The Adsorption of PEM Degradation Products on Pt Catalyst

ABSTRACT

The polymer electrolyte fuel cell is a promising alternative technology for automotive applications, using H₂ gas for power.  After operation, the polymer electrolyte membrane in the fuel cell can degrade and produce organic contaminants that can decrease the fuel cell performance.  Electrochemical quartz crystal microbalance (EQCM) technique was used to determine the effects of organic compounds Da-Naf and Da-3M, representing degradation products from a Nafion^®membrane and a 3M™ membrane, respectively. The effects of Da-Naf and Da-3M concentration on Pt catalyst surface coverage were studied.  By using EQCM with cyclic voltammetry, a richer set of data was obtained than by using cyclic voltammetry alone. The results suggest that both Da-Naf and Da-3M adsorb onto Pt catalyst sites, with Da-3M occupying more sites than Da-Naf, possibly due to a difference in chemical structure. Neither Da-Naf nor Da-3M adsorbed irreversibly to the Pt electrode. Due to the fact that these contaminants can be produced within the fuel cell and their apparent poisoning potential, the poisoning mechanism of both Da-Naf and Da-3M should be studied further.