Electrode Reactions in Hydrogen Fuel Cells (AQA GCSE Chemistry) : Revision Note

Electrode reactions in hydrogen fuel cells

Higher tier only

• The cell consists of an electrolyte which is usually phosphoric acid and porous carbon electrodes coated with a catalyst

• Hydrogen enters at the anode where it is oxidised and oxygen enters at the cathode where it is reduced

• The following reaction occurs at the anode:

2H₂ → 4H⁺ + 4e^–

• The following reaction occurs at the cathode:

4H⁺ + O₂ + 4e^– → 2H₂O

• The overall reaction is:

2H₂ + O₂→ 2H₂O

• The electrons move around the external circuit from the anode to the cathode

• This movement of electrons is used to drive an electric motor