Synthesis And Application Of Samarium Ion Doped Titanium Dioxide And Silicon Dioxide Composites

In recent years,the rare earth compounds have been widely used in high-performance luminescent devices,displays,photocatalysis,biofluorescence imaging and detection and other fields.As a widely used semiconductor material,TiO₂ can be used as the matrix material of rare earth doping due to its low cost,high transparency in visible light regions,outstanding thermal,chemical and mechanical properties.Based on these properties,TiO₂ can also be combined with other different materials to improve matrix properties,such as composite with SiO₂.The TiO₂-SiO₂composites combine the advantages of both to effectively enhance the physical and chemical properties of the material.It has been found that rare earth ion doped TiO₂-SiO₂ composites can be used as a dual functional material for luminescence and photocatalysis,and the doping of rare earth ions not only endows the material with luminescence properties,but also improves its photocatalytic properties by reducing the recombination rate of TiO₂ electron-holes.In addition,the morphology and size of the material can also affect luminescence properties and photocatalytic efficiency.Therefore,the preparation and application of rare earth ion doped TiO₂-SiO₂composites with a certain morphology are of great significance.This paper mainly discusses the synthesis and applications of Sm³⁺doped TiO₂-SiO₂ composites with different morphologies in the field of luminescence and photocatalysis.The problems of TiO₂ particle high agglomeration,fast electron-hole recombination rate and difficult recovery were solved,which improves the luminescence intensity and photocatalytic activity of the sample.The samples were characterized by scanning electron microscope,X-ray diffraction patterns,fluorescence spectrophotometer,nitrogen adsorption desorption and ultraviolet-visible light absorbance spectra.Luminescence properties,photocatalytic degradation of polyacrylamide(HPAM)and structure of Sm³⁺ion doped TiO₂-SiO₂ composites were discussed in detail.It is found that there is a serious sample loss in photocatalytic experiments,and it is necessary to prepare photocatalyst that is easy to recover.Therefore,on this basis,the mesoporous TiO₂/SiO₂:Sm³⁺composite nanofiber has been successfully synthesized,which can easily be removed from the solution without causing secondary contamination of water and can be recycled.The following is specific studies of this article:1.The TiO₂:Sm³⁺particles,SiO₂@TiO₂:Sm³⁺spheres and SiO₂@TiO₂:Sm³⁺rods were successfully fabricated via the solvothermal method followed by the calcination at700,800 and 900?,respectively.The effects of morphology and calcination temperature on photocatalytic activities and luminescent properties were studied.The results demonstrated that the SiO₂@TiO₂:Sm³⁺rods calcined at 700? exhibited the highest luminescence intensities.This was attributed to possess the least specific surface area,which decreased the quenching center of surface defects,as well as without rutile phase.Moreover,SiO₂@TiO₂:Sm³⁺rods annealed at 800? were the optimum for improving the photodegradation efficiency of hydrolyzed polyacrylamide(HPAM)under simulated solar light irradiation.The degradation experiments results confirmed that the synergistic effect of the crystallinity/Ti-O-Si bond and rutile-anatase heterojunction were the main reason for excellent photocatalytic activities.2.The TiO₂-SiO₂:Sm³⁺composite nanofiber was synthesized using electrospinning to evaluate the photocatalytic efficiency of the sample by the degradation efficiency of HPAM under simulated solar light.Subsequently,the effect of Sm³⁺ions doping on photocatalytic activity was discussed.The results show that TiO₂:Sm³⁺nanofibers are large hole materials,TiO₂-SiO₂:Sm³⁺composite nanofibers are mesoporous materials,and SiO₂ modified TiO₂ pore structure has obvious advantages in increasing the surface area of nanofibers.In addition,it is found that the appropriate amount of Sm³⁺ions doped to the composite nanofiber can inhibit the recombination of electron-hole pairs,expand the light absorption range,and improve the utilization rate of light.However,the addition of excessive Sm³⁺ions can seriously affect the crystallization of TiO₂ and increase the number of electron-holes recombination center,with a slight blue shift in the light response range,resulting in the decrease in photocatalytic properties.Due to the excellent flexibility shown by TiO₂-SiO₂:Sm³⁺nanofiber under calcination of 600?,TiO₂/SiO₂:Sm³⁺composite nanofiber has a complete structure after the photocatalysis process,which is easy to remove from the solution.