Preparation And Photocatalytic Properties Of MOF-808-based Nanocomposites

Environmental pollution and energy crisis have always been crucial issues that constrain the development of human society.Photocatalysis,as an new green technology for energy conversion and environmental purification,has become an significant means to solve these problems.It has been widely applied in air purification,sewage treatment and other fields.In the photocatalytic reaction process,the construct and synthesis of photocatalytic materials are the core issues affecting the performance and efficiency of photocatalytic reactions.Metal-Organic Frameworks（MOFs）are a new type of crystalline porous material with a periodic network structure formed by self-assembly processes of organic ligands and inorganic metal centers（metal ions or metal clusters）.It has character of large specific surface area,high porosity and designable structure.Researchers have repeatedly tried to explore MOFs as a new type of photocatalyst and have received extensive attention.Based on the research of MOFs in recent years including the design and synthesis of MOFs materials and its application in other catalytic fields,this thesis describes the enhanced light absorption of sunlight by composites structures based-MOF materials.Through rational analysis,the photocatalytic materials based-MOFs were designed and synthesized to promote the effective separation of charge during the catalytic reaction.Three kinds of MOF composites nanomaterials were designed and synthesized based on Zr-MOF-808 with large specific surface area and high stability and investigated the performances of photocatalytic sewage purification,photocatalytic hydrogen production and photocatalytic organic reaction.These composites materials facilitate the rapid transfer and separation of photogenerated electrons and holes,promote the efficient use of photogenerated charges,and greatly improve the performance of photocatalytic reactions.The main research results obtained in this thesis are as follows:1.MOF-808/BiOBr（abbreviated as M8B）composites photocatalytic materials were successfully prepared by simple hydrothermal method.The prepared M8B composites samples were analyzed by a series of analytical methods to characterize the structure,morphology and properties.The results exhibit that MOF-808 has an effect on the microstructure of BiOBr.The large specific surface area of MOF-808restrain the uniting if BiOBr and increase the photocatalytic reaction sites,which accelerates the transfer of photoelectrons.The degradation of Rhodamine B（RhB）,methyl orange（MO）and ciprofloxacin（CIP）under visible light conditions indicated that 0.3-M8B had the best degradation activity.Cyclic photocatalytic experiments on CIP degradation showed that it has good stability and reusability.2.CdS/MOF-808/RGO（abbreviated as CM8R）ternary composites photocatalyst was synthesized by low temperature water bath method.The prepared ternary materials were characterized by XRD,FT-IR and so on.The results show that the ternary structure effectively inhibits the photocorrosion phenomenon of CdS,and the introduction of RGO accelerates the transfer of photogenerated electrons.The visible light photocatalytic hydrogen production experiments show that the CdS/MOF-808composites with 50%CdS content has the best hydrogen production.After the introduction of RGO,the photocatalytic efficiency is increased by 1.63 times,and it is8.35 times of the hydrogen production of pure CdS.It still maintained high activity and stability after four cycles of photocatalytic hydrogen production experiments.3.MOF-808/TiO₂（abbreviated as M8Ti）core-shell composites photocatalyst was prepared by solvothermal method.The elemental valence,light absorption performance,and charge separation efficiency of the prepared composites photocatalyst were measured by XRD,XPS,and PL.Photocatalytic oxidation of benzyl alcohol conversion experiments indicated that the prepared composites photocatalyst exhibited higher photocatalytic performance and higher selectivity than the two monomer materials.