Oxygen Diffusion and Surface Exchange Coefficients of Porous La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ Decorated with Co 3 O 4 Nanoparticles

• Published in: Journal of the Electrochemical Society 2022-03, Vol.169 (3), p.34514
• Main Authors: Ascolani-Yael, J., Montenegro-Hernández, A., Baqué, L. C., Toscani, L. M., Caneiro, A., Mogni, L. V.
• Format: Article
• Language: English
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1945-7111/ac49ce

This work presents a comparative study of the diffusion D c h e m and surface exchange coefficients k c h e m of porous La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3− δ (LSCF) and Co 3 O 4 nanoparticles decorated LSCF electrodes. The study was carried out using the 3DT-EIS method, which combines Electrochemical Impedance Spectroscopy experiments with FIB-SEM tomography data through an adapted Transmission Line–Adler Lane Steele electrochemical model.A reduction of the polarization resistance of about 60% was measured for the Co 3 O 4 decorated LSCF respect to the reference LSCF cathode, in air at 700 °C. The Co 3 O 4 decoration was found to modify the ORR surface reaction limiting mechanism from O 2 dissociation to O-ion incorporation, whereas the diffusion coefficient was not modified by the decoration, which represents a surface diffusion process for both electrodes. After the EIS measurements, the Co 3 O 4 particles were almost no longer visible by Field-Emission SEM on the surface of the decorated sample, but signs that these particles play an active role in Sr Segregation were observed by STEM-EDS, in particular by concentrating the segregated SrO in the surroundings of the decorated particles.