Preparation Of High Efficiency Titanium-based Composite Electrode And Its Photoelectrocatalytic Performance

Organic pollution is one of the biggest environmental protection problems our in our country.Dyes and their intermediates have a wide range variety,with a high concentration,color depth,organic matter complex composition,toxic,and poor characteristics of bio-degradable.TiO₂ photocatalysis with high chemical stability is well known to be able to degrade refractory organic substances in the water and finally mineralized to CO2 and H₂O which has been widely applied in the field of water purification.However,the efficient recovery of TiO₂ from treated water for recycle still remains an unsolved issue.Therefore,the preparation and modification of new TiO₂ carbon paper electrode and 3D-TiO₂ nanotube electrode were studied in this paper.The formation mechanism,physical and chemical properties and photocatalytic degradation of pollutants were studied,and the influencing factors of photoelectrocatalytic degradation were analyzed.Catalytic application of organic pollutants to provide a theoretical basis.The main research results are as follows:?1?The TiO₂ nano-cluster particles?NCs?were synthesized on carpon papers by a hydrothermal method.The electrodes ware characterized by XRD,FESEM,UV-vis spectrum,and electrochemical test?CV?CA?LSV?to optimize the photoelectrocatalytic activity performance.? The experiments determine the following optimum conditions:precursor concentration was 0.6 mL of isopropyl titanate,10 mL of hydrochloric acid solution,0.2 g of cetyltrimethylammonium bromide,0.34 mL of ethylene glycol,temperature was 150?;reaction time was 5 h.? The carbon paper showed superior conductivity as base materials.The TiO₂ NCs was single crystal rutile phase with highly sensitive and steady photocurrent responses.Under the mercury lamp,the bias voltage of +0.7 V was applied,the photocatalytic degradation of 5 mg/L methyl orange was 98%?2 h?,and the degradation rate was still greater than 85%in the 6 time repeated experiments.?2?The hightly ordered 3D-TiO₂ nanotube arryas?3D-TNAs?have been prepared by anodizing method on Ti mesh.? The optimum anodic oxidation conditions were as follows:Solvent was Vethylene glycol:Vwater = 1:1,0.5 wt%NH4F,anodized voltage of 20 V,ultrasonic mass transfer,oxidation 90 min.The photocatalytic area,photocurrent and photoelectrocatalytic degradation rate were improved by 2 times,1 times and 2 times respectively,compared with the 2D-TiO₂ nanotube arrays?2D-TNAs?synthesized under the same experimental conditions.? The ZnxCdyS/3D-TNAs heterojunction electrodes was synthesized by successive ionic layer adsorption and reaction?SILAR?method.The 3D-TNAs were immersed in the zinc acetate,cadmium acetate,Na₂S solution respectively.The best SILAR experimental conditions were as follows:The concentration is 0.01 mol/L,the number of loading times was 12,the calcination conditions are nitrogen atmosphere to 2?/min temperature to 500? for 2 h.Before the loading of sulfide,the 3D-TNAs were immersed in 1 mg/L graphene oxide?GO?to fabricate the ZCS/GO/3D-TNAs composite films,which was to form the Z-shaped model significantly improved the photoelectrocatalytic performance.? Sulfide modified electrodes used in the actual wastewater degradation test need to be improved.?3?The rutile-anatase mixed TiO₂?RAT?was assembled into 3D-TNAs using solution evaporation self-assembly?EISA?.?The optimum experiment conditions were as follows:P123 was used as template and aged for 2 days.After anodizing,mesh was directly immersed in sol-gel to aged,then heated to 500? at 5?/min,and calcined for 2 h to synthesize 3D-TNAs/TiO₂?EISA?Electrode,the photocurrent is 2.5 times higher than that of the 3D-TNAs electrode,and the photoelectric coupling performance is best at +0.8 V.? The removal rate of MO was still more than 98%after 6 times.?The photocatalytic degradation rate is affected by the concentration of organic pollutants,catalyst concentration,reaction temperature,light intensity and electrolyte concentration.Under the same concentration of electrolyte,the photoelectric removal rate of low concentration pollutants accorded with the first order kinetics.-ln?C_t/C₀?=kt,The reaction rate constant k is exponentially related to the initial concentration of pollutants k=aC₀ⁿ¹,and the reaction temperature is in accordance with the Arrhenius formula k=Aexp?-Ea/RT?,and the intensity of the index is k=aIⁿ³,and the area of the electrode material Corresponding to k=b?AsD?n,the relationship between the reaction rate constantand the parameters is k=A·e-Ea/RT·C0ⁿ¹·Iⁿ²?AsD?ⁿ³ summarized as the relationship between the concentration of pollutants and the time is C,/C₀ = e^-kt = e^{-A·e-Ea/RT·C₀n1·In2·?A_sD?n3·t}...