Preparation And Photo-catalytic Activity Of TiO₂ Hollow Spheres

Nowadays,the creation of effective photocatalytic materials with large specific surface area,high catalytic activity,visible-light-respond,become a hot topic in photo-catalytic research.The modifications of TiO₂ photocatalyst is studied widely,such as metallic or non-metallic doping,noble metal depositing as well as supported TiO₂.Porous hollow sphere materials,core-shell structure materials and macroporous materials with good stability,low density,large specific surface area and other characteristics,have promising applications in the catalytic reaction,optoelectronic devices,and environmental protection.In this paper,combined hydrothermal with so-gel and template methods,a series of TiO₂-based photocatalysts were successfully synthesized,including porous hollow spheres, core-shell structure and macroporous materials.The structures,morphologies and compositions of the samples were characterized by SEM,TEM,X-ray diffraction, TGA-SDTA,FT-IR spectrometer and UV-Vis spectrophotometer.The photo-catalytic activities of the products were evaluated via the photo-catalytic degradation of methyl blue under UV-light irradiation.The main results are summarized as follows:1.A smart and compact floating-type photocatalytic reactor was designed,with the advantages of uniform light intensity,high light utilization and high mass transfer rate,reaction time automatic controlling,sampling convenience,safety and reliability.It can be used to investigate photo-catalyst activities and photocatalytic reaction factors scientifically and accurately.2.Carbonaceous micro-sphere templates with rich oxygen-containing groups on their surface were synthesized under hydrothermal condition using glucose as starting materials. TiO₂,WO₃ and W doped TiO₂ porous hollow spheres were prepared through template-deposition-surface reaction method.The influence of W contents and calcination temperatures on the catalytic activites of W doped TiO₂ porous hollow spheres was systematically examined.TiO₂ macroporous catalyst was prepared by so-gel method,and the relationship between its photocatalytic activity and the amount of carbon microspheres used was also investigated.3.Ag@C core-shell micro-spheres with rich oxygen-containing groups on their surface were synthesized under hydrothermal condition using glucose and AgNO₃ as starting materials.With Ag@C as templates,deposition-surface reaction was used to prepare Ag/TiO₂, Ag/AgCl/TiO₂ and Ag/WO₃ porous hollow spheres,while so-gel method was used to prepare Ag/NiO,Ag/SnO₂ and Ag/WO₃ macroporous materials.4.Monodisperse polystyrene(PS) microspheres were synthesized through dispersion polymerization method,and their surface was modified by concentrated sulfuric acid.With the sulfonated PS microspheres as templates,Fe-TiO₂-PS,Fe-TiO₂,α-FeO(OH)-PS andα-Fe₂O₃ porous hollow microspheres were successfully prepared under hydrothermal condition.The influence of Fe-doped amount on the photocatalytic activity of Fe-TiO₂ porous hollow microspheres was also examined.5.Monodisperse SiO₂ microspheres were prepared by Stober method,then Ag nanoparticles were deposited on their surface by Ag⁺ reduction in aqueous solution, carbonaceous materials was sequentially encapsulated on Ag/SiO₂ microspheres with glucose as the carbon precursor during hydrothermal process to form Ag/SiO₂@C microspheres.With Ag/SiO₂@C microsphere as templates,Ag/SiO₂@TiO₂ composites were successfully fabricated with template-deposition-surface reaction method.The photo-catalytic activity of the obtained Ag/SiO₂@TiO₂ was investigated.