Titanium Tetraisopropoxide Precursor Research Articles

Optical Study on Co-Sensitization of Betanin Dye with Cadmium Sulfide to Fabricate Dye Sensitized Solar Cell

Natural dyes are low-cost, eco-friendly, readily available and have optical characteristics which render them useful in energy research. The titanium tetra isopropoxide precursor can be employed using sol-gel synthesis to get titanium dioxide nanoparticles (TiO2 NPs). The FESEM analysis confirmed the deposition of TiO2 NPs on Indium Tin Oxide (ITO) substrate, which is necessary for the photo-conversion mechanism to produce electricity. One of the natural dyes that is extracted from red beets is known as betanin dye (Bd). Due to their aligned energy levels, Bd and cadmium sulfide (CdS) are used together to provide effective optical characteristics, making them suitable as dye sensitizers. The presence of Cd-S, C-N and hydroxyl groups assigned to 500, 1633, and 3300 cm-1 respectively, was demonstrated by the FTIR analysis. The energy gap of 2.16, 2.13 and 2.2 eV for Bd, CdS and Bd-CdS composite was estimated using Tauc's plot and UV-visible spectra demonstrated maximum absorbance at 485, 510 and 528 nm, respectively. The Bd absorbs broad light in visible region due to the addition of CdS. The major charge-transport phenomenon in dye-sensitized solar cells (DSSC) involves an increase in photo-current density, due to its luminous nature. However, the recombination of charge carriers prevents the overall performance of the DSSCs. The power conversion efficiency of the DSSC constructed from Bd dye and Bd-CdS composite was 0.234% and 0.367%, respectively. This optical investigation suggests co-sensitization as a sure-fire method to improve the efficiency of DSSCs extracted from natural dyes, making them reliable for future indoor applications.

Electrospun composite nanofibre adsorbents for effective removal of Cd2+ from polluted water

In this research, a novel three-dimensional material was produced through the combination of CNT, graphene and PAN/TTIP and the effect of MWCNT and graphene hybridization on TiO2 Nanofibers was studied. TiO2/PAN-(MWCNT/GO)-g-PCA Nanofibers were synthesized using multi-wall carbon Nanotubes-graft-poly citric acid (MWCNT-g-PCA), Graphene oxide-graft-poly citric acid (GO-g-PCA) and Polyacrylonitrile (PAN)/Titanium tetra isopropoxide precursors (TTIP) by electrospinning technique. The effective parameters such as the (MWCNT/GO)-g-PCA content, applied voltage, distance between needle and collector, (TTIP/PAN) precursors contents and feed rate were optimized. The Nanofibers were produced with the best morphology and characterized by FTIR, TG-DTA, SEM and XRD analysis. Prepared Nanofibers after calcination process used as Nano filter and Nanoadsorbent for complete removal of Cadmium ions from polluted water successfully.

Precursor nature and molarities effect on the optical, structural, morphological, and electrical properties of TiO2 thin films deposited by spray pyrolysis

Titanium oxide thin films were deposited by a simple and low-cost spray pyrolysis technique using two different precursors: Titanium chloride (TiCl3) and Titanium Tetra-isopropoxide (TTIP) on glass substrates. X-ray diffraction shows that most of the TiO2 thin films are amorphous in structure. The optical transmittance of the sprayed TiO2 films deposited from Titanium chloride is in the range of 80 % and for the films deposited from TTIP, it attains 90 % in the visible region. The optical band gap energies of the films deposited from TiCl3 and TTIP are about 3.5 and 3.7 eV respectively. The electrical resistivity of the films varies from 3.2*103 to 4.6*104 (Ω.cm) for the films prepared from TiCl3 precursor and 9.4*102 to 6.5*103(Ω.cm) for the films prepared from TTIP precursor.

Growth stages of nano-structured mixed-phase titania thin films and effect on photocatalytic activity

The development of nano-structured mixed-phase titania thin films and the relationship to photocatalytic activity (PCA) is of interest for pollution reduction and antimicrobial applications. A set of films grown by pulsed pressure metallorganic chemical vapour deposition using titanium tetraisopropoxide precursor was studied. The growth method is single-stage, scalable and produces high-quality, adherent films. Film thicknesses were 101 nm to 4.0 μm. Three growth stages were identified. All films were a mixture of anatase and rutile. Early stage films had rounded morphologies, low surface roughness and low PCA. Transition stage films developed columnar [110] orientated anatase dendrites, contained amorphous carbon and had reduced UV transmittance. Late stage films had strong anatase (220) and rutile (200) textures, contained amorphous carbon and exhibited highly branched anatase dendrites with nanoscale secondary plates. PCA was determined from degradation of stearic acid and correlated with increasing surface roughness. The most active film had formal quantum efficiency of (6.62 ± 0.64) × 10−4 molecules/photon, 59 times higher than a commercially available control. The performance is attributed to the combination of phases yielding polymorphic phase boundaries and amorphous carbon enhancing the adsorption of organic molecules, the unusual (220) anatase texture yielding nanostructured anatase dendrites in combination with nanocrystalline rutile and hierarchical porosity.

Optimization of Rhodamine B Decolorization by Adsorption and Photoelectrodegradation Combination System

<p>A combination of adsorption and photoelectrodegradation system was performed to reduce the concentration of Rhodamine B dye in water.<strong> </strong>The adsorption was conducted using silica and alumina activated by acid and base under various predetermined pH of Rhodamine B. The photoelectrodegradation process was performed using Ti/TiO<sub>2</sub> electrode as a cathode and Ti/TiO<sub>2</sub>-NiO as an anode. TiO<sub>2</sub> was synthesized from titanium tetra-isopropoxide precursor (TTiP) by sol-gel method. TiO<sub>2</sub>-NiO composite was synthesized with the same precursor with the addition of Ni(NO<sub>3</sub>)<sub>2</sub>.6H<sub>2</sub>O. The result shows that the activation changes the amount of OH total in the adsorbent. The acid-activated adsorbent showed an optimum adsorption activity when Rhodamine B was in base condition caused by zwitter ionic structure. It reversely occured to base-activated adsorbent where an optimum absorption activity reached at acid condition. The application of base-activated silica in adsorption and photoelectrodegradation combination system decreased the concentration of Rhodamine B dye up to 98.79% using photoanode Ti/TiO<sub>2</sub>-NiO under pH 2 at bias potential 6 V.</p>

Methyl Violet Degradation Using Photocatalytic and Photoelectrocatalytic Processes Over Graphite/PbTiO3 Composite

Photocatalytic and photoelectrocatalytic degradation of methyl violet dye using Graphite/PbTiO3 composites has been conducted. The purposes of this research were to examine photocatalytic and photoelectrocatalytic degradation of methyl violet using Graphite/PbTiO3 composite. Synthesis of Graphite/PbTiO3 composite was successfully performed via sol-gel method by mixing graphite powder, titanium tetra isopropoxide precursor solution (TTIP) and Pb(NO3)2. The Graphite/PbTiO3 composites were characterized using X-Ray Diffraction (XRD), Fourier Transform-Infra Red (FT-IR), and Scanning Electron Microscopy (SEM). The XRD diffractogram and IR spectrum of Graphite/PbTiO3 composite revealed all characteristic peak of graphite and PbTiO3. Photocatalytic degradation process showed that Graphite/PbTiO3 composite with ratio 1/1 decreased concentrations of methyl violet up to 92.20 %. While photoelectrocatalytic degradation processed for 30 minutes at neutral pH and 10 V voltage degraded the methyl violet until 94 %. However, the photoelectrocatalysis is still not significance to improve methyl violet degradation compared with photocatalysis.

Photocatalytic and Photoelectrocatalytic Degradation of Methyl Violet Using Graphite/PbTiO3 Composite

Photocatalytic and photoelectrocatalytic degradation of Methyl Violet dye using Graphite/PbTiO 3 composites has been conducted. The purposes of this research were to synthesis the Graphite/PbTiO 3 composite electrode and determine its effectiveness on Methyl Violet degradation. Synthesis of Graphite/PbTiO 3 composite was successfully performed via sol-gel method by mixing graphite powder, titanium tetra isopropoxide precursor solution (TTIP) and Pb(NO 3 ) 2 . The Graphite/PbTiO 3 composites were characterized using X-Ray Diffraction (XRD), Fourier Transform-Infra Red (FT-IR) and Scanning Electron Microscopy (SEM). The XRD diffractogram and IR spectrum of Graphite/PbTiO 3 composite revealed all characteristic peak of graphite and PbTiO 3 . Photocatalytic degradation process showed that Graphite/PbTiO 3 composite decreased concentrations of Methyl Violet up to 92.20%. While photoelectrocatalytic degradation processed for 30 minutes at neutral pH and 10 V voltage degraded the Methyl Violet until 94%.

Relationships among growth mechanism, structure and morphology of PEALD TiO2 films: the influence of O2 plasma power, precursor chemistry and plasma exposure mode

Titanium dioxide (TiO2) thin films have generated considerable interest over recent years, because they are functional materials suitable for a wide range of applications. The efficient use of the outstanding functional properties of these films relies strongly on their basic characteristics, such as structure and morphology, which are affected by deposition parameters. Here, we report on the influence of plasma power and precursor chemistry on the growth kinetics, structure and morphology of TiO2 thin films grown on Si(100) by plasma-enhanced atomic layer deposition (PEALD). For this, remote capacitively coupled 13.56 MHz oxygen plasma was used to act as a co-reactant during the ALD process using two different metal precursors: titanium tetrachloride (TiCl4) and titanium tetraisopropoxide (TTIP). Furthermore, we investigate the effect of direct plasma exposure during the co-reactant pulse on the aforementioned material properties. The extensive characterization of TiO2 films using Rutherford backscattering spectroscopy, ellipsometry, x-ray diffraction (XRD), field-emission scanning electron microscopy, and atomic force microscopy (AFM) have revealed how the investigated process parameters affect their growth per cycle (GPC), crystallization and morphology. The GPC tends to increase with plasma power for both precursors, however, for the TTIP precursor, it starts decreasing when the plasma power is greater than 100 W. From XRD analysis, we found a good correlation between film crystallinity and GPC behavior, mainly for the TTIP process. The AFM images indicated the formation of films with grain size higher than film thickness (grain size/film thickness ratio ≈20) for both precursors, and plasma power analysis allows us to infer that this phenomenon can be directly related to the increase of the flux of energetic oxygen species on the substrate/growing film surface. Finally, the effect of direct plasma exposure on film structure and morphology was evidenced showing that the grid removal causes a drastic reduction in the grain size, particularly for TiO2 synthesized using TiCl4.

One-pot synthesis of high aspect ratio titanium dioxide nanorods using oxalic acid as a complexing agent

We report the novel one-pot synthesis of high aspect ratio titanium dioxide (TiO2) nanorods using a simple hydrothermal technique. Specifically, oxalic acid and sodium hydroxide (NaOH) were used as additives to promote the conversion of titanium tetraisopropoxide (TTIP) into a one-dimensional TiO2 morphology. All resultant products were characterized by X-ray powder diffraction and scanning electron microscopy. Influential factors on the growth mechanisms of TiO2 nanorods are discussed. This approach contrasts the typical approach of using spherical TiO2 as a starting material in the fabrication of one-dimensional TiO2 structures, and instead allows for the direct synthesis of TiO2 nanorods from TTIP precursors.

(Invited) Vacuum Ultraviolet Photochemical Atomic Layer Deposition of Alumina and Titania Films

Conventional atomic layer deposition (ALD) is a thermo-chemical process where co-reagents are sequentially pulsed in cycles onto a heated substrate. As an alternative to substrate heating, various forms of other “non-thermal” ALD processes are being investigated. Herein, the photochemical atomic layer deposition of Al2O3 and TiO2 thin films at 60°C is reported using a shuttered vacuum ultraviolet light source to excite molecular oxygen as a co-reagent with the metal precursors. The growth mechanisms using trimethyl aluminium and titanium tetraisopropoxide precursors, are investigated using in-situ quartz crystal microbalance and post-deposition ellipsometric measurements. The photochemical ALD Al2O3 films exhibit different capacitance equivalent thicknesses for irradiated and masked regions respectively, even after post-deposition annealing. The photochemical ALD titania films are amorphous and when incorporated into Pt / TiO2 / Pt metal - insulator - metal structures, the titania exhibits a resistive switching behavior.

First-Principles Thermochemistry for the Thermal Decomposition of Titanium Tetraisopropoxide.

The thermal decomposition of titanium tetraisopropoxide (TTIP) is investigated using quantum chemistry, statistical thermodynamics, and equilibrium composition analysis. A set of 981 Ti-containing candidate species are proposed systematically on the basis of the thermal breakage of bonds within a TTIP molecule. The ground state geometry, vibrational frequencies and hindrance potentials are calculated for each species at the B97-1/6-311+G(d,p) level of theory. Thermochemical data are computed by applying statistical thermodynamics and, if unknown, the standard enthalpy of formation is estimated using balanced reactions. Equilibrium composition calculations are performed under typical combustion conditions for premixed flames. The thermodynamically stable decomposition products for different fuel mixtures are identified. A strong positive correlation is found between the mole fractions of Ti species containing carbon and the TTIP precursor concentration.

Combinatorial HV-CVD survey of barium triisopropyl cyclopentadienyl and titanium tetraisopropoxide for the deposition of BaTiO3

Barium titanate is a very promising material for the integration of optical communication into electronic integrated circuits. For a successful integration into CMOS compatible technology, a growth process has to be found which allows forming crystalline BaTiO3 at sufficiently low temperatures. We describe the combinatorial analysis of BaTiO3 formation by high vacuum chemical vapor deposition using barium triisopropyl cyclopentadienyl and titanium tetraisopropoxide as metal sources; water, oxygen, or ozone are used as oxidizing agents. We analyzed the impact of these oxidizing agents on the interaction of the precursor molecules on the substrate surface. Furthermore, we characterized the films concerning chemical composition and identified growth conditions leading to deposit composition corresponding to the stoichiometric BaTiO3 formation. XRD analysis confirms the formation of crystalline BaTiO3 phases for deposition temperatures as low as 370 °C. We report about the combinatorial characterization of barium cyclopentadienyl and titanium tetraisopropoxide precursor interaction and fast determination of parameters for the formation of crystalline barium titanate using high vacuum chemical vapor deposition.

One-step synthesis and properties of MnOx/TiO2 nanocomposites prepared by chemical vapor condensation process

MnOx/TiO2 nanocomposites were synthesized using metal-organic precursors in one-step by modified chemical vapor condensation. The flow rate of manganese precursor was supplied from 0.1 to 0.6 L min− 1. The titanium tetraisopropoxide precursor was supplied at a constant flow rate. The synthesized materials were characterized by TGA-DTG, BET, TEM, XRD, and XPS. The result of TGA showed the Mn precursor's main degradation to be above 100 °C. Characterization of the Mn/TiO2 samples by BET and TEM showed that the flow rate of Mn precursor had little effect on surface area, pore volume, or particle size. XRD showed that amorphous Mn became crystalline with increasing Mn precursor vapor concentration.

TiO2 Nanoparticles prepared by MOCVD: effect of temperature, flowrate, and precursor

ABSTRACTTitanium dioxide nanoparticles were produced by metal organic chemical vapour deposition method. The effect of deposition temperatures (400–900 °C), flowrates of the carrier gas (200–600 mL/min), and the precursors [titanium (IV) butoxide (TBOT) and titanium tetraisopropoxide (TTIP)] on the particle size, surface area, crystallinity, and photocatalytic activity of the samples were investigated. The results showed that the particle size decreased and the surface area increased with increasing deposition temperature from 400 to 700 °C. However, particle size increased and surface area decreased with increasing temperature from 700 to 900 °C because of sintering effects. The phase transition from anatase to rutile occurred at temperatures above 700 °C. Increasing flowrate of carrier gas reduced particle size, increased surface area, and enhanced crystallinity of the titanium dioxide nanoparticles. Sample produced at 900 °C has the best photocatalytic activity compared with other samples including the commercial Degussa P25. Crystallinity was found to have a more significant role on photocatalytic activity in contrast to particle size. It is noteworthy that for samples deposited at 700 °C, the TBOT precursor was found to produce smaller and more uniform particle size compared with the TTIP precursor. However, it is easier to form crystalline phase using TTIP than TBOT. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.

Role of surface intermediates in enhanced, uniform growth rates of TiO2 atomic layer deposition thin films using titanium tetraisopropoxide and ozone

Atomic layer deposition (ALD) growth of TiO2 thin films from titanium tetraisopropoxide (TTIP) and ozone has been studied as a function of dose and purge recipes. A novel dosing scheme was designed to introduce the TTIP precursor into the reaction chamber in multiple “μpulses” with orwithout delay times for desorption of surface product species, analogous to conventional ALDpurge cycles. Larger doses led to significantly higher growth rates while maintaining excellent uniformity across 100 mm wafers, effects which underscore the importance of surface residence times in rather complex surface reaction pathways. The production of H2O/OH surface species during the TTIP half-cycle is intrinsic to the reaction, leading to secondary reaction mechanisms and believed responsible for the enhanced growth rates and accompanying high uniformity.

Nucleation−Growth of TiO2 Nanoparticles Doped with Iron Acetylacetonate

We report on the preparation of Fe-doped TiO2 nanoparticles by a sol−gel route using a titanium tetraisopropoxide precursor. A turbulent micromixing of the injected fluids enables homogeneous reaction conditions in the reactor bulk and monodispersity of the produced nanoparticles. The dopant iron acetylacetonate Fe(acac)3 is injected into the solution at the nucleation stage. The doping agent takes surface sites of TiO2 nanoparticles resulting in the Fe(acac)2−TiO2 complex. The reaction progresses by elimination of the residual acetylacetate until the formation of the Fe−TiO2 complex, in which Fe can coordinate three TiO2 nanoparticles. The released acac groups take surface sites of the composite nanoparticles and slow down the induction kinetics. We show that the micromixing quality is critical even in the case of the apparently slow sol−gel induction kinetics.

Properties of composite films of titania nanofibers and Safranin O dye

Titania (TiO 2) nanofibers and composite thin films of titania nanofibers and Safranin O dye (SAF) were studied. TiO 2 nanofibers were prepared by electrospinning technique from titanium tetra-isopropoxide precursor solution in ethanol. Surface topology of the nanofibers was observed using scanning electron microscopy (SEM), their crystal structure was studied by X-ray diffraction (XRD) and the chemical composition by X-ray photoelectron spectroscopy (XPS). Properties of the TiO 2 nanofibers were studied in dependence on the values of relative air humidity in the range from 15% to 55%. It was necessary to maintain the relative humidity lower than 30% during electrospinning in order to obtain high quality nanofiber films. The average minimum diameter of the as-prepared TiO 2 nanofibers was found to be around 100 nm. Nanofiber diameter diminishes to about 50 nm after annealing at 420 °C for 1 h. The as-prepared titania nanofiber films were completely amorphous while anatase crystal phase was detected in the films after annealing. In order to prepare the composite films, solution of SAF dye with poly(vinylpyrrolidone) in ethanol/water was dropped off on the prepared titania nanofibers surface. Opto-electrical properties of SAF dye and the resulting nanocomposite films were studied by UV–Vis spectroscopy and current–voltage characteristics. Safranin O is characterized by two strong absorption peaks; one at 274 nm and a wide band with splitting between 420 nm and 600 nm. The optical energy band gap of titania nanofibers was estimated from the UV–Vis measurements to be 3.4 eV. The charge transport in the composite films is influenced by the space charge limited currents due to the very high resistance of the materials.

TiO2 doping by hydroxyurea at the nucleation stage: towards a new photocatalyst in the visible spectral range

We report an original method of preparation of OCN-doped TiO(2) for photocatalysis in the visible spectral range. The preparation is achieved by a sol-gel route using titanium tetraisopropoxide precursor. Special attention was paid to fluid micromixing, which enables homogeneous reaction conditions in the reactor bulk and monodispersity of the produced clusters/nanoparticles. The dopant hydroxyurea (HyU, CH(4)N(2)O(2)) is injected into the reactive fluid at the nucleation stage, which lasts tens of milliseconds. The doping results in a strong yellow coloration of the nanocolloids due to the absorption band in the spectral range 380-550 nm and accelerates the aggregation kinetics of both nuclei at the induction stage and sub-nuclei units (clusters) at the nucleation stage. FTIR, Raman and UV-visible absorption analyses show the formation of a stable HyU-TiO(2) complex. EXAFS spectra indicate no appreciable changes of the first-shell Ti atom environment. The doping agent takes available surface sites of TiO(2) clusters/nanoparticles attaining ∼10% molar loading. The reaction kinetics then accelerates due to a longer collisional lifetime between nanoparticles induced by the formation of a weak [double bond, length as m-dash]OTi bond. The OCN-group bonding to titanium atoms produces a weakening of the C[double bond, length as m-dash]O double bond and a strengthening of the C-N and N-O bonds.

Preparation of nanostructured Al 2O 3–TiO 2 composite films by MOCVD

Nanostructured Al 2O 3–TiO 2 composite films were prepared on glass substrates by metalorganic chemical vapor deposition (MOCVD) using aluminum acetylacetonate and titanium tetraisopropoxide precursors. Oxygen and argon were used as the reactive and carrier gases, respectively. Deposition temperature ( T dep) was varied from 723 to 873 K and total pressure was kept constant at 133–266 Pa. The formation of composite films was achieved by mixing the precursor vapors, which were obtained by heating the aluminum and titanium precursors at 403 and 323–353 K, respectively. The films were characterized by XRD, SEM, EPMA and TEM. The crystalline structure and the surface morphology of the nanostructured Al 2O 3–TiO 2 composite films were strongly dependent on the precursor and deposition temperatures.

Nanoparticle Microreactor: Application to Synthesis Of Titania by Thermal Decomposition of Titanium Tetraisopropoxide

The nanoparticle microreactor (NPMR) is a new concept that we have introduced to describe a very small-scale system capable of converting an aerosol precursor to solid particles. The liquid precursor of about 1 µl is injected by a syringe through a septum into a tubular evaporator of 1.0 cm3 in volume with stopcocks at both ends. The evaporator has been preheated by a heating tape to a temperature sufficiently high for vaporization to occur in half a minute. By opening the stopcocks, the vaporized precursor is transported by a carrier gas stream into a quartz tube which is mounted along the axis of a tubular furnace. The nanoparticle aggregates produced in the reactor are sampled by deposition on an electron micrograph grid at the reactor exit. The NPMR was applied first to the synthesis of TiO2 particles by thermal decomposition of titanium tetraisopropoxide (TTIP) in a nitrogen carrier gas, with TTIP concentrations varying from 1.0 to 7.0 mol% or 2.35×10−6 to 1.65×10−5 in TiO2 volume loading, and decomposition temperatures from 300°C to 1000°C. Studies were made with a 2 mm reaction tube and a 4 mm tube with sheath gas. With the 2 mm tube, a considerable fraction of the TTIP precursor was consumed at the wall by surface reaction, resulting in very small particles. With the 4 mm tube, the primary particle size was comparable to that reported in the literature for steady flow experiments using a 22.2 mm tube. Primary particle sizes ranged from 200 to 400 nm. Depending on TTIP concentration and reactor temperature, the particles exhibited a bimodal size distribution, probably due to a two-stage nucleation. A fourfold increase in the gas flow rate had little effect on particle size, indicating that particle growth ended early, within one-fourth the tube length. Residence time in the reactor was between 0.35 and 1.4 s, and total run time about 1 min. The NPMR has potential for rapid assembly of large databases and is adaptable to combinatorial discovery of nanoparticles with novel properties. Design requirements for an ‘ideal’ aerosol microreactor are discussed briefly.