Study On Modifications Of Metalorganic Frameworks （MOFs） Materials And Their Photocatalytic Performances For Preparation Of H₂O₂

Hydrogen peroxide（H₂O₂）is an important chemical product,which is widely used as a strong oxidant.Among many H₂O₂ preparation technologies,photocatalysis,a green and low-cost technology,has attracted the attention of researchers in recent years.However,the key problem of photocatalysis lies in the selection and development of highly efficient semiconductor materials.Metal-organic frameworks（MOFs）materials are favored because of their high specific surface area,high porosity,diverse and adjustable structures However,the single semiconductor band edge position is often not suitable for the reaction system potential potential limits the reaction.Therefore,this paper proposes a MOFs-based material,through the introduction of adapted semiconductor materials,matches the potential potential of the reaction system,widen its absorption range of light,enhances the separation efficiency of photogen flow,and improves the optical catalytic performance of catalysts.Two types are used in two types,respectively Different semiconductor materials g-C₃N₄ and Bi VO₄ modify MOFs to improve the optical catalytic performance of H₂O₂.The specific research results are as follows:（1）In this work,a series of g-C₃N₄/MIL-53（Fe）（CN/M）composite photocatalysts were prepared by converting melamine into g-C₃N₄/MIL-53（Fe）into G-C₃N₄/Mil-53（Fe）（CN/M）in air atmosphere by high temperature roasting method.X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）and X-ray photoelectron spectroscopy（XPS）were used to demonstrate the presence of both MIL-53（Fe）and g-C₃N₄ in the samples,indicating the successful preparation of the composite.In addition,the formation of typeⅡheterostructure between MIL-53（Fe）and g-C₃N₄ was further elucidation by UV visible diffuse reflection（UV-VIS DSR）,XPS valence band spectroscopy（VB-XPS）and free radical capture experiments,and the preparation mechanism of H₂O₂ was proposed.In the evaluation of photocatalytic performance,CN/2M composite catalyst with mass ratio of g-C₃N₄ to MIL-53（Fe）at 1:2 showed the best photocatalytic performance,and the H₂O₂ concentration of 50 mg catalyst reached 104.5μmol/L after 3 h exposure to visible light.（2）BiVO₄ was prepared by hydrothermal method and introduced into MIL-53（Fe）synthesis system to prepare a series of BVO/M composite photocatalysts.The successful preparation of BVO/M was demonstrated by XRD,SEM,TEM and XPS.In addition,the Z-type heterostructure between MIL-53（Fe）and Bi VO4 was demonstrated by capture experiments and band edge position analysis,and the photocatalytic mechanism was proposed.When the mass ratio of Bi VO₄ to MIL-53（Fe）was 1:8,the BVO/8M composite catalyst showed the best photocatalytic performance.After 3 h of visible light exposure,the concentration of H₂O₂ was 290.8μmol/L with 50 mg catalyst.After 5 repeatability tests,the catalyst still maintained 65%catalytic activity.