Characterization of CO tolerance of PEMFC by ac impedance spectroscopy

The CO tolerance of a proton exchange membrane fuel cell (PEMFC) was invest igated by ac impedance spectroscopy. The impedance of the fuel cell could b e obtained by feeding oxygen into the cathode side and simulated gas into a node side. Furthermore, the anode impedance could be obtained by feeding hy drogen into the cathode side and simulated gas into anode side. The CO gas had a greater effect on the charge transfer reaction thigh frequency are) a nd hydrogen dissociative chemisorption (medium frequency are) but little ef fect on the low frequency are. Although the cathode impedance is a main par t at high temperature, irrespective of CO concentration (less than or equal to 100 ppm), the impedance of the full cell depends on anode impedance at low temperature and high CO concentration. It was found that CO gas has lit tle effect on cathode impedance. (C) 2001 Published by Elsevier Science B.V .