Influence of platinum dispersity on oxygen transport resistance and performance in PEMFC

Platinum dispersity on the carbon support is first shown as a factor of local oxygen transport resistance in this work, while its impact on PEMFC performance is also analyzed. The dispersity of platinum is defined as the distribution density of Pt particles on the surface of carbon supports. In order to exclude the influence of catalyst layer thickness, different platinum dispersity cathode catalyst layers are prepared by mechanical mixing Pt/C with different mass ratios, different Pt loadings with the same amount of Pt and carbon in the MEAs to keep the thickness of catalyst layers consistent. Initial fuel cell performance is much higher with lower Pt dispersity. Oxygen transport resistance is measured through limiting current density method, and the total oxygen transport resistance Rtotal, Fick diffusion resistance RF, and local oxygen transport resistance R are calculated. All of them increase at higher Pt dispersity. Platinum dispersity shows obvious influence both on performance and oxygen transport resistance. Thus, increasing the ratio of platinum particles distributed at the surface of carbon supports and the density of platinum particles on carbon supports can be effective ways to solve the problem of performance loss with low Pt loading at high current densities.