ISSN:
1572-8838
Keywords:
electrocatalysis
;
dimensionally stable anodes
;
mixed oxides
;
corrosion
;
impedance
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Electrical Engineering, Measurement and Control Technology
Notes:
Abstract An electrode of nominal composition Ti/Ir0.3Ti0.7O2 was prepared by thermal decomposition of the chloride precursor mixture at 450°C. A systematic study of the corrosion behaviour of this anode was performed under accelerated conditions (j=400mAcm−2) in acidic media. Simultaneously, CV and EIS measurements were done at regular time intervals until the end of the electrode service life (∼528h). It was possible to identify the various stages of the electrode deactivation, and quantify the associated parameters. Three main steps were identified in the electrode deactivation mechanism. During the first 170h, the loss of the more external (porous) part of the oxide active layer occurred. This is supported by the decrease in the parameter-values related to the electrochemically active surface area of the anode (qa and Cdl) and an increase in the Rct-values. The second stage is evidenced by a potential step afterwards remaining practically constant up to ∼380h , suggesting that the more compact and still very active region of the electrode is now exposed. Finally, for tcor〉400h the anode potential increases again. This behaviour, together with the Rct against time, suggests that the most internal part of the original coating, less rich in IrO2, is now exposed to the solution and is corroded. For t ≥∼510h the anode potential increases rapidly, the electrode being totally deactivated at t≃528h, when the anodically grown TiO2 film is exposed to the solution. During the complete deactivation process, the growth of a TiO2 film, due to Ti-support oxidation, in addition to that already present (IrO2 doped TiO2 film formed during the calcination step), is evidenced by the increase in the Rf-values, as well as decreasing Cf-values. However, for tcor〈450h the rate of this process is not significant. Only for tcor〉450h Ti-support oxidation becomes the main feature of the deactivation process.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1003431130954
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