Oxygen Diffusion and Surface Exchange Coefficients of Porous La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ Decorated with Co₃O₄ Nanoparticles

Abstract

This work presents a comparative study of the diffusion (Dchem) and surface exchange coefficients (kchem) of porous La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and Co3O4 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 Co3O4 decorated LSCF respect to the reference LSCF cathode, in air at 700 °C. The Co3O4 decoration was found to modify the ORR surface reaction limiting mechanism from O2 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 Co3O4 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.

Perspective on high-temperature surface oxygen exchange in a porous mixed ionic-electronic conductor for solid oxide cells

“…1a) and ECR (Fig. 1b) methods, 1,39,40,[50][51][52][53][54][55][56] noting that data determined with OIE are not available for porous LSCF. For the coefficients measured with the same method, the data at the same temperature reported by different groups are very different.…”

Pr2Ni0.8Co0.2O4+δ impregnated La0.6Sr0.4CoO3−δ oxygen electrode for efficient CO2 electroreduction in solid oxide electrolysis cells

“…The conductivity, oxygen diffusion coefficient, and oxygen surface exchange coefficient of the material all inuence the OER activity of the oxygen electrode. [34][35][36] Both LSC and PNCO are ion-electron hybrid conductor materials. LSC has better conductivity as an anode material compared to PNCO.…”

BaCO3 Nanoparticles-Modified Composite Cathode with Improved Electrochemical Oxygen Reduction Kinetics for High-Performing Ceramic Fuel Cells

“…Currently, researchers are mainly focused on mitigating these problems by reducing the SOFCs' operating temperature to a temperature below 800 • C [5][6][7][8]. Unfortunately, reducing the operating temperature typically leads to sluggish oxygen reduction reaction (ORR) kinetics, thereby hindering the overall SOFC output performance [9][10][11][12]. Therefore, the availability of cathode materials with high ORR activity at reduced temperatures is critical for promoting the commercialization of SOFC technology.…”