In Situ, ionic conductivity measurement of ionomer/binder-free Pt catalyst under fuel cell operating condition

This paper presents an experimental investigation of the ionic conductivity within ionomer-free, extended surface platinum (Pt) electrodes. Nanostructured thin film (NSTF) electrodes with low platinum loading and no ionomer binder offer comparable power densities to conventional Pt/C electrodes under properly humidified conditions and are a promising electrode for cost reduction and improved durability. Despite these advantages, the charge transport on these electrodes is not clearly understood. Here we present a new in situ technique that we have applied to directly measuring the ionic conductivities within operating polymer electrolyte fuel cell (PEFC) electrodes made of Pt black catalyst without an ionomer or binder. The effects of various fuel cell conditions such as electrode polarization, oxygen concentration, and humidity are investigated.