Isopropoxide Precursor Research Articles

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%.

Elaboration and Enhanced Activity of the Mixed Oxide Zr x Ti 1 - x O 2 Nano-photocatalyst

The photocatalysis activity of mixed nanocomposite ZrxTi1-xO2 catalyst was studied. The catalysts with x=0, 0.1 and 0.2 were prepared via sol-gel method in a reactor with rapid micromixing using titanium tetra- isopropoxide and zirconium tetra-propoxide precursors and n-propanol solvent. The colloids were coated on cleaned borosilicate beads and treated at temperatures in the range between 400 and 600 °C to achieve crystalline anatase phase. The prepared materials were characterized by ICP-OES, BET, TDA and optical absorption measurements. The photocatalytic experiments were carried out in a continuous-flow fixed bed reactor on the gaseous ethylene decomposing. The photocatalytic activity of the prepared material was depended on the elemental compositions and calcination temperature. The enhanced activity, 50% higher compared to pure anatase TiO2, was obtained in the material containing 10 mol% Zr and thermally treated at 500 °C.

Fabrication of A/R-TiO2 composite for enhanced photoelectrochemical performance: Solar hydrogen generation and dye degradation

Anatase/rutile TiO2 nanorods composites were prepared by a facile hydrothermal method followed by dip coating method using titanium isopropoxide in acetic acid and ethanol solvent. The effects of the titanium isopropoxide precursor concentration, on the formation of dip coated anatase/rutile TiO2 nanorods composite were systematically explored. The growth of anatase on rutile TiO2 nanorods can be controlled by varying the titanium isopropoxide concentration. The morphological study reveals that anatase TiO2 nanograins formed on the surface of rutile TiO2 nanorod arrays through dip coating method. Photoelectrochemical analyses showed that the enhancement of the photocatalytic activities of the samples is affected by the anatase nanograins present on the rutile TiO2 nanorods, which can induce the separation of electrons and holes. To interpret the photoelectrochemical behaviors, the prepared photoelectrodes were applied in photoelectrochemical solar hydrogen generation and orange II dye degradation. The optimized photocurrent density of 1.8mAcm−2 and the 625μmolhydrogen generation was observed for 10mM anatase/rutile TiO2 NRs composites. Additionally, 96% removal of the orange II dye was achieved within 5h during oxidative degradation under solar light irradiation. One of the benefits of high specific surface area and the efficient photogenerated charge transport in the anatase/rutile TiO2 nanorod composite improves the photoelectrochemical hydrogen generation and orange dye degradation compared to the rutile TiO2. Thus, our strategy provides a promising, stable, and low cost alternative to existing photocatalysts and is expected to attract considerable attention for industrial applications.

Hydrothermal tuning of the morphology and crystallite size of zeolite nanostructures for simultaneous adsorption and photocatalytic degradation of methylene blue dye

We herein have reported on tuning of the morphology and crystallite size of the hydrothermally prepared zeolite nanostructures by using different aluminum sources. The investigation revealed that aluminum sulfate and aluminum chloride precursors produced non-crystalline forms, while aluminum isopropoxide, alumina, and aluminum metal precursors generated analcime nanoparticles with crystallite size of ca. 94.79, 112.57, and 105.87nm, respectively. However, sodium aluminate precursor gave a mixture of analcime and nacrite phases with a crystallite size of ca. 77.95nm. The as-prepared nanostructures were identified using XRD, FT-IR, FE-SEM, EDS, UV–Vis spectroscopy and BET surface area. The results exhibited that the direct optical energy gaps (Eg) and BET surface area were found to be (3.29eV and 20.18m2/g), (3.15eV and 16.28m2/g), (3.21eV and 18.67m2/g), and (2.69eV and 17.82m2/g) for the zeolite products prepared using aluminum isopropoxide, sodium aluminate, alumina, and aluminum metal precursors, respectively. The results also showed that the as-prepared zeolite nanostructures could be simultaneously used as adsorbents and photocatalysts for the removal of methylene blue (MB) dye from aqueous solutions. The adsorption of methylene blue dye over the zeolite adsorbents obeys pseudo-second-order model and intra-particle diffusion model. Interestingly, zeolite photocatalyst prepared using aluminum isopropoxide degraded the MB dye with percentage of 85% and 100% within 180 and 110min in the presence of UV and (UV+H2O2), respectively. The degradation processes followed the pseudo-first-order model. The prepared zeolites are proposed as promising candidates for the removal of MB from aqueous media.

Hydrothermal influence over the peptized TiO2 nanocrystals for anodic performance in the lithium ion battery

TiO2 nanocrystals in rutile, anatase and mixed phase were prepared from the titanium iso-propoxide precursor by employing a controlled amount of HCl as a peptizing agent along with the hydrothermal treatment without any surfactants at 100°C, 150°C and 200°C for 10h. The as obtained nanocrystals at 150°C (NP150) is found to be shorter nanorods with an average diameter of ~12nm and length of ~32nm showing a typical anatase characteristics with 2θ peak positions at 25.27°, 37.80°, 48.09°, 54.02°, 54.77°, 62.80°, 69.16° and 70.17°. However, the 100°C and 200°C samples with same reaction protocol produces only aggregated nanoparticles with a rutile and a mixed anatase/rutile crystal phases, respectively. The as obtained shorter nanorod structures when processed for the electrochemical test as anode materials in lithium ion battery shows an excellent first and second discharge capacities of 366 and 182mAhg−1 with a plateau of 1.72V, much higher than those of nanoparticle (100°C and 200°C). The enhanced capacity could be attributed to the defect free, anatase crystal phase, stable morphology, high surface area and an enhanced conductivity due to the nanorods morphology which could effectively withstand expansion/contraction occurring during the successive lithium ion insertion/extraction process.

Al2O3 thin films prepared by plasma-enhanced chemical vapor deposition of dimethylaluminum isopropoxide

Al2O3 thin films were deposited by plasma-enhanced chemical vapor deposition using a dimethylaluminum isopropoxide precursor in the absence of additional oxygen sources. The deposition rate ranged from 0.77 to 1.07Å/s and increased with increasing deposition temperature between 300 and 500°C. The O/Al ratios in the films deposited at 300–500°C were ~1.5, consistent with the formula Al2O3 and the carbon contents were 8.3–9.7at.%. The film deposited at 30°C had relatively higher values of O/Al ratio (2.04) and carbon content (47.1at.%). Al2p, O1s, and C1s peaks observed from X-ray photoelectron spectroscopy analysis were mainly attributed to Al2O3. Fourier transform infrared analyses indicated that the functional groups such as Al2O3 bending and stretching vibrations were primarily from Al2O3 species with some carbon contents. From the dry etching test, the Al2O3 film deposited at 400°C had the high etch selectivity of 9.13 over SiO2, which showed the potential for application to the dry etch hard mask material.

Synthesis of nanoscale titanium dioxide by precipitation using supercritical anti-solvent

The method of synthesis of nanoscale titanium dioxide from organic precursor using supercritical fluid technology was suggested. It was demonstrated that the obtained product consists of amorphous particles with a narrow size distribution. It possesses a high porosity and a large value of specific surface area. The effect of temperature, pressure, and concentration of the titanium(IV) isopropoxide precursor on the average size of TiO2 nanoparticles has been studied. The method allows preparation of titanium dioxide free from precursor compounds. Complex physico-chemical study of the obtained product has been performed.

Comparison of the photoelectrochemical performance of particulate and nanotube TiO2 photoanodes

The aim of this work has been the comparison of the photoelectrocatalytic properties of two types of TiO2-based photoanodes. Sol-gel particulate TiO2 (SGT) layers were grown on Ti substrates (using an iso-propoxide precursor) and TiO2 nanotubes (TNTs) were formed by appropriate anodization of the same substrate in glycerin solutions. EIS spectroscopy was employed to determine the intrinsic photoelectrocatalytic activity and surface area of the photoanodes. The intrinsic catalytic activity was assessed by the product RctQdl (where Rct is the charge transfer resistance). Photovoltammetry experiments showed that the incident photon-to-current efficiency (IPCE) of the TNTs electrodes was 3.5 times higher than that of the SGT ones due to a higher surface area and lower recombination rates. Furthermore, the photoelectrodes were tested against the photoelectrolysis of an antibiotic, where the TNTs showed a 4-fold enhancement in the Chloramphenicol photo-electrolytic degradation rate under +0.5V reverse bias compared to the SGT.

Hydrothermal synthesis of TiO2/carbon composites and their application for removal of organic pollutants

TiO2/carbon composites were synthesized by hydrothermal carbonization, using titanium isopropoxide and glucose precursor solution to obtain composites with Ti/C molar ratios ranging from 0.05 to 0.30. Characterization of obtained composites was performed by thermogravimetric analysis, scanning electron microscopy, nitrogen adsorption–desorption isotherms, X-ray diffraction, UV–Vis diffuse reflectance spectroscopy and Fourier transform infrared spectroscopy. The possibility of using TiO2/carbon composites as photocatalysts for UV assisted degradation of methylene blue in aqueous solution and selected pharmaceuticals from multicomponent solution was examined. It was found that increase in the glucose concentration, i.e. increased carbon content, leads to the higher porosity and increase in the share of photocatalytically active anatase phase in obtained TiO2/carbon composites. Sample obtained from the most concentrated glucose solution (TiO2/HTC4), showed the superior photocatalytic activity under UV irradiation toward both methylene blue and selected pharmaceuticals. In addition, TiO2/HTC4 show high recycling ability with degradation ratio of methylene blue higher than 81% after five cycles. Also, TiO2/HTC4 is expected to be a promising candidate for photocatalytic processes using visible light.

Electronic properties of atomic layer deposition films, anatase and rutile TiO2 studied by resonant photoemission spectroscopy

The TiO2 films are prepared by atomic layer deposition (ALD) method using titanium isopropoxide precursors at 250 °C and analyzed using resonant photoemission spectroscopy (resPES). We report on the Ti2p and O1s core levels, on the valence band (VB) spectra and x-ray absorption spectroscopy (XAS) data, and on the resonant photoelectron spectroscopy (resPES) profiles at the O1s and the Ti3p absorption edges. We determine the elemental abundance, the position of the VB maxima, the partial density of states (PDOS) in the VB and in the conduction band (CB) and collect these data in a band scheme. In addition, we analyze the band-gap states as well as the intrinsic states due to polarons and charge-transfer excitations. These states are found to cause multiple Auger decay processes upon resonant excitation. We identify several of these processes and determine their relative contribution to the Auger signal quantitatively. As our resPES data allow a quantitative analysis of these defect states, we determine the relative abundance of the PDOS in the VB and in CB and also the charge neutrality level.The anatase and rutile polymorphs of TiO2 are analyzed in the same way as the TiO2 ALD layer. The electronic properties of the TiO2 ALD layer are compared with the anatase and rutile polymorphs of TiO2. In our comparative study, we find that ALD has its own characteristic electronic structure that is distinct from that of anatase and rutile. However, many details of the electronic structure are comparable and we benefit from our spectroscopic data and our careful analysis to find these differences. These can be attributed to a stronger hybridization of the O2p and Ti3d4s states for the ALD films when compared to the anatase and rutile polymorphs.

Preparation of N-functionalized TiO2 particles using one-step sol–gel method and their photocatalytic activity

Nitrogen functionalized TiO2 (N-TiO2) particles having an excellent dispersibility were prepared by sol–gel method. Generally, N-TiO2 particles have been made at the harsh preparation conditions including either high temperature or high pressure with nitrogen sources. However, in this research, N-TiO2 particles were prepared through facile sol–gel reaction with titanium(IV) (triethanolaminato)-isopropoxide (TTEAIP) precursor at mild conditions. The diameter of titania spheres could be tunable from 250 to 2200nm by varying TTEAIP concentrations. Photocatalytic performances of N-TiO2 were examined through the degradation of methylene blue. N-TiO2 particles exhibited 3–10 times better performance of methylene blue photodegradation than that of commercial P25.

Preparation and characterization of low fouling novel hybrid ultrafiltration membranes based on the blends of GO−TiO2 nanocomposite and polysulfone for humic acid removal

In this work, graphene oxide (GO)−TiO2 nanocomposite was synthesized by in situ sol−gel reaction at pH=2 using GO nanosheets suspension and titanium isopropoxide precursor. The synthesized GO−TiO2 nanocomposite was explored as a filler to fabricate improved antifouling novel hybrid ultrafiltration membranes for removal of humic acid from aqueous solution. Membranes were fabricated from polymer blend solutions containing polysulfone and GO−TiO2 with varied loading amount (0–5wt%) by the non-solvent induced phase separation (NIPS) method. Contact angle, atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and outer surface zeta potential studies were conducted in order to characterise the membranes in terms of roughness, structure, surface properties and charge. The porous hydrophilic hybrid membranes were shown to have an asymmetric structure with improved surface roughness. The water permeability and antifouling capacity of hybrid membranes with 10ppm HA solution were dependent on the loading amount of GO–TiO2. Incorporation of GO–TiO2 nanocomposite was found to improve the antifouling characteristics of the membranes when challenged with HA solutions. Irreversible HA fouling was substantially reduced with increased loading of GO−TiO2 nanocomposite (wt%). The lowest irreversible fouling ratio (3.2%) was obtained for the membrane containing 5wt% nanocomposite (to total wt% of PSf, MG−5). Ultrafiltration of HA solutions of varied concentrations using hybrid membranes was studied at pH=7 and 1bar feed pressure. The removal efficiency of hybrid membranes for HA was controlled by the membrane surface charge concentration, porosity and HA exclusion. The membrane MG−5 had the highest HA removal efficiency for 10ppm HA solution at pH=7.

Structure of Isolated Vanadia and Titania: A Deep UV Raman, UV–Vis, and IR Spectroscopic Study

Dispersed vanadia and titania are of great interest due to their (photo)catalytic properties. The structure of isolated (highly dispersed) vanadia and titania has been studied using a combination of deep UV Raman, UV–vis, and IR spectroscopy. Highly dispersed vanadia and titania were prepared by incipient wetness impregnation of the corresponding isopropoxide precursors onto silica SBA-15. Using resonance Raman spectroscopy, a wide range of vanadium (0.00001–0.7 V/nm2) and titanium (0.001–0.7 Ti/nm2) loadings can be analyzed. At very low loadings (<0.05 M/nm2) the structure of both highly dispersed vanadia and titania is characterized by tetrahedral coordination of the central atom and anchoring to the support by one or more M–O–S linkages. At higher loadings, titania partly forms oligomeric surface structures according to UV–vis results. In the case of highly dispersed vanadia samples (<0.1 V/nm2), Raman spectroscopy reveals distinct differences in the vanadia surface structures under ambient and dehydra...

Route to High Surface Area, Mesoporosity of Polyaniline–Titanium Dioxide Nanocomposites via One Pot Synthesis for Energy Storage Applications

This paper reports the synthesis of mesoporous polyaniline–titanium dioxide (Pani–TiO2) nanocomposites via a one pot approach in the presence of aniline and titanium iso-propoxide precursor under ice bath conditions. Scanning and transmission electron microscopy showed that the Pani–TiO2 was mesoporous in nature. BET analysis revealed the Pani–TiO2 to have a 2-fold higher surface area than Pani. The shift of the peaks in the FTIR and XRD pattern showed that TiO2 had perfectly intercalated into the Pani matrix, which suggests a strong interaction between Pani and TiO2. The electrochemical properties of Pani and the mesoporous Pani–TiO2 were examined by cyclic voltammetry and charge/discharge studies. The mesoporous Pani–TiO2 electrode exhibited a high specific capacitance of 935 F g–1 at 1 A g–1 current density. The mesoporous Pani–TiO2 displayed excellent cyclic stability up to 2000 cycles and delivered a high energy density of 94.8 Wh kg–1 at a 977 W kg–1 power density.

Effect of Ag-doped TiO2 thin film passive layers on the performance of photo-anodes for dye-sensitized solar cells

Ag-doped nanocrystalline structures of TiO2 in the form of colloidal particles are synthesized by using AgNO3 solution with Acetyl acetone and diacetyl monoxime modified titanium isopropoxide precursor. Thin layers of undoped and Ag-doped TiO2 sols are deposited on conducting glass substrate by dip coating technique. The thin films are developed by repeated coating of the sols for 5, 10 and 15 times which results the formation of thin layers with different thickness. These layers are annealed at 450°C so as to use them as bottom/ seed layers of fabricating photoanodes for dye sensitized solar cells. The optical properties of undoped and Ag-doped TiO2 thin layers are studied in details. Effective mass model is used to find the particle size and peak wavelength relationship for the nanocrystals of TiO2. Quantum efficiency of dye sensitized solar cells assembled using the fabricated photoanodes with Ag-doped TiO2 shows increase in efficiency by about 4% in comparison to the undoped TiO2 layers. The improved performance is attributed to ease of transportation of electron through passivating layer to the external circuit.

Photochemical synthesis, characterization, photoinduced electron transfer, charging and discharging in copper-titania colloid

Abstract One of major goals in photocatalysis and photochemistry is to understand photoinduced charge transfer. Colloidal solutions serve as convenient model systems for mechanistic studies of charge transfer. For the first time, colloid Cu(0)-V O -TiO 2 was prepared by the “one-pot” photochemical synthesis from copper nitrate and titanium isopropoxide precursors in ethanol under UV–vis light. The Cu(0)-V O -TiO 2 colloid shows the surface plasmon resonance (SPR) absorption band of metallic copper and contains oxygen vacancy V O . Kinetics of the synthesis of Cu(0)-V O -TiO 2 colloid follows the zeroth-order kinetic rate law, while synthesis of Cu 2 O colloid under the same conditions follows the first order rate law. Under UV–vis light, Cu(0)-V O -TiO 2 colloid undergoes repeated accumulation of negative charge on metallic copper after photoexcitation of TiO 2 , and discharge of electrons from metallic copper occurs in the dark.

Synthesis and characterization of TiO2 nanoparticles by microwave method and investigation its photovoltaic property

In the present work, TiO2 nanoparticle was synthesized with the aid of titanium (IV) isopropoxide precursor by microwave method. Besides, the effects of various experimental variables including reaction time and irradiation power on the morphology and particle size of products were explored by SEM images. The as-prepared TiO2 nanoparticles were characterized extensively by techniques like XRD, SEM, TEM, and PL. To examine the application of TiO2 nanoparticle as an absorption layer, a thin film of CdS was put on the TiO2 film by chemical bath in order to make up a solar cell.

Electrical and band structural analyses of Ti1−xAlxOy films grown by atomic layer deposition on p-type GaAs

Amorphous Ti1−xAlxOy films in the Ti-oxide-rich regime (x < 0.5) were deposited on p-type GaAs via atomic layer deposition with titanium isopropoxide, trimethylaluminum, and H2O precursor chemistry. The electrical properties and energy band alignments were examined for the resulting materials with their underlying substrates, and significant frequency dispersion was observed in the accumulation region of the Ti-oxide-rich Ti1−xAlxOy films. Although a further reduction in the frequency dispersion and leakage current (under gate electron injection) could be somewhat achieved through a greater addition of Al-oxide in the Ti1−xAlxOy film, the simultaneous decrease in the dielectric constant proved problematic in finding an optimal composition for application as a gate dielectric on GaAs. The spectroscopic band alignment measurements of the Ti-oxide-rich Ti1−xAlxOy films indicated that the band gaps had a rather slow increase with the addition of Al-oxide, which was primarily compensated for by an increase in the valance band offset, while a nearly-constant conduction band offset with a negative electron barrier height was maintained.

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.

(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 “energy – enhanced” ALD processes are being investigated. Herein, the photochemical atomic layer deposition of Al2O3 and TiO2thin films at 60°C is reported using a shuttered vacuum ultraviolet (VUV) light source to excite molecular oxygen as a co-reagent with the metal precursors. The growth mechanisms using trimethyl aluminium (TMA) and titanium isopropoxide precursors, are investigated using in-situ quartz crystal microbalance (QCM) and post-deposition ellipsometric measurements. The figure below illustrates the mass gain / loss processes during a series of ALD cycles of TMA with O2/ UV excitation from a VUV lamp with peak emissions at 125 nm (9.9 eV) and 160 nm (7.7 eV). Further, the figure shows the growth per cycle (GPC) derived from the QCM data and also separately from single wavelength (633 nm) ellipsometry measurements made on silicon (100) samples exposed to the same growth conditions. Both data sets indicate that as the VUV illumination time is extended beyond 5 s to 10 s the overall mass gain per cycle saturates and becomes approximately constant, which is consistent with other self limiting ALD processes. The photochemical process is exploited to achieve area-selective film deposition. Selective area deposition was achieved by projecting the VUV light through a metalized magnesium fluoride photolithographic mask. The selectivity of deposition is a function of the UV exposure time and the mask – substrate separation. The photochemical atomic layer deposition of TiO2 thin films from titanium isopropoxide exhibits similar growth characteristics to the Al2O3 photochemical process, however subtle differences in the growth mechanisms are attributed to the different reactions of the excited oxygen species (O( 3P)) with the Al-CH3 and Ti-OCH(CH3)2 bonds. Figure 1