Use of Ti/IrO2/SnO2-Sb2O5 electrodes for ozone production

Ozone production in 5M H2SO4 With Ti/IrO2/SnO2-Sb2O5 electrodes was studied. Electrodes have been prepared at 550 degrees C by spray pyrolysis of a solution of precursors containing tin and antimony chlorides. The aim of this work was to elucidate the mechanism of activation and desactivation of Ti/IrO2/SnO2-Sb2O5 electrodes for ozone production. Under galvanostatic conditions the anodic potential and O-3 production increases firstly reaching a maximum then suddently decrease. We explain this observation by considering that the SnO2 layer prepared by spray pyrolysis is under stoechiometric for oxygen. During the activation SnO2 becomes stoechiometric. This condition is necessary for ozone production. XRD analysis showed no modification of the structure of the bulk during ozone production. Nevertheless XRF analysis revealed an unhomogeneity of the atomic Sb/Sn ratio on the surface of the electrode leading to pitting corrosion which is responsible of the desactivation of the electrode.