Oxygen reduction on Ni{sub}xCo{sub}(3-x)O{sub}4 spinel particles/polypyrrole composite electrodes: hydrogen peroxide formation

摘要

The oxygen reduction reaction (orr) was studied on composite electrodes GC/PPy/PPy(Ni{sub}xCo{sub}(3-x)O{sub}4)/PPy with x = 0.3 and 1, in 2.5 × 10{sup}(-3) M KOH + 0.8 M KCl at room temperature. The orr takes place on the oxide particles with formation of hydrogen peroxide (H{sub}2O{sub}2), which diffuses through the polymer layers to reach the bulk of electrolyte solution. The amount of H{sub}2O{sub}2 produced, determined indirectly by iodine spectrometry, depended strongly on the oxide stoichiometry. The effects of the orr and of the generation of H{sub}2O{sub}2 on the conductivity of PPy and on the behaviour of the embedded oxide particles are discussed.