Mitigation studies of sulfur contaminated electrodes for PEMFC

•Mitigation studies for sulfur contaminated PEMFC electrode has been done.•Pt/G catalyst is be more tolerant towards SO2 than Pt/C catalyst.•Successive polarization is found to be a better method for recovery compared to air flow regulation.•Cycling method is an ideal method for half cell studies.

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.

Graphical abstractSulfur dioxide (SO2) present in the air feed stream has a detrimental effect on the performance of Polymer Electrolyte Membrane Fuel Cell (PEMFC). The platinum on graphene as a catalyst support was found to have better tolerance towards SO2 contamination than the tolerance level of conventional platinum supported on Vulcan XC catalyst. Electrochemical and single cell contamination tests were performed to study the extent of SO2 poisoning on both the catalysts. Figure optionsDownload full-size imageDownload as PowerPoint slide