Catalysts All Around Us

Fuel cells (continued)

Proton exchange membrane fuel cell

Fuel cells have been developed to power buses and cars. In the proton exchange membrane fuel cell (PEMFC), a platinum coating on the anode helps split hydrogen supplied to it into protons and electrons

2H2

4H+ + 4e-

Making the circuit

The protons pass through a thin membrane to reach the cathode. The electrons go round an external circuit before also reaching the cathode. At the cathode another platinum catalyst helps oxygen supplied to it to combine with the protons and electrons to produce water and heat.

O2 + 4e + 4H+

2H2O

Some vehicles use gasoline or methanol as the fuel. This is first converted (reformed) into hydrogen for use in the fuel cell. Platinum/ruthenium anodes are needed since pure platinum would be poisoned by any carbon monoxide or carbon dioxide in the hydrogen stream.

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