Syntheses And Properties Of Zn/Fe-based Metal-Organic Framework Materials And Their Composites/Derivatives

In this thesis,ZIF-8@Zn2GeO4 composite photocatalyst and ZIF-8@Zn2GeO4:Mn2+fluorescence sensor were prepared by chemical self-assembly method using Zn/Fe-Metal-Organic Framework(MOF)as the platform material.MOF derivative materials such as Zn2Fe2O4,ZnO/ZnFe2O4 photocatalytic materials and NixCo1-xFe2O4 gas sensing materials were successfully prepared through the chemical pyrolysis method.We also carried out the detailed investigations on the structures,compositions and chemical properties of these as-prepared MOF-based composites and derivative materials.(1)The Zn2GeO4 nanorods were prepared using hydrothermal method,which were then added into the synthetic system of ZIF-8 to prepared the ZIF-8 nanoparticle-modified ZIF-8@Zn2Ge04 composites via chemical self-assembly method.The as-prepared ZIF-8@Zn2Ge04 material showed highly efficient photocatalytic reduction property toward the degradation of Cr(VI)ions in water solution,and the toxic Cr(?)ions can be reduced to trivalent Cr3+ ions efficiently.Based on the research of this work,Mn2+doped Zn2GeO4 nanorods were prepared and used instead of Zn2GeO4 in fabricating ZIF-8@Zn2Ge04:Mn2+composite.The as-obtained ZIF-8@Zn2GeO4:Mn2+ materials possess excellent dual emission fluorescence property,in which the ZIF-8 constituent emits blue light and the fluorescence intensity does not change with temperature increase,while the Zn2GeO4:Mn2+component emits green light and its fluorescence intensity decreases with temperature increase.Therefore,the ZIF-8@Zn2GeO4:Mn2+composite has great potential in applications of ratiometric temperature sensors,as well as Cu2+metal ion sensing.(2)The hierarchical Zn2Fe2O4 nanocomposites were successfully prepared by solvent evaporation strategy combined with annealing of Fe-MOF precursors.The well-organized porous fractionated Zn2Fe2O4 micro/nanostructures exhibited excellent visible-light driven photocatalytic performance toward MB dye degradation.In addition,the as-prepared hierarchical Zn2Fe2O4 composite is magnetic and can be easily separated and recovered with an extra magnet.Using similar synthetic strategy,series of hierarchical NixCo1-xFe2O4(0.0 ? x ?0.5)microcubes have been successfully prepared.Different Ni/Co ratios in the as-prepared samples did not change the phase structure of these microstructures.The obtained cubic hierarchical NixCo1-xFe2O4,(0.0 ? x?0.5)composites presented highly acetone sensing properties,among which the Ni0.1Co0.9Fe2O4 composite showed the strongest response performance and excellent reproducibility,and the proposed acetone sensing mechanism was also discussed.The proposed solvent evaporation and co-templated strategies allow for the accurate acquisition of other new inorganic materials with interesting morphology,structure,chemical composition and tunable sensing properties.(3)Using Zn(Fe)-MOF as a single precursor,the flower-like ZnO/ZnFe2O4 heterostructure nanospheres were prepared through a simple calcination treatment.The structure and morphology evolution of ZnO/ZnFe2O4 heterostructure was studied in detail.The prepared flower-like ZnO/ZnFe2O4 nanocomposite exhibited excellent photocatalytic performance under Xe lamp illumination and good repeatability for degradation of RhB and MB dyes.Additional,the ZnO/ZnFe2O4 photocatalyst is magnetic and can be separated from the reaction system very easily using an extra magnet.Also,the ZnO/ZnFe2O4 photocatalyst showed good reusability.The strategy proposed in this work further demonstrated the effective preparation of other novel multi-component multifunctional nanocomposites using MOF hydrolysis method.