RESUMO
Electrochemical removal of nitrogen oxides (NOx) by perovskite electrodes is a promising method due to its low cost, simple operation and no secondary pollution. In this study, a series of La0.8Sr0.2Mn1-xCuxO3 (x = 0, 0.05, 0.1 and 0.15) perovskites are fabricated as the improved electrodes of solid electrolyte cells (SECs) for NOx removal and the effects of Cu doping are investigated systematacially. Multiple characterization methods are carried out to analyze the physicochemical properties of perovskites firstly. Then the performances of cells based on various perovskites are evaluated by the measurements of electrochemical properties and NOx conversions. The results show that the Cu-doped electrode has more surface oxygen vacancies and a better redox property, thus having a higher NOx conversion and smaller polarization resistance. The electrode based on La0.8Sr0.2Mn0.9Cu0.1O3 has the maximum 70.8% NOx conversion and the lowest 36.3 Ω cm2 Rp value in the atmosphere of 1000 ppm NO at 700 °C. First-principle calculation reveals that the Cu-doped electrode is easier to form surface oxygen vacancy, while the surface oxygen vacancy plays an important role on electron transfer between electrode and NOx molecule. This study not only provides a new strategy to enhance the electrode performance for NOx removal in SECs but reveals the fundamental effect of Cu doping on the properties of La0.8Sr0.2MnO3 perovskites.
