Influence of BaO in perovskite electrodes for the electrochemical reduction of NO x

Abstract

Using the point electrode method, the effect of BaO on electrochemical reduction of NO x was investigated using the perovskites La0.85Sr0.15MnO3 (LSM15) and La0.85Sr0.15CoO3 (LSCo15) as electrode materials. The experiments were carried out in the temperature range 400–600 °C in 1% NO and 10% O2, respectively. For the LSM15 electrode the ability to reduce NO compared to O2 was increased when applying 20 wt% BaO in the electrode while the current density of the electrode was decreased approximately a decade. For the pure LSM15 electrode the highest current density ratio of NO and O2 was obtained at 400 °C while the optimal temperature in term of current density ratios was 500 °C for the LSM15 + BaO and LSM15 + BaO + Pt electrodes. The activity of the electrode decreases when applying BaO or BaO + Pt to the electrode except for the LSM15 + BaO + Pt electrode at 500 °C where the activity is approximately the same as for the LSM15 electrode. The formation of Ba(NO3)2 was clearly seen when applying 16.7 wt% BaO and 2 wt% Pt to the electrode. Generally it was observed that at 400 °C the activity of the electrodes were low, while at 600 °C the kinetics favored oxygen reduction compared to reduction of nitric oxide. The LSCO15 electrode containing BaO reacted to form a K2NiF4-structure and was not tested further.