Mixed conductor ceria proven as excellent catalyst for fuel cell anodes

Researchers at the California Institute of Technology have discovered that ceria (or cerium dioxide) is an excellent catalyst for fuel cell anodes. This discovery was made through careful electrochemical characterization using a.c. impedance spectroscopy, an important tool for studying the electrical transport behavior of ceramics. The study is published in the Journal of the American Ceramic Society.

By applying an a.c. electrical voltage to the ceria (a white crystalline powder used in the manufacture of ceramics) and measuring the a.c. electrical current, researchers demonstrated they could precisely quantify the amount of the electrical current carried by the electrons. This information is critical for any application researchers might have in mind for materials which ideally conduct only ions, and, in particular, as the electrolyte in fuel cells.

"This will likely change the way that people perform and interpret the results of a.c. impedance spectroscopy measurements," states Professor Sossina Haile, one of the study researchers. "It turns out that there is more information to be had than people previously understood."

It was further discovered that for the reaction of H2 gas with oxygen ions from the ceramic to form H2O, ceria behaves as its own catalyst. This is significant because this hydrogen electro-oxidation reaction is exactly what takes place in a fuel cell anode. Getting fuel cells to perform efficiently requires getting such electrochemical reactions to occur rapidly.

"There had long been suspicion that ceria was somehow a good thing in the [fuel cell] anodes," adds Professor Haile. "This now clearly explains why and how, and puts the observations beyond debate."

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Sossina M. Haile is associate Professor of Materials Science and Chemical Engineering at the California Institute of Technology. Her research broadly encompasses solid state ionic materials and devices, with particular focus on fuel cells. Ms. Haile is available for questions and interviews. Please call (626) 395-2958 or email smhaile@caltech.edu.

About the Journal of the American Ceramic Society
Published on behalf of the American Ceramic Society, the Journal of the American Ceramic Society is the premier source for ceramic science research, providing scientists, engineers, and students with rigorously peer reviewed, original research for nearly 100 years. Ranked first among all journals in the materials science-ceramics category, the journal publishes 12 issue per year filled with top quality research that spans the diverse segments of ceramic science. Topics cover a broad range including: Glass science, crystal chemistry, microscopy and microstructure, bioceramic science, powder preparation and colloidal science.

About the American Ceramic Society
The American Ceramic Society (ACerS) is a 100-year-old non-profit organization that serves the informational, educational, and professional needs of the international ceramics community. The Society's more than 7,500 members comprise a wide variety of individuals and interest groups that include engineers, scientists, researchers, manufacturers, plant personnel, educators, students, marketing and sales professionals, and others in related materials disciplines. ACerS provides members and subscribers in 80 countries with access to periodicals and books, meetings and expositions, and on-line technical information. Find more information at www.ceramics.org.

About Blackwell Publishing
Blackwell Publishing is the world's leading society publisher, partnering with more than 665 academic, medical, and professional societies. Blackwell publishes over 800 journals and, to date, has published close to 6,000 text and reference books, across a wide range of academic, medical, and professional subjects.


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