New Oxide Catalyst Support Generation for PEFC - Application in Meas, Performance and Stability Issues

The stability of fuel cell performance still remains a significant challenge for polymer electrolyte fuel cell (PEFC) technology. The well-known carbon corrosion degradation process [1] leads to an intense research for an alternative catalyst support materials. One of the actual trends in this field is focused on conductive metal oxide development, as they can exhibit a high electrochemical stability when used in their highest oxidation states, and can be tailored with a high specific surface compatible with the targeted PEFC application.

Up to date, the literature reports stability studies for new oxide catalyst supports but the degradation protocols are realised at the laboratory level (typically room temperature, high potential range, non-optimised catalytic layer) [2].  Only few data are available regarding the processing of these new alternative supports for Pt in a PEFC and their stability under real working conditions of the derived MEAs.

For this purpose Pt/IrTiO₂ and Pt/Sb-doped SnO₂ (SbSnO₂) catalysts were studied. Pt/IrTiO₂ provided by Umicore^® was used as a model catalyst, whereas Pt/SbSnO₂ catalyst was synthesized in our laboratories. For this purpose, a SbSnO₂ powder was first synthesized by a modified sol-gel method. Platinum nanoparticles obtained by the polyol method [4] were further deposited on this oxide support. Different cathodes were prepared by direct spraying of optimised suspensions of Pt/IrTiO₂ and Pt/SbSnO₂ catalyst nanoparticles on a Nafion^® XL-100 membrane.

The fuel cell performances and stabilities of the various membrane-electrode assemblies are examined in details. The results are compared with the MEAs based on the state of the art Pt/C (46%wt on High surface area carbon, Tanaka) catalyst and prepared by the same spraying procedure.

Acknowledgement

The authors thank Umicore AG & Co KG and the Competence Center for Energy and Mobility (CCEM) Switzerland for their financial support within the project DuraCat.

References

[1] F.N. Buchi, M. Inaba, T.J. Schmidt, editors. Polymer Electrolyte Fuel Cell Durability, Springer(2009).

[2] Y. Takabatake, Z. Noda, S.M. Hayashi, K. Sasaki, International Journal of Hydrogen Energy 39,   5074-5082 (2014).

[3] E. Fabbri, A. Rabis, R. Kötz, T. J. Schmidt, Physical Chemistry Chemical Physics 16, 13672-13681 (2014).

[4] E. Fabbri, A. Patru, A. Rabis, R. Kötz, T. J. Schmidt, Chimia 68, 217–220 (2014).