A novel one step synthesized Co-free perovskite/brownmillerite nanocomposite for solid oxide fuel cells

作者：Ortiz Vitoriano Nagore; Ruiz de larramendi Idoia; Gil de Muro Izaskun; Larranaga Aitor; Ignacio Ruiz de larramendi Jose; Rojo Teofilo^*

来源：Journal of Materials Chemistry, 2011, 21(26): 9682-9691.

DOI：10.1039/c1jm10911a

Cobalt-free perovskite oxides Pr1-xCaxFe0.8Ni0.2O3 (PCFN) were investigated as novel cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs). Ca and Ni substitution in the PrFeO3 material shows that a wide range of perovskites Pr1-xCaxFe0.8Ni0.2O3 (0 < x < 0.9) can be prepared by sintering in air at 600 degrees C. Perovskites with 0 < x < 0.4 exhibit orthorhombic single phases (Pnma space group), whereas 0.4 < x < 0.9 show a coexistence of the perovskite and the brownmillerite-type structure (Ca2Fe2O5). The structure of the polycrystalline powders was analyzed by X-ray powder diffraction, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The analysis on the synthesized powders shows the presence of clusters formed by 30-100 nm nanoparticles. High-Resolution TEM (HRTEM) studies were carried out to confirm the existence of Ca2Fe2O5. The dc four-probe measurement exhibits a total electrical conductivity, over 100 S cm(-1) at T >= 600 degrees C when 0 < x < 0.6, pointing out that strontium can be substituted for calcium without modifying the electrochemical properties. The Pr0.4Ca0.6Fe0.8Ni0.2O3/Ca2Fe2O5 composite cathode presents the better performance in electrochemical measurements, showing an area specific resistance value of 0.09 ohm cm(2) at 850 degrees C.

• 出版日期2011