On the influence of the Pt to carbon ratio on the degradation of high surface area carbon supported PEM fuel cell electrocatalysts

Abstract

In the presented work we investigate the influence of the Pt to carbon ratio on the degradation behavior of Pt based proton exchange membrane fuel cell (PEMFC) catalysts. In order to enable a systematic investigation, we utilized a recently developed colloidal synthesis approach for preparing catalysts with identical Pt nanoparticles (NPs), but varying Pt loadings. Two different commercially available, standard carbon supports were used, Vulcan XC72 and Ketjenblack EC-300. We evaluated the influence of the platinum loading on the electrochemical surface area (ECSA) loss by applying accelerated stress tests simulating a load-cycle in a PEMFC and start-up/shutdown conditions. Simulating load cycles, no clear influence of the Pt loading on the ECSA loss is observed, whereas the ECSA loss significantly increases with increasing Pt loading when simulating start-up/shutdown conditions.