Degradation of polymer electrolyte fuel cells under the existence of anion species

The degradation of Pt supported on carbon catalysts (Pt/C) due to four anion species (Cl−, F−, SO42−, NO3−) was investigated by operation tests using single cells of a polymer electrolyte fuel cell (PEFC). A loss of cell voltage and of electrochemical surface area (ECA) of the cathode catalyst, and an increase in oxygen gain were shown only when a solution containing Cl− was supplied. Scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis after 50 h tests showed partial Pt dissolution and deposition in the membrane (Pt band) only in the inlet-side of the membrane electrode assembly (MEA). The partial loss of Pt led to the concentration of current density and degradation of cell performances.