Synthesis and Characterization of Uncracked IrO2?SnO2?Sb2O3?Oxide Films Using Organic Precursors and Their Application for the Oxidation of Tartrazine and Dibenzothiophene

摘要

A ternary coating film of IrO2?SnO2?Sb2O3 on a Ti substrate was prepared by thermal decomposition in an adapted protocol of the Pechini method to obtain DSA type electrodes. The polymeric precursor mixture was prepared with nonchlorinated salts of iridium, tin, and antimony in different molar proportions. Iridium(III) acetylacetonate, tin(II) acetate, and antimony(III) acetate were used in small amounts to obtain compact, thin, and uncracked oxide films with homogeneous texture compared with a commercial film of Ti|IrO2?SnO2?Sb2O5. The polymeric precursor solution was brushed onto a pretreated titanium substrate and calcined at 500 °C to convert the coating into IrO2?SnO2?Sb2O3. Physical and electrochemical characterization was performed by SEM, EDX, DRX, and cyclic voltammetry. The formation of ternary oxides was explained according to redox reaction mechanisms involving decarboxylation and thermal decomposition. Even though the polymeric precursor solution was deposited by brushing, the oxide films was thin and homogeneous (3.05 ± 0.35 μm thickness). The DSA electrode performance was tested to evaluate the electrochemical oxidation of tartrazine and dibenzothiophene in aqueous and acetonitrile/water media, respectively. All DSAs demonstrated high effectiveness for the decolorization and mineralization of tartrazine (up to 90% and 70%, respectively), mainly by hydroxyl radicals. On the other hand, dibenzothiophene was converted to both dibenzothiophene sulfoxide and dibenzothiophene sulfone by direct electron transfer.