Facilitating oxygen reduction by silver nanoparticles on lanthanum strontium ferrite cathode

Abstract

Single-phase silver (Ag)-doped La0.85-xSr0.15AgxFeO3-δ (x = 0–0.05) materials (LSAF) were synthesized by wet synthesis route and calcined at 800 °C in air. The materials exhibited no thermal degradation in Ar and synthetic air below sintering temperature at 1200 °C of the cathode for solid oxide fuel cells. Exsolution of Ag nanoparticles from the perovskite lattice at 420 °C in reducing 5% H2/N2 was investigated, and electrocatalytic activity of the cathodes towards oxygen reduction reaction for solid oxide fuel cells was demonstrated. Scanning electron microscopy confirmed exsolution of Ag nanoparticles with increased effective surface area, and the particles were distributed with a good contact on the surface of the perovskite. Electrochemical performance of novel materials was tested and compared. Enhanced cathode with Ag nanoparticles revealed the area specific resistance of 0.23 and 0.15 Ω cm2 at 800 °C in 20% O2/N2 before and after Ag exsolution, respectively. The area specific resistance of the cathode decreased with Ag exsolution, operation temperature, and increasing oxygen partial pressure.