NiO and Co3O4 nanoparticles decorated La0.8Sr0.2MnO3-based electrodes for electrochemical NOx removal in solid electrolyte cells

Abstract

Solid electrolyte cells (SECs) have great application prospect for nitrogen oxides (NOx) removal due to no required reductant addition in contrast to the conventional selective catalytic reduction (SCR) method. Perovskites are the potential electrode materials in SECs but their reaction activity is insufficient at the intermediate-low temperature. Herein, NiO and Co3O4 nanoparticles are decorated on the La0.8Sr0.2MnO3-based electrode to improve the electrode activity. A variety of characterizations were conducted to analyze the electrode properties, and the electrode performance was systematically evaluated. The results show that the decorated NiO and Co3O4 nanoparticles both improved the electrode performance significantly and the NiO-modified electrode had a better performance. Compared with the unmodified electrodes, the surface NiO nanoparticles decreased the area-specific polarization resistance by 63.1% to 81.7 Ω cm2 while the NO conversion was increased by 85.9% to 59.3% at 1.4 V in 1000 ppm NO, 700 ℃. The electrochemical impedance spectra revealed that the nanoparticles not only promoted the species adsorption, dissociation and diffusion processes but facilitated the charge transfer between electrode and electrolyte. The first-principle calculation confirmed that the decorated NiO nanoparticles decreased the energy gap of electrodes and promoted the electron transfer between electrode and NO molecule, in agreement well with the experimental results. This work presented a new way to increase the NOx removal performance of SECs and offered guidance for the future construction of high-performance electrodes.