Synthesis,Structure,Spectral Properties And Photocatalytic Degradation Research Of The Novel Polyoxotungstates

Polyoxotungstates(POTs)have been studied extensively by domestic and overseas research groups.The increasing interest in this field is justified by not only their intriguing structural motifs,but also their fascinating properties and great potential applications in many fields such as magnetism,catalysis,adsorption,etc.In this thesis,on the basis of summarizing the related literature of at home and abroad,we obtained eleven POTs,the mainly work content is as follows:1.Eleven novel POTs were obtained through conventional hydrothermal technique.We also concluded the synthesis rules.The eleven compounds can be clarified to three types according to the polyanion:(1)Compounds 1-7 are classical Keggin structure,of which,compounds 1?5 for SiW 12,the central metal atom of compounds 6 and 7,Zn and Cu,respectively;(2)Compounds 8 and 9 are Dawson-like structure with Sb;(3)Compounds 10 and 11 are also tungstoantimonate of the dipolymer for trivacant Keggin structure,referred to as Krebs type.Addtionally,TOPOS 4.0 program was introduced to analysis 3D-networks of compounds 2-11.Among them,the topology type of compounds 2,8,9,11 have not reported,yet.2.We also carried out X-ray power diffraction,IR,2D-IR correlation spectra(2D-IR COS),Raman,UV-DRS,TGA,and XPS to characterize compounds.For the thermal--perturbation 2D-IR correlation spectra,we analyzed the dynamic changes of the functional groups and the thermal response signals of intermolecular forces;magnetic-perturbation 2D-IR correlation spectra show the response of group which magnetic metal ion attached.The LMCT bands of O??W at near 255 nm and the d-d bands of transition appear in more than 340 nm are found in UV-DRS spectra;TGA results show that the skeleton of polyanions will slow decomposition when higher than 320 ?.3.The studies of the variable temperature magnetic susceptibility demonstrates that compounds 7-9 have potential application in magnetic material.Among them,7 for ferrimagnetic,8 for ferromagnetism,and 9 is ferromagnetism.In the experiments of photocatalytic degradation of different organic dyes(RhB,MB,MO),we found that:(1)Compound 2 greatly improve the degradation of MB solution,the conversion rate as high as 92.49%in 40 min;(2)The conversion rate of compound 4 photocatalytic degradation of RhB reach 95.62%under the condition of Xe lamp radiate simulated sunlight and pH=3.0;(3)Under Xe lamp radiate visible light,in different pH,the compound 8 at pH=3.0 has excellent photocatalysis properties reach 74.98%in RhB degradation.In short,compounds 2,4,8 have strong ability of photocatalytic activity,which can greatly improve the efficiency of degradation;(4)The photocatalytic activity of keggin structure stronger than Dawson structure and the possible photocatalytic mechanism has been deduced in terms of structure,which provide experimental and theoretical basis for its application.4.Gaussian 03w program was applied to calculate the polyanion[CuW12O40]6-of compound 7.Thus,we obtained a lot of information,such as the single point energy,frontier orbital energy and Mulliken charge of calculated system.What's more,the relationship of the bonding nature and reactive center was also analyzed and discussed.