Abstract

SrCo0.50Fe0.45M0.05O3−δ (M=Ru and Ir) air electrodes for Solid Oxide Fuel Cells were studied to reduce Co content and introduce a small fraction of noble metal catalysts. X-Ray Diffraction and Thermo-Gravimetric Analysis confirmed single-phase perovskites, with higher oxygen vacancies for the Ir-doped sample (δIr=0.24 vs δRu=0.19 @780 °C). Using 3D tomography from Focused Ion Beam-Scanning Electron Microscopy and Electrochemical Impedance Spectroscopy kinetic parameters were calculated via an adapted Adler Lane Steele model. DRT analysis revealed overlapping processes, validating the use of a Transmission Line Model for Nyquist plot fitting. Higher surface exchange rates were obtained for the sample doped with Ru, being kchem−Ru=2.58·10−4 and kchem−Ir=1.88·10−4cm·s−1 while the chemical diffusion coefficient was smaller for this sample Dchem−Ru=1.26·10−8 and Dchem−Ir=3.47·10−8cm2·s−1, related to a higher surface catalytic activity combined with a smaller concentration of oxygen vacancies compared to the Ir doped sample. These findings provide valuable insights into optimizing air electrode materials, offering a pathway for enhanced cathode performance. © 2025