Hydrogen oxidation and oxygen reduction at Pt microelectrode on polymer electrolytes

In order to improve the activities of the materials for polymer electrolyte fuel cells, it is important to know not only the quality of the polymer el ectrolyte but the reactions at the electrolyte. In this study, the oxygen r eduction reaction (O. R. R.) and hydrogen oxidation reaction (H. O. R.) on Pt microelectrode have been investigated using different equivalent weight (EW) in the temperature range of 30 to 70 degrees C. The diffusion coeffici ent and the solubility of oxygen and hydrogen in the electrolytes were also measured by the electrochemical methods. The solubility of oxygen and hydr ogen increased with increase of the hydrophobic moiety, i.e., high EW value and the reverse tendency was observed with diffusion coefficient for both gases. No significant dependence of EW was observed for O. R. R. and H. O. R. The water content in the polymer electrolyte affected more for these fac tors, compare to EW.