Literature and our group studies indicated that foreign cations have severe effects on the performance and durability of the PEMFC. Among all cations, Ca2+ deserves special attention because it is one of the most abundant elements within the earth’s crust. Prior efforts have focused on the effects of Ca2+ on PEMFC operation [8-10] and membrane transport properties . However, the effects of Ca2+ on the ORR kinetics have hardly been studied. Okada et al.  studied the effects of Ca2+ on the O2 reduction kinetics at a Nafion® film covered Pt rotating disk electrode. Their results showed that impurity ions, even in small amounts, significantly hinder the rate of the O2 reduction charge transfer step. However, the Nafion® film covered Pt electrode is different from the supported catalyst layer for a PEMFC. The O2 transport properties in a Ca2+ form ionomer are poorly understood. In addition, the H2O2 yield has not been measured. In this presentation, detailed analyses of the changes in the Pt/C electrochemical surface area, ORR diffusion-limited and kinetic currents, Tafel slope, H2O2 yield, O2 permeability and ionomer sulfonate site occupation will be presented and discussed.
Authors are grateful to the United States Department of Energy (award DE-EE0000467), the Office of Naval Research (award N00014-12-1-0496), and the Hawaiian Electric Company.
 R. O’Hayre, D.M. Barnett, and F.B. Prinz, J. Electrochem. Soc., 152, A439 (2005).
 B. Millington, S. Du, and B.G. Pollet, J. Power Sources, 196, 9013 (2011).
 T. Okada, H. Satou, M. Okuno, and M. Yuasa, J. Phys. Chem. B, 106, 1267 (2002).
 M.F. Serincan, U. Pasaogullari, and T. Molter, Int. J. Hydrogen Energy, 35, 5539 (2010).
 J. St-Pierre, J. Power Sources, 196, 6274 (2011).
 M.A. Uddin, and U. Pasaogullari, J. Electrochem. Soc., 161, F1081 (2014).
 J. Durst, M. Chatenet, and F. Maillard, Phys. Chem. Chem. Phys., 14, 13000 (2012).
 J. Qi, X. Wang, M.O. Ozdemir, M.A. Uddin, L. Bonville, U. Pasaogullari, and T. Molter, J. Power Sources, 286, 18 (2015).
 X. Wang, J. Qi, O. Ozdemir, A. Uddin, U. Pasaogullari, L.J. Bonville, and T. Molter, J. Electrochem. Soc., 161, F1006 (2014).
 M.A. Uddin, J. Qi, Xiaofeng Wang, U. Pasaogullari, and L. Bonville, Int. J. Hydrogen Energy, 40, 13099 (2015).
 T. Okada, N. Nakamura, M. Yuasa, and I. Sekine, J. Electrochem. Soc., 144, 2744 (1997).
 T. Okada, J. Dale, Y. Ayato, O.A. Asbjørnsen, M. Yuasa, and I. Sekine, Langmuir, 15, 8490 (1999).