Mitigation studies of sulfur contaminated electrodes for PEMFC

The performance of Polymer Electrolyte Membrane Fuel Cell (PEMFC) is highly influenced by the contaminants present in the air, like sulfur compounds, nitrogen compounds, carbon oxides, chlorides etc. In particular, sulfur dioxide (SO2) on the cathode side has a severe effect on the performance of PEMFC. In the present paper we have attempted to mitigate the effect of SO2 poisoned catalyst layer of the fuel cell for both half cell and for single cell using a novel catalyst support. The mitigation strategies for the contaminated MEAs were studied by three different methods viz., electrochemical cycling, increased air stoichiometry and by successive polarization. The platinum on graphene as a catalyst support was found to have a better tolerance towards SO2 contamination when compared with the conventional platinum supported on Vulcan XC carbon catalyst. Electrochemical and single cell contamination tests were done to study the extent of SO2 poisoning on both the catalysts. The sulfur coverage was found to be less for Pt/G based catalyst, around 54% compared with Pt/C. The recovery by successive polarization was found to be better compared to air flow regulation. This may be attributed to the indirect removal of sulfur ions from Pt through scavenged OH− ions.