Titanium Isopropoxide Solution Research Articles

Photocatalytic behavior of TiO2 films synthesized by microwave irradiation

Titanium dioxide was synthesized on glass substrates from titanium (IV)isopropoxide and hydrochloride acid aqueous solutions through microwave irradiation using as seed layer either fluorine-doped crystalline tin oxide (SnO2:F) or amorphous tin oxide (a-SnOx). Three routes have been followed with distinct outcome: (i) equimolar hydrochloride acid/water proportions (1HCl:1water) resulted in nanorod arrays for both seed layers; (ii) higher water proportion (1HCl:3water) originated denser films with growth yield dependent on the seed layer employed; while (iii) higher acid proportion (3HCl:1water) hindered the formation of TiO2. X-ray diffraction (XRD) showed that the materials crystallized with the rutile structure, possibly with minute fractions of brookite and/or anatase. XRD peak inversions observed for the materials synthesized on crystalline seeds pointed to preferred crystallographic orientation. Electron diffraction showed that the especially strong XRD peak inversions observed for TiO2 grown from the 1HCl:3water solution on SnO2:F originated from a [001] fiber texture. Transmittance spectrophotometry showed that the materials with finer structure exhibited significantly higher optical band gaps. Photocatalytic activity was assessed from methylene blue degradation, with the 1HCl:3water SnO2:F material showing remarkable degradability performance, attributed to a higher exposure of (001) facets, together with stability and reusability.

OBTENCIÓN DE PARTÍCULAS DE TiO2 POR SOL-GEL, ASISTIDO CON ULTRASONIDO PARA APLICACIONES FOTOCATALÍTICAS

La síntesis de las partículas de TiO2 se realizó mediante la técnica sol-gel asistida conradiación ultrasónica a partir de una solución alcohólica de isopropóxido de titanio. Luegose sometió a un tratamiento térmico en atmósfera de aire a 350 ºC por 1 h. Difracción derayos X y microscopía electrónica de transmisión confirmaron que el tamaño de los dominioscristalinos se encuentran entre 10 y 37 nm. El estudio de espectroscopía infrarroja confirmala presencia de grupos -OH en la superficie del TiO2. La modificación de la morfología y elárea superficial, debido a la influencia del tiempo de exposición a la radiación ultrasónica,se evidencia con los estudios de microscopía electrónica de barrido y BET, respectivamente.Las propiedades del TiO2 obtenido se estudiaron monitoreando la degradación de solucionesde anaranjado de metilo en presencia de radiación UV-A. Se observó que a mayor exposiciónde radiación ultrasónica durante la síntesis de las muestras de TiO2, mayor fue la constante develocidad para la reacción de fotocatálisis del anaranjado de metilo.

Effect of Liquid Feed-Stock Composition on the Morphology of Titanium Dioxide Films Deposited by Thermal Plasma Spray.

Titanium dioxide coatings were deposited on the surface of titanium foils by Thermal Plasma Spray (TPS) process. Three different TiO2 coatings were prepared using the commercial TiO2-P25 nanopowder and titanium isopropoxide precursor solution as feed-stocks. Structure and morphology of the TiO2-P25 powder and the plasma sprayed coatings were analyzed by X-ray diffraction (XRD), Raman spectroscopy, N2 adsorption-desorption isotherms, UV-visible spectroscopy and Scanning Electron Microscopy (SEM). XRD and Raman results indicate that the TiO2 coatings were composed of an anatase/rutile mixture that is conditioned by the suspension composition used to be sprayed. Coatings prepared from TiO2-P25 nanoparticles in water suspension (NW-P25) and titanium isopropoxide solution suspension (NSP-P25) are incorporated into the coatings without phase transformation and their anatase/rutile ratio percentage remains very similar to the starting TiO2-P25 powder. On the contrary, when titanium isopropoxide solution is used for spraying (SP), the amount of rutile increases in the final TiO2 coating. SEM analysis also reveals different microstructure morphology, coating thickness, density and porosity of the three TiO2 films that depend significantly on the type of feed-stock employed. Interestingly, we have observed the role of titanium isopropoxide in the formation of more porous and cohesive layers of TiO2. The NSP-P25 coating, prepared with a mix of titanium isopropoxide solution based on TiO2 nanoparticles, presents higher deposition efficiencies and higher coating thickness than the film prepared with nanoparticles suspended in water (NW-P25) or with titanium isopropoxide solutions (SP). This is due to the precursor solution is acting as the cement between TiO2 nanoparticles, improving the cohesive strength of the coating. In sum, NSP-P25 and NW-P25 coatings display a good photocatalytic potential, based on their light absorption properties and mechanical stability. Band gap of the nanoparticulated coatings displays a light absorption at wavelengths below 379 and 399 nm for NW-P25 and NSP-P25 respectively. On the contrary, the SP coating, despite to present lower band-gap value, has bad cohesive properties with surface crackings that makes it mechanically unstable. Therefore, mixtures of P25 nanoparticles with titanium isopropoxide as feed-stock materials can produce promising photocatalytic coatings.

Effect of Anatase Synthesis on the Performance of Dye-Sensitized Solar Cells.

Anatase nanoparticles were synthesized from a titanium isopropoxide solution using a hydrothermal process at different pressures in an autoclave system while keeping the volume of the solution constant. As the autoclave pressure was increased from 1 to 71 atm (23 to 210 °C), the crystal size in the nanoparticles increased from 9 to 13.8 nm. The anatase nanoparticles were used to build dye-sensitized solar cells (DSSC). Mesoporous films of this oxide were deposited over conducting SnO2:F substrates using the screen-printing technique and then annealed at 530 °C at 1 atm of air pressure. The morphology of the mesoporous film surface of anatase, studied using scanning electron microscopy, revealed that the crystal size and pore distribution were functions of the pressure conditions. The energy band gap of the films as a function of the crystal size exhibited quantum effects below 11.8 nm. The effects of the anatase synthesis conditions and properties of the mesoporous film on the DSSC-type solar cell parameters, η%, VOC, JSC, and FF, were also investigated: the mesoporous anatase films prepared at 200 °C (54 atm of pressure in the autoclave) and annealed at 530 °C in air generated the best solar cell, having the highest conversion efficiency.

Titanium Dioxide Coating Prepared by Use of a Suspension-Solution Plasma-Spray Process

Titanium dioxide coatings were prepared from titanium isopropoxide solution containing nano TiO2 particles by use of a plasma-spray process. The effects of stand-off distance on coating composition and microstructure were investigated and compared with those for pure solution precursor and a water-based suspension of TiO2. The results showed that the anatase content of the coating increased with increasing stand-off distance and the rate of deposition decreased with increasing spray distance. Anatase nanoparticles in solution were incorporated into the coatings without phase transformation whereas most of the TiO2 in the precursor solution was transformed into rutile. The microstructure of preserved anatase particles bound by rutile improved the efficiency of deposition of the coating. The amount of anatase phase can be adjusted by variation of the ratio of solution to added anatase TiO2 nanoparticles.

Characterisation of Sol-Gel Synthesis of Phase Pure CaTiO3 Nano Powders after Drying

According to a few recent studies, calcium titanate (CT) is a material that is similar to hydroxyapatite in biological properties. However, calcium titanate is not currently being used in the biomedical applications as to hydroxyapatite. The objective is to prepare nano calcium titanate powders from the equimolar solution of calcium oxide, ethanol and Titanium (IV) isopropoxide via sol-gel synthesis. The phase analysis and morphology of powder particles were studied by X-ray diffraction (XRD), while the composition and size of powder particles were determined by Transmission electron microscope (TEM) attached with energy dispersive x-ray spectrometer (EDS). As results, XRD confirm the presence of phase pure crystalline CaTiO3 after drying at 100°C for 24 hours, while TEM analysis confirms about 13 nm sizes of CaTiO3 particles and some agglomerated particle of 20-30 nm. Moreover, EDS analysis indicates that the approximately stoichiometric Ca/Ti ratio 1:1 was obtained in the CaTiO3 powders. Finally, it can be concluded that described sol-gel synthesis could be novel method for the production of nano CaTiO3 particles at lower temperature compared to any other methods of production.

Hierarchical decoration of anodic TiO2 nanorods for enhanced photocatalytic degradation properties

In the present work vertically aligned TiO2 nanorods were fabricated by anodization of Al/Ti dual layer structures. Anodization of Al leads to the formation of a porous alumina layer which is used as a template for the growth of TiO2 nanorods. We have studied the characteristics of these nanorods after annealing by high resolution TEM, showing a core–shell structure along the length of the nanorods formed from the expansion of the TiO2 nanorod into the alumina template during growth. Modification of the nanorods by spin coating of a solution of titanium isopropoxide (TIPO) in isopropanol yields enhanced photocatalytic activity up to 12 times due to the increase in surface area, light absorption volume, and the creation of a crystalline coating with an anatase-phase.

Morphologic, structural, and optical characterization of sol‐gel derived TiO2 thin films for memristive devices

AbstractSol‐gel derived TiO2 thin films were prepared by spin‐ coating from an alcoholic solution of titanium isopropoxide. With the aim to develop titania layers suitable for memristive devices, the films were deposited onto test structures based on fused silica quartz substrates patterned with a Ti (5nm)/Pt (50nm) layer. The reported fabrication protocol is suitable for the development of a memristive device. Optical, structural, and morphological features of the samples were investigated with complementary techniques, such as scanning electron microscopy (SEM), prism coupling m‐line and micro‐Raman spectroscopy as well as transmittance and profilometry measurements. The quality of the surface of the obtained films was evaluated by SEM technique, and the morphology of samples deposited with different fabrication protocols was investigated. Additionally, a computer code for the refractive index and thickness estimation from the transmittance spectra was developed by unconstrained optimization procedure. The results of simulation were in good agreement with the experimental data obtained by m‐line measurements. Moreover, the porosity of a specific set of test unannealed films has been estimated. TiO2 films exhibit thickness of tens of nm, and micro‐Raman spectroscopy in conjunction with SEM indicate the presence of anatase phase after thermal annealing at 400 °C. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Ultra-rapid photocatalytic activity of Azadirachta indica engineered colloidal titanium dioxide nanoparticles

Titanium dioxide nanoparticles were effectively synthesized from aqueous leaf extract of Azadirachta indica under pH and temperature-dependent condition. 5 mM titanium isopropoxide solution worked as a primary source for the synthesis of titanium dioxide nanoparticles. The green synthesized titanium dioxide nanoparticles were confirmed by UV–Vis spectroscopy. Fourier transform infrared spectrum of synthesized titanium dioxide nanoparticles authorized the presence of bioactive compounds in the leaf extract, which may play a role as capping and reducing agent. The high-resolution scanning electron microscopy and dynamic light scattering analyses results showed the interconnected spherical in shape titanium dioxide nanoparticles having a mean particle size of 124 nm and a zeta potential of −24 mV. Besides, the colloidal titanium dioxide nanoparticles energetically degrade the industrially harmful methyl red dye under bright sunlight.

Direct synthesis of hierarchically porous TS‐1 through a solvent‐evaporation route and its application as an oxidation catalyst

Synthesis of hierarchically porous zeolites has drawn intensive interest because of their improved catalytic performance. It is highly desirable to find ways to generate these materials in a low‐cost and scalable way for their commercial applications. A solvent evaporation route has been established to synthesize hierarchically porous titanosilicalite‐1 (TS‐1). In the protocol, hexadecyltrimethoxysilane was added to an ethanolic solution of titanium isopropoxide, tetraethyl orthosilicate and tetrapropylammonium hydroxide, i.e. the embryo solution of TS‐1. The solution was subjected to solvent evaporation‐induced self‐assembly to afford an ordered dry gel. Subsequent steam‐assisted crystallization converted the dry gel into a hierarchically porous TS‐1. X‐ray powder diffraction (XRD), UV–visible diffusive reflectance spectroscopy, N2 physisorption and electron microscopic characterizations have been employed to elucidate the structure. Ti is incorporated into the tetrahedral sites of the MFI structure and mesopores around 20 nm penetrating the crystalline framework are formed. Hexadecyltrimethoxysilane plays a key role in creating mesopores as well as increasing the crystal size. The hierarchically porous TS‐1 exhibits improved activity in styrene oxidation and phenol hydroxylation. Copyright © 2014 John Wiley & Sons, Ltd.

Thermogravimetric study of the surfactant–diethanolamine–titanium isopropoxide system behavior

Mesoporous anatase TiO2 materials with specific surface areas between 70 and 110 m2 g−1 were prepared via sol–gel technique using surfactants oleic acid and Triton-X (TX), in the presence or absence of diethanolamine, in methanol. Surfactants like TX or oleic acid (OA), as well as a gelating and chelate agent like diethanolamine (DEA) are commonly used in TiO2 formation from a titanium isopropoxide solution. Thermogravimetric methods were applied in order to evaluate the effect of the addition of such molecules in a precursor suspension before TiO2 materials preparation. The in situ investigation of such systems showed that numerous interactions occur between large molecules such as TX and OA that attributed on both steric effects and hydrogen bond formation. Materials prepared through modified sol–gel technique seem to be stabilized through DEA addition in the precursor suspension.

A simple route for decorating TiO2 nanoparticle over ZnO aggregates dye-sensitized solar cell

The development of a simple and reproducible route to modify ZnO surface with TiO2 is urgent for harnessing multiple interfaces and enhancing performance of ZnO dye-sensitized solar cell (DSSC). Here, we reported a simple method to decorate TiO2 nanoparticles for ZnO DSSC. By simple immersing ZnO film into butyl alcohol solution of tetrabutyl titanate (TBOT), TiO2 nanoparticles were well decorated onto ZnO nanocrystal surface. By taking the advantage of the hydrolysis and condensation differential of different TiO2 precursors, the simple method allows an easy tune over the TiO2 modification structure on ZnO surface for DSSC application. The influence of ZnO/TiO2 modification structure on the photoelectron collection mechanism of DSSC was discussed. The DSSC with ZnO/TiO2 nanoparticle has better photoelectron collection mechanism comparing with that of ZnO/TiO2 layer modified by titanium isopropoxide (TTIP) solution, leading to larger photocurrent and better DSSC performance. The DSSC performance of ZnO/TiO2 nanoparticle declines as the concentration of TBOT greater than 0.50M, which is mainly caused by the electron collection mechanism change originating from ZnO/TiO2 modification structure.

Thorn-ball shaped TiO2 nanostructures: Influence of Sn2+ doping on the morphology and enhanced visible light photocatalytic activity

A novel solution based route to synthesize thorn-ball shaped Sn2+ doped TiO2 nanostructures in a large scale without the use of any reducing agents is demonstrated. White precipitates are formed instantaneously when a solution of cetyltrimethylammonium bromide with milli-molar quantities of stannous chloride dihydrate (SnCl2·2H2O) is mixed to a solution of titanium isopropoxide in hydrochloric acid. The morphology of the precipitates analyzed using scanning electron microscope and transmission electron microscope reveal a complex morphology with crystalline nanorods grown uniformly over the balls. When the precipitates were treated hydrothermally by suspending in ethylene glycol (EG), further reduction takes place and “Thorn-ball shaped nanostructures” with very thin and long nanorods are formed. The thorn-ball samples (ST2-HTB) showed a large surface area of ∼244m2g−1 and the band-gap was ∼0.3eV narrower than that of pure TiO2, P25 (∼3.2eV), enhancing its visible light absorption. The samples exhibited a superior efficiency in the photocatalytic degradation of Rhodamine B (RhB) under visible light irradiation to P25, and the efficiency was comparable to P25 under UV irradiation despite of their polycrystalline nature. Under visible light irradiation the degradation of RhB using thorn-ball nanostructure photocatalysts was accompanied by a gradual shift in the absorption peak owing to formation of several N-de-ethylated intermediates of RhB. Photodegradation reaction mechanism of RhB under visible light irradiation, was proposed to be initiated by the valence band holes or through the conduction band electrons. The novel strategy demonstrated here for preparing thorn-ball nanostructures opens a new horizon to design complex structures of TiO2 for various applications.

CaCu3Ti4O12 Ceramic Synthesized by Sonochemical-Assisted Process

CaCu3Ti4O12 powders were synthesized by sonochemical-assisted process via a precursor solution of calcium nitrate trihydrate, titanium isopropoxide and copper nitrate trihydrate. The reaction process was conducted with the assistance of intense sonication using Sonics Model VCX 750 until the completely precipitated product was reached, followed by calcinations process. The physical microstructures, morphologies of as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. From XRD observation, it is evident that CaCu3Ti4O12 ceramic could be obtained by this synthesis process. It was additionally revealed that its crystallization and particle size was strongly dependent on the reaction time and calcinations temperature.

Synthesis and Characterization of SiO2/TiO2 Pillared Layered Manganese Oxide

Abstract A novel pillaring procedure without alkylamine or tetraalkylammonium pretreatment has been developed to prepare SiO2/TiO2 pillared layered manganese oxide with large surface area. SiO2/TiO2 pillared layered manganese oxide is prepared by solvothermal treating H-type layered manganese oxide at 220 °C for 12 h in a mixed solution of absolute ethanol, tetraethylorthosilicate, and titanium isopropoxide. The obtained SiO2/TiO2 pillared layered manganese oxide is expected to be a selective catalyst or an improved battery material.

The Preparation of Titanium Dioxide Gas Sensors by the Electric Field Assisted Aerosol CVD Reaction of Titanium Isopropoxide in Toluene

AbstractThin films of titanium dioxide are deposited on gas‐sensor substrates at 450 °C from the aerosol‐assisted (AA)CVD of titanium isopropoxide solutions in toluene under the influence of electric fields. Electric fields are generated by applying a potential difference between the inter‐digitated electrodes of the gas‐sensor substrate during the deposition. The deposited films are analyzed and characterized using scanning electron microscopy (SEM), X‐ray diffraction (XRD), and Raman spectroscopy (RS). It is found that an increase in electric field strength during deposition causes changes in the film microstructure, preferential orientation, and growth rate. The gas‐sensor properties of the films are also examined. It is found that applying an electric field during the deposition improves the film microstructure and leads to a two‐fold enhancement in the sensing properties of the film.

Airbrush Spray Coating of Amorphous Titanium Dioxide for Inverted Polymer Solar Cells

One of the main topics of organic photovoltaics manufacturing is the need for simple, low cost, and large area compatible techniques. Solution-based processes are the best candidates to achieve this aim. Among these, airbrush spray coating has successfully applied to deposit both active and PEDOT layers of bulk-heterojunction solar cells. However, this technique is not yet sufficiently studied for interfacial layers (electron and hole transporting layers or optical spacers). 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Good surface covering results from the coalescence of droplets after optimizing the spray coating system. 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Facile synthesis of mesoporous lithium titanate spheres for high rate lithium-ion batteries

Lithium titanate is synthesized from titanium isopropoxide and lithium acetate solution under hydrothermal environment and calcinations. Introducing acidized carbon black during synthesis can produce mesoporous Li 4Ti 5O 12. The crystalline structure and morphological observation of the as-synthesized mesoporous Li 4Ti 5O 12 are characterized by X-ray diffraction (XRD) and scanning electron microscopy, respectively. The mesoporous structure can be directly observed through BEI images of the cross-section sample. Besides, N 2 adsorption/desorption isotherm also displays a hysteresis loop, implying the beneficial evidence of mesoporous structure. The pore size distribution of mesoporous lithium titanate evaluated by BJH model is narrow, and the average size of voids is around 4 nm. It is demonstrated that the electrochemical performance is significantly improved by the mesoporous structure. The mesoporous lithium titanate exhibits a stable capacity of 140 mAhg −1 at 0.5 C. Besides, the reversible capacity at 30 C remains over half of that at 0.5 C. The superior C-rate performance is associated with the mesoporous structure, facilitating lithium transportation ability during cycling.

Polyol-Mediated Synthesis of TiO&lt;sub&gt;2&lt;/sub&gt; Nanoparticles

TiO2 nanoparticles were synthesized from a triethylene glycol solution of titanium isopropoxide (Ti(O-iPr)4) by refluxing at 270°C for 12 hrs. The as-prepared sample was heated at 600 °C for 3 hrs in order to study the thermal stability of the sample. The X-ray diffraction patterns of the samples were well indexed to the anatase phase. The field emission TEM images show uniform spherical morphologies with average sizes of 25 nm. The electrochemical measurements revealed that the discharge capacities of the heated sample exhibited high capacities and good rate performances without capacity fading during extended cycles, due to their electrochemically beneficial highly crystalline structures, nano-sized particles, and uniform distribution.

TiO&lt;sub&gt;2&lt;/sub&gt; Nanomaterials Studied by &lt;sup&gt;44&lt;/sup&gt;Ti(EC)&lt;sup&gt;44&lt;/sup&gt;Sc Time Differential Perturbed Angular Correlations: Volume and Surface Properties

TiO2 nanoparticles (anatase) with diameters between 2 and 4 nm were synthesized by controlled hydrolysis of a solution of titanium(IV)isopropoxide to which 44Ti in 4M HCl was added. Inactive nanoparticles were analyzed by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM), the active ones were analyzed by measuring the nuclear quadrupole interaction (NQI) of the I = 1 state in 44Sc using time differential perturbed angular correlation (TDPAC). Rather broad distributions were obtained. We also synthesized nanowires with typical diameters of 2 nm and 100 nm length using shape controllers. They were analyzed by HRTEM and XRD. The material turned out to be TiO2(B). The 44Ti was added by impregnation and diffusion at 180°C for two hours. Two well-defined NQI signals were observed which we tentatively assigned to the volume fraction and the “surface” fraction, i.e. Ti probes with OH-termination. In addition, we studied AMT-100 (anatase, uncoated, 6 nm) from Tayca, Eusolex T-2000 (rutile, Al2O3-coated, 20×20×100 nm3, simethicone additive) and P25 (mainly anatase, uncoated, 20 nm diameter) using the impregnation and diffusion method. P25 and the isolated rutile fraction from P25 yield spectra which correspond to anatase and rutile volume signals plus their surface signals, respectively. TDPAC thus proved very useful in characterizing the nanomaterials, especially their disorder, by measuring the NQI. In addition, information on surface properties is obtained. The relatively narrow surface signals indicate a lower degree of disorder and are possibly also a result of partial motional averaging of Ti-signals with OH-bonds due to mobile H-atoms.