TiO2 Nanoparticles Solution Research Articles

Co-Sedimentation of TiO<SUB>2</SUB> Nanoparticles and Polymer Beads to Fabricate Macroporous TiO<SUB>2</SUB> Photoelectrodes

Dye-sensitized solar cells based on highly porous nanocrystalline TiO2 films have drawn considerable attention due to their high conversion efficiency and low production cost. TiO2 nanocrystalline electrodes have been investigated extensively as a key material. In this study, we discuss dye-sensitized solar cells based on macroporous TiO2 films using a highly-dispersed aqueous solution of TiO2 nanoparticles and polymeric particles. After drying this solution on the conducting glass substrate, the sacrificial polymer particles were removed selectively by thermal sintering at high temperatures over 400 degrees C or chemical treatment at the low temperature of 150 degrees C. This method provides the flexible control of TiO2 fractions or pore size or fabrication temperature. Also highly-dispersed TiO2 particles with a high crystallinity would provide a promising solution on low-temperature process for flexible DSSCs.

SYNTHESIS OF MESOPOROUS TITANIA BY POTATO STARCH TEMPLATED SOL-GEL REACTIONS AND ITS CHARACTERIZATION

Mesoporous titania powders with high-order crystalline building blocks had been synthesized through the sol-gel process using potato starch gel template. Internal spongelike pore structure of starch gel template was generated by heating the starch granules at 95 °C in water solution and freezing the starch gel at -15 °C. The synthesis routes were performed by immersing the starch gel template for 4 days into the white colloidal solution of TiO2 nanoparticles, which were prepared by hydrolyzing titanium (IV) tetraisopropoxide (TTIP) in ethanol at pH 1. Mesoporous TiO2 powders were obtained by two different ways of template removal, performed by calcination of the TiO2-starch composites at 600 °C for 4 h or combination of extraction with ethanol-HCl (2:1) at 80 °C and calcination at 500 °C for 4 h. Fourier Transform Infra Red (FT-IR) spectra shows both of template removal methods result in decreasing of characteristic vibrational band of the starch hydrocarbon on the resulted TiO2 powders. The X-Ray Diffraction (XRD) pattern imply that the concentrations of starch gel template influence the anatase crystallite peaks intensity of the synthesized TiO2 powders. TiO2 templated by 20% of starch sponges gel has highest intensity of anatase crystallite. Scherrer calculation inidicated that anatase particle size has nanoscale dimmension up to 12.96 nm. The nano-architecture feature of mesoporous TiO2 scaffolds was also evaluated by the Scanning Electron Microscope (SEM). It is shown that mesoporous TiO2 framework consist of nanocrystalline TiO2 particles as buiding blocks. The N2 adsorption-desorption isotherm curves assign that TiO2 powder resulted from extraction-calcination route has higher mesoporosity than that of only calcinated. The synthesized mesoporous TiO2 powder exhibits high Brunauer-Emmet-Teller (BET) specific surface area up to 65.65 m2/g. Keywords: mesoporous TiO2, potato starch, template

Synthesis of Titanium Dioxide Nanomaterial by Pulsed Laser Ablation in Water

Synthesis of colloidal solution of TiO2 Nanoparticles by pulsed laser ablation in water, without any surfactant is studied. Fundamental wavelength of Nd:YAG laser operating at 35 mJ/pulse energy, 10 ns pulse width and 10 Hz repetition rate is used for the ablation of titanium target placed in water. Laser ablation of Titanium target in the water produces violet colored, highly stable colloidal solution for months even in the absence of any capping agents. UV-Visible absorption, Photoluminescence, X-ray diffraction, SEM and FTIR spectroscopic technique are used for the characterization of produced Nanomaterials. Six emission bands are observed in the photoluminescence spectrum of the produced sample. Origin of all the lines in the PL spectrum has been discussed. Possible reaction mechanism for the laser matter interaction and synthesis of nanomaterial are discussed.

The Effects of Sintering on the Photocatalytic Activity of N-Doped TiO2 Nanoparticles

N-Doped titanium oxide nanoparticles (NPs) were synthesized through the hydrolysis of N-substituted titanium isopropoxide precursors and postsynthesis treated by sintering at different temperatures in a nitrogen atmosphere and in air. X-ray diffraction (XRD) results revealed that the presence of oxygen during the sintering also affects the crystallization of the N-doped TiO2 NPs. The air and N2 sintering produced different nitrogen concentrations and visible-light absorbances. The N-doped TiO2 NPs sintered at 200–250 °C in air for 1/2 h produced the best photocatalytic nanoparticles for visible-light decomposition of methylene blue in water. On the other hand, sintering in N2 atmosphere at any temperature provided photocatalysts with about half-the activity for visible-light decomposition of methylene blue compared to the air-sintered NPs. The zeta potential of the N-doped TiO2 NPs solution used in the photocatalytic tests shows that higher sintering temperatures create more negative charges on the NP sur...

Preparation and characterization of TiO2 and polymer nanocomposite films with high refractive index

AbstractNovel nanocomposite films of TiO2 nanoparticles and hydrophobic polymers having polar groups, poly (bisphenol‐A and epichlorohydrin) or copolymer of styrene and maleic anhydride, with high refractive indices, high transparency, no color, solvent‐resistance, good thermal stability, and mechanical properties were prepared by incorporating surface‐modified TiO2 nanoparticles into polymer matrices. In the process of preparing colloidal solution of TiO2 nanoparticles, severe aggregation of particles can be reduced by surface modification using carboxylic acids and long‐chain alkyl amines. These TiO2 nanoparticles dispersed in solvents were found not to aggregate after mixing with polymer solutions. Transparent colorless free‐standing films were obtained by drying a mixture of TiO2 nanoparticles colloidal solution and polymer solutions in vacuum. Transmission electronic microscopic studies of the films suggest that the TiO2 nanoparticles of 3–6 nm in diameter were dispersed in polymer matrices while maintaining their original size. Thermogravimetric analysis results indicate that the nanocomposite film has good thermal stability and the weight fraction of observed TiO2 nanoparticles in the film is in good accordance with that of theoretical calculations. The refractive index of nanocomposite films of TiO2 and poly(bisphenol‐A and epichlorohydrin) was in the range of 1.58–1.81 at 589 nm, which linearly increased with the content of TiO2 nanoparticles from 0 to 80 wt %. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Langmuir−Schaefer Films of Nafion with Incorporated TiO2 Nanoparticles

An easy method of incorporating TiO(2) nanoparticles into Nafion perfluorinated ionomer is proposed. Ultrathin films of Nafion were prepared by employing the Langmuir-Schaefer (LS) technique. The pressure-area isotherm study of a Langmuir monolayer of Nafion at the air-water interface on different concentrations of NaCl as the subphase allowed us to find the best experimental conditions for the deposition of stable Langmuir-Schaefer films. Incorporation of TiO(2) nanoparticles was performed by dipping Nafion LS films in a solution of TiO(2) nanoparticles. The uniformity of the TiO(2) incorporation was detected by UV-visible spectroscopy. The morphology of the Nafion, Nafion/TiO(2) nanoparticles thin films, and the changes due to the annealing procedure were investigated by atomic force microscopy. Interestingly, the AFM investigation showed that Nafion and Nafion/TiO(2) LS films have thermal stability up to 600 degrees C.

A Novel Nanoparticle/Lamellar Oxide Hybrid: TiO2-pillared MoO3

ABSTRACTThe intercalation into MoO3 with TiO2 nanoparticles has been accomplished via the exfoliating-restacking route. The molybdenum oxide lithiated by LiBH4 is exfoliated in degassed and deionized water. And subsequent restacking of exfoliated MoO3 in the TiO2 nanoparticle solution results in TiO2-pillared MoO3. X-ray diffraction pattern indicates that the TiO2 nanoparticles are successfully intercalated in the interlayer of MoO3. The interlayer expansion of MoO3 with the Ad value of 11.2 Å is consistent with the size of TiO2 nanoparticle. Well-defined (00l) reflections reveal highly ordered lamellar character of TiO2-pillared MoO3. The pre-edge feature in the X-ray absorption spectrum of the TiO2-pillared MoO3 confirms that guest TiO2 in the interlayer of MoO3 is pillared in the form of anatase.