Synthesis of Different TiO2 Nanostructures and Their Physical Properties

Titanium dioxide （TiO2） nanosheet, nanorod and nanotubes are synthesized using chemical vapor deposition （CVD） and anodizing processes. TiO2 nanosheets are grown on Ti foil which is coated with Au catalyst in CVD, TiO2 nanorods are synthesized on treated Ti foil with HCl by CVD, and TiO2 nanotubes are prepared by the three-step anodization method. Scanning electron microscopy shows the final TiO2 structures prepared using three processes with three different morphologies of nanosheet, nanorod and nanotube. X-ray diffraction verifies the presence of TiO2. TiO2 sheets and rods are crystalized in rutile phase, and TiO2 tubes after annealing turn into the anatase crystal phase. The optical investigations carried out by diffuse reflection spectroscopy reveal that the morphology of TiO2 nanostructures influencing their optical response and band gap energy of TiO2 is changed for different TiO2 nanostructures.

Fabrication and Photocatalysis of TiO2 Flower-like Nanostructures

TiO2 nanostructures were fabricated by a reaction of Ti foils in H2O2 solution at mild temperature, Porous TiO2 nanostructurcs, well adhered to Ti foil surfaces, were formed at 80 ℃ in 10 rain, and then flower- like and rod nanostructures formed in succession after a longer reaction time. Samples prepared at 80 ℃ for 4 h arc amorphous, and anatase-dominated crystal phase emerged in the sample prepared for as long as 10 h. Almost pure anatase phase were obtained in TiO2 nanostructures by annealing the samples at a temperature of 300 ℃. Photoeatalysis of the TiO2 nanostructures was characterized by the degradation of RhB dye molecules in an aqueous solution exposed to ultraviolet light. Results show a 7 cm^2 annealed TiO2 flower-like nanostrueture having the degradation rate of RhB as fast as 29.8 times that of the dye solution exposed to ultraviolet light alone.

Insights into Theranostic Properties of Titanium Dioxide for Nanomedicine

Titanium dioxide(TiO2)nanostructures exhibit a broad range of theranostic properties that make them attractive for biomedical applications.TiO2 nanostructures promise to improve current theranostic strategies by leveraging the enhanced quantum confinement,thermal conversion,specific surface area,and surface activity.This review highlights certain important aspects of fabrication strategies,which are employed to generate multifunctional TiO2 nanostructures,while outlining post-fabrication techniques with an emphasis on their suitability for nanomedicine.The biodistribution,toxicity,biocompatibility,cellular adhesion,and endocytosis of these nanostructures,when exposed to biological microenvironments,are examined in regard to their geometry,size,and surface chemistry.The final section focuses on recent biomedical applications of TiO2 nanostructures,specifically evaluating therapeutic delivery,photodynamic and sonodynamic therapy,bioimaging,biosensing,tissue regeneration,as well as chronic wound healing.

Preparation and photocatalytic activity of Cu^(2+)-doped TiO_2/SiO_2

Cu^2＋-doped nanostructured TiO2-coated SiO2 （TiO2/SiO2） particles were prepared by the layer-by-layer assembly technique and their photocatalytic property was studied. TiO2 colloids were synthesized by the sol-gel method using TiOSO4 as a precursor. The experimental results showed that TiO2 nanopowders on the surface of SiO2 particles were well distributed and compact. The amount of TiO2 increased with the increase in coating layers. The shell structure appeared to be composed of anatase titania nanocrystals at 550℃. The 2-layer coated TiO2 particles on the surface showed a higher degradation rate compared with all the different-layer samples. The photocatalytic activity of Cu^2＋-doped TiO2/SiO2 was higher than that ofundoped TiO2/SiO2. The optimum dopant content was about 0.10wt%.

Anti-UV Capability of Rare Earth Doping TiO_2

The sol-gel process is used in the preparation of nanostructure materials with Ti(OC_ 4 H_ 9 )_ 4 as precursor in the start materials. TiO_ 2 gelatin is obtained through hydrolysis and condensation process. Rare earth such as La_ 2 O_ 3 , CeO_ 2 , Eu_ 2 O_ 3 and Gd_ 2 O_ 3 are introduced into the nanostructure TiO_ 2 to improve the anti-UV capacity. The phase structure of pure TiO_ 2 and doped TiO_ 2 and their anti-UV capacity are studied by means of XRD and UPF. The optimum doping and heat treatment temperature are chosen.

Synthesis and Characterization of Titania and Rare Earth Doped Titania Nanoparticles by Sol-gel Process

Titania sol has been prepared by the sol-gel process with Ti（OC4H9）4, as precursor. TiO2 gel was obtained through hydrolysis and condensation process. Rare earth such as La2O3, CeO2 and Gd2O3 were introduced into the nanostructure TiO2. After TiO2 and rare earth doped TiO2 powders were calcined at 400℃, 500℃, 600℃, 700℃ and 800℃ respectively, the characteristic analyses of the TiO2 samples were studied by UV-VIS, XRD and TEM etc. It was found that there are some stringer absorption peaks at 200 - 325 nm. The rare earth doping can increase the phase transition temperature convertin8 anatase phase into rutile phase, can decrease the grain size of TiO2particles and can improve the ann-UV capacity of the coating fabrics.

Structural Phase Transition in Nanostructured TiO_2

Using DTA (difFerential thermal analysis) measurement on nanostructured TiO2, we find two endothermic peaks on the DTA curve. From XRD (X-ray diffraction) analysis of the original nanostructured TiO2 and its heat-treated samples, we obtain the following results: the first endothermic peak corresponds to the desorption of physical or chemical absorption, the second one is related to the structural phase transition from brookite to anatase then to rutile, and this structural phase transition is beneficial to the grain growth of nanocrystal

TiO2/EDTA-rich carbon composites： Synthesis, characterization and visible-light-driven photocatalytic reduction of Cr(Ⅵ)

TiO2/EDTA-rich carbon composites （TiO2/EDTA-RC） have been successfully synthesized via a low temperature carbonization process. TiO2/EDTA-RC exhibits marked absorption of visible light and excellent photoreduction of Cr（Ⅵ） activity under visible light irradiation （λ 〉 420 nm）. Due to the high carboxyl group content and strong coordination ability of EDTA, TiO2-EDTA complex can be easily fabricated between EDTA incorporated in carbon sheet and titanol group on the surface of TiO2. TiO2- EDTA complexes on the surface of TiO2/EDTA-RC, the LMCT complex, are responsible for the prominent photoreduction of Cr（Ⅵ） properties of TiO2/EDTA-RC under visible light irradiation. In addition, the unique structure of TiO2/EDTA-RC is also propitious to the visible-light photocatalytic reduction of Cr（Ⅵ）. Carbon sheet of TiO2/EDTA-RC acts as a supporter. Tio2 nanoparticles and EDTA homogeneously disperse into the carbon sheet supporter and form the TiO2-EDTA complexes, which can avoid the aggregation of TiO2 nanoparticles in the aqueous solution and provide more photocatalytic reaction points for the reduction of Cr（Ⅵ）.

Direct Electrochemistry of Cytochrome c at a Hierarchically Nanostructured TiO_(2) Quantum Electrode

Monodisperse TiO2 nanoparticles and urchin-like hierarchical TiO2 nanospheres assembled with ultrathin quantum nanowires(about 2 nm)have been synthesized by a simple template-free wet chemical method.The morphology,structure,and crystallinity of the TiO2 nanomaterials were investigated by field emission scanning electron microscopy(FESEM),X-ray diffraction(XRD),and high resolution transmission electron microscopy(HRTEM).Electrochemical measurements with the hierarchically nanostructured TiO2 nanospheres as an electrode showed much better reversibility for direct electrochemistry of cytochrome c(cyt c)and much higher sensitivity than for an electrode composed of the monodisperse TiO2 nanoparticles.The excellent performance of the hierarchical TiO2 nanospheres may result from a quantum size effect,and their favorable nanostructure(with the presence of an abundance of both uniform macropores and mesopores),excellent structural stability and high specific surface area.The relative ionic strength had significant effect on the direct electrochemistry.Very high ionic strengths relative to cyt c concentration(I/c)induced a conformational change of cyt c on the nanostructure-coated electrode,from the native state to a partially unfolded one in 25 mmol/L phosphate buffer solution(pH 6.8).

Light-harvesting Complex Ⅱ Sensitized Oxide Photoanodes with Organic Acceptor Molecule as Electron Transfer Mediator

Dye sensitized solar cell（DSSC） is a promising thin film solar cell that has been widely investigated after its birth because of its advantages,such as flexibility,low-cost,easyfabrication and so on[1-3].For DSSCs,sensitizers play a core role due to their responsibility for the generation of the photo carriers resulted from light absorption and the transfer of the photo-generated electrons into semiconductor photoanodes[4].Keywords：Light-harvesting complex Ⅱ; Anthraquinone 2-carboxylic acid; ZnO; TiO2 nanostructure; Solar cell