Particle-Scaled Visualization of Active Sites in LSM/ScSZ Composite Cathode of SOFC through Oxygen Isotope Labeling

Abstract

Active sites for oxygen reduction reaction in strontium-doped lanthanum manganite (LSM)/scandia-stabilized zirconia (ScSZ) composite cathode of solid oxide fuel cell (SOFC) was visualized in particle scale by oxygen isotope labeling. In order to quench a reaction, a SOFC power generation equipment with a nozzle for direct helium impinging jet to the cell was prepared. A typical electrolyte-supported cell was operated by supplying 18O2 at 1073 K and abruptly quenched to room temperature. During the quench, the temperature of the cell was decreased from 1073 K to 673 K in 1 sec. The 18O concentration distribution in the cross section of the quenched cathode was obtained by secondary ion mass spectrometry (SIMS) with a spatial resolution of 50 nm. The obtained 18O concentration mapping gives the inhomogeneous distribution of active sites in the composite cathode.