Polarization curve of a PEM fuel cell with the account of a finite rate of oxygen adsorption on Pt surface

We report a model for performance of the cathode catalyst layer in PEM fuel cell; the model takes into account a finite rate of oxygen adsorption on Pt surface. An analytical polarization curve of the cathode catalyst layer is derived. The curve is fitted to recent experimental polarization curves; the equivalent current density of O2 adsorption on Pt surface is estimated to be 0.18 A  cm P t − 2 . We show that decrease in the cell performance due to finite rate of O2 adsorption at a small catalyst loading can be mitigated by making a gradient electrode with the catalyst loading growing toward the membrane.