Electrochemical Reduction of Oxygen and Nitric oxide at low Temperature on La_1-xSr_xCr_0.97V_0.03O_3-δ Cathodes

Five La1-xSrxCr0.97V0.03O3-δ (x = 0, 0.05, 0.15, 0.25, 0.35) perovskites were synthesized and characterized by powder XRD and cyclic voltammetry on cone-shaped electrodes in 10% oxygen in argon or 1% nitric oxide in argon at 200, 300 and 400°C. It was shown that the activation energy for the reduction of oxygen is higher than the activation energy for the reduction nitric oxide. The activity for the reduction of both oxygen and nitric oxide was shown to be highest for the end member La0.65Sr0.35Cr0.97V0.03O3-δ. The highest ratio between the current densities in the nitric oxide and oxygen containing atmospheres was found for the end member LaCr0.97V0.03O3-δ. The chromites also showed activity as anodes for either oxygen evolution or oxidation of nitric oxide to nitrogen dioxide.