Redox behavior of supported Pd particles and its effect on oxygen reduction reaction in intermediate temperature solid oxide fuel cells

Nano-structured Pd-infiltrated YSZ cathodes (Pd + YSZ) are prepared by impregnation method and their electrocatalytic activity and reduction–oxidation behavior are investigated. It is observed that nano-sized PdO particles are uniformly distributed on the surface of the YSZ scaffold and decomposed at a temperature below 800 °C in air. Coexistence of Pd and PdO in the Pd + YSZ cathode is detected at temperatures between 650 and 750 °C. The polarization resistance RE of the Pd + YSZ cathode decreases continuously as oxygen partial pressure increases from 0.001 to 1 atm at 600 and 850 °C, whereas it reaches a minimum in the vicinity of 0.03 atm of oxygen partial pressure at 750 °C. In air with an oxygen partial pressure of 0.21 atm, the Pd + YSZ shows the lowest activation energy for the oxygen reduction reaction in the temperature range of 650 and 750 °C.