraft, remote weather stations, large parks, rural locations and in certain military applications. A fuel cell system running on hydrogen can be compact, lightweight and has no major moving parts. Because fuel cells have no moving parts and do not involve combustion, in ideal conditions they can achieve almost 100% reliability.
This technology is based on a research work published by Applied Physics Letters under the name "Enhanced low-temperature protonic conductivity in fully dense nanometric cubic zirconia" (Volume 89, Issue 16, Article 163116, October 16, 2006). Here is a link to the abstract. "The authors report on the consolidation of nanostructured bulk cubic zirconia with a grain size of about 15 nm and a relative density greater than 98%. This material exhibits a change in the conduction mechanism with considerable protonic conductivity when exposed to moisture. The marked reduction of the resistivity of zirconia at low temperatures brings it to a level comparable to that typical of other protonic conductors, but with the advantage of superior mechanical and chemical stabilities."
For more information, you can read the technology description of the pending patent about "Fuel Cells Using Low-Temperature Conducting Materials." "Researchers at the University of California, Davis, have developed a novel method to fabricate nanometric oxides that exhibit enhanced conductivity by a different mechanism. Conduction in these materials (e.g., cubic zirconia and other materials with similar properties) takes place by protonic movement as opposed to ionic mobility, making it possible to operate a fuel cell at much lower temperatures. The marked reduction of the resistivity in these materials at low temperatures are comparable to that typical of other protonic conductors, but with the advantage of superior mechanical properties, chemical stabilities, and the lack of need for a catalyst."
Sources: UC Davis News, July 9, 2007; and various websites
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