Strong Lanthanoid Substitution Effect on Electrocatalytic Activity of Double-Perovskite-Type BaLnMn2O5 (Ln = Y, Gd, Nd, and La) for Oxygen Reduction Reaction

The oxygen reduction reaction (ORR) catalytic activity was systematically studied on the BaLnMn(2)O(5) series (Ln = Y, Gd, Nd, and La) with a layered double-perovskite-type structure in an alkaline aqueous solution. The onset ORR. potential and the number of electrons involved in ORR were found to be strongly Ln-dependent: both values were significantly higher for larger Ln = La and Nd than for smaller Ln = Gd and Y, despite similarities in their chemical compositions and crystal structures. The enhanced ORR activity of the Ln = La and Nd compounds is likely attributed to their stronger affinity to oxygen species, consistent with the greater oxygen storage capability of these compounds, as revealed by the water dissolution reaction at elevated temperatures.