Electrochemical Oxidation of H[sub 2] and H[sub 2]∕CO Mixtures in Higher Temperature (T[sub cell]>100°C) Proton Exchange Membrane Fuel Cells: Electrochemical Impedance Spectroscopy

Abstract

Electrochemical impedance spectroscopy (EIS) of the electrochemical oxidation of and mixtures on the proton exchange membrane fuel cell anode ( or electrocatalysts) was performed at higher temperature and ambient pressure. Anode polarization studies were also conducted with the same mixture-fed streams. Both impedance and anode polarization provide information on the mechanism of electrochemical oxidation of and mixtures. The impedance spectra are presented and compared at various CO concentrations (, 1 and 2%), cell temperatures , relative humidity conditions , as well as different dc bias potentials for characterizing the CO tolerance of the electrocatalysts. CO poisoning is alleviated by increasing the cell temperature, and relative humidity plays a strong role in the EIS and anode polarization. The impedance spectrum of the CO poisoned anode is strongly dependent on the dc bias potential. Under certain dc bias potential conditions, pseudoinductive behavior appears in the complex impedance plots, corresponding to the onset oxidation of CO as indicated from anode polarization.