Study On Titanium Supported Nanostructured Ir-Ta Oxide Anodes Prepared By Sol-Gel Method

Titanium supported IrO₂-Ta₂O₅ oxide anodes with excellent electrocatalytic activity and electrochemical stability have found extensive use in such fields as wastewater treatment, electroplating, electrosynthesis and so on. One of the new directions in this field is to prepare the oxide anode presenting better electro-catalytic activity and longer service life with high ratio of performance / cost. The purpose of this study is to prepare electrode material with nano structure by sol-gel method, in order to increase the surface area and improve electrode performance.In this paper, anodes of titanium supported IrO₂-Ta₂O₅ were prepared by sol-gel method. The microstructure and electrochemical properties of the anodes were studied with scanning electron microscopy (SEM) and energy dispersed X-ray spectroscopy (EDX), atomic force microscopy (AFM) and X-ray diffraction (XRD); chlorine evolution and oxygen evolution potential, potentiodynamic polarization, cyclic voltammetry, electrochemical impedance spectroscopy and accelerated life test.The Pechini method is a good choice to prepare Ti/IrO₂-Ta₂O₅ oxide anodes. The appropriate surfactant (SDS) can improve brushing performance and surface quality. As compared with the anode formed using the traditional method of thermal decomposition, the oxide anode prepared by Pechini method with the addition of SDS presents many large cracks, large electrochemically active surface area and high electro-catalytic activity for oxygen evolution, but lower stability.The effects of the preparation parameters on the electrochemical properties and morphological feature of Ti/IrO₂-Ta₂O₅ anodes prepared by Pechini method were investigated. Mixture uniform design was used in the optimization of preparation process of oxide anodes. Taking the actual situation and the performance into consideration, the optimum preparation condition of Ti/IrO₂-Ta₂O₅ anodes prepared by Pechini method was determined.The effect of sintering temperature on the properties of Ti/IrO₂-Ta₂O₅ anodes was investigated. It was shown that, the Ti/IrO₂-Ta₂O₅ anode prepared at 500℃possessed the longest service life. With the increase of the sintering temperature, the electro-catalytic activity for oxygen evolution on Ti/IrO₂-Ta₂O₅ anodes was lower, with the decrease of the electroactive surface area and the double layer capacitance.It has been indicated that the coating thickness affects obviously the morphology and electrochemical properties of Ti/IrO₂-Ta₂O₅ anode. The oxygen overpotential and polarization resistance rapidly decrease for an iridium content of 1.98-3.77g/m2, after which the decrease is more gradual. Cyclic voltammetric charge is almost proportional to iridium content in the active layer.The sol-gel method based on the metallic acetylacetonates route has also been investigated. As compared with the anode formed using the traditional method of thermal decomposition, the oxide anode prepared by this sol-gel method presents many large cracks, the segregation of IrO2. It also has larger electrochemically active surface area, but lower stability.