Single Pore Modeling of Oxygen Reduction in Ionomer-free Catalyst Layers of PEFCs

摘要

We present a continuum single pore model of oxygen reduction in ionomer-free, ultrathin catalyst layers (UTCLs) of PEFCs. We postulate that protons are transported into water-fooded pores through their electrostatic interaction with the metal surface charge density. The previously developed steady state variant of the model showed the potential of zero charge of the metal phase to be a crucial parameter determining the electrocatalytic performance of the UTCL. In the present work, we outline equivalent circuit representations for the impedance response in various limiting cases. In contrast to the response of electrolyte-filled pores, all circuit elements are highly dependent on applied potential. We discuss the capabilities of the model to determine the kinetic, electrostatic, and transport contributions to the overall Faradaic current density, and metal|solution interfacial pa rameters of UTCL materials.