Co_2MnO_4 spinel-palladium co-infiltrated La_(0.7)Ca_(0.3)Cr_(0.5)Mn_(0.5)O_(3-δ) cathodes for intermediate temperature solid oxide fuel cells

摘要

The effect of co-infiltration of Co_2MnO_4 (CM) spinel oxides and Pd on the electrochemical activity and microstructure stability of La_(0.7)Ca_(0.3)Cr_(0.5)Mn_(0.5)O_(3-δ) (LCCM) cathodes for the O_2 reduction reaction of intermediate temperature solid oxide fuel cells (IT-SOFCs) has been investigated in detail. The microstructure, thermal stability, electrochemical activity and stability of the Co_2MnO_4-Pd/PdO powders and Co_2MnO_4-Pd/PdO co-impregnated LCCM cathode were measured using thermal gravimetric analysis, X-ray diffraction, scanning electron microscopy and electrochemical impedance spectroscopy. The results indicate that the addition of spinel oxides effectively inhibits the growth and coalescence of the Pd/PdO nanoparticles and stabilizes the microstructure of the Pd/PdO at high temperatures. The best electrochemical activity and stability of LCCM cathodes were obtained on the cathode co-infiltrated with 50 wt% PdO/50 wt% Co_2MnO_4. The enhancement is due to the significantly improved stability of the microstructure as a result of the inhibited grain growth and agglomeration of Pd/PdO nanoparticles by the co-infiltrated Co_2MnO_4 spinel phase.