Design, Preparation And Performs Of TiO₂-based Composite Photocatalytic Materials

Nano-structured TiO₂materials have been investigated in photocatalysis field due to itsconsiderably high photocatalytic activity, long-term stability, non-toxic nature, and low cost.However, its practical application is limited due to low quantum yield and null visible-lightphotoresponse. Therefore, we focus on design and development of new and efficientTiO₂-based composite photocatalyst with higher photocatalytic activity. The structure,physical and chemical properties, optical absorption properties, morphology, and porosity ofthe materials were well characterized by many techiniques. We investigate systemically thephotocatalytic activity under the visible light irradiation, and explain the reasons for enhancedthe photocatalytic activity and mineralization of organic pollutions. Some new and interestingresults are as following:1. The saturated and monovacant Keggin unit functionalized titania materials,H₃PW₁₂O₄₀/TiO₂and K₇PW₁₁O₃₉/TiO₂, were prepared by one step sol-gel co-condensationfollowed by solvothermal treatment. The structure, optical absorption properties, morphology,and porosity of the materials were well characterized by inductively coupled plasma atomicemission spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectronspectroscopy, X-ray diffraction patterns, UV-vis diffuse reflectance spectroscopy,Transmission electron microscope and N2adsorption/desorption. Subsequently, theirsimulated sunlight photocatalytic activity was evaluated by the degradation andmineralization of dye rhodamine B （RB） and endocrine-disrupting chemical diethyl phthalate（DEP）. Special attention was paid to provide direct evidences for the explanation of thedifferent photoexcited electron-hole pair separation rates of the H₃PW₁₂O₄₀/TiO₂,K₇PW₁₁O₃₉/TiO₂, and pure TiO₂by the photoelectrochemical experiment; simultaneously, thetarget active species yielded in the K₇PW₁₁O₃₉/TiO₂-and H₃PW₁₂O₄₀/TiO₂-catalyzed DEPdegradation systems were also investigated by the free radical and hole scavengingexperiment. Accordingly, reasons for the photocatalytic activity difference between theK₇PW₁₁O₃₉/TiO₂and H₃PW₁₂O₄₀/TiO₂as well as pure TiO₂were revealed. Finally,K₇PW₁₁O₃₉/TiO₂and H₃PW₁₂O₄₀/TiO₂were chosen to evaluate the recyclability of thephotocatalysts by four times’ RB degradation reaction.2. Titanic acid nanotubes were firstly prepared by alkaline hydrothermal treatment ofTiO₂nanoparticles followed by acid washing using anatase TiO₂powder as staring material.Metallic platinum and indium oxide codoped titania nanotubes were fabricated bymulticomponent assembly combined with solvothermal treatment. The preparedPt/In₂O₃TiO₂nanotubes exhibited anatase phase with homogeneously dispersed metallic Ptnanoparticles on the innter and outer surfaces of nanotubes. The material was used as a novelphotocatalyst to degrade dye RB and phthalate ester under the simulated sunlight irradiation,and the enhanced photocatalytic activity in comparison to In₂O₃TiO₂and TiO₂nanotubes aswell as Pt/In₂O₃TiO₂nanoparticles was obtained. The enhanced photocatalytic activity isexplained in terms of efficient separation of the photogenerated electrons and holes due to the introduction of In₂O₃and Pt as well as the nanotubular geometries.Base on the above research, the method of efficient and recyclable TiO₂basednanocomposite photocatalytic materials prepared was supplied. Meanwhile, it has suppliedthe basic researcher data for solar photocatalytic technology to decrease the phthalate esterand dye effluents.