Impedance analysis of working pemfcs in the presence of carbon monoxide

A three-electrode membrane electrode assembly including anode, cathode, and pseudoreference electrode was used in a working proton exchange membrane fuel cell (PEMFC). The pseudoreference electrode was directly prepared onto a Nafion membrane by an impregnation-reduction method. The electrochemical behaviors of the anode and cathode were separately studied when this three-electrode cell performed. The CO tolerance of the fuel cell with various anode compositions of RuPt 0.12-3.33 was investigated with both polarization curves and ac impedance analysis. An equivalent circuit model was proposed to explain the impedance spectra for both the anode and the cathode. With the presence of CO, the overpotential due to CO poisoning on the anode was due to the increase of both charge-transfer resistance and ohmic resistance in the catalytic layer.