PEMFC Cathode Contamination Evaluation with Membrane Conductivity Cell, CA, CP, CV, EIS, GC/MS and ISE - Acetonitrile

Acetonitrile contamination in proton exchange membrane fuel cells (PEMFCs) was studied in situ with chronoamperometry, chronopotentiometry, cyclic voltammetry, electrochemical impedance spectroscopy, gas chromatography/mass spectroscopy, and ex situ with a membrane conductivity cell, ion selective electrode. PEMFCs significantly lost and partially regained performance for all tested electrodes. A significant effect on the membrane proton conductivity was noted in PEMFC but not in conductivity cells. The impact was dependent on the applied potential. Acetonitrile adsorption inhibits the hydrogen oxidation/evolution and the Pt oxidation and PtOx reduction reactions. Several peaks located at 0.17/0.22, 0.40/0.58, 0.65/0.78 V, and 0.9 V vs the hydrogen reference electrode were attributed to the redox of acetonitrile intermediates and products. Clear mechanistic insights were highlighted but a more complete integration of all these results and others obtained with a rotating ring/disc electrode (RRDE) will lead to a more definitive version of the acetonitrile contamination mechanism.