Synthesis Of Porphyrin-based Metal-organic Hybrid Materials And Investigation Of Photocatalytic Performance

The rapid development of global industry and the economy,coupled with the growing demand for healthy living conditions,has led to the emergence of environmental pollution as a significant challenge in the process of human development.Over the past few decades,researchers have been engaged in exploring various solutions to address this issue,with a particular focus on Advanced Oxidation Processes（AOPs）,particularly in the context of solar energy-based semiconductor photocatalysis.Nevertheless,traditional homogeneous reactions and single-component semiconductor photocatalysts have certain limitations in practical applications,including issues with secondary pollution,low utilization efficiency of visible light,and the inability to reuse catalysts.Consequently,the development of heterogeneous catalysts with a broad visible light absorption range,high efficiency of photogenerated carrier utilization,and facile recycling has become a primary focus in the field of AOPs.The concept of utilizing porphyrins as functional materials is strongly influenced by their pervasive presence in nature and their pivotal role in photosynthesis.Metal-Organic Frameworks（MOFs）,as an emerging porous crystalline material,are composed of metal ions or metal clusters combined with multi-coordinated organic ligands,which have the main advantages of high crystallinity,large porosity and specific surface area,adjustable pore size,structural diversity,and designability,etc.Metal-Organic Gels（MOGs）,as the"twin"of MOFs,are composed of metal ions or metal clusters bonded by coordination bonds,hydrogen bonding,π-hydrogen bonding,and other organic ligands.In addition to the high porosity and large specific surface area of MOFs,MOGs have the main advantages of structural diversity and designability,including high crystallinity,high porosity,and large specific surface area,structural diversity,and designability.In addition to the principal advantages of MOFs,they also possess processability and a second class of larger pores（which can accommodate guest molecules）,which provides a solid foundation for expanding the properties of organic-inorganic hybrid materials.The preparation of porphyrin-based metal-organic hybrid materials by introducing porphyrin into MOFs/MOGs is anticipated to extend their visible light absorption properties and improve their catalytic properties.The coupled catalytic system is formed by modifications such as the introduction of active centers,semiconductor compounding,and the deposition of noble metals combined with photocatalysis,bisulfate activation,and the Fenton reaction.These modifications are designed to achieve effective utilization of solar energy and efficient separation of photogenerated carriers.The objective is to obtain the composite system photocatalysts with high AOPs performance.The current catalytic system under the coupled catalytic system has rarely been studied.Consequently,its catalytic efficiency and mechanism in environmental remediation are still unclear.In light of the aforementioned considerations,this thesis will focus on the construction of porphyrin-based metal-organic hybrid material composite catalysts and their application in environmental remediation.The specific research content will be as follows:（1）Magnetic 5,10,15,20-tetrakis（4-carboxyphenyl）porphyrin（TCPP）-based metal organic gel（MMOG）was prepared by an in situ as-reaction at room temperature.This MMOG can be used as a novel visible light-assisted heterogeneous Fenton catalyst.In the presence of visible light and hydrogen peroxide,MMOG demonstrated a 94.2%degradation efficiency of rhodamine B within 40 min.MMOG also exhibited high killing rates（>99.999%）against Escherichia coli（E.coli）and Staphylococcus aureus（S.aureus）under visible light.This easily synthesized MMOG with photo-Fenton activity under visible light and magnetic recovery has potential applications in environmental remediation and biomedical applications.（2）A Co-doped Fe-based metal organic gel（CFM）was prepared by introducing cobalt ions into Fe-MOG.The CFM was found to be capable of promoting potassium persulfate（PMS）activation and visible-light-induced photocatalysis for the removal of norfloxacin.Furthermore,the magnetic Fe₃O₄ was introduced to endow the CFM with strong magnetic recovery performance.The introduction of cobalt ions into Fe-MOG optimized its electronic structure,which enabled the CFM to excel in synergistic photocatalytic-PMS activation,visible-light absorption,and improved photo-induced charge separation efficiency,and used to catalyze norfloxacin,which is more difficult to degrade than rhodamine B.The Vis/50%-CFM/PMS system achieves up to 96.8%removal of Norfloxacin and 78.3%removal of total organic carbon in 60 min.Density Functional Theory（DFT）and Quantitative Structure-Activity Relationship（QSAR）modeling were employed to comprehensively analyze the degradation process and toxicity of the intermediates.Furthermore,the Vis/50%-CFM/PMS system demonstrated antimicrobial effects against Escherichia coli and Staphylococcus aureus.This study offers a novel perspective for the advancement of innovative photocatalyst-PMS activation coupled systems for environmental remediation.（3）The preceding work demonstrated that the combination of the advantages of PMS activation and photocatalytic techniques represents a potential strategy for enhancing AOPs.The Ti O₂ nanosheets were coupled with 5,10,15,20-tetrakis（4-pyridylphenyl）porphyrin（Tp Yp）-based MOFs to construct Co-Tp Yp/Ti O₂ heterojunction heterostructures,which exhibited synergistic photocatalytic-PMS-activation properties and were used for the degradation of bisphenol A（BPA）,which is more difficult to degrade than norfloxacin.The composite material exhibited nearly complete degradation of BPA within 60 min.The effects of initial p H,PMS dosage,and co-existing ions on the degradation of BPA were investigated and elucidated.Degradation pathways of BPA were inferred from DFT calculations and Liquid Chromatography Mass Spectrometry results.The toxicity of the degradation intermediates was evaluated by using the QSAR model.Finally,a synergistic photocatalytic-PMS activation mechanism for BPA degradation on composites was proposed and validated.This study provides new ideas for the construction of efficient AOPs materials in the future.（4）In addition to the common organic pollutants previously discussed,there are also a considerable number of inorganic pollutants present in the environmental remediation process.The objective of this chapter is to combine the advantages of membrane technology and photocatalytic technology for the treatment of inorganic pollutants.Zr-TCPP loaded with Ag NPs was prepared by in situ reaction.The prepared composites exhibited enhanced photocatalytic activity in the Cr（VI）photoreduction reaction,with a reduction rate of Cr（VI）reaching 94.1%within 30 min.Furthermore,in order to enhance the characteristics of traditional powder catalysts that are challenging to recycle during practical utilization,the catalysts and polyacrylonitrile were combined to fabricate membrane nanofiber filters with photocatalytic reduction of Cr（VI）by electrostatic spinning technology,which can be easily recycled for reuse.This work provides novel insights into photocatalyst reconfiguration strategies and broadens the application of traditional powder photocatalysts.