Impregnation of Pt|YSZ Oxygen Electrodes with Microquantities of Praseodymium Oxide

The method of electrochemical impedance is used to study the polarization conductivity of porous platinum electrodes in the Pt|YSZ|Pt cells over the temperature range from 500 to 700°C in air. Electrodes are impregnated with microquantities of praseodymium oxide PrOx (from 10–4 to 0.1 mg/cm2) by the impregnating them with praseodymium nitrate solution, with further thermal treatment: slow heating (50°С/h) up to 850°C. This processing resulted in the formation of the praseodymium oxide nanofilm on the electrolyte surface. The introducing of PrOx, even in an amount of 10–4 mg/cm2, is found to significantly increase the electrode polarization conductivity. Analysis of the electrochemical impedance spectra was performed by DRT (distribution of relaxation times) method, which revealed a change of the rate-determining stage of the electrode process in the concentration range of praseodymium oxide from 1 × 10–3 to 3.3 × 10–3 mg/cm2. The studied electrodes are discussed in terms of the island model of dense-oxide-PrOx-electrodes in which platinum plays the role of the current collector.