Oxygen Reduction Mechanisms in Nanostructured La 0.8 Sr 0.2 MnO 3 Cathodes for Solid Oxide Fuel Cells

SACANELL, JOAQUÍN; HERNÁNDEZ SÁNCHEZ, JOAQUÍN; RUBIO LÓPEZ, ADRIÁN EZEQUIEL; MARTINELLI, HERNÁN; SIEPE, JIMENA; LEYVA, ANA G.; FERRARI, VALERIA; JUAN, DILSON; PRUNEDA, MIGUEL; MEJÍA GÓMEZ, AUGUSTO; LAMAS, DIEGO G.

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2017 vol. 121 p. 6533 - 6539

1932-7447

In this work we outline the mechanisms contributing to theoxygen reduction reaction in nanostructured cathodes of La0.8Sr0.2MnO3(LSM) for Solid Oxide Fuel Cells (SOFC). These cathodes, developed fromLSM nanostructured tubes, can be used at lower temperatures compared tomicrostructured ones, and this is a crucial fact to avoid the degradation of thefuel cell components. This reduction of the operating temperatures stemsmainly from two factors: (i) the appearance of significant oxide ion diffusionthrough the cathode material in which the nanostructure plays a key role and(ii) an optimized gas phase diffusion of oxygen through the porous structure ofthe cathode, which becomes negligible. A detailed analysis of our ElectrochemicalImpedance Spectroscopy supported by first-principles calculationspoint toward an improved overall cathodic performance driven by a fasttransport of oxide ions through the cathode surface.