Composite cathode material LSCF-Ag for solid oxide fuel cells obtained in one step sintering procedure

Abstract

The lanthanum strontium cobalt ferrite (LSCF)-Ag composite cathode material was prepared in aqueous solution by new one-step method. In this method silver nanoparticles obtained by the reduction of [Ag(NH3)2]+ complex with sucrose were directly deposited onto the surface of LSCF powder. UV–Vis spectra of supernatant solution taken during synthesis showed the presence of a sharp excitation band near 397 nm attributed to the surface plasmon excitation of silver nanoparticles. Obtained composite powder was sintered to samaria doped ceria electrolyte in one step sintering procedure at 1000 °C. The presence of silver in LSCF cathode facilitates the oxygen reduction. The comparison of impedance spectra of LSCF-Ag cathodes with spectra reported in literature for similar LSCF cathodes shows that this effect is important at lower oxygen partial pressures. The analysis of the electrochemical impedance spectra recorded in the range 10−2–1010 Hz reveals that the second high frequency semicircle ascribed to the electrolyte grain boundary impedance is distorted due to process belonging to oxygen reduction reaction.