Chen D, Bishop S R, Tuller H L. Praseodymium-cerium oxide thin film cathodes: Study of oxygen reduction reaction kinetics[J]. Journal of electroceramics, 2012, 28(1): 62-69.

ABSTRACT

Praseodymium-Cerium Oxide (PrxCe1-xO2−δ;PCO), a potential three way catalyst oxygen storage materialand solid oxide fuel cell (SOFC) cathode, exhibits surpris-ingly high levels of oxygen nonstoichiometry, even underoxidizing (e.g. air) conditions, resulting in mixed ionicelectronic conductivity (MIEC). In this study we examinethe redox kinetics of dense PCO thin films using impedancespectroscopy, for x00.01, 0.10 and 0.20, over the tempera-ture range of 550 to 670°C, and the oxygen partial pressurerange of 10−4to 1 atm O2. The electrode impedance wasobserved to be independent of electrode thickness and in-versely proportional to electrode area, pointing to surfaceexchange rather than bulk diffusion limited kinetics. Thelarge electrode capacitance (10−2F) was found to be consis-tent with an expected large electrochemically inducedchange in stoichiometry for x00.1 and x00.2 PCO. ThePCO films showed surprisingly rapid oxygen exchangekinetics, comparable to other high performance SOFC cath-ode materials, from which values for the surface exchangecoefficient,kq, were calculated. This study confirms thesuitability of PCO as a model MIEC cathode materialcompatible with both zirconia and ceria based solid oxideelectrolytes.