Titanium ( IV ) Isopropoxide Research Articles

Facile Synthesis of F-TiO2/TiOF2 Mixture by High-Thermal Direct Fluorination and Its Photocatalytic Evaluation.

In this study, the mixture of F-TiO2/TiOF2 has been easily synthesized using titanium (IV) isopropoxide (TTIP) as titanium source by direct fluorination at high temperature according to different partial pressure of fluorine gas. The morphological properties and crystalline of thermally fluorinated photocatalysts were investigated using scanning electron microscope (SEM) and X-ray diffraction (XRD). Chemical composition and optical properties of thermally fluorinated photocatalysts were analyzed by X-ray Photoelectron Spectroscopy (XPS) and Photoluminescence (PL) spectrometer. The phase of F-TiO2/TiOF2 mixture was generated with different proportion by high-thermal direct fluorination. With the increase of the fluorine partial pressure, the proportion of cubic-shaped TiOF2 increased in comparison with globular-shaped TiO2. Also, the degradation rate constant of thermally fluorinated photocatalysts exhibited approximately 70 times more than that of TiO2, which were not treated fluorine gas. It is attributable to the increase of the surface hydroxyl group content and oxygen vacancies.

L-Lactide Ring-Opening Polymerization with Tris(acetylacetonate)Titanium(IV) for Renewable Material.

A new Ti-type of catalyst for L-lactide polymerization was synthesized by reaction of titanium(IV) isopropoxide (TTIP) with acetylacetone (AA). Moreover, PLA was prepared by the bulk ring-opening polymerization using synthesized Ti catalyst. Polymerization behaviors were examined depending on monomer/catalyst molar ratio, polymerization temperature and time. The structure of synthesized catalysts was verified with FT-IR and 1H NMR and the properties of poly(L-lactide) (PLLA) were examined by GPC, DSC and FT-IR. There existed about 30 minutes of induction time at the monomer/catalyst molar ratio of 300. The molecular weight (MW) increased as monomer/catalyst molar ratio increased. The MW increased almost linearly as polymerization progressed. Increasing polymerization temperature increased the molecular weight of PLLA as well as monomer/catalyst molar ratio. The melting point (T(m)) of polymers was in the range of 142 to 167 degrees C. Lower T(m) was expected to be resulted from relatively lower molecular weight.

Study on Electrochemical Analysis of Supercapacitor Electrodes Containing Modified Reduced Graphene Oxide and Titanium Dioxide

Graphene has attracted tremendous attention in spacious energy storage fields due to its high conductivity, excellent electrical and mechanical stability, and large specific surface area [1]. However, graphene shows lower electrochemical performance than theoretical reports because of restacking or agglomeration induced by strong van der Waals interactions between adjacent layers. To prevent this phenomenon and improve electric properties, transition metal oxides or hydroxides are generally introduced into the interlayer of graphene [2]. Among diverse transition metal oxides, TiO2 which has numerous advantages such as a high specific energy density, strong oxidizing power, low cost and environment friendly considered as a promising electrode material. In reported study, TiO2 / rGO composite was synthesized by two-step method [2]. Herein, we firstly designed a facile one-step method through the sol-gel approach to synthesize TiO2 / rGO composites, and they exhibited excellent electrochemical performances. Graphite oxide (GO) was synthesized by a modified Hummers method [3] and as reported before [4-5]. GO was dispersed in DI water and sonicated for 30 min. The mixture of titanium (IV) isopropoxide (TIP), ethanol and acetic acid added in the GO solution. Ammonium hydroxide was then added until pH 8~9 in dropwise under stirring for 1 hour at room temperature to form a brownish-black suspension. After this process, the obtained solution was sealed into a Teflon lined stainless steel autoclave at 160ºC for 3 hours. We can finally obtained TiO2 / rGO composite after filtering, washing and drying in air at 60ºC for 12 hours. We analyzed morphological properties of the synthesized composites using scanning electron microscopy (SEM), transition electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). We confirmed TiO2 / rGO hybrid composites were well anchored on the interlayer of the graphene nanosheets. We also examined electrochemical performances of the composites with cyclic voltammetry (CV), electrical impedance spectroscopy (EIS) and galvanostatic charge-discharge curve. We studied a facile one-step sol-gel method for synthesis of titanium dioxide (TiO2) / reduced graphene oxide (rGO) composite. In conclusion, the as-prepared composite can be considered as promising electrode materials owing to high capacitance and long cycle life. Acknowledgments This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning, Korea (Grant No.: NRF-2011-0009007).

Extremely enhanced photovoltaic properties of dye-sensitized solar cells by sintering mesoporous TiO2 photoanodes with crystalline titania chelated by acetic acid

The study presents a significant improvement on the performance of dye-sensitized solar cells (DSSCs) through incorporating the crystalline titania chelated by acetic acid (TAc) into the mesoporous TiO2 photoanodes. The effects of TAc on the blocking layer, mesoporous TiO2 layer, and post-treatment have been investigated. The TAc blocking layer displays compact construction, revealing superior response time and resistance to suppress dark current compared to the blocking layer made from titanium(IV) isopropoxide (TTIP). The power conversion efficiency of DSSCs with the TAc treatment can reach as high as 10.49%, which is much higher than that of pristine DSSCs (5.67%) and that of DSSCs treated by TTIP (7.86%). We find that the TAc incorporation can lead to the decrease of charge transfer resistance and the increase of dye adsorption. The result may be attributed to the fact that the TAc possesses high crystallinity, exposed (101) planes, and acid groups chelated on surface, which are favorable for dye attachment and strong bonding at the FTO/TiO2 and the TiO2/TiO2 interfaces, These improvements result in the remarkable increase of photocurrent and thereby that of power conversion efficiency.

TiOx thin films grown on Pd(100) and Pd(111) by chemical vapor deposition

The growth of ultrathin TiOx (0≤x≤2) films on Pd(100) and Pd(111) surfaces by chemical vapor deposition (CVD), using Titanium(IV)isopropoxide (TTIP) as precursor, has been investigated by high resolution photoelectron spectroscopy, low energy electron diffraction and scanning tunneling microscopy. Three different TiOx phases and one Pd–Ti alloy phase have been identified for both surfaces. The Pd–Ti alloy phase is observed at the initial stages of film growth. Density functional theory (DFT) calculations for Pd(100) and Pd(111) suggest that Ti is alloyed into the second layer of the substrate. Increasing the TTIP dose yields a wetting layer comprising Ti2+ species (TiOx, x ∼0.75). On Pd(100), this phase exhibits a mixture of structures with (3×5) and (4×5) periodicity with respect to the Pd(100) substrate, while an incommensurate structure is formed on Pd(111). Most importantly, on both surfaces this phase consists of a zigzag pattern similar to observations on other reactive metal surfaces. Further increase in coverage results in growth of a fully oxidized (TiO2) phase on top of the partially oxidized layer. Preliminary investigations indicate that the fully oxidized phase on both Pd(100) and Pd(111) may be the TiO2(B) phase.

Effects of Electrospinning Solution Properties on Formation of Beads in Tio2 Fibers with PdO Particles

TiO2 fibers with catalytic PdO particles are of interest for use as porous catalytic converters to react NOx and CO to control air pollution. The fibers are first electrospun as template polymer fibers. The template polymer fibers are calcined to form the ceramic fibers. The electrospinning solution composition significantly affects the average fiber diameter and fiber morphologies (beads) which in turn affect the catalyst performance. In this work, solutions containing Polyvinylpyrrolidone (PVP), Titanium (IV) Isopropoxide (TTIP), and Palladium (II) Chloride (PdCl2) were electrospun with the goal of fabricating beadless submicron composite fibers. The fibers were calcined to produce ceramic TiO2 submicron fibers with Palladium oxide (PdO) nanoparticles. To determine the solution recipes that form smooth PdO-TiO2 fibers without beads, fibers were electrospun and evaluated from solutions with varied mass concentrations of PVP and PdCl2 salt. The solution concentrations indirectly influenced the electrospinning performance through solution viscosity, surface tension and electrical conductivity. The ceramic fibers were produced with average diameters in the range of 180–280 nm and with minimal formation of beads when the solution had viscosity in the range of 52 to 80 cP and conductivity in the range of 45–67 μs/cm. It was found that the surface tension of the solutions did not vary significantly and did not strongly affect the formation of beads.

Synthesis and characterization of anatase TiO2 nanosheet arrays on FTO substrate

We have exploited a green approach to prepare layered titanate Na2-xHxTi2O5•H2O nanosheet arrays on FTO substrate by hydrothermal hydrolysis of titanium(IV) isopropoxide (TTIP) with aids of Na2EDTA and TEOA as co-coordination agents, which were then treated by HNO3 to replace Na+ by H+, followed by a calcination at 450 °C to topotactically transform into anatase TiO2 nanosheet arrays. SEM, TEM, XRD, and Raman spectroscopy have been employed to characterize the nanosheet films. The TiO2 nanosheet arrays were further applied as electron transport materials of CH3NH3PbI3 perovskite solar cells, achieving power conversion efficiency of 6.99%.

Preparation and optical properties of iron-modified titanium dioxide obtained by sol–gel method

In this paper twelve TiO2:Fe powders prepared by sol–gel method were analyzed being into consideration the kind of iron compound applied. As a precursor titanium (IV) isopropoxide (TIPO) was used, while as source of iron Fe(NO3)3 or FeCl3 were tested. Fe doped TiO2 was obtained using two methods of synthesis, where different amount of iron was added (1, 5 or 10% w/w). The size of obtained TiO2:Fe particles depends on the iron compound applied and was found in the range 80–300nm as it was confirmed by SEM technique. TiO2:Fe particles were additionally investigated by dynamic light scattering (DLS) method. Additionally, for the TiO2:Fe particles UV–vis absorption and the zeta potential were analyzed. Selected powders were additionally investigated by magnetic force microscopy (MFM) and X-ray diffraction techniques. Photocatalytic ability of Fe doped TiO2 powders was evaluated by means of cholesteryl hemisuccinate (CHOL) degradation experiment conducted under the 30min irradiation of simulated solar light.

Nanoparticulate titanium dioxide synthesized by sol–gel and solution combustion techniques

Nano-sized titanium dioxide is renowned for its prominent photocatalytic properties. Various synthesis techniques have been successfully employed in production of nano-titanium dioxide. Some of the techniques require expensive initial reagents as well as extensive preparation time. A rapid, simple and cost-effective technique capable of producing high quality nano-particles is highly desirable. This study, therefore, aims at examining effects of synthesis techniques and initial reagents on chemical compositions and particle sizes of titanium dioxide. A solution combustion technique as well as a sol–gel method using Titanium (IV) isopropoxide (TTIP) and submicrometer-sized titanium dioxide as initial reagents were employed as synthesis techniques. Experimental results indicated that all synthesized powders contained pure anatase titanium dioxide. Average particle sizes of powders prepared by the solution combustion technique from TTIP and submicrometer-sized titanium dioxide were 44 and 77nm whereas, powder sizes prepared by the sol–gel method averaged at 48 and 85nm respectively.

Synthesis of titania- and silica-polymer hybrid materials and their application as refractive index-matched layers in touch screens

Titania- and silica-polymer hybrid materials were prepared with an in situ sol-gel process for refractive index-matched, optical thin-film applications. A random copolymer of methyl methacrylate (MMA) and 3-(trimethoxysilyl) propyl methacrylate (MSMA) (poly(MMA-co-MSMA), MMA:MSMA = 78:22 molar ratio) capped with trialkoxysilane in MSMA units was used as a precursor. The precursor was further reacted with titanium (IV) isopropoxide (TTIP) and tetraethyl orthosilicate (TEOS) to synthesize the high (H) and low (L) refractive index hybrid materials, respectively, with an acid-free sol-gel method, which prevents the corrosion of neighboring metals or metal oxides used in optical thin-film applications. The refractive indices of the H and L materials were controlled by the concentrations of TTIP and NaCl used during the acid-free sol-gel process, respectively. The H material on a glass substrate exhibited a high optical transparency of 96%, with respect to bare glass at 550 nm, and a high refractive index of 1.82 when the precursor was reacted with TTIP (90 wt% of the precursor). The L material on a glass substrate showed a high optical transparency of ~100%, with respect to bare glass at 550 nm, and a low refractive index of 1.44 when the precursor was reacted with 2.5 M of NaCl. An indium tin oxide (ITO)/L/H/poly(ethylene terephthalate) thin-film substrate, with the optimum thicknesses of each layer calculated with Macleod software, had a reflexibility difference (ΔR) of < 1% over 65% of the visible spectrum, as well as good flexibility and a long lifetime. These results indicate that the spin-coatable L and H materials could replace the typical low and high refractive index inorganic materials (SiO2 and Nb2O5, respectively) used for flexible touch screen applications.

Preparation, Characterization and Photocatalytic Activities of TiO2‐coated Activated Carbon Catalysts for Rhodamine B Photodegradation

TiO2 ‐coated activated carbon (TiO2 /AC) catalysts with high activity and easy separation were prepared by the coating method and their photocatalytic performances were studied for degradation of rhodamine B (RhB) dye. For this purpose, first, anatase TiO2 nanocrystal was prepared via sol–gel process of titanium(IV) isopropoxide (TTIP), followed by reflux treatment at a relatively low temperature (130 °C) without further treatments. Second, four different amounts of AC were separately coated with TiO2 by dipping in TiO2 sol (10%, w/w) at room temperature. The catalysts were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area, and UV–vis diffuse reflectance spectroscopy (DRS). Coating AC with TiO2 produced catalysts with higher BET surface areas and greater crystallite sizes as compared to bare TiO2 . RhB (50 mg/L) was almost completely discolored in 50 min, and the mineralization efficiency was 100% in 60 min for the catalysts containing 10 and 15% AC. Furthermore, all catalysts showed much higher photocatalytic activities than the commercial Degussa P‐25.

Synthesis of polycarbonate-r-polyethylene glycol copolymer for templated synthesis of mesoporous TiO2 films.

We synthesized a novel polycarbonate Z-r-polyethylene glycol (PCZ-r-PEG) copolymer by solution polycondensation. Successful synthesis of PCZ-r-PEG copolymer was confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H-NMR), gel permeation chromatography (GPC), and transmission electron microscopy (TEM). PCZ-r-PEG copolymer was used as a structure-directing agent for fabrication of mesoporous thin film containing a titanium dioxide (TiO2) layer. To control the porosity of the resultant inorganic layer, the ratio of titanium(IV) isopropoxide (TTIP) to PCZ-r-PEG copolymer was varied. The structure and porosity of the resulting mesoporous films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. Mesoporous TiO2 films fabricated on an F-doped tin oxide (FTO) surface were used as photoanodes for quasi-solid-state dye-sensitized solar cells (qssDSSCs). The highest efficiency achieved was 3.3% at 100 mW/cm2 for a film thickness of 750 nm, which is high considering the thickness of TiO2 film, indicating the importance of the structure-directing agent.

A comparative study on titanium dioxide sol-gel treatment for protein fabrics, focusing on UV transmittance effects

Sol-gel technology offers a promising route to impart new properties to textile substrates. However, relatively little attention has been paid to the effect of precursor concentration in the sol-gel processing on the inherent properties of sol-gel treated textile substrates. In this study, titanium (IV) isopropoxide (TTIP) was used as the precursor material, and colourless TiO2 sol solutions were prepared at three precursor concentrations. Wool fabrics were coated with as-prepared TiO2 sol solutions via a dip-dry-cure technique. The optical, morphological, tensile properties and washing durability of both untreated or sol-gel treated wool fabrics were then evaluated. The results show that TiO2 sol-gel prepared at a relatively higher precursor concentration resulted in a thicker coating and a better UV protection on the treated wool fabric. TTIP precursor concentration also played an important role in the washing durability of TiO2 sol-gel coatings. Both the tensile strength and elongation at break of the treated wool fabrics were largely improved, however the degree of improvement seemed to be less dependent on the precursor concentrations of as-prepared TiO2 sol-gels.

Photocatalytic Decolorization Study of Methyl Orange by TiO&lt;sub&gt;2&lt;/sub&gt;–Chitosan Nanocomposites

The photocatalytic decolorization of methyl orange (MO) by TiO2-chitosan nanocomposite has been studied. This study was started by synthesizing TiO2-chitosan nanocomposites using sol-gel method with various concentrations of Titanium(IV) isopropoxide (TTIP) as the TiO2 precursor. The structure, surface morphology, thermal and optical property of TiO2-chitosan nanocomposite were characterized by X-ray diffraction (XRD), fourier transform infra red (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and diffuse reflectance ultra violet (DRUV) spectroscopy. The photocatalytic activity of TiO2-chitosan nanocomposite was evaluated by photocatalytic decolorization of methyl orange as a model pollutant. The results indicate that the particle size of TiO2 increases with increasing ofthe concentration of TTIP, in which TiO2 with smallest particle size exhibit the highest photocatalytic activity. The highest photocatalytic decolorization was obtained at 5 h of contact time, initial concentration of MO at 20 ppm and at solution pH of 4. Using these conditions, over 90% of MO was able to be decolorized using 0.02 g of TiO2-chitosan nanocomposite under UV light irradiation. The TiO2-chitosan nanocomposite could be reused, which meant that the TiO2-chitosan nanocomposites can be developed as an effective and economical photocatalyst to decolorize or treat dye in wastewater.

Mixed-phase nanocrystalline TiO2 photocatalysts produced by flame spray pyrolysis

Titanium dioxide nanostructured powders with different structural properties and improved photocatalytic performance were synthesized by flame spray pyrolysis (FSP) under systematically varied FSP operation conditions, starting from organic solutions containing titanium(IV) isopropoxide (TTIP) as Ti precursor. The primary particle size, crystalline phase, specific surface area, porosity and morphology of the so obtained photocatalyst powders were investigated by means of Raman spectroscopy, XRD, BET, SEM and UV–vis absorption analysis. An increase of the molar ratio between the dispersion oxygen gas and the TTIP fed into the flame was demonstrated to lead to TiO2 materials with decreased primary particles size, from ca. 21 to 7nm, with a higher brookite content and an increased BET surface area, from ca. 70 up to 250m2g−1. The photocatalytic activity of the as-synthesized TiO2 powders was investigated employing formic acid decomposition in aqueous suspension as test reaction. With the TiO2 powders synthesized with high O2/TTIP flux molar ratio a formic acid photomineralization rate was attained significantly overcoming that obtained with commercial P25 TiO2.

Modification of dye-sensitized solar cell working electrode using TiO2 nanoparticle/N-doped TiO2 nanofiber composites

Nanocomposite films of N-doped TiO2 nanofibers (NFs) and commercial-grade TiO2 nanoparticles Degussa (P25) were utilized as working electrode of typical dye-sensitized solar cells (DSSCs). N-doped TiO2 NFs were fabricated via electrospinning method using ammonium acetate (CH3COONH4) as nitrogen source and titanium (IV) isopropoxide (TiP) in ethanol as starting precursor in combination with calcinations process. The electrospun NFs were characterized by XRD, Raman spectroscopy, XPS, SEM, and TEM. The photoelectric conversion performance of the DSSCs with composite film electrode was compared to the device using pure P25 film. The result shows that as calcination temperature increases, the anatase-to-rutile phase transformation and the fiber size reduction of NFs were observed. The energy conversion efficiency (η) of the device tends to increase with increasing calcined temperature with specific nanofiber loading content, indicating the significant enhancement in the device performance by the incorporation of the NFs. This enhancement of DSSCs may attribute to high surface area, higher light scattering and light harvesting, low charge recombination, and fast electron-transfer rate by loaded NFs.

Thick mesoporous TiO2 films through a sol–gel method involving a non-ionic surfactant: Characterization and enhanced performance for water photo-electrolysis

A method for the preparation of TiO2 thick films made of anatase nanocrystallites and featuring a mesoporous structure is described. Modification of a typical sol–gel synthesis that uses Titanium (IV) isopropoxide (TTIP) as precursor, through both the incorporation of a non-ionic surfactant (Tween 20) and the optimization of thermal treatments, allows to increase the thickness of each spin-coated layer, and to obtain by successive runs porous, transparent, homogeneous and crackless films with thickness up to 1.2 μm. The effect of the changing the Tween 20/TTIP ratio (R, ranging from 0.25 to 1.00) on the crystallographic, morphological and optical properties has been studied by X-ray Diffraction, N2 adsorption, UV–Visible Spectroscopy and Field Emission Scanning Electron Microscopy, in both powder and film form. The size of particles decreases slightly with increasing R, while the specific surface area increases somewhat. For all the R values, including R = 0, nanoparticles behave as direct semiconductors, in contrast with bulk anatase: changes in the band gap extent caused by the porous structure are negligible. Photo-electrochemical performance and carrier dynamics were studied using the films as anodes for the water photo-electrolysis reaction by means of Linear Sweep Voltammetry, Amperometry and Electrochemical Impedance Spectroscopy. Increasing R values improves the photo-catalytic performance of the TiO2 films and leads to a comprehensive faster charge transfer at the oxide–solution interface, so that those with R = 1 offer highest performance, due to the combination of both higher thickness and improved quality of the material.

Selective synthesis of TiO2 nanocrystals with morphology control with the microwave-solvothermal method

In this paper, a method to synthesize anatase TiO2 nanorods by hydrolysis of titanium(IV) isopropoxide (TTIP) in the presence of benzyl alcohol and acetic acid at 210 °C was tested. The novelty of the present approach relies on the evaluation of the shape-controlled synthesis of anatase TiO2 nanocrystals via a microwave-solvothermal method in 45 min. The different TiO2 nanocrystals were obtained by tuning the TTIP/acetic acid ratio under optimized synthetic conditions and were characterized in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), micro Raman (together with microphotoluminescence) and FT-IR spectroscopies. The acetic acid coordinated on the nanocrystal surface was removed by the reduction of its carboxyl group via a “super-hydride reaction”, and the photocatalytic activity of bare TiO2 nanocrystals, under visible light irradiation, was also evaluated: the best performing TiO2 anatase nanocrystals exhibited a discrete photoactivity, completely degrading Rhodamine B solution in five hours.

Effect of Concentration TTIP on Size Nano-Powder Titanium Dioxide (TiO&lt;sub&gt;2&lt;/sub&gt;)

In this work, titanium Dioxide (TiO2) powder was prepared by sol gel method using Titanium (IV) Isopropoxide (TTIP) as precursor and Ethanol (C2H5OH) as solvent. The sol-gel was heated at temperature 150°C in 1 hour. Titanium Dioxide (TiO2) powder was milled with constant ball to powder ratio (BPR) of 10:1 with speed 600 rpm. Then the sample was characterized using Particle Size Analyzer, Raman Spectroscopy and Scanning Electron Microscope (SEM). Titanium Dioxide (TiO2) powder was prepared with three different concentration of TTIP to the size of Titanium Dioxide (TTIP) powder. Titanium Dioxide (TTIP) powder was milled with ball milling to produce nanopowder of Titanium Dioxide (TiO2).

Effect of Calcinations Temperature on Structural Properties, Phase Transformation and Photocatalytic Activity of Electrospun TiO2 Nanofibers

TiO2 nanofibers were fabricated via an electrospinning method. Titanium (IV) isopropoxide (TIP) and poly (viny pyrrolidone) (PVP) were used as a starting precursor. The electrospun TiO2 nanofibers were obtained by injecting the precursor through a needle under a strong electrical field. As-spunfibers were calcined at 500, 600, 700, 800 and 900 °C for 2 h. The structural of properties of the nanofibers were characterized using X-ray diffraction (XRD) and Scanning electron microscope (SEM). XRD results indicated that the crystallinity of TiO2 nanofibers corresponds to rutile and anatase phase of TiO2 depending on calcinations temperature. SEM results indicated that the surface morphology and size TiO2 nanofibers. The photocatalytic degradation of RhB may be attributed to significant absorption enhancement in visible region by phase transformation of TiO2 nanofibers and fiber size dependence active surface areas.