Effects of Hydrogen Sulfide on the Performance of a PEMFC

An exploratory study of H 2 S poisoning of membrane electrode assemblies (MEAs) in proton exchange membrane fuel cells (PEMFCs) consisting of Pt and Pt-Ru alloy electrodes is presented. Steady-state polarization curves are reported for each electrode after exposure to 50 ppm H 2 S at 70°C. Significant findings include ( i ) partial recovery of the MEA after 3.8 h of exposure to H 2 S ; ( ii ) the degree of the recovery is influenced by the electrochemical oxidation of two surface species observed during cyclic voltammetry experiments; ( iii ) in contrast to CO poisoning, Ru has no effect on increasing MEA tolerance toward H 2 S poisoning; and ( iv ) increasing the Pt loading by 60% appears to quadruple the partially recovered current density at 0.6 V ( i.e. , 0.125 A / cm 2 for Pt-Ru alloy and 0.575 A / cm 2 for Pt electrodes) after exposure to neat H 2 for 24 h.