Abstract
In this study, the impact of various infiltrates on the kinetics and rate-limiting step of oxygen reduction reaction (ORR) is examined with LaNi0.6Fe0.4O3- δ (LNF) as the cathode backbone of a solid oxide fuel cells (SOFC). Five materials were infiltrated: LaNi1-xFexO3- δ, LaxSr1-xCoyFe1-yO3-δ (LSCF), La1-xSrxMnO3-δ (LSM), Gd1-xCexO2-δ (GDC) and Pr6O11. The dependence of electrode polarization resistance on the precursor concentration, temperature, oxygen partial pressure is presented with related discussions on ORR kinetics and rate-determining step for ORR. A one-step infiltration of all five materials resulted in a dramatic decrease in polarization resistance (Rp) and related activation energy (Ea), which is ascribed to a significant facilitation of surface processes such as dissociative adsorption with electron transfer and diffusion of oxygen intermediates. Finally, a short-term durability test in a Cr-containing environment indicated that the LSCF-infiltrated cell is susceptible to Cr poisoning unlike the GDC- or LNF-infiltrated cells as expected but advantageous in terms of morphological stability during operation.
Published Version
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