Preparation Of Visible Light Responsive Metal-organic Polymeric Materials And Study On Their Environmental Catalytic Activity

In the industrial production process of electroplating,printing and dyeing,smelting,and tanning,a large amount of toxic and harmful wastewater will be produced.If not properly treated,it will have a serious impact on the ecological environment and human health.Photocatalysis has been widely used in recent years due to its use of sunlight as a driving force and no secondary pollution.It has been widely used in the fields of reducing attenuated heavy metals,oxidizing and degrading organic substances,and killing bacterial microorganisms.At present,the development of new and efficient visible light catalytic materials and the improvement of solar energy utilization rate is one of the research hotspots.In recent years,photocatalysis of metal-organic framework materials?MOFs?has gradually emerged.The metal nodes and organic connectors constituting the MOFs can be regarded as isolated semiconductor quantum dots and light absorbing antennas,respectively,which are advantageous for enhancing/regulating visible light absorption.In addition,compared with traditional metal oxide semiconductors,MOFs materials have high specific surface area,rich topological structure and easy-adjusted pore structure,and have been applied to photocatalytic reduction of CO₂,hydrogen production,and pollutant degradation.In this study,Fe was rich in Fe on the surface and 2-methylimidazole?2MI?and terephthalic acid?H₂BDC?were used as organic ligands.They were prepared by room temperature crystallization,solvothermal and UV in situ reduction.Fe?II?-2MI,Fe?III?-2MI,Fe-BDC/Fe-2MI heterojunction and Ag@Ag-2MI and other visible light catalysts or electrodes for use in Cr???-containing wastewater treatment or photocatalytic antibacterial.Firstly,Fe?II?-2MI powder photocatalyst was prepared at room temperature.Thermogravimetric analysis?TGA?and X-ray diffraction?XRD?showed that Fe?II?could be stably complexed with 2MI and showed an amorphous shape.It has a large specific surface area?245.3 m²/g?and a good photocurrent response.Efficient reduction of Cr???after visible light irradiation for 75 minutes.In addition,the cycle experiments showed that Fe?II?-2MI had good stability.Mechanistic studies show that Fe?II?-2MI has suitable conduction band and valence band position,which is beneficial to Cr???reduction and organic oxidation.In addition,Fe?III?-2MI photoelectrocatalytic electrode was prepared by solvothermal method.XRD and XPS characterization showed that Fe?III?-2MI was successfully loaded on FTO.The photoelectric performance characterization showed that the Fe?III?-2MI electrode prepared when the Fe?III?-2MI precursor concentration was 0.13 M had a good visible light response.The mixed wastewater of Cr???and phenol was used as a simulated pollutant.After visible light irradiation for 5 hours,the reduction rate of Cr???reached 100%,the degradation rate of phenol was 80%,and the effect did not decrease significantly after repeated cycles.The Fe-BDC/Fe-2MI heterojunction was further prepared by solvothermal method.XRD and SEM characterization showed that the introduction of 2MI had a significant effect on the morphology and structure of Fe-BDC,from granular MIL-53?Fe?to spindle-shaped MIL-88B?Fe?.Compared with Fe-BDC and Fe-2MI of single ligand,heterojunction composites exhibit better photoelectrochemical performance and Cr???reduction performance.Among them,when the starting metal ion,H₂BDC,and 2MI molar ratio is 1:0.5:10,the prepared Fe-BDC/Fe-2MI has the best and stable photocatalytic performance.At the end of the study,a preliminary discussion on photocatalytic antibacterial agents was carried out to expand the practical application of MOFs.The Ag@Ag-2MI photocatalytic antibacterial agent was prepared by room temperature crystallization and in situ UV reduction.The SPR effect on the surface of the catalyst greatly improved the visible light response,and the Escherichia coli can be effectively killed under visible light.