Abstracts Book - IMRC 2018

• SC2-O005 Invited Talk
PEROVSKITE OXIDE NANOPARTICLES FOR THE OXYGEN
EVOLUTION AND REDUCTION REACTIONS
Francesca Deganello 1 , Jose Guadalupe Rivera-Morales 2 , Jesus Valdez 3 , Maria Luisa Testa 1 ,
Valeria la Parola 1 , Maria Laura Tummino 1 , Aycan Yurtsever 3 , German Orozco 2 , Ana C. Tavares 3
1
CNR, Istituto per lo Studio dei Materiali Nanostrutturati, Italy. 2 Centro de Investigación y
Desarrollo Tecnológico en Electroquímica, , Mexico. 3 Institut National de la Recherche
Scientifique, Université du Québec, Centre Énergie, Matériaux et Télécommunications, Canada.
Oxygen evolution and reduction reactions are the fundamental processes
occurring at the air electrode of metal-air batteries and fuel cells. However, large
overpotentials are required for these reactions to occur at an appreciable rate.
Thus, development of catalysts capable of reducing the activation losses of the
oxygen electrode is highly desirable. We will present our recent results on the
development of perovskite–type transition metal oxides, one of the most
promising class of low-cost materials to be used as electrocatalysts in air
electrodes. La0.5Sr0.5Co0.8Fe0.2O3-d (LSCF) nanoparticles were prepared by
solution combustion synthesis using different fuels, and the synthesis
conditions were varied to tune the oxygen deficiencies and the distortions in the
crystal structure. These nanoparticles were then deposited on carbon
electrodes and the electrochemical characterization of LSCF-based electrodes
was carried out in alkaline medium. As a result, considerable differences in the
catalytic activity were found between the nanoparticles grown under different
conditions. For instance, the catalyst prepared using sucrose as a fuel revealed
high activity for oxygen evolution reaction. In contrast, the catalyst prepared
using citric acid as a fuel and carbon as hard template, showed the highest
activity for the oxygen reduction to water. The structural stability of the catalysts
subjected to accelerated stability tests was evaluated by comparative studies
using analytical scanning electron microscopy. Spatially-resolved elemental
mapping of electrode surfaces showed that the Sr atoms were depleted most
after 1000 cycles under oxygen evolution or reduction conditions. Correlations
between synthesis conditions, structure, activity and stability of the catalysts will
be discussed.
Acknowledgment:
The financial support of CRSNG, FQRNT, and CFI (Canada) funding agencies and
CNR (Italy, STM2014 short-term mobility program) is gratefully acknowledged.