Abstract

SrCo0.50Fe0.45M0.05O3- delta (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 (delta Ir=0.24 vs delta Ru=0.19 @780 degrees 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 & sdot; 10-4 and kchem-Ir = 1.88 & sdot;10- 4 cm & sdot;s- 1 while the chemical diffusion coefficient was smaller for this sample Dchem- Ru = 1.26 & sdot;10- 8 and Dchem-Ir = 3.47 & sdot;10- 8cm2 & sdot;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.