| Recently,the increasing pollutants in water bring great threat to the environment.In fact,the design and development of renewable energy materials can be an effective way to solve a large number of pollutants in water.In recent decades,metal organic frameworks（MOFs）have been widely used in adsorption,catalysis,gas separation and storage,and drug delivery due to their ordered porous structure,high specific surface area,high absorption capacity and charge carrier transport characteristics.In recent decades,metal-organic frameworks（MOFs）have been received recent attention in adsorption,catalysis,gas separation and storage and drug deliverydue to their ordered porous structure,high specific surface area,high absorption capacity,and charge-carrier transport characteristics.Furthermore,MOFs has become a high-efficiency photocatalyst for effectively degradation of water pollution,because MOFs have higher light energy utilization,and the electron of MOFs can migrate to the environment to produce free radicals under light.To further understand the coordination chemistry of rigid aromatic dicarboxylic acid,and to evaluate the influence of different coordination geometry of metal ions on the resulting framework,five organic carboxylic acid complexes and two titanium dioxide composites based on organic phosphonic acid complexeswere synthesized via solvothermal methods,and their applications in the field of photocatalysis were studied.The main research contentsare as follows:（1）Five complexes with photocatalytic effect were synthesized via solvothermal method.And the crystal structure andof complexes werecharacterized by X-ray single crystal diffraction,elemental analysis,Fourier infrared spectrum（FTIR）,and thermal gravimetric analyzer（TGA）.Based on solid UV diffuse absorption spectrum（UV-VIS）and X-ray photoelectron spectroscopy（XPS）,the band gaps（Eg）,valence band values（Ev）and conduction band values（Ec）,between the highest occupiedhighest occupied molecular orbits（HOMO）and the lowest unoccupied molecular orbits（LUMO）of the five complexes were calculated.In addition,the photocatalytic experiments shows that all the five complexes has good catalytic reduction properties for 4-nitrophenol under sunlight,while the complexe 1 showed better catalytic reduction effect for 4-nitrophenol under ultraviolet light.（2）The complex of Ni-MOF based on organic phosphonic acid ligandswas synthesized via hydrothermal method,and a series of Ni-MOFx/P-TiO2 composites with different mass ratios were successfully prepared by self-assemblytechnology.The structure of the composite was characterized by XPS,XRD,scanning electron microscopy（SEM）,UV-Vis,transmission electron microscopy（TEM）and FTIR.Test results of photocatalytic degradation oftetracycline（TC）and reduction of Cr6+of Ni-MOFx/P-TiO2 show thattheir photocatalytic activity is better than that of a single component.It isattributed to the composites effectively inhibits the recombination of photo-generated electrons and holes,thereby effectively improving the utilization rate of light.（3）A novel Zn-MOFx/P-TiO2 composite was successfully synthesized via hydrothermal method and self-assembly technology,and their structure and catalytic properties were characterized.The results showed that the photocatalytic degradation rate of Zn-MOFx/P-TiO2 reached maximum value of 75%within 25 min under simulated sunlight,and withoutcatalyst,which was 6.68 times and 1.07 times whencompared with single component Zn-MOFs or P-TiO2.Research on photocatalysis mechanism showed that super-oxide radical was the main active materials in this system.And the successfully synthesized composites could effectively inhibit the rebuilding of photogenerated carriers,thereby improving the light utilization efficiency.In addition,Zn-MOFx/P-TiO2 composites also exhibited excellent stability and recyclability.This study broadened the application range of organic phosphonic acid-based MOFs and TiO2,and provided a new idea for designing a new type of environmentally friendly organic phosphonic acid-based MOF/semiconductor materials. |
