Cathode: O2(g) + 2H2O(l) + 4e–-----> 4OH–(aq)
Anode: 2H2 (g) + 4OH–(aq)-----> 4H2O(l) + 4e–
Overall reaction being:
2H2(g) + O2(g) ----->2H2O(l )
Advantages: (i) Fuel cells are efficient and free from pollution.
(ii) The only product in the reaction of fuel cell is water which can be removed and the astronauts of a spacecraft can drink it.