Preparation And Properties Of Ru-Ti Composite Electrode Based On TNTs Interlayer

With the increasing awareness of environmental protection and the popularization of the concept on energy conservation in recent years,more and more attention has been paid to the pollution caused by the chemical production process based on chlor-alkali industry,the impact of products on the environment and how to produce low-energy chlor-alkali products.Titanium-based metal compound coated electrode,commonly known as DSA?Dimension stable anode?,has been widely used in chlor-alkali industry because of its excellent electrocatalytic activity,no secondary pollution and long service life.In this paper,ordered titanium dioxide nanotube arrays?TNTs?were grown on Ti plates by anodic oxidation.DSA electrodes with high electrochemical activity and stability were prepared by thermal decomposition with TNTs as interlayer under different conditions.On the one hand,TNTs provide a large specific surface area,which enhances the binding force between the active substance and the substrate,making the distribution of the active substance more uniform and loose.On the other hand,TNTs as an interlayer plays a protective role on the electrode substrate,reducing the generation of non-conductive TiO₂ layer in the service process,which is conducive to improving the electrochemical activity and stability of DSA electrode.In chapter 3,we reported a novel RuO₂-TiO₂ composite electrode prepared by thermal decomposition process using TiO₂ nanotube arrays?TNTs?as an interlayer.Specifically,the TNTs interlayer was fabricated by anodic oxidation on pure Ti plate,followed by heat-treatment?450??to transform its amorphous structure to anatase structure.This TNTs interlayer not only has a good protection for Ti substrate,but also has a low resistance.The resultant RuO₂-TiO₂ electrode presents superior performance toward chlorine evolution reaction?ClER?and longer service lifetime?132 h?than that without interlayer?59 h?.Experimental results show that anodizing time determines the length of TiO₂ nanotubes and brings about different catalytic activity and stability.The RuO₂-TiO₂/TNTs/Ti electrode with an optimal RuO₂-TiO₂ coating(4.5 g·m^-2)presents a better spatial structure,homogeneous crystal particles,uniformly distribution and more active sites.However,high calcination temperature?>600??has a detrimental impact,i.e.the collapse of TNTs and a“cracked mud”structure,which provide a path for oxygen and electrolyte to penetrate into the substrate and cause the spalling of coating,eventually lead to a serious decline in electrocatalytic activity and stability.In chapter 4,DSA electrodes doped with different metal oxides were prepared by thermal decomposition.The relatively loose structure of MnO₂-RuO₂/TNTs/Ti electrode reduces the difficulty of proton exchange between the electrolyte and the active surface.The electrolyte can exchange protons with the"external"and"internal"active surface,resulting in a larger integrated charge of cyclic voltammetry.Higher electrocatalytic activity was obtained due to more active points on the surface.Because the radius of Ti⁴⁺?68 pm?is very close to Ru⁴⁺?67 pm?and Ta⁵⁺?65 pm?,the Ta₂O₅-RuO₂/TNTs/Ti electrode can form a solid solution with strong bonding force during thermal decomposition,so Ta₂O₅-RuO₂/TNTs/Ti electrode has the longest service lifetime achieved 234 h,which is much longer than that of other electrodes service lifetime.In chapter 5,RuO₂-IrO₂/TNTs/Ti electrodes with high chlorine evolution activity were prepared by thermal decomposition method.The influences of degradation temperature and initial electrolyte concentration on the degradation rate of Cl^-were studied detailedly,based on which the Quasi-First-Order degradation kinetics model and quasi-second-order degradation kinetics model were established.The activation energy in the degradation temperature range was 18.57 kJ·mol^-1,which indicated that the reaction was controlled by the diffusion process It was found that the increase of initial concentration was conducive to degradation,the higher initial concentration provided the necessary driving force for the diffusion of electrode solution on the coating surface.By calculating and comparing the parameters in the degradation kinetics equation,it is found that the results are in good agreement with the experimental results,and the Cl^-degradation process can be further studied as a theoretical basis.