Title: Oxygen reduction mechanisms in nanostructured La0.8Sr0.2MnO3 cathodes for Solid Oxide Fuel Cells,
Abstract: In this work we outline the mechanisms contributing to the oxygen reduction
reaction in nanostructured cathodes of La0.8Sr0.2MnO3 (LSM) for Solid Oxide
Fuel Cells (SOFC). These cathodes, developed from LSM nanostructured tubes, can
be used at lower temperatures compared to microstructured ones, and this is a
crucial fact to avoid the degradation of the fuel cell components. This
reduction of the operating temperatures stems mainly from two factors: i) the
appearance of significant oxide ion diffusion through the cathode material in
which the nanostructure plays a key role and ii) an optimized gas phase
diffusion of oxygen through the porous structure of the cathode, which becomes
negligible. A detailed analysis of our Electrochemical Impedance Spectroscopy
supported by first principles calculations point towards an improved overall
cathodic performance driven by a fast transport of oxide ions through the
cathode surface.