A kinetic study of La0.75Sr0.25Cr0.5Mn0.5O3- nano-structured electrodes for intermediate temperature symmetric solid oxide fuel cells

La0.75Sr0.25Cr0.5Mn0.5O3-delta (LSCM) mixed conducting has been studied as nanostructured air and fuel electrode, for intermediate temperature symmetric Solid Oxide Fuel cell (S-SOFC). The possible mechanisms involved in the oxygen reduction and hydrogen oxidation reactions of these LSCM nanostructures porous electrodes deposited on La0.8Sr0.2Ga0.8Mg0.2O3-delta (LSGM) electrolyte, were analyzed by electrochemical impedance spec-troscopy (EIS) at 700 degrees C varying the oxygen partial pressure (pO2) and the hydrogen partial pressure (pH2). This analysis was complemented by the study of the electrical conductivity by the four-probe DC technique in the range between 300 and 800 degrees C in flowing dry atmospheres of air or H2. Results suggested that the O2 reduction reaction mechanism involves the O2- dissociative adsorption and O-ion migration near the surface region, while the H2-oxidation reaction limiting-step is controlled by a slow charge transfer process, and H2- dissociative adsorption on the ultimate O-layer.