Structure Design And Performance Study Of Catalysts Based On Hydroxyl Radical Regulation

In recent years,industrial wastewater and domestic sewage lead to water pollution,affecting people’s lives.In various water treatment methods,advanced oxidation process（AOPs）will produce a large number of hydroxyl radicals（·OH）and superoxide radicals（·O₂^-）in the reaction process.Because of the characteristics of fast reaction speed and thorough decomposition of organic matter,it has become an important method for the treatment of organic pollutants in various wastewater.Both hydroxyl radical（·OH）and superoxide radical（·O₂^-）have high redox potential and strong oxidation ability.They can decompose organic matter into CO₂,H₂O,and inorganic matter,and they can be transformed into water after they play a role,without secondary pollution.In AOPs,photocatalysis and heterogeneous electro Fenton reaction have been widely concerned.Photocatalysis technology directly uses light energy to produce free radicals（·OH,·O₂^-）with oxidation and reduction capability.Photonic crystal has two characteristics of photonic band gap and slow photon effect,which can increase the material’s ability to capture light and avoid the recombination of photogenerated electrons and holes,and greatly promote the degradation of pollutants.The 2-electron oxygen reduction reaction（2e-ORR）is expected to be an effective way to generate H₂O₂ in situ by generating intermediate species·OH.As a competitive reaction of 2e-ORR,the 4-electron oxygen reduction reaction（4e-ORR）hopes to generate less H₂O₂.Therefore,in this paper,several different catalysts were prepared to study their effects on the degradation of wastewater:1.The lattice constant,filling ratio,number of periodic layers,and incident angle of（GO/TiO₂）_N one-dimensional photonic crystal photocatalyst were obtained by calculation.It was found that when the lattice constant d₀=125 nm,d _GO/d=0.45,n=21,θ=0°,the photonic crystal has the optimal photonic band gap.After that,the（GO/TiO₂）_N one-dimensional photonic crystal photocatalyst was prepared by sol-gel and spin coating.The degradation ability of three samples of GO/TiO₂ powder,GO/TiO₂ film and（GO/TiO₂）_N one dimensional photonic crystal photocatalyst to tetracycline was studied.The results show that（GO/TiO₂）_N one dimensional photonic crystal photocatalyst has the strongest degradation ability for tetracycline,The removal rate of tetracycline reached 64%within 60 min.Subsequently,PS template was prepared by template self-assembly method,and then WO₃/Zn Fe₂O₄ opal photonic crystal photocatalysts with different concentrations were prepared.The degradation efficiency of tetracycline by WO₃/Zn Fe₂O₄（10）photonic crystal photocatalyst was the fastest,reaching 60%in 100 minutes.WO₃ reverse opal template has a porous structure,which usually has a large specific surface area,can provide abundant active sites for degradation,and can promote the transfer and diffusion of charge and organic matter between pores.In addition,WO₃/Zn Fe₂O₄（10）has a Z-type structure,which greatly promotes the separation of photogenerated electrons and holes,and increases the ability of the material to capture light.2.Through carbonization,oxidation,and doping,N,P-BT-T electrocatalysts were prepared with biomass tar as raw material as the raw material.The high order carbon matrix was obtained by carbonization,and it was conducive to the rapid transfer of electrons;Abundant oxygen-containing functional groups were obtained by oxidation,which can be used as anchoring sites for subsequent heteroatom doping or form defects in the doping process;The electrocatalysts with pyrrole N,pyridine N,graphite N and P-C active sites were obtained by doping,which showed excellent 2e-ORR performance,Among them,N,P-BT-600 has the smallest electron transfer number（2.08）and the largest H₂O₂ yield（96.08%）.The actual yield of H₂O₂ reached 150 mg/L.N,S-ACTP₄₈-T electrocatalysts were prepared from coal tar pitch（CTP）by carbonization,oxidation,and doping.Firstly,microporous structure(with a surface area of 2127 m² g^-1)and ordered structure were obtained by carbonization,which ensure the rapid transfer of reactants（maximum diffusion coefficient）.Secondly,the highly ordered carbon matrix（I_D/I_G=0.86）ensured the rapid transport of electrons between the reaction interface and the collector.Finally,the N species containing only pyridine N and graphite N were precisely generated by Hantzsch synthesis method through the preferential site occupation of S atom and abundant C=O functional groups on the surface,which greatly promoted the ORR performance of the materials.N,S-ACTP₄₈-900 has excellent 4e-ORR performance under the synergistic effect of O₂molecular mass transfer and O₂→OOH*→O*+OH*→H₂O reaction.In addition,N,S-ACTP₄₈-900 catalyst showed strong stability,and the stability decreased by 7.5%after 10000s.The methanol resistance of N N,S-ACTP₄₈-900 catalyst was better than that of Pt/C catalyst,and the current density retention rate was 98.3%.