Titanium ( IV ) Isopropoxide Research Articles

Simultaneous Li-Doping and Formation of SnO2-Based Composites with TiO2: Applications for Perovskite Solar Cells.

Tin oxide (SnO2) has been recognized as one of the beneficial components in the electron transport layer (ETL) of lead-halide perovskite solar cells (PSCs) due to its high electron mobility. The SnO2-based thin film serves for electron extraction and transport in the device, induced by light absorption at the perovskite layer. The focus of this paper is on the heat treatment of a nanoaggregate layer of single-nanometer-scale SnO2 particles in combination with another metal-dopant precursor to develop a new process for ETL in PSCs. The combined precursor solution of Li chloride and titanium(IV) isopropoxide (TTIP) was deposited onto the SnO2 layer. We varied the heat treatment conditions of the spin-coated films comprising double layers, i.e., an Li/TTIP precursor layer and SnO2 nanoparticle layer, to understand the effects of nanoparticle interconnection via sintering and the mixing ratio of the Li-dopant on the photovoltaic performance. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) measurements of the sintered nanoparticles suggested that an Li-doped solid solution of SnO2 with a small amount of TiO2 nanoparticles formed via heating. Interestingly, the bandgap of the Li-doped ETL samples was estimated to be 3.45 eV, indicating a narrower bandgap as compared to that of pure SnO2. This observation also supported the formation of an SnO2/TiO2 solid solution in the ETL. The utilization of such a nanoparticulate SnO2 film in combination with an Li/TTIP precursor could offer a new approach as an alternative to conventional SnO2 electron transport layers for optimizing the performance of lead-halide perovskite solar cells.

Sustainable in situ synthesis of silver/titanium dioxide/organofunctional trialkoxysilane nanocomposite coatings on cotton fabric to tailor superior multifunctional protective properties

Multifunctional properties are crucial for the production of high-quality technical textiles. In this study, a cotton fabric with simultaneously superior UV-protection, self-sterilisation, photocatalytic self-cleaning and flame retardant properties was produced using a sol–gel/hydrothermal process, in which titanium(IV) isopropoxide (TTIP) as a titanium dioxide (TiO2) precursor was combined for the first time with mixtures of organofunctional trialkoxysiloxanes, i.e., 3-(trihydroxysilyl)propyl methylphosphonate (TPMP) as a P-based flame retardant and dimethyloctadecyl [3-(trimethoxysilyl)propyl]ammonium chloride (SiQAC) or aminopropyltriethoxysilane (APTES) as the antimicrobial, biobarrier-forming precursors. The latter was used in two increased concentrations of APTES1 and APTES2. A sol–gel/hydrothermal approach was employed with a small amount of silver nitrate (AgNO3) added during the hydrothermal treatment to produce Ag-loaded TiO2. The results of scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), X-ray diffraction spectroscopy (XRD), inductively coupled plasma mass spectroscopy (ICP MS) and Fourier-transform infrared spectroscopy (FT-IR) confirmed the successful functionalisation of TiO2 by TPMP, SiQAC and APTES through the formation of Si–O–Ti bonds and the well-dispersed Ag/TiO2/TPMP/SiQAC, Ag/TiO2/TPMP/APTES1 and Ag/TiO2/TPMP/APTES2 coatings on the surface of the cotton fabric. The type of biobarrier-forming precursor significantly influenced the formation of the Ag species after the Ag loading of TiO2. The presence of SiQAC induced the formation of AgCl crystals, while APTES controlled the formation of silver nanoparticles (Ag NPs), which was more pronounced at the lower APTES1 concentration. The interactions between the coating components significantly influenced the functional protection performance, with the highest level of cooperation achieved in the Ag/TiO2/TPMP/SiQAC and Ag/TiO2/TPMP/APTES1 coatings, which exhibited the best overall multifunctionality, albeit with certain drawbacks. While the Ag/TiO2/TPMP/APTES1 coating provided excellent UV protection for the cotton, this was only improved by the Ag/TiO2/TPMP/SiQAC coating. At the same time, the Ag/TiO2/TPMP/APTES1 coating impaired the development of the char barrier by TPMP, which is due to the formation of Ag NPs. Nevertheless, both coatings showed high photocatalytic self-cleaning performance, complete self-sterilisation activity and improved burning behaviour.

Surface modification of jute-cotton union fabric using TiO2 and ZnO nanoparticles for multifunctional properties

In this study TiO2 and ZnO nanoparticles were employed as a protective coating to impart multifunctional properties, i.e. self-cleaning, water repellency, UV protection and antimicrobial activity onto jute-cotton union fabric. Through the sol-gel method, using titanium (IV) isopropoxide (TTIP) and zinc acetate as precursors, TiO2 and ZnO nanoparticles have been synthesized. Following the dip-pad-dry-cure method along with a 2 wt% of acrylic binder, the synthesized particles were applied on the jute-cotton union fabric. Subsequently, antibacterial activity, self-cleaning properties and physical properties like water absorbency, crease recovery, water vapor permeability, tensile strength, and tear strength of the treated fabric were tested and evaluated. The structural properties of the nano-particles were distinguished by Fourier Transform Infrared Spectroscopy (FTIR) and SEM. Upon comparing the test results of the coated fabric with the uncoated fabric, the results were found to be extremely satisfactory. This study provided valuable insights into the potential of TiO2 and ZnO coating in enhancing properties of jute-cotton union fabric.

Fabrication and Characterization of TiO2 Coatings on 304 Stainless-Steel Substrate for Efficient Oil/Water Separation

Oil spill accidents have been a prevalent threat to the environment. To aid in clean-up efforts, a stainless-steel filter with a hydrophilic and oleophobic coating was fabricated for efficient and affordable oil/water separation. Two solutions were used to deposit the coatings. One was sourced from a titanium (IV) isopropoxide (TTIP) precursor dissolved into 1-butanol and the other through the mixing of titanium dioxide nanopowder with glacial acetic acid. The solutions were applied to 304 stainless-steel mesh filters of varying aperture sizes ranging from 30 microns to 240 microns. The coating was applied through a multiphase deposition method followed by sintering at 450 °C. The filter performance was evaluated by contact angle measurement and a filtration test using a mixture of motor oil and water, while the surface morphology and structure of the coatings were characterized by SEM-EDS and XRD. The mesh with smaller aperture size showed oil retention improvement of up to 99%. The TiO2 nanopowder coating, with a 92% oil retention efficiency, outperformed the coating via the TTIP precursor.

Room temperature fabrication and post-impregnation of LMO-ST composites: Engineering and modeling of dielectric properties

In this work, the effect of changing the Li2MoO4-SrTiO3 (LMO-ST) compositional proportion (1–100 wt%) on the microstructure, dielectric properties, and relative density of LMO-ST composites fabricated at room temperature was investigated. The results showed that increasing the LMO binder content resulted in a higher relative density (up to 93%), but a lower dielectric constant in the range of 75 to 5. Good agreement between the experimental results and the predicted values of relative permittivity was obtained using the Lichtenecker model, reformulated for a three-phase composite system. Modeling further explained the detrimental effects of porosity on the dielectric properties. To address this issue, impregnation with titanium (IV) isopropoxide (TTIP) was found to reduce overall porosity and improve relative permittivity from 72 to 99 at 1 MHz. The room temperature fabrication offers a wide range of relative permittivity for LMO-ST composites.

Impact of the Precursor on the Physicochemical Properties and Photoactivity of TiO2 Nanoparticles Produced in Supercritical CO2.

The synthesis of TiO2 nanoparticles (NPs) in supercritical media has been reported over the last two decades. However, very few studies have compared the physicochemical characteristics and photoactivity of the TiO2 powders produced from different precursors, and even fewer have investigated the effect of using different ratios of hydrolytic agent/precursor (HA/P) on the properties of the semiconductor. To bridge this knowledge gap, this research focuses on the synthesis and characterization of TiO2 NPs obtained in a supercritical CO2 medium from four different TiO2 precursors, namely diisopropoxytitanium bis (acetylacetonate) (TDB), titanium (IV) isopropoxide (TIP), titanium (IV) butoxide (TBO), and titanium (IV) 2-ethylhexyloxide (TEO). Further, the effect of various HA/P ratios (10, 20, 30, and 40 mol/mol) when using ethanol as a hydrolytic agent has also been analyzed. Results obtained have shown that the physicochemical properties of the catalysts are not significantly affected by these variables, although some differences do exist between the synthesized materials and their catalytic performances. Specifically, photocatalysts obtained from TIP and TEO at the higher HA/P ratios (HA/P = 30 and HA/P = 40) led to higher CO2 photoconversions (6.3-7 µmol·g-1·h-1, Apparent Quantum Efficiency < 0.1%), about three times higher than those attained with commercial TiO2 P-25. These results have been imputed to the fact that these catalysts exhibit appropriate values of crystal size, surface area, light absorption, and charge transfer properties.

Numerical simulation of TTIP/[formula omitted]-xylene precursor solution spray flames in the counterflow configuration

Sprays of precursor solutions are used in flame spray pyrolysis (FSP) to produce functional nanoparticles with specific properties. The present study concerns the precursor titanium(IV) isopropoxide (TTIP) in p-xylene. A dilute monodisperse spray carried by an air stream is directed against an air stream to establish a counterflowing laminar spray flame. The complex thermophysical properties of the bi-component droplets are incorporated into the code as well as the detailed chemical reactions of the system with 213 chemical reactions among 52 species; the chemical reaction mechanism includes thermal decomposition of the TTIP and the combustion of p-xylene. The droplets are modeled using the multicomponent evaporation model. Drag and gravity forces are considered in the equation of droplet motion. Monodisperse spray flame structures are presented depending on the gas strain rate, the initial droplet size, the precursor mass loading as well as the equivalence ratio. The preferential evaporation of the more volatile p-xylene provides the gaseous fuel for combustion, and the thermal decomposition of the precursor TTIP considerably reduces the flame temperature.

Simulation study of superheating in evaporating droplets of (TTIP + p-xylene) in spray flame synthesis

Spray flame synthesis is an important technique for the production of metal oxide nanoparticles. Micro-explosions of the burning and evaporating droplet are an important breakup mechanism that is usually necessary in order to achieve a homogeneous product quality. There is an ongoing debate on the causes of these micro-explosions. With the present simulation study, we contribute to the clarification of this issue. Simulations of the evaporation of droplets of titanium (IV) isopropoxide (TTIP) dissolved in p-xylene, for which detailed information on thermophysical properties is available, are carried out for two scenarios representing single droplet combustion experiments and spray flame combustion, respectively. A one-dimensional model is developed, in which both the energy transport and the mass transport inside the droplet and the corresponding convective boundary conditions are considered. From the temperature and concentration profiles in the droplet, the superheating is calculated, considering the non-ideality of the liquid phase. The results show that superheating sets in inside the droplet. Hence, after reaching a certain threshold, a sudden evaporation will occur inside the droplet — and cause the micro-explosion. This effect is related to large values of the Lewis number, indicating that the heat conduction is much faster than the mass diffusion. As the Lewis number is not only large for the system studied here but also for other precursor solutions used in spray flame synthesis, the explanation of the observed micro-explosions is expected to hold in many cases.

Solid‐State NMR Spectroscopic Investigation of TiO2 Grown on Silica Nanoparticles by Solution Atomic Layer Deposition

AbstractAtomic layer deposition in solution (sALD) is just emerging as a technology for the preparation of thin films. Unlike ALD from the gas phase, it allows for mild reaction conditions in a solvent phase and at room temperature, thus decreasing the energy requirements of the process and widening the range of accessible precursor molecules. In this work, the deposition of thin films of titania on silica is investigated using titanium(IV) isopropoxide (TTIP) and water as precursors, which are alternatingly brought into contact with the support in a home‐built plug flow reactor. The mechanism of covalent grafting of the precursor to the surface, subsequent hydrolysis, and reaction to a layer of titania are investigated in detail using magic angle spinning (MAS) solid‐state nuclear magnetic resonance (NMR) spectroscopy. TTIP preferentially reacts with Q2 groups of condensed silica. 2D solid‐state NMR spectra allow to clearly show the successful grafting of this compound to the support by the appearance of a characteristic signal at −107 ppm, which is tentatively attributed to silicon nuclei in a SiOTi bond, and to reveal the presence of titanol groups on the emerging TiO2 film.

Antireflection cum photocatalytic with superhydrophilic based durable single layer mesoporous TiO2 - ZrO2 coating surface for efficient solar photovoltaic application

The cover glass of the solar panel benefits greatly from the antireflection cum photocatalytic with durable superhydrophilic (SHF) coating on float glass, which is here referred to as solar cover glass (SCG). In this study, such coatings were coated as a single layer on SCG as a replacement for the glass that covers solar cells, and their performance was compared to that of the bare texture solar cover glass (TSCG) which available in market. Using the sol–gel dip-coating method, coatings were created from stable sol utilizing titanium (IV) isopropoxide (TTIP), zirconium (IV) oxychloride octahydrate (ZOC), and block co-polymer P123 (surfactant), then dried at 80 °C/2 h and heated for at 400 °C/h. The coatings were deposited on glass with dimensions of 150 mm × 150 mm and had a thickness of 186 ± 10 nm. They had a refractive index value of 1.4295±0.002 and water contact angle (WCA) of 5 – 6°. These coatings were found to be homogeneous and had good adhesion and pencil hardness ∼4H. The coatings' hardness and elastic modulus were also measured using the nano-indentation method with an optimum 500 µN stress and were found to be 0.7909 ± 0.05 GPa and 37.59 ± 1 GPa, respectively. The formation of mesoporous coating as observed by ATR FT-IR and the genesis of the Ti-O-Zr network structure was confirmed by TEM, FESEM, AFM and Raman spectroscopy analysis. Coated glass showed an increase of > 3 % in average transmission in the wavelength range of 700 to 1100 nm due to a lower RI value than substrate along with chemical and thermal stability of the coatings. Moreover, upto 5% increase in photocurrent density Jsc (mA/cm2) was found as compared to uncoated glass substrate (SCG). Furthermore, the degradation of methylene blue (MB) dye under UV irradiation and analysis using Raman spectroscopy indicated the photocatalytic ability of the coatings. Its triple functional single layer coated float glass (SCG) is therefore anticipated to be helpful and effective as a replacement for TSCG for home to agricultural applications.

Thermodynamics of Azo Dye Adsorption on a Newly Synthesized Titania-Doped Silica Aerogel by Cogelation: A Comparative Investigation with Silica Aerogels and Activated Charcoal.

The adsorption isotherms of azo dyes on a newly synthesized titania-doped silica (TdS) aerogel compared to silica aerogels and activated charcoal (AC) are systematically investigated. Monolithic TdS aerogels were synthesized by the cogelation process followed by supercritical drying of tetraethyl orthosilicate (TEOS) as a gel precursor and titanium(IV) isopropoxide (TTIP) as a metal complex precursor for co-polymerization in ethanol solvent. An acid-base catalyst was used for the hydrolysis and condensation of TEOS and TTIP. The effect of Ti4+ doping in a silica aerogel on the mesoporous structure and the adsorption capacity of methylene blue (MB) and crystal violet (CV) dyes were evaluated from the UV-vis absorption spectra. In order to compare the adsorption isotherms, the surface areas of silica and TdS aerogels were first normalized with respect to AC, as adsorption is a surface phenomenon. The azo dye equilibrium adsorption data were analyzed using different isotherm equations and found to follow the Langmuir adsorption isotherm. The maximum monolayer adsorption capacities for the adsorbent TdS aerogel normalized with the AC of the Langmuir isotherm are 131.58 and 159.89 mg/g for MB and CV dyes, respectively. From the Langmuir curve fitting, the Q max value of the TdS aerogel was found to increase by 1.22-fold compared to AC, while it increased 1.25-1.53-fold compared to the silica aerogel. After four cycles, regeneration efficiency values for MB and CV dyes are about 84 and 80%, respectively. The study demonstrates the excellent potential and recovery rate of silica and TdS aerogel adsorbents in removing dyes from wastewater. The pore volume and average pore size of the new aerogel, TdS, were found to be lower than those of the silica aerogel. Thus, a new TdS aerogel with a high capacity of adsorption of azo dyes is successfully achieved.

Solution-Processed Large-Area Organic/Inorganic Hybrid Antireflective Films for Perovskite Solar Cell.

In recent years, organic/inorganic hybrid materials have attracted much attention in the field of multilayer antireflection films because of their excellent optical properties. In this paper, the organic/inorganic nanocomposite was prepared from polyvinyl alcohol (PVA) and titanium (IV) isopropoxide (TTIP). The hybrid material has a wide, tunable window of refractive index, i.e., 1.65-1.95, at a wavelength of 550 nm. The atomic force microscope (AFM) results of the hybrid films show the lowest root-mean-square surface roughness of 2.7 Å and a low haze of 0.23%, indicating that the films have good potential for optical applications. The double-sided antireflection films (10 × 10 cm2) with one side of hybrid nanocomposite/cellulose acetate and the other side of hybrid nanocomposite /polymethyl methacrylate (PMMA) achieved high transmittances of 98% and 99.3%, respectively. After 240 days of aging testing, the hybrid solution and the antireflective film remained stable with almost no attenuation. Furthermore, the application of the antireflection films in perovskite solar cell modules increased the power conversion efficiency from 16.57% to 17.25%.

Super‐Wideband Electromagnetic Absorbing TiC/SiOC Ceramic/Glass Composites Derived from Polysiloxane and Titanium Isopropoxide with Low Thickness (&lt;1 mm)

Herein, TiC/SiOC ceramic/glass composites with excellent electromagnetic wave (EMW) absorbing performance are fabricated by pyrolysis of polycarbosiloxane and titanium (IV) isopropoxide (TTIP). By taking advantage of the polymer‐derived route, the phase compositions and microstructures are easily tuned. The composites are investigated by X‐ray diffraction (XRD) analysis, scanning electron microscope, and transmission electron microscopy/energy dispersive spectroscopy. Nanoscaled TiC is formed and uniformly distributed without clustering within the SiOC matrix. Thermogravimetric Analysis (TGA) and in situ XRD results revealed good thermal stability and oxidation resistance mechanism. The presented material system (TiC/SiOC) shows a super‐wide microwave absorption bandwidth (EAB) of 13.5 GHz, including the entire Ka‐band (26.5–40 GHz) with a low thickness requirement (&lt;1 mm). The superior EMW absorption properties of the ceramics are attributed to the optimal interface polarization, as well as the ordering, concentration, and interconnectivity of the conductive network, which all determine the electrical conductivity in the composites.

Molecularly Imprinted Methyl-Modified Hollow TiO2 Microspheres

The possibility of generating organically modified hollow TiO2 microspheres via a simple sol-gel synthesis was demonstrated for the first time in this work. A mixture of titania precursors, including an organically modified precursor, was used to obtain methyl-modified hollow TiO2 microspheres selective for bilirubin by the molecular imprinting technique (Methyl-HTM-MIM). Methyl-HTM-MIM were prepared by a sol-gel method using titanium (IV) isopropoxide (TTIP), and methyltitanium triisopropoxide (MTTIP) as precursors. Two ratios of titania precursors were tested (1/6 and 1/30 molMTTIP/molTTIP). With the characterization results obtained by the SEM and ATR-FTIR techniques, it was possible to establish that only the 1/30 molMTTIP/molTTIP ratio allowed for the preparation of hollow spheres with a reasonably homogeneous methylated-TiO2 shell. It was possible to obtain a certain degree of organization of the hybrid network, which increased with calcination temperatures. By adjusting isothermal adsorption models, imprinting parameters were determined, indicating that the new methylated microspheres presented greater selectivity for bilirubin than the totally inorganic hollow TiO2 microspheres. The effectiveness of the molecular imprinting technique was proven for the first time in an organically modified titania material, with imprinting factor values greater than 1.4, corresponding to a significant increase in the maximum adsorption capacity of the template represented by the molecularly imprinted microspheres. In summary, the results obtained with the new methyl-HTM-MIM open the possibility of exploring the application of these microspheres for selective sorption (separation or sensing, for example) or perhaps even for selective photocatalysis, particularly for the degradation of organic compounds.

Characterization of TiO2 nanofibers with enhanced photocatalytic properties prepared by plasma assisted calcination

In this article, we present a novel approach to produce titania (TiO 2 ) nanofibers with enhanced properties using plasma pre-treatment. Nanofibers were produced from electro-spun polyvinylpyrrolidone (PVP) based nanofibers with titanium(IV) isopropoxide (TTIP) as a precursor. PVP/TTIP fibers were plasma treated using diffuse coplanar surface barrier discharge (DCSBD) followed by thermal calcination at 500 °C, 600 °C and 700 °C. The morphology of nanostructures was characterized using SEM, BET and XRD, the chemical composition was analyzed by XPS, ATR-FTIR, the photocatalytic activity was evaluated by degradation of methylene blue and band gap was determined from diffuse reflectance spectra (DRS) using Tauc plot. Initial plasma treatment caused decomposition of polymer matrix, which led to faster oxidation and crystalline phase transition at lower temperature during the following thermal processing/calcination. The results showed enhanced photocatalytic properties of plasma pre-treated fibers despite the fact they possess higher proportion of rutile and lower specific surface area. UV–vis DRS measurements exhibit lower band gap energy at 700 °C, but difference between plasma treated (PT) and non-treated (NT) samples at the same temperature was not observed.

A new model for puffing and micro-explosion of single titanium(IV) isopropoxide/p-xylene precursor solution droplets

In flame spray pyrolysis, the precursor solution droplet undergoes heating and evaporation, followed by gas phase combustion and generation of nanoparticles. Depending on the precursor solution, the precursor/solvent droplet may experience puffing and micro-explosion. A new one-dimensional model is developed to describe these processes in the spherically symmetric droplet interior with emphasis on the puffing and the micro-explosion. After the initial droplet heating, the preferential evaporation of the higher volatile component causes the accumulation of the lower volatile precursor at the droplet surface and thus forms a liquid shell that hinders the evaporation process. In the droplet interior away from the liquid shell, the higher volatile component accumulates and when the temperature reaches the boiling point of that liquid, puffing occurs. If the pressure inside the droplet exceeds the ambient pressure, the droplet undergoes micro-explosion. The present study concerns single precursor/solvent droplets of titanium(IV) isopropoxide (TTIP) in p-xylene at room temperature in hot convective air at atmospheric pressure. A parameter study is performed to show the dependence of the puffing and the micro-explosion on the initial precursor loading, the initial droplet size, the ambient gas temperature, and the relative velocity between the droplet and the ambience. There are situations where micro-explosion follows the puffing or puffing repeats until the end of the droplet lifetime with no micro-explosion. This is the first model to successfully describe the puffing in precursor solution droplets and the micro-explosion which may follow the puffing.

Role of a novel cationic gemini surfactant (CGS) on a one-step sol-gel process and photocatalytic properties of TiO2 powders.

TiO2 nanoparticles were prepared using a sol-gel process in combination with a novel cationic gemini surfactant (CGS) with amide functional groups at low temperatures. Titanium (IV) isopropoxide (TIP) and CGS were used as the starting materials and as effective agents, respectively, to orient the nanoparticles during the sol-gel synthesis. To reveal both the structural and morphological properties of the nanopowders prepared in this work, they were characterized using X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET) surface area apparatus. The pore volume and pore size were calculated using the Barrett-Joyner-Halenda (BJH) model on the desorption branch. The experimental results show that the surface area and average crystallite size of the obtained TiO2 nanopowders vary between 160-203 m2/g and 27-49 nm, respectively. It was observed that the N2 adsorption-desorption isotherms for almost all samples of TiO2-X% CGS (X: mass of CGS) show the typical Type I with a hysteresis loop of H4. The photocatalytic activities of the CGS-modified nanocomposites are evaluated not only by the photocatalytic degradation of methyl orange (MO) but also by the reduction of Cr(VI) as model pollutants in the presence of visible light.

Optical and structural properties of cost-effective nanostructured calcium titanate blue phosphor

The current study reports nanostructured CaTiO3 powder produced by two different novel modified sol-gel methods. The chemical reaction between the calcium oxide (CaO) extracted from chicken eggshell (ES) and titanium (IV) isopropoxide (TTIP) leads to the synthesis of calcium titanate nanopowder. Further leaf extract has also been added in one method which shows the significant effect to reduce particle size up to a certain extent. X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) were examined to confirm the nanometric particle size. Further, the crystalline structure and phase involvement were also investigated by Rietveld refinement. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–Vis), and photoluminescence spectra (PL) characterization were used to study the functional groups, elemental composition, and optical properties of the material. The photoluminescence emission that occurred in the sample was due to the distortion between [TiO6] – [TiO6] complex clusters causing a difference in the charge density, which can promote a charge transfer between these clusters. The CIE chromaticity coordinates were determined and it shows that the synthesized sample is a promising candidate for the blue color phosphor application. The present phosphors were highly useful for UV chip excited white LED applications.

Synthesis Control of Charge Separation at Anatase TiO2 Thin Films Studied by Transient Surface Photovoltage Spectroscopy.

For the efficient photocatalytic oxidation of organic pollutants at surfaces of semiconductors, photogenerated holes shall be separated toward the surface and transferred to reactive surface sites, whereas the transfer of photogenerated electrons toward the surface shall be minimized. In this Research Article, the identification of suitable synthesis control of charge separation combined with an in-depth understanding of charge kinetics and trapping passivation mechanisms at the related surfaces can provide tremendous opportunities for boosting the photocatalytic performance. In this work, a comprehensive transient surface photovoltage spectroscopy study of charge separation at anatase TiO2 thin films, synthesized by ultrasonic spray pyrolysis from titanium(IV) isopropoxide (TTIP)–acetylacetone (AcacH) based precursor is reported. By varying the amount of AcacH in the precursor solution, an experimental approach of synthesis control of the charge transfer toward TiO2 surface is provided for the first time. An increased amount of AcacH in the precursor promotes transition from preferential fast electron to preferential fast hole transfer toward anatase surface, correlating with a strong increase of the photocatalytic decomposition rate of organic pollutants. Suitable mechanisms of AcacH-induced passivation of electron traps at TiO2 surfaces are analyzed, providing a new degree of freedom for tailoring the properties of photocatalytic systems.

The Influence of the Precursor's Nature and Drying Conditions on the Structure, Morphology, and Thermal Properties of TiO2 Aerogels.

A cost-effective solution for the synthesis of high-porosity TiO2 aerogels, which can be used as a mesoporous perovskite network charge-carrier material during the manufacture of solar cells, is described. The effects of the synthesis parameters (precursor (titanium (IV) isopropoxide (TIP) and tetrabutyl orthotitanate (TBOT)), additional solvent exchange (n-hexane (nH), cyclohexane (CH), and diethyl ether (DE)), subcritical drying (800 mbar vacuum, 70 °C, 8 h), aging, and calcination on the aerogel’s structure have been investigated. Methods of XRD, FT-IR, BET, Raman, STA, SEM, UV–vis, and thermal conductivity measurements were applied to find out the relation between the synthesis conditions and the properties of the synthesized aerogels. Amorphous aerogels are polydispersed systems with the highest probability of pore diameter from 0.5 to 15 nm. An nH-exchanged, aged aerogel synthesized from the precursor TIP shows the highest diameter of pores. After calcination, the aerogels tend to crystallize into an anatase phase and the size of the crystallites depends on the precursor’s nature. Calcination leads to a significant increase in both the apparent and true density of the aerogels, and it also results in an increase in porosity and thermal conductivity.