Mechanical Alloying Preparation of La[sub 0.6]Ca[sub 0.4]CoIr[sub 0.25]O[sub 3.5−δ] as a Bifunctional Electrocatalyst in Alkaline Electrolyte

Abstract

La 0.6 Ca 0.4 CoIr 0.25 O 3-5-δ was prepared by a mechanical alloying process from mixtures of La 0.6 Ca 0-4 CoO 3 and IrO 2 . Scanning electron microscopy images on the resulting powders exhibited particles with irregular shape at 300-500 nm in size. X-ray diffraction analysis confirmed formation of a perovskite with complete disappearance of rutile signals from IrO 2 , indicating successful incorporation of Ir 4+ at the Co 3+ sites. Supported on carbon nanocapsules, the La 0.6 Ca 0.4 CoIr 0.25 O 3.5-δ demonstrated superior performance over those of La 0-6 Ca 0.4 CoO 3 in both charging and discharging current density-voltage polarizations. In addition, galvanostatic charging and discharging measurements at 25 and 100 mA/cm 2 indicated that the electrocatalytic abilities of La 0.6 Ca 0.4 CoIr 0.25 O 3.5-δ are stable and sustainable.