Developments in membrane-electrode assembly and stack technology have significantly improved the performance of polymer electrolyte membrane fuel cells; such that systematic studies focused on improving major challenges of overall cost and durability have become increasingly important. Consequently, interest in the examination of system derived impurities and their subsequent effects on performance durability has grown.Studies involving commercial polymer electrolyte membranes and model compounds have shown that when perfluorinated sulfonic acid (PFSA) membranes are exposed to hydroxyl radicals during fuel cell operating conditions, several chemical decomposition products can be generated. Along with losses in membrane conductivity and structural integrity, such PFSA membrane degradation products may also adsorb on the platinum based electrocatalyst, possibly leading to a loss in catalyst electrochemical surface area (ECA), oxygen reduction reaction (ORR) activity, or both.This work investigates adsorption characteristics and effects from seven model compounds, representing PFSA membrane chemical degradation species, on ECA and ORR activity for platinum based electrocatalysts including polycrystalline Pt, high surface area carbon supported Pt, and extended surface Pt. Adsorption properties due to carboxylate and sulfonate functional groups, fluorocarbon chain length, and model compound concentration investigated using a variety of electroanalytical techniques including cyclic and linear sweep voltammetry, electrochemical quartz crystal microbalance, and electrochemical surface-enhanced infrared absorption spectroscopy (SEIRAS) will be reported.The authors would like to acknowledge funding from the U.S. Department of Energy and collaborations with colleagues at 3M and GM. Membrane degradation products for this study were provided by 3M.

Adsorption characteristics of polymer electrolyte membrane chemical degradation products and their impact on oxygen reduction reaction activity for platinum catalysts

248th National Meeting (2014)

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