Polymer Electrolyte Membrane fuel cells (PEMFC) convert the chemical energy of the oxidation reaction

O₂ + 2H₂ à 2H₂O,

into useful electrical energy by dividing the reaction into two steps. The Hydrogen Oxidation Reaction (HOR):

H₂ à_Pt 2H⁺ + 2e⁻,

is completed on the anode, while the Oxygen Reduction Reaction (ORR):

O₂ + 4H⁺ + 4e⁻ à _Pt 2H₂O,

takes place on the cathode. The anode and cathode are separate by a membrane which is a good protonic conductor and a poor electrical conductor, and is more or less impermeable to gas phases. The voltage, and power, produced by the fuel cell depends upon the concentrations of the reactants, particularly the oxygen and protons at the cathode.

In typical operation hydrogen gas is blown down a flow field on the anode side of the cell, while air (oxygen+nitrogen) is blown down a flow field on the cathode side. Roughly 10-20% of the hydrogen which enters the anode flow field is not consumed and one wishes to recirculate this fuel to increase efficiency. However, nitrogen has the tendency to cross over the membrane from the cathode to the anode and contaminate the hydrogen effluent. The goal is to develop a model for the PEMFC operation which includes nitrogen cross over, and devise a strategy to mitigate its impact.