NOVEL ELECTRODES FOR POLYMER BASED FUEL CELLS

Research on fuel cells has intensified during the last years due to the increasing demand for energy supply and for reduction of environmental pollution. One particular class of fuel cells are polymer electrolyte membrane fuel cells which are used in the transportation as well as stationary sector. The centerpiece is the membrane electrode assembly consisting of polybenzimidazole-based membrane and two electrodes that are subjected to harsh conditions during operation. As a result, degradation occurs, which limits the lifetime of the fuel cells. In order to minimize such effects, new electrode materials need to be developed and tested. In our study, we investigated nanometer-size Pt / Ru catalysts on carbon support material and analyzed their aging behavior in various conditions in detail [1,2]. Coupled cyclo-voltammetry and scanning transmission electron microscopy experiments were conducted on identical nanoparticles which revealed that dissolution and agglomeration are the essential degradation mechanism [1]. In continuous fuel cell operation, Pt and Ru diffuse into the membrane where they deposit again as nanoparticles with a different crystal structure and composition [2]. Another electrode type was testes where novel platinum networks were grown on tungsten oxide support materials [3]. Here, we were able to discover the growth mechanism and to correlate the accompanying lower degradation rate to the high stability of the networks.

[1] K. Hengge, T. Gänsler, E. Pizzutilo, C. Heinzl, M. Beetz, K. J. J. Mayhofer, C. Scheu, International Journal of Hydrogen Energy 2017, 42 (40), 25359.

[2] K. Hengge, C. Heinzl, M. Perchthaler, D. Varley, T. Lochner, C. Scheu, Journal of Power Sources 2017, 364, 437.

[3] K. Hengge, C. Heinzl, M. Perchthaler, S. Geiger, K. J. J. Mayrhofer, C. Scheu, Crystal Growth & Design 2017, 17, 1661.