The Construction Of Efficient TiO₂ Visible Light Photocatalyst And Its Application Research

Although metal or non metal doped TiO₂ can improve its visible-light photocatalytic activity,this increase is still limited,not enough to make it widely been used in natural sunlight.In comparison to single-component modified/doped TiO₂,co-doping is more effective to enhance visible light photocatalytic activity of TiO₂ because of their synergistic effect and characteristics.However,most TiO₂ photocatalysts reported in literature used low surface area TiO₂ spheres or powders as supports so far,considerably decreasing their photocatalytic efficiency and cycle life.This dissertation developed two new methods for the preparation of the hollow TiO₂-based visible light photocatalysts?C/N-TiO₂ and Ag-C/N-TiO₂?,in which the preparation of C/N-TiO₂ catalyst mainly includes the preparation of monodisperse cationic polystyrene microspheres?CPS?,template-directed self-assembly of TiO₂ precursor,and calcination of CPS at 450?in NH₃/Ar mixed atmosphere,while silver,carbon/nitrogen modified TiO₂ catalyst was prepared by depositing silver nanoparticles on the surface of C/N-TiO₂.The structure and morphology of as-synthesized photocatalysts were characterized through TEM,SEM,BET,XRD,UV-vis and XPS.The results show that two catalysts?C/N-TiO₂ and Ag-C/N-TiO₂?both can narrow the band gap of TiO₂?2.83 eV and 2.71 eV respectively?,manifesting excellent photocatalytic performance for the degradation of methylene blue?MB?and rhodamine B?RhB?under visible light irradiation.Such as the C/N-TiO₂ catalysts are able to degrade about 91.7% of the original MB dye after the visible-light irradiation in a short period of 10 minutes.In addition,we also found that their photocatalytic performances are better than those of P25,carbondoped TiO₂ and other TiO₂-based photocatalysts reported in the literature under comparative conditions.This dissertation also proposes a method for the preparation of Fe₂O₃ modified TiO₂ photocatalyst?TiO₂/Fe₂O₃?with controllable visible light activity.This method only involves the calcination of mixture?commercial P25 powder and magnetic Fe₃O₄ nanoparticles?prepared by a mechanical method.The morphology and properties of TiO₂/Fe₂O₃ composite were characterized by transmission electron microscopy,X ray diffraction,X-ray photoelectric spectroscopy and UV-vis spectrophotometry.The results confirmed the fusion of TiO₂ and Fe₂O₃,promoting the transport and separation of photogenerated electron/hole.The as-synthesized TiO₂/ Fe₂O₃ catalyst exhibits higher photocatalytic activity than that of P25 because of synergistic effect.Compared with the other Fe₂O₃ modified TiO₂,the as-prepared TiO₂/Fe₂O₃ catalyst holds a slightly lower photocatalytic activity than P25,far beyond other Fe₂O₃ modified TiO₂ photocatalysts reported in literature under UV irradiation.For example,irradiated with ultraviolet light for 100 minutes,the TiO₂/ Fe₂O₃ catalyst can degrade about 80.8% of the original RhB concentration,slightly less than the value?91.2%?for P25.In addition,TiO₂/Fe₂O₃ photocatalyst can be easily synthesized by one-step method,which can effectively overcome the tedious process for the preparation of Fe₂O₃/TiO₂ photocatalysts using the existing methods,providing a new direction for the practical application of TiO₂/Fe₂O₃ visible light photocatalyst?...