Oxygen transport paths in screen-printed Pt-Al2O3 composite model electrodes on YSZ

Abstract In this work, Pt-Al 2 O 3 composite electrodes without open porosity, screen-printed on polycrystalline YSZ, were analysed in order to identify relevant oxygen transport paths in thick-film electrodes. By using electrochemical impedance spectroscopy, the electrode processes were investigated at different oxygen partial pressures ( p O 2 ) and temperatures ( T ). Special sample layouts allowed the separation of three phase boundary (tpb) and electrode area-dependent transport processes. We found that the area-related transport path is dominating at low temperatures and high p O 2 , with a relatively low activation energy of 0.2 to 0.6 eV and a p O 2 − 0.7 dependence. In contrast, the tpb-related transport path dominates at high temperatures and low p O 2 , with activation energies between 0.8 and 1.4 eV and a p O 2 − 0.3 behaviour. A tracer experiment was performed additionally to visualize the location of oxygen incorporation below the electrode.