Hydrogen is a much discussed alternative to gasoline for powering cars. It can be burned in a fuel cell to produce water and electrical energy. At the anode of a polymer-electrode fuel cell, hydrogen molecules are split into electrons and protons. At the cathode, the protons combine with oxygen and the electrons, which have traveled around an external circuit, supplying power.
A limiting factor in automotive fuel-cell performance is the slowness of the reaction at the cathode. Platinum is effective in promoting that reaction but it is both expensive and scarce. About 75% of the world’s supply comes from South Africa and most of the rest from Russia. To be cost competitive with internal combustion engines, hydrogen fuel-cell cathodes must lower the Pt content by a factor of four.
Platinum’s high price tag has motivated much research on alternatives for the oxygen reduction occurring at the fuel-cell cathode. The focus...
