Titanium Dioxide Core Research Articles

Water-Soluble Hybrid Core–Shell Nanoparticles with Titanium Dioxide Core and Poly(Acrylic Acid) Shell

Water-Soluble Hybrid Core–Shell Nanoparticles with Titanium Dioxide Core and Poly(Acrylic Acid) Shell

Titanium Dioxide-Coated Zinc Oxide Nanorods as an Efficient Photoelectrode in Dye-Sensitized Solar Cells.

Well-arrayed zinc oxide nanorods applied as photoelectrodes for dye-sensitized solar cells were synthesized on an aluminum-doped zinc oxide substrate by the multi-annealing method. In order to improve the chemical stability and surface-to-volume ratio of photoanodes in dye-sensitized solar cells, the synthesized zinc oxide nanorods were coated with pure anatase phase titanium dioxide film using a novel mist chemical vapor deposition method. The effects of the titanium dioxide film on the morphological, structural, optical, and photovoltaic properties of zinc oxide–titanium dioxide core–shell nanorods were investigated. It was found that the diameter and surface-to-volume ratio of zinc oxide nanorods were significantly increased by coating them with titanium dioxide thin film. The power conversion efficiency of dye-sensitized solar cells was improved from 1.31% to 2.68% by coating titanium dioxide film onto the surface of zinc oxide nanorods.

Formation of titanium dioxide core-shell microcapsules through a binary-phase spray technique.

Core-shell microcapsules consisting of a titanium dioxide shell and a hydrophobic solvent core have been prepared with diameters of a few micrometers and a narrow size distribution using a simple and fast airbrush technique. These microcapsules were prepared at room temperature in a single-step process in which an oil with a dissolved titanium alkoxide precursor was forced together with an aqueous solution, containing a surface-active polymer, through a narrow spray nozzle using a nitrogen gas propellant. Several different parameters of chemical, physical, and processing origin were investigated to find an optimal recipe. Two different alkanes, one ketone, and four alcohols were tested and evaluated as core materials, alone or together with the antifungal biocide 2-n-octyl-4-isothiazolin-3-one (OIT). Long-chain alcohols were found suitable as core oil due to their low solubility in water and surface activity. The addition of the surface-active polymers in the water phase was important in aiding the formation and stabilization of the titanium dioxide shell. An impressive loading of 50 wt% of the semi-hydrophobic OIT was possible to encapsulate using this simple and applicable procedure.

Synthesis of Si/TiO2 core–shell nanoparticles as anode material for high performance lithium ion batteries

We demonstrated that titanium dioxide (TiO2) significantly enhances the reversible capacity of silicon nanoparticles (SiNPs) used as the anode material for lithium ion batteries. The novel silicon and titanium dioxide core–shell nanoparticles (Si/TiO2) was prepared via a facile sol–gel method with the following heat-treatment process. The as-prepared materials were confirmed by X-ray diffraction, Raman spectra and transmission electron microscope. As an anode material for battery, the electrode was investigated by a series of electrochemical measurements. The as-prepared Si/TiO2 electrode exhibits superior electrochemical performance in comparison with pure SiNPs, which realizes an initial capacity as high as 2636.9 mAh/g and still retains 1010.7 mAh/g even after 100 cycles of charging and discharging. The excellent cycle stability and capacity retention of the as-prepared electrode would be attributed to the existence of TiO2 layers to accommodate the large volume changes of silicon and enhancement ability to minimizes loss of pulverization during the lithium insertion/desertion cycles. Therefore, the as-prepared Si/TiO2 is believed to be an potential anode material for lithium-ion battery applications.

Synthesis and characterization of local clay–titanium dioxide core–shell extender pigments

A simple chemical technique has been used to prepare core–shell extender pigments based on Nigerian indigenous clays as core and titanium dioxide as shell. The prepared core–shell extender pigments were characterized using X-ray fluorescence and scanning electron microscopy. The physico-chemical properties of these extender pigments were also evaluated according to ASTM measurements. The study showed that the prepared core–shell pigments were nontoxic and environmentally friendly. They are of low cost and can be incorporated in semi-gloss paints, paper, rubber, and plastic composites without much effect on the volume. The characteristics of these pigments showed that they combine the properties of both their precursors, and have the potential to overcome their disadvantages, e.g., low hiding power of clays and photochemical activity of titanium dioxide.

Preparation and characterization of calcium carbonate–titanium dioxide core–shell (CaCO3@TiO2) nanoparticles and application in the papermaking industry

A novel and convenient method for preparing TiO2-coated CaCO3 composite particles was proposed and authenticated, meanwhile, the reaction mechanism was discussed. In this paper, carbonization was selected to prepare calcium carbonate, titanium sulfate was the titanium source, as it had a relatively low price compared to organic titanium sources, and urea was the precipitant to synthesize the target product with the direct precipitation method. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis results proved that CaCO3 was covered by TiO2 particles. As verified by Field Emission Scanning Electron Microscopy (FESEM), a film of TiO2 had coated the surface of the CaCO3 core. The average nanoparticle size of the composite was found to be about 250nm and well-dispersed. UV–visible absorption spectra in the solid phase study results showed that CaCO3@TiO2 possessed high ultraviolet absorption capacity. The whiteness of the CaCO3@TiO2 filler-containing paper sheet was 73.8%, which is similar to TiO2-incorporated paper (73.16%), and higher by about 3% than pure fiber paper (70.35%).

Improved microbial growth inhibition activity of bio-surfactant induced Ag–TiO2 core shell nanoparticles

Surfactant induced silver–titanium dioxide core shell nanoparticles within the size range of 10–50nm were applied in the antibacterial agent to inhibit the growth of bacterial cells. The single crystalline silver was located in the core part of the composite powder and the titanium dioxide components were uniformly distributed in the shell part. HRTEM and XRD results indicated that silver was completely covered by titanium dioxide and its crystal structure was not affected after being coated by titanium dioxide. The effect of silver–titanium dioxide nanoparticles in the inhibition of bacterial cell growth was studied by means of disk diffusion method. The inhibition zone results reveal that sodium alginate induced silver–titanium dioxide nanoparticles exhibit 100% more antibacterial activity than that with cetyltrimethylbromide or without surfactant. UV–vis spectroscopic analysis showed a large concentration of silver was rapidly released into phosphate buffer solution (PBS) within a period of 1 day, with a much smaller concentration being released after this 1-day period. It was concluded that sodium alginate induced silver–titanium dioxide core shell nanoparticles could enhance long term cell growth inhibition in comparison with cetyltrimethylbromide or without surfactant. The surfactant mediated core shell nanoparticles have comparatively rapid, less expensive and wider applications in modern antibacterial therapy.

High-capacity carbon-coated titanium dioxide core–shell nanoparticles modified three dimensional anodes for improved energy output in microbial fuel cells

Three-dimensional (3D) electrodes have been intensively investigated as alternatives to conventional plate electrodes in the development of high-performance microbial fuel cells (MFCs). However, the energy output of the MFCs with the 3D anodes is still limited for practical applications. In this study, a 3D anode modified with a nano-structured capacitive layer is prepared to improve the performance of an microbial fuel cell (MFC). The capacitive layer composes of titanium dioxide (TiO2) and egg white protein (EWP)-derived carbon assembled core–shell nanoparticles, which are integrated into loofah sponge carbon (LSC) to obtain a high-capacitive 3D electrode. The as-prepared 3D anode produces a power density of 2.59 ± 0.12 W m−2, which is 63% and 201% higher than that of the original LSC and graphite anodes, respectively. The increased energy output is contributed to the enhanced electrochemical capacitance of the 3D anodes as well as the synergetic effects between TiO2 and EWP-derived carbon due to their unique properties, such as relatively high surface area, good biocompatibility, and favorable surface functionalization for interfacial microbial electron transfer. The results obtained in this study will benefit the optimized design of new 3D materials to achieve enhanced performance in MFCs.

Design of Aerosol Coating Reactors: Precursor Injection

Particles are coated with thin shells to facilitate their processing and incorporation into liquid or solid matrixes without altering core particle properties (coloristic, magnetic, etc.). Here, computational fluid and particle dynamics are combined to investigate the geometry of an aerosol reactor for continuous coating of freshly-made titanium dioxide core nanoparticles with nanothin silica shells by injection of hexamethyldisiloxane (HMDSO) vapor downstream of TiO2 particle formation. The focus is on the influence of HMDSO vapor jet number and direction in terms of azimuth and inclination jet angles on process temperature and coated particle characteristics (shell thickness and fraction of uncoated particles). Rapid and homogeneous mixing of core particle aerosol and coating precursor vapor facilitates synthesis of core-shell nanoparticles with uniform shell thickness and high coating efficiency (minimal uncoated core and free coating particles).

Assemblies of Titanium Dioxide-Polystyrene Hybrid Nanoparticles for Dielectric Applications

Macroscopic assemblies of hybrid nanoparticles composed of titanium dioxide core surrounded by covalently grafted polystyrene corona have been prepared by a combination of phosphonate coupling and “click” chemistry. The attached polymer chains existed in the brush regime, with grafting density inversely proportional to the degree of polymerization. Solution casting afforded preparation of robust films of the composite material where all the polymer chains were covalently bound to the uniformly distributed inorganic particles. Inorganic content from 60 to 80 wt % (27 to 50 vol %) was obtained by varying the molecular weight of polystyrene as well as by using the mixture of high and low molecular weight polymer for grafting. The TiO2 grafted with 105 g/mol polystyrene had a volume fraction of nanoparticles of 27% and exhibited glass transition at 110 °C and ∼100% extensibility above Tg. Thin films of this material had a dielectric constant of 6.4 and a dielectric loss of 0.04 at 1 kHz.

Titanium Dioxide−Polymer Core–Shell Particles Dispersions as Electronic Inks for Electrophoretic Displays

The preparation of inorganic–organic core–shell particles is presented. These particles, composed of a titanium dioxide core and a polymer shell, are prepared via precipitation polymerization and inverse microsuspension polymerization. The electrical and optical properties of dispersions of these particles in a paraffin oil are measured in view of the formulation of electronic inks for electrophoretic displays. Encapsulation of TiO2 by precipitation polymerization is improved by pretreating the pigments with 3-(trimethoxysilyl)propyl methacrylate, making it possible to prepare particles with a TiO2-to-polymer ratio varying over a wide range. This ratio has a considerable influence on the optical properties of the dispersion but also on the interactions between pigments and electrodes. The polymer shell can then be further functionalized by introducing acidic groups at the particle’s surface. Encapsulation of the TiO2 can also be achieved by inverse microsuspension polymerization of poly(sodium acrylate), allowing the introduction of the acidic groups in one step only. Finally, dispersions of TiO2−polymer particles in black dyed paraffin oil have successfully been applied in an A4-sized segmented electrophoretic display panel.

Nanoglued Titanium Dioxide Aerogels for Photocatalysis

A titania–silica binary aerogel, composed of titanium dioxide thermally processed into its anatase form and nanoglued to a glass surface using an about-to-gel silica sol, was prepared to test for photocatalytic efficiency. The titanium dioxide core of this binary aerogel was characterized as being approximately 100% anatase through X-ray diffraction analysis, an important conclusion in that the anatase crystalline form has been shown to be more efficient as a photocatalyst than other morphologic forms of titanium dioxide. The surface areas for the four titania aerogel catalysts prepared ranged from 91.47–130.70 m2/g, and the catalysts had the highest density of pore radii of between 20–30 A. The BET surface areas found were approximately twice as large as that of the current research standard, Degussa P-25. The increase in surface areas allows for more decontamination to take place based on Langmuir–Hinshelwood kinetics. The catalysts were tested in water containing Escherichia coli at a concentration o...

Carboxylic acid functional group containing inorganic core/polymer shell hybrid composite particles prepared by two-step dispersion polymerization

Titanium dioxide core and polymer shell composite particles were produced in two-step dispersion polymerization of methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDMA) and methacrylic acid (MAA). Fourier transforms IR (FT-IR) spectroscopy was used to measure the content of MAA composite particles. Dynamic light scattering (DLS) was characterized the composite particle size and size distribution. The field emission SEM (FE-SEM) result of the composite particles regular spherical shape and no bare TiO2 was detected on the whole surface of the samples. TGA results indicated that the encapsulated TiO2 and estimated density of composite particles. Encapsulated TiO2 was up to 85.4% and the density was ranged from 1.60 to 1.84g/cm3.

Preparation and characterization of titanium dioxide core and polymer shell hybrid composite particles prepared by two-step dispersion polymerization

Titanium dioxide core and polymer shell composite poly (styrene- co-divinylbenzene)-methacrylic acid [P (St- co-DVB)-MAA]] particles were prepared by two-step dispersion polymerization. Fourier transform IR spectroscopy and elemental analysis were used to measure the content of methacrylic acid in composites particles. X-ray measurement photoelectron spectroscopy (XPS) measurements indicated the presence of an MAA unit on the surface of the composite particles. The combined results of the elemental analysis and the XPS measurements showed that the copolymer on the surface of poly (St- co-DVB)-MAA composite particles was rich in MAA compared with that in the interior of the composite particles. Field-emission scanning electron microscopy (FE-SEM) was used to study the morphology characterization. The composite particles produced showing good spectral reflectance compare with bare TiO 2. TGA results indicated that the encapsulation efficiency and estimated density of composite particles. Encapsulation of TiO 2 was up to 87.4% and the density was ranged from 1.78 to 2.06 g/cm 3. Estimated density of the composite particles is suitable to 1.73 g/cm 3, due to density matching with suspending fluid.

Preparation and characterization of titanium dioxide core and polymer shell hybrid composite particles prepared by two-step dispersion polymerization

Preparation and characterization of titanium dioxide core and polymer shell hybrid composite particles prepared by two-step dispersion polymerization

Physical and electrochemical characterization of nanocomposites formed from polythiophene and titaniumdioxide

A simple method for covering titanium dioxide particles with a polythiophene film by chemical preparation was developed. The resulting nanocomposites consisted of a titanium dioxide core with a grain size of 25–250 nm and a polythiophene shell between 1 and 2 nm thickness. The composites were characterized by scanning electron microscopy, thermogravimetry, X-ray photoelectron spectroscopy, cyclovoltammetry, impedance spectroscopy and photocurrent spectroscopy. The content of polythiophene in the composite (determined by thermogravimetry), was between 2% and 5%. Disk-like electrodes were prepared by pressing and then characterized by various electrochemical methods. A reversible redox potential of the polythiophene of +1.0 V (NHE) was determined by cyclic voltammetry. The reduced form of polythiophene behaved as a p-type semiconductor so that the composite with n-type TiO 2 contained the properties of a p/n-junction. In the photocurrent spectra (depending on the applied potential), the characteristic anodic peaks of the TiO 2 at λ=320 nm and cathodic peaks of the polythiophene around λ=500 nm were found. A new cathodic peak observed at 370 nm was explained as a new feature of the pn interface.