A redox stable Pd-doped perovskite for SOFC applications

Abstract

Structural and microstructural investigations of Pd-doped lanthanum strontium ferrite with stoichiometry La_0.6Sr_0.4Fe_0.95Pd_0.05O_3−δ (LSFPd) were carried out under oxidizing and reducing conditions using XRD, Rietveld refinement, XPS, SEM, and TEM analyses. LSFPd exhibited a smart behaviour with a reversible redox structural transformation occurring upon switching from air to hydrogen and then back to air. Exsolution of nanometric metal particles was observed after reduction, and reincorporation of metal cations onto the perovskite structure was confirmed after reoxidation. The electrochemical performances were evaluated on electrolyte supported cells using LSFPd as symmetric electrodes. The self-regenerating redox process largely improved the anodic performance of LSFPd-based SOFCs because it mitigates the coarsening of metallic electrocatalysts at high temperature promoting a redox stable behaviour. Fuel cell tests revealed promising performance in terms of maximum power output and redox stability.