Durability of Carbon-Supported La-Mn-Based Perovskite-Type Oxides as Oxygen Reduction Catalysts in Strong Alkaline Solution

Abstract

The durability of carbon-supported La-Mn-based perovskites for the oxygen reduction reaction in strong alkaline solutions was investigated. Carbon-supported perovskite-type oxide nanoparticles were prepared by using a reverse micelle method. The durability of the carbon-supported LaMnO3 nanoparticles was compared with that of carbon-supported LaMnO3 prepared by the mechanical mixing of LaMnO3 with the carbon support. As a result, the durability of the carbon-supported LaMnO3 nanoparticles was less than that of the carbon-supported LaMnO3 prepared by the mixing method due to a difference in the surface area of LaMnO3, which has an effect on the oxygen reduction reaction. In order to improve the durability of the carbon-supported LaMnO3 nanoparticles, Ca and Fe were substituted at the A-sites and B-sites of the perovskite lattice, respectively. As a result, it was found that the partial substitution of Ca and Fe is effective in improving the durability of LaMnO3 under cathodic polarization in strong alkaline solutions. In particular, the substitution of Ca at the A-site not only improved the durability of the oxide but also enhanced the oxygen reduction activity owing to an increase in the average valence state of the B-sites of the perovskite lattice.