Alleviation of O2 competition with NO in electrochemical reduction through nanoceria supported on LSM cathode

[Display omitted] •Nano-sized ceria infiltrated on LSM can alleviate negative impact of oxygen on NO electrochemical reduction.•Higher OSC of LSM-GDC(nano) and oxygen vacancies regeneration under polarization favors to extend the limit of oxygen tolerance.•Besides OSC, gas or chemical diffusion is another key kinetic limit to improve performance. Inhibition of O2 competing with NO will promote NO electrochemical abatement, and further will facilitate its application in the purification of exhaust emitted from a gasoline engine. This study discovered that (La0.75Sr0.25)0.95MnO3 cathode with nano-sized Ce0.9Gd0.1O1.95 (GDC) particles (denoted as LSM-GDC(nano)) in solid-state cell can alleviate the negative impact of oxygen content on NO conversion. When oxygen content increases gradually from 0 to 1%, NO conversions decrease to 60% and 30% for LSM-GDC(nano) and LSM-GDC cathodes, respectively. In comparison with LSM-GDC, the abundance of oxygen vacancies available for oxygen adsorption in LSM-GDC(nano) is responsible for higher OSC values under polarization. Postmortem XPS spectra of Ce 3d for the cathodes further confirm that Ce4+ reduction- into Ce3+ under polarization can regenerate oxygen vacancies, and that the redox cycle of Ce4+/Ce3+ between polarization and external atmosphere takes place during electrochemical reduction of NO. The DRT method precisely reveals that LSM-GDC(nano) improves adsorption and dissociation of O2 significantly, which is also confirmed by DFT calculations. However, the limit of gas/chemical diffusion is still prominent in the presence of relatively higher oxygen content, even at higher applied voltages.