Study On Preparation Of High Corrosion Resistance Ti-based Anode And Its Electro-Catalytic Performance In Acid

Since the Ti-based anode was gone into industrial application in 1960s,it quickly replaced the graphite electrode and became one of the most widely used electrodes in the electrolysis industry due to its advantages of low overpotential and high stability.However,the Ti-based anode prepared by traditional thermal decomposition usually has a lot of cracks,and these cracks provided channels for electrolytes and reactive oxygen species generated during electrolysis to reach the Ti substrate.And it will result in the generation of insulating Ti O₂layer between the coating and the Ti substrate.Subsequently,as the Ti O₂ layer grows and thickens,the conductivity of the electrode gradually decreases,and the growth stress of the Ti O₂ layer will cause the coating to peel off from Ti substrate,the active materials will be lost,and the electrode will be deactivated.The phenomenon is especially prone to occur in an acidic electrolysis environment.Therefore,finding an effective method to protect the titanium substrate is of great significance for the electrochemical application of titanium.Based on the application of the traditional titanium-based RuTi coated anode（Ti-RuTi）in the chlorine evolution reaction（Chlorine Evolution Reaction,CER）and oxygen evolution reaction（Oxygen Evolution Reaction,OER）,this paper explores the heat treatment in the electrode preparation process.The effects of a series of process parameters such as time and coating thickness on the electrode surface state and electrocatalytic performance.On this basis,a high-corrosion-resistant titanium-based anode was constructed by introducing a high-corrosion-resistant ternary oxide interlayer（mixed crystal of Sn O₂,Ti O₂and Nb₂O₅,STN）between the titanium substrate and the RuTi coating.The adaptability of the STN interlayer to various Ru-based coatings was verified by changing the RuTi composition.Based on the research on titanium plate electrodes,the adaptability of STN to different shapes of titanium substrates was further expanded,and it was applied to the corrosion protection of porous titanium diffusion layers in proton exchange membrane electrolyzed water（PEM）.The cladding coating on the surface of the mesh constructs a Ti-STN-RuTi multifunctional titanium diffusion layer with high corrosion resistance.The following are the main results:（1）The traditional Ti-RuTi anode was prepared by the dip-pyrolysis method.By adjusting and optimizing the etching acid concentration,dip times,pyrolysis time and the ratio of metal elements in the dip solution during the preparation process,different processes were explored.The effect of parameters on the electrode surface state,crystallization and electrocatalytic performance.（2）STN coating（Ti-STN）was coated on the surface of titanium foil substrate by dipping-pyrolysis method.A series of surface characterization analysis results showed that the surface of the coating was dense and evenly distributed,which proved that the traditional thermal decomposition method can achieve Control of coating morphology and structure.The potentiodynamic polarization curve test results show that the corrosion potential of Ti-STN increases by 584 m V relative to the bare titanium foil,and the corrosion current decreases by two orders of magnitude.Protects titanium substrates from corrosion during long-term electrolysis in ambient conditions.The surface of Ti-STN was coated with ruthenium-based coatings（Ru Sn,RuTi,Ru Nb）of different compositions to verify the performance of the STN layer in the actual electrolysis process and its adaptability to various ruthenium-based coatings.The polarization curve and chronopotentiometry tests were carried out on the electrode,and the results showed that the STN layer extended the life of the electrode without adversely affecting the catalytic activity of the electrode.This kind of ruthenium-based coating has strong adaptability.（3）Build a PEM water electrolysis hydrogen production system,prepare and characterize the properties of the membrane electrode anode Y₂Ru₂O₇catalyst,study the influence of the diffusion layer porosity and the electrolytic cell compression on the electrolytic cell pressure,and further explore and analyze the reasons.Different assembly processes affect the nature of the cell pressure of the electrolyzer by changing the contact resistance and mass transfer capacity of the catalyst and the diffusion layer.The effect of different shapes of titanium substrates on the performance of the electrolytic cell was studied,and on the basis of optimizing the PEM assembly process,a multi-functional titanium diffusion layer with high corrosion resistance of Ti-STN-RuTi structure was prepared.The monitoring of the cell pressure changes during the long-term electrolysis process of the PEM electrolytic cell shows that the cell pressure of the bare titanium diffusion layer begins to rise significantly after 100h of operation,while the Ti-STN-RuTi diffusion layer can ensure the stable operation of the PEM for at least 200 h.More than twice that of the titanium diffusion layer.This shows that the STN layer can adapt to a variety of electrolysis environments,and it has good protection performance for various forms of titanium-based materials such as titanium foil,titanium felt and titanium mesh.Comparing the cell pressure of the PEM assembled with the bare titanium and Ti-STN-RuTi diffusion layers under the same electrical density,it is found that the Ti-STN-RuTi is slightly lower than that of the bare titanium,which is the contribution of the RuTi active enhancement layer,which proves the function of the enhanced diffusion layer.Envisioned realization.