OXYGEN REDUCTION ON Cu1 ,Mn16O4 SPINEL PARTICLES COMPOSITE ELECTRODES EFFECT OF PARTICLES SIZE

Abstract

ABSTRACT The oxygen reduction reaction (orr) was studied on CG/PPy/PPy(Ox)/PPy and CG/paint/CC(Ox)PPy composite electrodes, CG representing conducting glass, PPy polypyrrole, CC carbon cloth and Ox mixed valence spinel oxide particles of transition metals Cu 1.4 Mn 1.6 O 4 in 0.2 M KCl pH = 9.2, at room temperature. PPy is electrochemically polymerized and serves as a protective layer to dispersed oxide particles in the carbon cloth. Oxide particles size varied from 7.6 to 11.2 µm. The orr takes place on the oxide particles with formation of hydrogen peroxide which diffuses to electrolyte solution. The amount of peroxide ions produced was detected using the rotating ring-disk electrode technique and determined indirectly by iodine spectroscopy. The peroxide ions production depends strongly on the oxide particle size. Keywords: Copper manganites, Spinel oxide, Composite electrode, Polypyrrole, Oxygen electroreduction. INTRODUCTION The importance of the cathodic oxygen reduction reaction (orr) to water either directly or indirectly via hydrogen peroxide is widely recognized due to their applications such as oxygen electrode in fuel cells, lithium-air batteries, wastewater treatments and, organic and inorganic synthesis. In fuel cells the orr is the only employed reaction to accept electrons from chemicals such as methanol, ethanol or other molecules