Taf. Lassali et al., Faradaic impedance investigation of the deactivation mechanism of Ir-basedceramic oxides containing TiO2 and SnO2, J APPL ELEC, 30(5), 2000, pp. 625-634
Ti-supported IrO2/SnO2/TiO2 coatings were prepared by thermal decomposition
of the chloride precursor mixtures (400 degrees C). The effect of the repl
acement of TiO2 by SnO2 on the service life of the Ti/IrO2 + TiO2 coating w
as investigated under galvanostatic polarization at 0.8 A cm(-2) in 1.0 mol
dm(-3) HClO4. The deactivation mechanism of the electrodes, using OER as t
he reaction model, was investigated through the periodic recording of volta
mmetric curves (VC) and impedance spectra (EIS) as a function of the anodiz
ation time. Bulk composition and morphology of the electrode coatings were
investigated by energy dispersive X-ray (EDX) and scanning electron microsc
opy (SEM) before and after accelerated life tests. The service life showed
a dependence on the electrode composition. Replacement of TiO2 by SnO2 in t
he Ir0.3Ti0.7O2 electrode led to a decrease in the service life of these sy
stems above 30% mol SnO2 content. This behaviour is directly related to mor
phological factors and the absence of synergetic effects. The behaviour of
the parameters supplied by the EIS, VC, SEM, and EDX analyses made it possi
ble to describe the overall deactivation mechanism.