La0.75Sr0.25Cr0.5Mn0.5O3-δ-Ce0.8Sm0.2O1.9 as composite electrodes in symmetric solid electrolyte cells for electrochemical removal of nitric oxide

Symmetric solid electrolyte cells with La0.75Sr0.25Cr0.5Mn0.5O3-delta (LSCM)-Ce(0.8)Sin(0.2)O(1.9) (SDC) composite electrodes are employed for nitric oxide (NO) removal. The LSCM powders are synthesized and the cells with LSCM-SDC composite electrodes are fabricated successfully. The results show that moderate SDC addition in LSCM electrode improves the cell performance due to the expansion of three phase boundaries (TPBs). The electrode with 30 wt% SDC has the highest NO conversion of 69.2% and the lowest polarization resistance at 750 degrees C in 1000 ppm NO. The cathodic polarization activates the cathode because of the Cr/Mn ions reduction, more surface oxygen vacancies and Cr metal exsolution. The cell has good tolerances for H2O, CO2, and SO2, but excess O-2 competes with NO for TPBs seriously. The sufficient stability and flexible operation mode of the cell are also proved. Finally, the NO adsorption mechanism on LSCM surface is revealed by density functional theory (DFT) calculations.