Enhancement of bifunctional catalysis by Ir doping of La0.6Ca0.4CoO3 perovskites

Abstract

La0.6Ca0.4Co0.8Ir0.2O3 was prepared by solid state reaction synthesis from mixtures of La(NO3)(3)center dot 6H(2)O, Ca (NO3)(2)center dot 4H(2)O, Co(NO3)(3)center dot 6H(2)O, and IrO2 at stoichiometric ratio. Images from scanning electron microscopy on the as-synthesized powders exhibited particles in irregular shape at 100-250 nm in size. X-ray diffraction analysis confirmed the formation of perovskite without the rutile signals from IrO2, suggesting successful incorporation of Ir4+ at the Co cation sites. The carbon nanocapsules (CNCs) were used as an electrocatalyst support. Electrodes for electrochemical measurements were fabricated by depositing mixtures of CNCs, La0.6Ca0.4Co0.8Ir0.2O3 and polymeric binders on commercially available noncatalyzed gas diffusion electrodes. In alkaline electrolyte, the La0.6Ca0.4Co0.8Ir0.2O3/CNCs demonstrated superior performances than those of La0.6Ca0.4Co0.8Ir0.2O3/CNCs and IrO2/CNCs in both charging and discharging current-potential polarization measurements. (c) 2008 Elsevier B.V. All rights reserved.