Revving Up Fuel Cells
Progress toward hydrogen-powered cars depends on less expensive but greater capacity fuel-cell systems [see “On the Road to Fuel-Cell Cars”; SciAm, March 2005]. Researchers have taken big steps on both the cost and storage challenges. A team from Quebec came up with a recipe that uses iron instead of expensive platinum to catalyze the electricity-making reaction of hydrogen and oxygen. The key was carbon structures containing microscopic pores, which were filled with iron to provide plenty of active sites for chemical reactions. The iron-based substance, described in the April 3 Science, produced catalytic activity within 10 percent of the best platinum versions and 35 times better than previous, nonprecious metal catalysts.
Pores are also driving the search for materials that can store hydrogen for delivery to fuel cells. A team from the University of Michigan at Ann Arbor says it has made a material that has a record-high surface area for holding gases. This hydrogen sponge consists of zinc oxide clusters linked by an organic material; one gram has the surface area of 5,000 square meters, nearly the size of a football field. Details of the substance, dubbed UMCM-2, appear in the April 1 Journal of the American Chemical Society.
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