Synthesis of La(0.6)Ca(0.4)Co(0.8)Ir(0.2)O(3) perovskite for bi-functional catalysis in an alkaline electrolyte

Abstract

The amorphous citrate precursor method was employed to prepare perovskite of La(0.6)Ca(0.4)Co(0.8)Ir(0.2)O(3) as a bi-functional electrocatalyst for oxygen reduction and evolution in an alkaline electrolyte. The X-ray diffraction pattern of the as-synthesized powders exhibited a majority phase identical to that of La(0.6)Ca(0.4)CoO(3), indicating successful incorporation of Ir4(+) at the Co cation sites. Scanning Electron Microscope images demonstrated a foam-like microstructure with a surface area of 13.31 m(2) g(-1). For electrochemical characterization, the La(0.6)Ca(0.4)CO(0.8)Ir(0.2)O(3) particles were supported on carbon nanocapsules (CNCs) and deposited on commercially available gas diffusion electrodes with a loading of 2.4 mg cm(-2). In current- potential polarizations, La(0.6)Ca(0.4)Co(0.8)Ir(0.2)O(3)/CNCs revealed more enhanced bifunctional catalytic abilities than La(0.6)Ca(0.4)CoO(3)/CNCs. Similar behaviors were observed in galvanostatic profiles for oxygen reduction and evolution at current densities of 50 and 100mAcm(-2) for 10 min. Moreover, notable changes from zeta potential measurements were recorded for La(0.6)Ca(0.4)Co(0.08)Ir(0.02)O(3) relative to La(0.06)Ca(0.4)CoO(3), In lifetime determinations, where a repeated 3 h sequence of oxygen reduction/resting/oxygen evolution/resting was imposed, La(0.6)Ca(0.4)Co(0.8)Ir(0.2)O(3)/CNCs delivered a stable and sustainable behavior with moderate degradation. (C) 2008 Elsevier B.V. All rights reserved.