Effect of Ba Content on the Activity of La(1‐x)Ba(x)MnO(3) Towards the Oxygen Reduction Reaction

The electrocatalytic activity of La(1‐x)Ba(x)MnO(3) nanoparticles towards the oxygen reduction reaction (ORR) is investigated as a function of the A‐site composition. Phase‐pure oxide nanoparticles with a diameter in the range of 40 to 70 nm were prepared by using an ionic liquid route and deposited onto mesoporous carbon films. The structure and surface composition of the nanoparticles are probed by XRD, TEM, EDX, and XPS. Electrochemical studies carried out under alkaline conditions show a strong correlation between the activity of La(1‐x)Ba(x)MnO(3) and the effective number of reducible Mn sites at the catalysts layer. Our analysis demonstrates that, beyond controlling particle size and surface elemental segregation, understanding and controlling Mn coordination at the first atomic layer is crucial for increasing the performance of these materials.