| Abstract
| - There are growing interests in anodes for oxygen evolution because of the importance of this reaction inmany electrochemical processes such as water electrolysis, electroplating, electrosynthesis, metal electrowinning,and electroflotation. Ternary IrOx−Sb2O5−SnO2 has been shown to be among the best elecytrocatalysts foroxygen evolution. Its high stability and relatively low cost will make it more attractive than IrOx and manyother electrocatalytic materials. In this paper, the open-circuit potential, voltammetric behavior, oxygen evolutionmechanism, and kinetics of the IrOx−Sb2O5−SnO2 coated titanium anodes were studied. It was found thatthe open-circuit potential could change significantly during the initial period of time probably because of thehydration of the coating film. Cyclic voltammograms obtained on Ti/IrOx−Sb2O5−SnO2 were somewhatdifferent from those on IrOx coated anodes. Apparent cathodic peaks from Ir(III)/Ir(IV) and Ir(IV)/Ir(V) wereobserved. However, the corresponding anodic peaks were very weak. Voltammetric investigation also showedthat Ti/IrOx−Sb2O5−SnO2 could provide fast electron transfer. Despite high anodic stability, severe damageoccurred when a Ti/IrOx−Sb2O5−SnO2 electrode was cathodically polarized. An O2 evolution mechanisminvolving cyclic formation and decomposition of ⋮IrO2 was proposed. The Tafel slope and ∂E/∂log aH+obtained were 86 and 45 mV dec-1, respectively.
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