Synthesis and Characterization of La[sub 0.6]Ca[sub 0.4]Co[sub 0.8]Ru[sub 0.2]O[sub 3] for Oxygen Reduction Reaction in an Alkaline Electrolyte

We employed an amorphous citrate precursor (ACP) method to synthesize stoichiometric La0.6Ca0.4Co0.8Ru0.2O3 powders. Result from X-ray diffraction demonstrated a perovskite La0.6Ca0.4CoO3 lattice, indicating the incorporation of Ru3+ at the Co3+ sites. Image from the scanning electron microscope revealed a foamlike microstructure with various pores at 0.5-3 mu m. La0.6Ca0.4Co0.8Ru0.2O3 exhibited a higher H2O2 decomposition rate in KOH solution as opposed to that of ACP-derived La0.6Ca0.4CoO3, which suggested an improved catalytic ability for oxygen reduction reaction (ORR). A similar behavior was observed during the ORR current-potential polarization using La0.6Ca0.4Co0.8Ru0.2O3 supported on Black Pearl 2000 as a gas diffusion electrode. In addition, impedance spectra at the open-circuit voltage and selective cathodic overpotentials also confirmed a smaller charge-transfer resistance for La0.6Ca0.4Co0.8Ru0.2O3. In galvanostatic measurements and lifetime evaluation, La0.6Ca0.4Co0.8Ru0.2O3 demonstrated steady voltage profiles with negligible degradation. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3384665] All rights reserved.