Double perovskite oxides Sr2MMoO6 (M=Fe and Co) as cathode materials for oxygen reduction in alkaline medium

The oxygen reduction reaction (ORR) was studied on Sr2MMoO6 (M = Fe and Co) double perovskites, prepared by a solid-state reaction, in 0.5 M NaOH at 25 °C with a rotating disk electrode (RDE). The two oxide powders were characterized by X-ray diffraction, scanning electron microscopy and BET analysis. The electrochemical techniques considered are linear voltammetry, steady state polarization and ac impedance spectroscopy. The electrocatalysts (SFMO/C, SCMO/C) consisting of the double perovskite oxides and carbon (Vulcan XC-72) were mixed and spread out into a thin layer on a glassy carbon substrate. At room temperature, a significantly electrocatalytic activity is observed for both electrocatalysts. Compared to SFMO/C, the SCMO/C electrocatalyst was found to show a relatively high electrocatalytic activity for O2 reduction, which agrees well with the results obtained using the ac impedance spectroscopy.