Characterization of MgMnxFe2-xO4 as a possible cathode material for electrochemical reduction of NOx

Spinel-type oxides of MgMn x Fe2−x O4, x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, were synthesized as a solid state reaction and characterized with dilatometry and resistivity measurements up to 1000 °C. Results showed a general decrease of the linear expansion and an increase in conductivity as a function of the Mn content. Point electrodes were analyzed from 300 to 600 °C in a pseudo-three-electrode setup in 1% NO, 1% NO2, and 10% O2 using cyclic voltammetry. The activities in O2 were in general very low whereas the activities in NO were slightly higher. The activities in NO2 were for all materials much higher than the activities in O2. Even though Mn tends to decrease the activity of the materials, current ratios of have relatively high values in both NO and NO2.