New Fuel Cell Polymer Is Platinum-Free
Fuel cells are, in principle, the most efficient way to convert hydrogen fuel into electricity. But they require expensive catalysts such as platinum to split hydrogen into ions and electrical current. Cheaper metals simply can't withstand the harsh acidic environment of the fuel cell. Now researchers in China have developed a fuel cell that uses a new membrane material to operate in alkaline conditions, eliminating the need for an expensive catalyst. The power output of the new prototype, which uses nickel as a catalyst, is still relatively low, but it provides a first demonstration of a potentially much less expensive fuel cell.
Conventional fuel cells consist of two electrodes coated with a platinum catalyst that splits hydrogen fuel into acidic hydrogen ions and electrons. The electrodes are separated by a polymer membrane that conducts acidic hydrogen ions from one side to the other, creating an external electrical current. The new fuel cell, developed by researchers led by Lin Zhuang, a professor of chemistry at Wuhan University, in Wuhan, China, uses a new membrane that conducts alkaline ions called hydroxyl groups. Alkaline fuel cells work by reacting hydrogen and oxygen to create hydroxyl ions and water, a reaction catalyzed in the Wuhan University fuel cell by the nickel anode. The hydroxyl ions are conducted across the polymer membrane, generating an external electrical current.
Most researchers have been focused on acidic fuel cells because membranes that work well under such conditions have already been developed. A stable hydroxyl-conducting membrane has been "the holy grail of electrochemistry," says Robert Savinell, a professor of chemical engineering at Case Western Reserve University, in Cleveland. Such a membrane would allow researchers to build fuel cells and batteries that don't require precious-metal catalysts but can use cheaper ones like nickel.
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