Effect of platinum dispersity, platinum loading and Pt-Oxide coverage on oxygen reduction reaction in PEMFC-Cathode

Abstract

The dispersion of platinum, as well as its charge are parameters which influence the oxygen reduction reaction in the cathode side of a PEM (Proton-Exchange Membrane) fuel cell. Therefore, they play an important role in the optimization of these performances. The impact of platinum dispersity and platinum loading on PEM fuel cell are analyzed in this work. The effect of platinum oxide coverage is also incorporated in the ORR (Oxygen reduction reaction) kinetic expression. A mathematical model has been developed using the electrochemical equations and the kinetics of the reactions on the cathode side. Different combinations of platinum dispersity and platinum charge were used to identify which ones led to the best performance. The model was validated using experimental data obtainable from scientific literature. The results showed that, when the current density is set at 0.4 A, a high dispersity of the Pt decreases the voltage generated by the cell by 0.05 V for a charge density of the Pt of 0.4 mg.cm-2. In addition, the voltage can reduce by 0.08 V for a density charge of the Pt of 0.3 mg.cm-2, and can reach 0.12 V for a charge density of the Pt of 0.2 mg.cm-2. Also, the results showed that the effect of the charge of the Pt is greater when the dispersity is large. However, its influence decreases when the dispersity is low. Therefore, we can reduce the charge of the Pt in the cathode of the PEMFC (Polymer Electrolyte Membrane Fuel Cell) fuel cell if we ensure better dispersity and subsequently a reduction in its cost.