Bi2-xRu2O7-z particles were prepared by co-precipitation method which was carried out by the calcination of the precipitates obtained by adding excess NaOH solutions into the metal salt solution containing Bi(III) and Ru(III). The obtained particles were loaded on a titanium disk by dropping the solution prepared by dispersing the oxide particles in distilled water under ultrasonic agitation. No binder and no ion exchange resin were used for this preparation. The oxide loaded titanium disk was analyzed by SEM and used as the working electrode for oxygen reduction and evolution. The concentration of KOH solution at 0.1 mol/L was used at 25 oC. The electrolyte was bubbled with oxygen or nitrogen to measure the net oxygen reduction current. The specific activity of the oxide catalyst was evaluated by the currents normalized with the amount of the loaded catalyst, iw, or the double layer charge, ic.
The polarization curves with the oxide loaded titanium disk at different amounts of oxide were measured, and the results indicated that oxygen evolution current increased with increasing the weight of catalyst, while the specific activities, iC and iW, was unchanged with the loaded oxide amount, suggesting that the double layer charge and the catalyst’s amount are linear to the active surface area for oxygen evolution. Although the oxygen reduction current also increased with increasing the weight of catalyst, the specific activity, iW, decreased with increasing catalyst’s weight, which implies that the inner site of catalyst’s layer hardly works for the sites of oxygen reduction under the condition that the active species is only dissolved O2. More detail results will be presented in this paper.