Study On Preparation And Properties Of Ti/SnO₂+Sb₂O₅/IrO₂+Ta₂O₅ Composite Electrode

In this thesis, Ti/SnO₂+Sb₂O₅/IrO₂+Ta₂O₅ composite electrode was prepared by thermal decomposition technology to improve the lifetime and reduce cost of Ti-based metal oxide anode. Firstly, effect of various calcination temperatures on the structure, surface morphology, stability and electrocatalytic properties of the intermediate layer and the surface active coating of Ti/SnO₂+Sb₂O₅/IrO₂+Ta₂O₅ electrode was investigated, and the optimal calcinations temperatures was determined mainly by the elctrocatalytic properties and accelerated life of the electrode. Secondly, the role of intermediate layer containing Sn-Sb element on Ti/SnO₂+Sb₂O₅/IrO₂+Ta₂O₅ electrode was discussed, and strcture model of the corresponding electrode was proposed. At last, the failure behavior of Ti/SnO₂+Sb₂O₅ArO₂+Ta₂O₅ electrode was investigated.Polarization curve measurements, cyclic voltametry (CV), electrochemical impedance spectroscopy (EIS) investigation and accelerated life test were used to obtain information about the electrochemical properties of the electrode.The surface morphology and composition of the intermediate layer and the surface coating were characterized by scanning electron microscopy and energy disperse spectroscopy (EDS).The crystal structure of the coated anode was examined by X-ray diffraction.Results indicated that calcination temperatures had remarkable influence on the properties of Ti/SnO₂+Sb₂O₅/IrO₂+Ta₂O₅ electrode. When the intermediate layer prepared at 500℃and the surface active coating parepared at 450℃, Ti/SnO₂+Sb₂O₅/IrO₂+Ta₂O₅ shows good electrocatalytic performance and long accelerated life.The present of an intermediate layer cotaining Sn-Sb element can effectively prevent from TiO₂ insulation layer formed during the electrolysis, depress the interfacial resistance of the electrode and improve the adhesive power between both the active coating and Ti substrate, which lead that accelerated life of Ti/SnO₂+Sb₂O₅/IrO₂+Ta₂O₅ electrode is as two times as that of Ti/IrO₂+Ta₂O₅ electrode. Furthermore, Ti/SnO₂+Sb₂O₅/IrO₂+Ta₂O₅ electrode has much better electrocatalytic performance than Ti/IrO₂+Ta₂O₅ electrode.The whole electrolysis process an be divided into three stages including "breaking in", stable and degradation regions by the analysis of the failure behavior.The results showed that the degradation was due to the dissolution of the active component and the deterioration of the interface between Ti base and oxide catalys.Moreover, the surface activity numbers were greatly reduced and the resistance was increased significiantly after passivation of the electrode.