Preparation Of Chlorine Evolution Anode Used In Seawater By Sol-gel Process And Studying On Their Electrochemical Performance

Sol-gel process is used to prepare DSA.The effect of dispersing time during the preparation of the sol on the performance of the anode is studied.The best composition is determined by studying the performance of the anode of different composition.The deactivation mechanism,the Cl₂ evolution efficiency and the effect of Mn²⁺on the anode's performance are also discussed.The composition distribution and oxidation are more even for the anode prepared by sol-gel process than the traditional thermal decomposition process.The Cl₂ evolution potential increases,the O₂ evolution potential decreases and the catalytic performance of the anode are improved with the dispersing time increasing.The Accelerated Service Test(AST)increases by 15～30 times,the Cl₂ evolution potential decreases a lot,the catalytic performance increases greatly,and current efficiency reaches as high as 93.83%by adding of Ir element.The AST reaches more than 12000mins by adding proper amount of Sn,the Cl₂ evolution potential and O₂ evolution potential all increase a little but still keep relatively large difference and high current efficiency.The deactivation of anode is mainly caused by the formation of insulating TiO₂-rich layer between coating and substrate when Ir,Sn added,because Ir,Sn have the similar ion diameter with Ru,Ti which form solid solution during heated at 440℃.The deactivation of the anode is caused by the dissolution of ru acitive component when Zr,Pd,Co added, because Zr,Pd,Co don't have the similar ion diameter with Ru,Ti and can't form solid solution during heated and these kinds of coating always have shorter AST time.The Cl₂ evolution performance of the anode mainly affects by combination strength of MnO₂ with the coating.The more large of the combination strength,the more decreased of the Cl₂ evolution performance.The Mn²⁺in seawater affects on current efficiency directly. The current efficiency decreased because of the depostion of MnO₂.The effect of Mn²⁺on the AST time and Cl₂ evolution performance is not obvious in short time but it will become more and more serious with the operation time increasing.The deposition of MnO₂ on the anode and the deactivation of the anode are caused by electronic self-catalysis process of MnO₂.