RUTHERFORD BACKSCATTERING SPECTROSCOPIC STUDY OF THE FAILURE-MECHANISM OF (RUO2+TIO2) TI THIN-FILM ELECTRODES IN H2SO4 SOLUTIONS/

RuO2-TiO2 electrodes 5000 Angstrom thick, which mimic the dimensionall y stable anodes in composition and the method of preparation, were pre pared and tested for their activity toward the chlorine evolution reac tion and subjected to lifetime testing in sulfuric acid solution. Ruth erford backscattering spectrometry was used concurrently with electroc hemical measurements to analyze the changes in the ruthenium content o f the coating. The decrease in electrode activity was found to be clos ely linked to a decrease in the Ru content, and the measured profiles indicate that the loss takes place across the thin coating. Failure is observed for electrodes with a Ru content below the critical concentr ation of 3 x 10(21) Ru atom/cm(3), but there is no evidence for the bu ildup of a pure TiO2 layer.