Beneficial effect of oxygen-ion conductor infiltration on the electrocatalytic properties of a heavily strontium-doped lanthanum nickelate Ruddlesden-Popper SOFC cathode.

The microstructure and electrocatalytic activity for oxygen reduction reaction of La_1.2Sr_0.8NiO_4-δ electrodes were examined as a function of electrode thickness. The length of catalytically active region and optimal thickness of La_1.2Sr_0.8NiO_4-δ electrode at 800 °C were gauged to be about 2 and 10 μm, respectively. Varying amounts of Ce_0.8Sm_0.2O_1.9 were infiltrated into the electrodes with the optimal thickness. The phase structure, microstructure and electrocatalytic properties of the infiltrated electrodes were investigated with respect to infiltrate loading and the history of cathodic polarization under different conditions. It was demonstrated that infiltrating an appropriate amount of Ce_0.8Sm_0.2O_1.9 into the electrode helped to improve the electrode performance, not only enhancing the electrocatalytic activity but also alleviating the degradation of the electrode property after experiencing cathodic polarization. The mechanisms underneath the beneficial effect were explained in relation to the microstructure of the infiltrated electrodes. The electrode infiltrated with 12 vol% Ce_0.8Sm_0.2O_1.9 showed a low polarization resistance of 0.049 Ω·cm² at 800 °C, while the increment of the polarization resistance of the infiltrated electrode after experiencing cathodic polarization was nearly half that of the pristine electrode after being likewise polarized. [ABSTRACT FROM AUTHOR]