Enhanced electrochemical property of La0.6Sr0.4Co0.8Fe0.2O3 as cathode for solid oxide fuel cell by efficient in situ polarization-exsolution treatment

La0.6Sr0.4Co0.8Fe0.2O3 (LSCF) is a conventional mixed ionic-electronic conductors which has been used as cathode for solid oxide fuel cells (SOFC). In order to further enhance its electrochemical property, the in situ polarization-exsolution treatment with a negative voltage of -2 V was applied at as low as 600 degrees C on LSCF to modify its surface. The surface turns from smooth to non-equilibrium fused under non-reductive atmosphere (T1) while nanoparticles formed under the treatment with H-2 (T2). Electrochemical characterization demonstrated an enhancement of the oxygen reduction reactivity (ORR) with as low as 30% and 20% area specific resistance (ASR) of the original one, respectively. The lowest ASR of LSCF under T2 was attributed to the modified component of the surface along with the lengthening triple phase boundary (TPB) and enhancement of the absorption of the oxygen on the surface. The results of peak power density (P-max) show that T1 makes little enhancement for the final performance while T2 leads to the P-max increased by 25% (as large as similar to 150 mW cm(-2)) at 600 degrees C. The detection of its reversibility indicated the "once-only use" character. The cathode under T2 treatment shows good stability with a slight degradation for the performance after 36 h. After all, the in situ rapid (only a few seconds) growth of nanoparticles by cathodic polarization-exsolution treatment under reductive atmosphere is an efficient way to enhance the electrochemical property of the cathode for solid oxide fuel cell. (c) 2017 Elsevier Ltd. All rights reserved.