Reverse Micelle Assisted Dispersion of Lanthanum Manganite on Carbon Support for Oxygen Reduction Cathode

It was tried to disperse oxide finely on carbon black support through a reverse micelle (RM) method using nonylphenyl ether (surfactant), and cyclohexane (solvent). An RM dispersion containing a nanosized precursor of the oxide [RM (C)] was prepared by mixing an RM dispersion containing nitrates of constituent metals [RM (A)] with another dispersion containing RM (C) was easily destabilized with the addition of ethanol to deposit the precursor, which was converted to hexagonal oxide or orthorhombic oxide by calcination in air or respectively. Carbon black powder was mixed at various stages of these preparation procedures. Among the resulting carbon-supported oxide powders, the one for which the carbon black was suspended into RM (A) was found to give an outstanding cathodic activity: It allowed current density as high as 300 mA cm −2 at −80 mV ( vs. Hg/HgO) in 8 M KOH at 60°C under air flow. Transmission electron microscope observation revealed that fine dispersion of the oxide particles in the carbon matrix is the origin of such high activity.