Oxygen Reduction Reaction Activity of Pyrochlore Oxide Electrocatalysts Prepared by Precipitation Method

摘要

The Mn-doped pyrochlores Pb_2Ru_1.5Mn_0.5O_(7-δ) (PRMns) samples were synthesized by a precipitation method, followed by heat-treatments at temperatures of 300-800°C. Effects of the heat-treatments on their electrocatalytic activities for oxygen reduction reaction (ORR) were examined by semi-steady state voltammetry with a rotating ring-disk electrode in 0.1 M KOH solution at 70°C. The PRMns showed the best ORR activity for the 500°C-heat-treated PRMn. The onset potential of the ORR current was over 1.0 V vs RHE, and the efficiency of 4-electron reduction was almost 100%. The maximum in the ORR activity for the 500°C-heat-treated PRMn resulted from a trade-off effect between their crystallinity and specific surface areas.