Performance and stability in H2S of SrFe0.75Mo0.25O3-δ as electrode in proton ceramic fuel cells

The H2S-tolerance of SrFe0.25Mo0.25O3-delta (SFM) electrodes has been investigated in symmetric proton ceramic fuel cells (PCFC) with BaZr0.8Ce0.1Y0.1O3-delta (BZCY81) electrolyte. The ionic conductivity of the electrolyte under wet reducing conditions was found to be insignificantly affected in the presence of up to 5000 ppm H2S. The fuel cell exhibited an OCV of about 0.9 V at 700 degrees C, which dropped to about 0.6 V and 0.4 V upon exposure to 500 and 5000 ppm H2S, respectively, on the fuel side. Post characterization of the fuel cell revealed significant degradation of the anode in terms of microstructure and chemical composition due to formation of sulfides such as SrS, MoS2 and Fe3S4. Nevertheless, the fuel cell was still functional due to the sufficient electronic conductivity of some of these sulfides.