Electrochemical characterization of the n = 2 Ruddlesden-Popper phases Sr2(FeM)O6+d (M : Fe, Co, Ni) by electrochemical impedance spectroscopy

L. MOGNI, F. PRADO, A. CANEIRO

JES Transactions

The Electrochemical Society

Año: 2008 vol. 6 p. 233 - 243

1938-6737

The electrochemical characterization of the porous Sr3FeMO6+δ (M= Fe, Co, Ni) electrode materials has been performed by a.c.electrochemical impedance spectroscopy (EIS) under pure O2atmosphere and temperatures between 500 and 800 ºC. Thick filmsof porous Sr3FeMO6+δ were deposited on both sides of a denseCe0.9Gd0.1O2-x electrolyte disc by spray deposition. To reach anadequate adherence between electrolyte and electrodes the cell washeat treated at 1000 ºC during 1 h. XRD and SEM were used toevaluate the structure and microstructure of the cells before andafter the EIS measurements. Data of the Area Specific Resistance(ASR), defined by ASR = Z´(ω→0)-Z´(ωHF), associated with theoverall oxygen reduction reaction, were obtained for the threecompositions (Sr3Fe2O6+δ, Sr3FeCoO6+δ, Sr3FeNiO6+δ ). The ASRvalues are quite similar for the Sr3FeNiO6+δ and Sr3FeCoO6+δcompositions, and they are higher than those of Sr3Fe2O6+δ. Theactivation energy (Ea) corresponding to the ASR for theSr3FeNiO6+δ material (∼1.3 eV) is higher than those ofSr3FeCoO6+δ and Sr3Fe2O6+δ, (∼ 0.9-1.0 eV).