Facile And Controlled Synthesis And Properties Of Titanium Dioxide Nano-heterostructures

As a kind of semiconductor material,nano-titanium dioxide?nano-TiO₂?shows excellentapplication prospectdue to its non-toxic,low cost,corrosion resistance,good stability as well as unique optical and electrical properties.Therefore,among the many semiconductor oxides,The research of nano-TiO₂ has become the front in the field of catalysis,photovoltaic,paint,gas sensors,drug delivery and so on.However,nano-TiO₂ band gap is wider,and the quantum yield is lower,which severely hamper the further application of nano-TiO₂.The research indicats that it is an efficient way to improve the photochemical properties of nano-TiO₂ by compounding with different band gap semiconductor materials,which can increase its optical carriers separation and expand its spectral response of the region.On the other hand,there were different reports about the cytotoxicity or biocompatibility of nano-TiO₂ and its heterojunction.Hence,the industrial production of nano-TiO₂ may cause concerns about environmental safety.Therefore,based on a large number of the latest scientific research and the development trends,in this thesiswe are committed to modify the properties of nano-TiO₂ by compounding with different band gap semiconductor materials.The samples werecharacterized byfield-emission scanning electron microscopy?FESEM?,transmission electron microscopy?TEM?,X-ray diffraction?XRD?,X-ray photoectron spectrometer?XPS?,N₂ adsorption-desorption,thermogravimetric-differential scanning calorimeter?TG-DSC?,ultraviolet-visible absorption?UV-Vis?and fluorescence characterization tests and so on.Andwe also testedtheir relevant applications.The main contents include the following aspects:?1?The anatase type TiO₂ quantum dotswere synthesized by combining the sol-gel and solvothermal method.The surface morphology and elemental composition of the TiO₂ quantum dots were characterized by TEM,XRD.The photocatalytic property of the nano-TiO₂ was investigated by the degradation of Rhodamine B?Rh B,10 mg/mL?,Methyl Orange?MO,10 mg/mL?andMethylene Blue?MB,20 mg/m L?as model reactions and the biocompatibility was tested by using MTT.The results indicated that the average diameter of the TiO₂ quantum dots was around 8.3nm and the Rh B solution could be completely degraded within 90 min,the MO solution could be completely degraded within 50 min,and the MB solution could be completelydegraded within 80 min,showing the TiO₂ quantum dots havegood photocatalytic property and biocompatibility for Hela and 3A cell.?2?The mesoporous nano-TiO₂-CdS composites microspheres with heterogeneous structure were synthesized by combining the sol-gel and solvothermal method.The surface morphology and elemental composition of the nano-TiO₂-CdS were characterized by FESEM,TEM,XRD,XPS,N₂ adsorption-desorption andTG-DSC.The photocatalytic property of the nano-TiO₂-CdS was investigated by the degradation of Rh B as a model reaction.In addition,protein detection and MTT were tested for its biological properties.The results indicated thatnano-TiO₂-CdS was around 1 ?m with mesoporous structurewhich was formed by nanoscale particles,the average pore diameter was about 12 nm and specific surface area was 60.79 m2/g.And the Rh B solution could be completely degraded within 50 min,indicating the preparednano-TiO₂-CdSwith heterogeneous structure had better photocatalytic property than the pure TiO₂.And itcan be directed to detect trypsin and it showed good biocompatibility for Hela and 3A cell.?3?The nano-TiO₂-Ag₂S with heterogeneous structure was synthesized by combining the sol-gel and solvothermal method.The surface morphology and elemental composition of the nano-TiO₂-Ag₂S was characterized by TEM,XRD.The photocatalytic property of the nano-TiO₂-Ag₂S was investigated by the degradationof Rh B,Congo Red?CR,20 mg/mL?and MB as model reactions.The results showed that the the average diameter of the synthesized nano-TiO₂-Ag₂S was around 6nm,the Rh B solution could be completely degraded within 100 min,the CR solution could be degraded to 90% within 100 min,and the MB solution could be degraded to 61% within 100 min,indicating the nano-TiO₂-Ag₂S had photocatalytic property.Moreover thenano-TiO₂-Ag₂S with heterogeneous structure showed good biocompatibilityfor Hela and 3A cell.?4?The nano-TiO₂-CuS with heterogeneous structure were synthesized by combining the sol-gel and solvothermal method.The surface morphology and elemental composition of the nano-TiO₂-CuS were characterized by TEM,XRD.The photocatalytic property of the nano-TiO₂-CuS was investigated by the degradation of Rh B,CR and MB as model reactions.The results showed that the average diameter of the synthesized nano-TiO₂-CdS was around 5 nm,the Rh B solution could be degraded to 40% within 120 min.And thenano-TiO₂-CuS with heterogeneous structure showed good biocompatibilityfor Hela and 3A cell.