THE REDUCTION OF OXYGEN ON TITANIUM-OXIDE ELECTRODES

The cathodic reduction of oxygen in 1 mol dm-3 sodium hydroxide solutions has been investigated at several types of titanium oxide cathodes. Layers of TiO2 were prepared on titanium by spraying and thermal decomposition of solutions of titanium n-butoxide in 2-propanol and titanium tetrachloride in methanol + water and also by anodization; the reduction was also studied at Ebonex(R), a conducting ceramic consisting mainly of Ti5O9. In all cases, the reduction of oxygen occurs largely by a 4e- reaction to water and the reaction occurs at potentials close to -1.0 V vs. SCE. Cyclic voltammetry in the absence of oxygen shows that, at these potentials, the surfaces undergo reduction and the electrochemistry of the Fe(CN)64-/Fe(CN)63- Couple has been used to probe further the properties of the TiO2 surfaces.