Tailoring Electrocatalytic Properties of Solid Oxide Fuel Cell Composite Cathodes Based on (La0.8Sr0.2)0.95MnO3+δ and Doped Cerias Ce1-xLnxO2-δ (Ln=Gd, La, Er, Pr, Tb and x=0.1-0.2)

Composites made of different doped cerias and (La_0.8Sr_0.2)_0.95MnO_3+δ were studied as potential solid oxide fuel cell cathodes. Tb, Pr, Gd and Er have been introduced as ceria dopants to enhance the electrocatalytic properties of (La_0.8Sr_0.2)_0.95MnO_3+δ composites fabricated within. Different electrochemical behaviors were observed for the studied composites depending on lanthanide cation nature, i.e., whether they can exhibit different oxidation states or not. Specifically, (La_0.8Sr_0.2)_0.95MnO_3+δ/ceria composites with a mixed valence dopants (Tb and Pr) in the CeO₂ structure are the best performing and present a limiting step at low frequencies; whereas those with ceria-doping elements with fixed oxidation state (Gd and Er) exhibit the limiting processes at higher frequencies. This fact is related to the higher magnitude of the TPB enlargement in the composite cathode achieved thanks to the promotion of mixed ionic-electronic conductivity in the Pr/Tb-doped ceria phase. The best cathode performance was obtained with (La_0.8Sr_0.2)_0.95MnO_3+δ_Ce_0.8Pr_0.2O_{2- δ} cathodes with the lowest values for the polarization resistance in the 900-700 °C temperature range. [ABSTRACT FROM AUTHOR]