Fuel Cells

Galvanic cells that are designed to convert the energy of combustion of fuels like hydrogen, methane, methanol, etc. directly into electrical energy are called fuel cells.

EMF of A Galvanic Cell

Hydrogen oxygen fuel cell

Vidyarthi Academy

Fuel cell using O2 and H2

Electrodes - Made of porous graphite impregnated with catalyst (Pt, Ag or a metal oxide).

Electrolyte - Aqueous solution of KOH or NaOH

Oxygen and hydrogen are continuously fed into the cell.

Reactions      

Cathode: O2(g) + 2H2O(l) + 4e– → 4OH–(aq)

Anode: 2H2(g) + 4OH–(aq) → 4H2O(l) + 4e–

Overall reaction:

2H2(g) + O2(g) → 2 H2O(l )

Efficiency of cell - 70%, Efficiency of thermal plants – 40%

Cell potential - 1.23 V