Titanium ( IV ) Isopropoxide Research Articles

Preparation of TiO2Nanowires/Nanoparticles Composite Photoanodes for Dye-sensitized Solar Cells

We fabricated dye-sensitized solar cells (DSSCs) with nanowire (NW)/nanoparticle (NP) composite and solidified nanogel as the photoelectrode and electrolyte, respectively. NWs were generated via pore-infiltration of titanium (IV) isopropoxide (TTIP) into a track-etched polycarbonate membrane with a pore diameter of 100 nm, followed by calcination at . Energy conversion efficiency of NW/NP-based DSSCs was always higher than that of NP-based cells. We attributed this to improved light scattering and electron transport by NWs, as verified by intensity modulation photocurrent spectroscopy (IMPS) and intensity modulation photovoltage spectroscopy (IMVS) analyses. Quasi-solid-state DSSCs with NW/NP composites exhibited 5.0% efficiency at 100 , which was much greater than that of NP-based cells (3.2%).

Effect of different conditions on the size and quality of titanium dioxide nanoparticles synthesized by a reflux process

In the work discussed in this paper, titanium dioxide (TiO2) nanoparticles with the anatase structure were synthesized by use of a reflux technique under different conditions. Titanium(IV) isopropoxide (TTIP), in ethanol–methanol solutions, was used as precursor. Prepared TiO2 powders were characterized by XRD, SEM, and TEM analysis. Different conditions, for example reactant concentration (TTIP:MeOH:EtOH:H2O), reflux time and temperature, and calcination temperature, were changed to achieve to best nanocrystallite material. It was found that variation of all these conditions could strongly affect crystallinity, morphology, and crystallite size. The size and crystallization of nanocrystallites, and their uniformity, were controlled by changing these conditions. The crystallite sizes of nanoparticles, estimated by use of the Scherrer formula, were from 9 to 27 nm. TiO2 nanoparticles of minimum size were obtained by use of minimum reflux and calcination temperatures.

Gas phase synthesis of encapsulated iron oxide–titanium dioxide composite nanoparticles by spray pyrolysis

Composite nanoparticles are of a great interest due to the possibility of combining properties of several different materials. In this study, a spray pyrolysis process utilizing flame-synthesized nanopowder was used to generate iron oxide–titanium dioxide (γ-Fe2O3–TiO2) composite nanoparticles. Iron oxide and titanium dioxide were selected because they are known to have magnetic and photocatalytic properties, respectively. First, dry γ-Fe2O3 nanopowder was prepared with the liquid flame spray technique. After that, the flame-synthesized nanoparticles were mixed with liquid titanium(IV) isopropoxide (TTIP) and isopropyl alcohol. This mixed-phase precursor was sprayed into a tube furnace where TTIP thermally decomposed to form solid TiO2, encapsulating the γ-Fe2O3 powder particles. The synthesized nanoparticles were characterized with aerosol measurements, transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The size distributions of the composite nanoparticles were broad, and the mode diameters were 80–130 nm. The particles consisted of a γ-Fe2O3 agglomerate that was either partially or fully encapsulated by a spherical TiO2 particle, depending on the concentration of TTIP in the mixed-phase precursor. The flame-synthesized iron oxide powder was crystalline maghemite, whereas, spray pyrolyzed titanium dioxide had amorphous phase. The as-synthesized composite nanoparticles were calcinated to attain crystalline anatase TiO2. The crystal structures as well as demonstrated photoactivity and magnetic response suggest that the composite nanoparticles could find use as magnetically separable photocatalyst.

Preparation of TiO2Double-Layer Films with Echinoid-Like Particles on Nanorods Array for Dye Sensitized Solar Cells

In brief, 15 mL D. I. water, 15 mL HCl, and0.5 mL titanium(IV) isopropoxide (TTIP) were mixed andstirred. FTO glass was placed in the teflon-lined stainlesssteel autoclave and the prepared solution was added. Thehydrothermal synthesis was conducted at 150 °C for 10 h,and then, the sample was washed with D. I. water and driedat 70 °C.TiO

Organic–inorganic coatings based on epoxidized castor oil with APTES/TIP and TEOS/TIP

Two series of organic–inorganic hybrid films were prepared from epoxidized castor oil (ECO) and the inorganic precursor titanium(IV) isopropoxide (TIP), combined with silicon precursors, either 3-aminopropyltriethoxysilane (APTES) or tetraethoxysilane (TEOS) with different organic to inorganic proportions. Films were pre-cured at room temperature under an inert atmosphere and subsequently submitted to thermal curing. The macro- and microscopic properties of the films, including adhesion, hardness, microstructure (SEM) and thermal properties, were determined as a function of the proportion of ECO to inorganic precursors. Morphological studies showed that the hybrid films were microscopically homogeneous. The addition of TIP decreases substantially the curing time. The hardness and tensile strength of the films increased with increased concentration of inorganic precursor. The combination of the silicon-rich inorganic precursors with TIP improved substantially the mechanical strength of the films. All of the films exhibited good adhesion to the aluminum surface. Aluminum coated with the films and submitted to intensive corrosion test presented excellent protection.

Photocatalytic of N-doped TiO2 Nanofibers Prepared by Electrospinning

Nitrogen-doped TiO2 nanofibers were prepared by electrospinning process using ammonium acetate (CH3COONH4) as nitrogen sources and titanium (IV) isopropoxide (TiP) in 2-methoxyethanol as starting precursor. The different amount of nitrogen in TiO2 was introduced into the fibers. The structural properties of nitrogen-doped TiO2 nanofibers were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and X-ray photoelectron spectroscopy (XPS). XRD results indicated that the crystallinity of as-prepared fibers and after calcined corresponds to phase of TiO2 independent on nitrogen content. XPS indicates that nitrogen was doped effectively into the fibers. Nitrogen-doped TiO2 nanofiber materials were utilized as the photocatalyst in dye photodegradation under visible light. The significant absorption enhancement in visible region was obtained by nitrogen-doped TiO2 nanofibers relating to the improvement of photocatalytic efficiency comparing to undoped-TiO2.

Effects of controlled surface treatment on titanium dioxide electrode nanostructure for dye-sensitized solar cells

A stable surface treatment for the nanoporous TiO2 electrode of dye-sensitized solar cells (DSCs) has been developed via sol-gel processing of titanium(IV) isopropoxide (TiP), enabling controllable performance improvements, which has been hitherto unachievable. A systematic study of the electrode chemistry and morphology was performed to examine the mechanisms by which the treatment contributes to enhancement in DSC performance. The electrode exhibited a linear increase in mass with TiP concentration and a corresponding reduction in porosity. The increase in nanoparticle diameter resulted in the increase in surface area without altering the surface chemistry, leading to an increase in dye loading. Current–voltage characteristics and incident photon-to-electron conversion efficiencies (IPCE) were analyzed. A linear increase in the short-circuit photocurrent was measured with TiP concentration, increasing by 30 % for a 4 mM TiP treatment, which resulted in a corresponding efficiency gain of 23 %. This was found to primarily result from a controllable increase in the charge collection efficiency, via a 30 % faster electron transport time and a 19 % increase in the electron lifetime. The results elucidate the underlying physical mechanisms for improvement in DSC performance by surface treatment.

Hybrid Templated Synthesis of Crack‐Free, Organized Mesoporous TiO2 Electrodes for High Efficiency Solid‐State Dye‐Sensitized Solar Cells

AbstractOrganic/inorganic hybrid templates, i.e., aluminium oxide (Al2O3) nanoparticles grafted with poly(oxyethylene) methacrylate, Al2O3‐POEM, are synthesized via surface‐initiated atom transfer radical polymerization (ATRP), as confirmed by Fourier transform‐infrared spectroscopy (FT‐IR) and thermogravimetric analysis (TGA). Upon combining the Al2O3‐POEM with titanium(IV) isopropoxide (TTIP), hydrophilic TTIP is selectively confined in the hydrophilic POEM chains through hydrogen bonding interactions. Following the calcination at 450 °C and the selective etching of Al2O3 with NaOH, the OM‐TiO2 films with high surface areas, good interconnectivity, and anatase phase are obtained. The solid‐state dye‐sensitized solar cells (ssDSSCs) fabricated with OM‐TiO2 photoelectrodes and a polymerized ionic liquid (PIL) show a high energy conversion efficiency of 7.3% at 100 mW cm−2, which is one of the highest values for ssDSSCs. The high cell performance is due to the well‐organized structure, resulting in improved dye loading, excellent pore filling of electrolyte, enhanced light harvesting, and reduced charge recombination.

Flame aerosol deposition of TiO2 nanoparticle films on polymers and polymeric microfluidic devices for on-chip phosphopeptide enrichment

Direct and fast (10s of seconds) deposition of flame-made, high surface-area aerosol films on polymers and polymeric microfluidic devices is demonstrated. Uniform TiO2 nanoparticle films were deposited on cooled Poly(methyl methacrylate) (PMMA) substrates by combustion of titanium(IV) isopropoxide (TTIP) - xylene solution sprays. Films were mechanically stabilized by in-situ annealing with a xylene spray flame. Plasma-etched microfluidic chromatography columns, comprising parallel microchannels were also coated with such nanoparticle films without any microchannel deformation. These microcolumns were successfully used in metal-oxide affinity chromatography (MOAC) to selectively trap phosphopeptides on these high surface-area nanostructured films. The chips had a high capacity retaining 1.2 μg of standard phosphopeptide. A new extremely fast method is developed for MOAC microchip stationary phase fabrication with applications in proteomics.

초임계 증착법을 통한 실리카와 타이타니아 역 오팔의 제조

정보 전달의 수단으로의 빛을 제어하는 기술에 대한 연구가 활발한 가운데, 최근 가장 각광 받고 있는 것이 광결정(Photonic crystals)을 갖는 물질이다. 이를 합성하는 다양한 방법 중에서 초임계 증착법(Supercritical deposition)을 사용하면, 복잡한 내부 구조물까지의 반응물의 침투가 용이하여 신속하고 효율적인 공정이 가능하다. 본 논문에서는 비독성, 비인화성 등으로 친환경 초임계 용매인 초임계 이산화탄소(Supercritical carbon dioxide) 분위기 하에서 고분자 콜로이드 주형에 금속 알콕사이드를 코팅하는 방법으로 매크로 기공을 갖는 역 오팔(Inverse opals) 구조물을 합성하였다. 반응온도와 압력은 <TEX>$40^{\circ}C$</TEX>와 80 bar로 고정하였으며, 반응 시간과 반응물의 비율을 조절하여 역 오팔의 구조의 변화를 살펴보았다. 실험에는 금속 알콕사이드로써 Tetraethyl orthosilicate (TEOS)와 Titanium (IV) isopropoxide (TTIP)가 사용되었으며, 각각을 통하여 실리카와 타이타니아 역 오팔을 합성할 수 있었다. Photonic crystals (PCs) are highly ordered porous materials which have been much attention because of its potential for controlling the light sauces. There are many methods for synthesizing this kind of materials among them we chose the supercritical deposition. With this method the reactants can easily infiltrate into the complex structure. In this paper, supercritical carbon dioxide (<TEX>$scCO_2$</TEX>) was used as a reaction medium, which is known as a sustainable solvent due to its nontoxic and noninflammable characteristics. We coated the colloidal template with metal alkoxide by using <TEX>$scCO_2$</TEX> and then obtained macro-porous inverse opals. The reaction was carried out at <TEX>$40^{\circ}C$</TEX> and 80 bar. We synthesized two different inverse opals which called silica and titania inverse opals by use of tetraethyl orthosilicate (TEOS) and titanium isopropoxide (TTIP) as a precursor, respectively.

Controlling anatase coating of diatom frustules by varying the binding layer

Diatoms have ordered three dimensional porous exoskeletons (frustules) comprised primarily of amorphous silica which can be used as templates for materials applications. Hydrolysis of titanium(IV) isopropoxide (TIP) in the presence of surface bound poly(4-vinyl pyridine) or citric acid results in the formation of anatase on the surface after calcining at 450 °C, however as shown with atomic force microscopy (AFM), different morphologies are formed. Citric acid preferentially resulted in a thin film of anatase over the surface of the frustule whereas poly(4-vinyl pyridine) resulted in the formation of nano-particles of anatase (90–100 nm) on the surface.

Facile hydrothermal synthesis of single crystalline TiOF 2 nanocubes and their phase transitions to TiO 2 hollow nanocages as anode materials for lithium-ion battery

Single-crystalline TiOF 2 nanocubes with edge length of around 200–300 nm have been synthesized under hydrothermal conditions using titanium (IV) isopropoxide (TIP) as titanium source, HF as etchant. The corresponding hollow TiO 2 nanocages with dominantly exposed {0 0 1} crystal planes can be easily obtained by calcinating TiOF 2 nanocubes under air atmosphere. It is also found that the presence of acetic acid not only being chemical modifier of TIP to lower its reactivity at relatively acid environment, but also gives rise to a uniform hollow TiO 2 nanocages which play the crucial role in hollow formation. The TiOF 2 electrode presented here exhibits much excellent electrochemical performance. The initial high specific capacity of TiOF 2 can be up to 1045 mAh g −1 at a rate of 30 mA g −1. The specific discharge capacity is 510 mAh g −1 after 40 cycles.

Development of an amorphous mesoporous TiO2 nanosphere as a novel carrier for poorly water-soluble drugs: Effect of different crystal forms of TiO2 carriers on drug loading and release behaviors

Cotton-like amorphous mesoporous titania (APMT) nanoparticles with 3-D netlike pores were synthesized by a simple and reproducible method and the potential of APMT as a carrier for poorly water-soluble drugs was explored. In order to study the effect of different crystal forms of titania on drug loading and release behaviors, a novel anatase mesoporous titania (ATMT) was also prepared through a facile method using pluronic F127 as a template and titanium(IV) isopropoxide (TIP) as a titania source. The model drug carvedilol (CAR) was effectively loaded into the pores of APMT and ATMT through solvent deposition method, according to results of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In compared with ATMT, APMT showed a more rapid release profile, which may be attribute to the netlike pores, small pore size (2–3nm) as well as absorbed water and hydrate water on the surface, based on results of X-ray diffraction (XRD), N2 adsorption/desorption, SEM/TEM and in vitro dissolution test. Definitely, the results confirmed that the drug loading and release behaviors were heavily dependent on the crystal forms of the carriers, which will provide a new thread for formulation of poorly water-soluble drugs.

Fabrication and performances of MWCNT/TiO2 composites derived from MWCNTs and titanium (IV) alkoxide precursors

Multi-walled carbon nanotubes (MWCNTs)/TiO2 composites were synthesized by sol-gel technique using titanium (IV) n-butoxide (TNB), titanium (IV) isopropoxide (TIP) and titanium (IV) propoxide (TPP) as different titanium alkoxide precursors. The as-prepared composites were comprehensively characterized by BET surface area, SEM, XRD, EDX and UV-Vis absorption spectroscopy. The samples were evaluated for their photocatalytic activity towards the degradation of methylene blue (MB) under UV irradiation. The results indicated that the sample MPB had best excellent photocatalytic activity among the three kinds of samples. Furthermore, we also used piggery waste to determine the photocatalytic activity for the MWCNT/TiO2 composites by using a chemical oxygen demand (COD) method. It seemed all of the samples have an excellent removal effect of COD. From the results of the bactericidal test, MWCNT/TiO2 composites with sunlight had a greater effect on E. coli than any other experimental conditions.

TiO2 chemical vapor deposition on Si(111) in ultrahigh vacuum: Transition from interfacial phase to crystalline phase in the reaction limited regime

The interaction between the metal organic precursor molecule titanium(IV) isopropoxide (TTIP) and three different surfaces has been studied: Si(111)-(7×7), SiOx/Si(111) and TiO2. These surfaces represent the different surface compositions encountered during TTIP mediated TiO2 chemical vapor deposition on Si(111). The surface chemistry of the titanium(IV) isopropoxide precursor and the film growth have been explored by core level photoelectron spectroscopy and x-ray absorption spectroscopy using synchrotron radiation. The resulting film morphology has been imaged with scanning tunneling microscopy. The growth rate depends on both surface temperature and surface composition. The behavior can be rationalized in terms of the surface stability of isopropoxy and isopropyl groups, confirming that growth at 573K is a reaction limited process.

Aerosol‐Assisted CVD of Titanium Dioxide Thin Films from Methanolic Solutions of Titanium Tetraisopropoxide; Substrate and Aerosol‐Selective Deposition of Rutile or Anatase

AbstractTitanium dioxide (TiO2) thin films are synthesized using aerosol‐assisted (AA)CVD of titanium (IV) isopropoxide (TTIP) in methanol. Deposition is carried out on glass, steel, and titanium substrates at 400–550°C. The films produce morphologies that are radically different to those from typical aerosol‐assisted processes, and from the use of TTIP in low or atmospheric pressure (AP)CVD. The films show some substrate‐dependent morphology and properties. In particular at 550°C the films on steel show needle‐ and rod‐like particles. X‐ray diffraction (XRD) and Raman spectroscopy of the TiO2 films show that on steel or titanium substrates only the rutile form can be obtained, whereas on glass either anatase, anatase/rutile mixtures, or rutile can be obtained, depending on substrate temperature. The TiO2 films formed at 550°C on all substrates are hydrophobic to water droplets, with contact angles in the range 101–110°. These films become hydrophilic on heating to above 100°C in air, or superhydrophillic when irradiated under 254 nm radiation generating water‐contact angles less than 5°. Surprisingly, use of TTIP under APCVD on steel substrates without an aerosol form exclusively the anatase form of TiO2 at 400–550°C, whereas use of a methanolic aerosol delivery system for the TTIP forms rutile. Hence use of the methanol aerosol has a controlling influence on the deposition chemistry. The TiO2 thin films are shown to be active photocatalysts using a dye‐ink test, and are also shown to be able to photo‐split water in a sacrificial system to evolve oxygen.

Formation of mesoporous TiO2 with large surface areas, interconnectivity and hierarchical pores for dye-sensitized solar cells

TiO2 nanoparticles with anatase/rutile mixed phase and <100 nm in size were surface-modified using hydroxyethyl methacrylate (HEMA) and sulfosuccinic acid (SA), which can coordinate to the TiO2 precursor, titanium(IV) isopropoxide (TTIP). The HEMA in TiO2-HEMA nanoparticles underwent a graft/crosslink polymerization to poly(hydroxyethyl methacrylate) (PHEMA), i.e.TiO2-PHEMA. Following the application of a sol–gel process with TTIP, 3-dimensional (3D) nanostructured TiO2 photoelectrodes with interconnectivity, large surface area and bimodal pores were successfully obtained. The energy conversion efficiency of a polymer electrolyte dye-sensitized solar cell (DSSC) fabricated with TiO2-PHEMA/TTIP photoelectrode reached 3.5% at 100 mW cm−2, which was much higher than those of pristine TiO2 (1.4%), TiO2/TTIP (1.6%) and TiO2-HEMA/TTIP (2.0%) photoelectrodes. The higher cell performance of TiO2-PHEMA/TTIP is due to enhanced light harvesting, reduced charge recombination and excellent penetration of polymer electrolytes into the TiO2 pores.

Synthesis and characterization of TiO 2 nanowires with controlled porosity and microstructure using electrospinning method

We have fabricated dye-sensitized solar cells consisting of TiO 2 thin film as an electrode material. The porous anatase TiO 2 nanowires were fabricated by a simple electrospinning process using a solution of dissolved poly(vinyl pyrrolidone) (PVP) and titanium (IV) isopropoxide (TTIP) in ethanol. The relationship of solution viscosity, diameter and beads of the PVP/TiO 2 composite nanowires was confirmed by FE-SEM. The TiO 2 nanowires were obtained to removal PVP by calcination, and decided on calcination temperature by TG-DTA. The crystalline phases of calcined TiO 2 nanowires were characterized by XRD. The anatase to rutile transformation and grain growth occurred during calcination of TiO 2 nanowires confirmed by TEM. The surface area and porosity were calculated from isotherm data by the BET and BJH method. The TiO 2 nanowires had higher surface area than a commercial powder (P25).

Controlled growth of TiO2 nanorods capped with carboxylate groups by the solvothermal process

A solvothermal method is described for preparing nanomaterials of titanium dioxide (TiO2) while controlling the growth of rod-shaped nanomaterials. Titanium (IV) isopropoxide (TTIP) and butyl ether were chosen as the precursor and solvent, respectively. Oleic acid and decanoic acid were used as the surfactant. TiO2 nanospherical particles and nano-rods were synthesized in mass quantities by adjusting the kind of surfactant, the concentration of the precursor, and the solvothermal reaction temperature. The synthesized TiO2 nanospherical particles and nanorods were uniform and transparent in the toluene. The TiO2 nanospherical particles were about 3.5 nm in size. The TiO2 nanospherical particles and nanorods were of a highly crystalline anatase structure. The direction of growth of the TiO2 nanorods was [001] and the band gap energy of the TiO2 nanorods, evaluated by optical absorption, was 3.34 eV.

Characterization and photodegradation characteristics of organic dye for Pt–titania combined multi-walled carbon nanotube composite catalysts

Multi-walled carbon nanotubes (MWCNTs), titanium(IV) isopropoxide (TIP) and potassium hexachloroplatinate(IV) (K 2PtCl 6) were used for the preparation of Pt/MWCNT/TiO 2 composites. The composites were comprehensively characterized by Brauer–Emett–Teller surface area, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive X-ray and UV–vis absorption spectroscopy. The photoactivity of the prepared materials under UV irradiation was tested using the conversion of methylene blue (MB) in aqueous solution. According to the results of MB removal experiment, it can be considered that the MB removal effect of the Pt/MWCNT/TiO 2 composites is affected by two kinds of effects: adsorption effect by MWCNTs and photocatalytic effect by TiO 2. Finally, the photocatalytic effect increases due to photo-induced-electron absorption effect by MWCNTs and electron trap effect by Pt metal.