Study On ORR Performance And Application Of Fluorine Doped Carbon Catalyst

In situ electrochemical synthesis of hydrogen peroxide（H₂O₂）is an alternative method of anthraquinone oxidation（AO）,which can overcome the disadvantages of high transportation cost and explosion risk of H₂O₂ prepared by anthraquinone method.Electrochemical synthesis of H₂O₂ is the process of producing hydrogen peroxide by electrocatalytic reduction of O₂.The core technology of electrocatalytic reduction of O₂ to H₂O₂ is to prepare catalysts with high activity and strong stability.Compared with noble metal catalysts,carbon based catalysts have the advantages of low cost and simple preparation,but they also have the disadvantages of insufficient activity.The traditional electro-Fenton technology has some technical defects,such as high p H value,metal rich sludge,secondary pollution and poor stability,which greatly limits its further application.In view of the above problems,this study designed and prepared fluorine doped carbon catalyst,studied its electrochemical performance of generating hydrogen peroxide through two electron ORR under acidic conditions,and the degradation activity of in-situ electro-Fenton degradation of Rhodamine B pollutants,explored the principle of fluorine doped carbon electrocatalytic reduction of oxygen gas to produce hydrogen peroxide,and achieved the following research results:（1）The prepared fluorocarbon catalyst has excellent performance of producing H₂O₂and good stability.Under the condition of p H=1,-0.1 V（vs.RHE）,the accumulation of H₂O₂ produced by electrocatalytic reduction of fluorocarbon catalyst can reach 2837.5 mg L^-1 under 3 h,and the selectivity of the catalyst can reach 95.7%.The calculation results of density functional theory（DFT）can show that the doping of fluorine atoms into the carbon skeleton is conducive to the adsorption of O₂,and different C-F bonds have a great impact on the orr performance.The C-F bond is conducive to the formation of H₂O through the four electron pathway,while CF₂ can not only promote the adsorption of O₂ on the catalyst surface,but also promote the desorption of OOH,so as to promote the formation of H₂O₂through the two electron pathway.（2）The system of fluorine doped carbon modified carbon felt as cathode,in-situ preparation of hydrogen peroxide and electro-Fenton degradation of Rhodamine B has excellent degradation performance.When the initial electrolyte p H is 3,the Fe²⁺concentration is 0.6 m M,the voltage is-0.8 V,and the Rh B concentration is 50 mg L^-1,the chroma removal rate of Rh B can nearly100%in 15 minutes,and the TOC removal rate is38%in 30 minutes.Under 8 cycles of degradation,the chroma removal rate of Rh B still reaches 100%in 15 min.