Particle Size Of TiO2 Research Articles

Preparation and visible-light photocatalytic activity of N-doped TiO2 by plasma-assisted sol-gel method

Abstract N-doped TiO2 was synthesized by a facile so-gel method using urea as nitrogen resource. To seek the efficient N doping of TiO2 photocatalysts, non-thermal N2 plasma was employed to treat N-doped TiO2 followed by calcination (N-TiO2 (NTP)) and compared with the conventional calcination (N-TiO2). The samples were evaluated under visible light irradiation for photocatalytic degradation of methyl orange (MO). To elucidate the plasma treatment effect, XRD, SEM, EDS, TEM, BET, UV–vis DRS, FT-IR and XPS techniques were used for catalyst characterization. N-TiO2 (NTP) possessed small particle size of 4.9 nm with better dispersion and narrow band gap of 1.6 eV. The visible-light photocatalytic activity of N-TiO2 (NTP) was much better than that of N-TiO2. And the photocatalytic degradation kinetics of the MO fitted with the Langmuir-Hinshelwood equation. The apparent reaction rate constant of N-TiO2 (NTP) was about 2.8 times as high as that of N-TiO2. The enhancement was ascribed to small particle size of N-doped TiO2 offering more surface active sites and high content of surface oxygen.

Study of structural, spectroscopic and photo-oxidation properties of in-situ synthesized Sc-doped titania

A semiconducting composite with enhanced photocatalytic properties – scandium doped titania (anatase/amorphous titania/brookite) – was prepared by hydrolysis of titanium (IV) tetrabutoxide in the presence of scandium (III) sulfate aqueous solution. The characterization of the final products was accomplished through X-ray diffraction (XRD), scanning and high resolution transmission electron microscopy (SEM, HRTEM), UV–visible spectroscopy (UV–Vis), X-ray photoelectron spectroscopy (XPS) and by registration of photocatalytic activity during photo oxidation of aromatic organic compound (hydroquinone). The Sc-doped powder-like product is a mixture of anatase/brookite or anatase/brookite/amorphous nanoparticles. The effects of Sc-doping on the phase composition, optical properties and photoactivity of TiO2 were investigated. The XRD analysis confirmed the absence of individual Sc-containing compounds. The phase composition and particle size of TiO2 were characterized by the Debye analysis of X-ray diffraction patterns. A direct correlation between Sc concentration and TiO2 phase composition was established: increasing in Sc concentration promotes amorphization of the samples. DFT calculations distinguish both brookite and amorphous titania among all TiO2 polymorphs as the most preferred hosts for substitutional Sc atoms. In full accordance with TEM observations the possible inclusion of Sc into a TiO2 lattice is primarily gainful for amorphization. Both experimental and theoretical absorbance spectra for amorphous titania demonstrate a shift of absorbance onset towards larger wavelengths. An improvement in the catalyst's photodegradation efficiency was attained with Sc concentration of 5.0 mol%.

Facile preparation of TiO2/acrylic resin superhydrophobic surface with excellent wear resistance

ABSTRACTSuperhydrophobic surfaces (SHSs) are widely applied in national defense, industrial, and agricultural production and daily life due to their unique structural characteristics and self‐cleaning properties. In this work, a multilayer structure was obtained on an aluminum substrate using a simple spray method. The acrylic resin was used as a substrate, and the SHS was prepared by combining the acrylic resin with the modified nano‐TiO2. The effects of different contents of surface modifier hexadecyltrimethoxysilane (cetyltrimethoxysilane), different spraying times, and different nanometer TiO2 particle sizes on SHS were studied. The results showed that the optimal modifier content was 16%. When the spraying time is 1 min and the mass ratio of 10‐nm TiO2 to 100‐nm TiO2 is 1:1, the contact angle (CA) of the surface is 170.89°, and the sliding angle is 2°. Furthermore, the stability of the SHS under different acid–base conditions, the stability in NaCl solution (3.5 wt %), and the dry friction resistance were further determined. The experimental results show that the prepared samples have certain acid resistance, NaCl resistance, and alkali resistance. After 100 times of dry friction, the CA is still 162.30°, which suggests that the TiO2/acrylic resin SHS has excellent dry friction resistance performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47762.

Can mixed anatase and rutile photocatalyst TiO2 be synthesized under high pressure in water?

We have reported for the first time the synthesis of mixed anatase and rutile TiO2 under 27 MPa in water at the temperature as low as 375 °C. XRD patterns show that the content of rutile in the mixed phase TiO2 is increased by 47.7% compared with the raw TiO2. The average particle size of the mixed phase TiO2 is increased obviously compared with the raw TiO2. Compared with that of the raw TiO2, the band gap of the mixed phase TiO2 is reduced to 2.94 eV while the absorbance is enhanced. Although the particle size increases, the mixed phase TiO2 still exhibits better photocatalytic performance.

X-ray radiation enhancement of gold- TiO2 nanocomposites

The interaction of ionizing radiation, such as X-rays, with materials at the nanoscale, holds promising applications in various fields, particularly in radiation therapy. In this regard, radiosensitizers are of importance due to their ability to augment cell sensitivity to radiation. Herein, the radiation enhancement response of Gold-titania (Au@TiO2) nanocomposites was evidenced by monitoring the methylene blue (MB) decomposition in the presence of the nanomaterial. This response was investigated for the first time as a function of parameters such as gold loading, TiO2 particle size, ligand used for synthesis, nanocomposite concentration, irradiation voltage, and dose rate. Au@TiO2 were fabricated by X-rays radiolytic synthesis, a method carried out at room temperature and pressure, in the absence of toxic chemicals, which is fundamental for medical applications. Results showed that the addition of Au@TiO2 to MB accelerates the dye reaction rate by increasing the number of reactive oxygen species in solution. Reaction rate enhancements ranging from ~40% to 78% were observed in the presence of Au@TiO2. The highest values were achieved when using TiO2 with 6.5 nm in particle size, 10% Au loading, and NaOH as the ligand. This combination of parameters led to an increase in the number of active sites in the nanomaterial, facilitating MB decomposition. Au@TiO2 radiosensitization was also tested in a biological environment with M. aeruginosa cells. The presence of the NCs during irradiation notoriously increased cell damage. Overall, Au@TiO2 have great promise as radiosensitizers, a feature that could be relevant to a number of medical, biological and environmental applications.

Inter-relation between size and arrangement of TiO2 nanoparticle layers on efficiency of dye-sensitized solar cells

The effects of TiO2 layer arrangement as photo-anode on the efficiency of dye-sensitized solar cells were investigated and presented. Four TiO2 nanoparticles being different from the TiO2 particle sizes and phases were prepared and characterized with TEM, AFM and XRD analyses. These TiO2 particles were used to prepare three-layered photo-anode with different layer arrangements. The J–V measurements and impedance spectroscopy of the assembled solar cells with these photo-anodes and N3 dye were investigated and interpreted. The photo-anode in which the particles were arranged from large to small (CBA) and the photo-anode in which the particle size is equal (BBB) presented the best efficiency. The BBB performance was related to the appropriate particle size in the B layer and was a driving force for electron transfer, which is inducted by the oxidized dyes. In the CBA sample, this driving force was enhanced by the different particle sizes in the layer interfaces.

Effects and mechanism of SiO2 on photocatalysis and super hydrophilicity of TiO2 films prepared by sol-gel method

TiO2/SiO2 films were deposited on glass substrates by sol-gel method, and the effects of SiO2 on the photocatalysis and hydrophilicity of TiO2 films were studied. Zeta potential measurements show that SiO2 can effectively inhibit the growth of TiO2 colloidal particles, and improve the stability of sols. XRD and AFM observations discover that, with the increase of SiO2, the size and crystallinity of TiO2 particles, and the porosity and roughness of films all gradually decrease. XPS and FTIR analyses indicate that SiO2 also affect the composition of the films. In addition, the blue shift of the absorption boundary gradually increases with SiO2. The fitting results show that the photocatalytic reaction of films basically follows the first-order kinetics law. The films with 15% SiO2 exhibit the best photocatalytic activity, whose degradation efficiency is about twice that of the pure TiO2 films. The films with 20%wt SiO2 have the best super hydrophilicity, whose water contact angle (WCA) drops to 2° in 3s. More significantly, its super hydrophilicity can last for more than 6 days under dark, that is, the films obtain an enhanced durable super hydrophilicity. In summary, the films with 15%wt–20%wt SiO2 own the best overall performance.

Photocatalytic activity of anatase titanium dioxide nanostructures prepared by reactive magnetron sputtering technique

In this work, nanostructured titanium dioxide (TiO2) photocatalysts with high optical and structural homogeneity were successfully synthesized by dc reactive magnetron sputtering technique. The TiO2 thin films were produced with high structural homogeneity without any heat treatment. Analysis of the X-ray diffraction patterns and UV–visible spectroscopy gave an indication that the structure of prepared films is anatase with energy band gap of 3.23 eV. The Fourier-transform infrared spectroscopy has confirmed the formation of Ti–O bond. The average size of TiO2 particles in the deposited films was ranging in 5–7 nm. These nanostructures are very applicable as photocatalysts as their photocatalytic activity was determined from the degradation rate with UV irradiation time as the first order reaction rate constant was determined to be 2.4 × 10−3 min−1.

Preparation and characterization of spherical titania and their influence on self-cleaning and anticorrosion properties of acrylic resin

Firstly, spherical TiO2 particles of micro-nano size were prepared by using the inclusion reaction product which resulted from the chemical reaction between urea and EtOH and the inclusion reaction product served as a template. The size of spherical TiO2 can be regulated by the ratio of urea solution. The spherical TiO2 particles are mainly composed of anatase. Then the above spherical TiO2 particles were used to enhance the properties of acrylic resin. With the increase of TiO2, the microstructure surface of TiO2/acrylic resin coating was in the uneven shape of lotus leaf. When the addition of TiO2 reaches up to 30 wt.%, it can enhance the anti-corrosion properties of the acrylic resin coating brushed on Q235 steel plate, the water contact angle on the surface of TiO2/acrylic resin coating is 121.5° and displays good self-cleaning properties in the water with sand whose concentration reaches 20 wt.%. The composite coatings exhibited the highest 5B rating determined by adhesion test ASTM D-3359-02 (American Society for Testing and Materials).

Preparation and application of novel bionanocomposite green membranes for gas separation

We report in this study the synthesis of thin-film bionanocomposite (BNC) membranes. In the presented study, at firstly, the synthesis and full characterization of new diamine and polyimide derived from amino acid (methionine) and benzimidazole fractions in the structure of pendant group are presented. Then, to improve the effect of surface modification, TiO2 was predisposed in ethanol via ultrasonic waves. Surface modification of TiO2 was conducted using 3-methacryloxypropyl-trimethoxysilane (MPS) under ultrasonic irradiation. The new BNC-containing chiral monomer (amino acid) is employed as a key monomer for the fabrication of a series of BNCs films with various TiO2 percentages under ultrasonic irradiation. The modified TiO2 presented good compatibility in PI matrix. The structures of the modified hybrid nanocomposites were identified with a FT-IR, whereas the size of the TiO2 in polyimides was characterized with a scanning electron microscope (SEM). SEM results indicated the formation and dispersion of nanometer scale size of inorganic domains inside the polyimide matrix due to the introduction of modified TiO2 and the interactions between organic and inorganic phases. The size of TiO2 particles in the modified system was about 25 nm. The transmission electron microscope analysis showing the well-dispersed nanosized titania NPs. Moreover, their thermal and mechanical properties exhibited a significant improvement. The studies on the optical properties of the hybrid films indicate redshift of the absorption band that increased with increased TiO2 content. The high TiO2, content in PI/TiO2, nanocomposite membranes resulted in the great enhancement of gas separation performance of the TiO2 polyimide nanocomposite materials compared with polyimide. When the TiO2, content in PI/TiO2, composite membranes was above 10 wt%, the permeability of the PI/TiO2 composite membranes was remarkably enhanced and the selectivity of PI/TiO2 composite membranes remained at a high level.

SYNTHESIS OF RUTILE TIO2 NANOPARTICLES BY CO-PRECIPITATION METHOD

Abstract. The objective of this research is to produce rutile TiO 2 nanoparticles by co-precipitation method and to determine its characterization using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffractometry (XRD), and Particle Size Analysis (PSA) methods. Synthesis of rutile TiO 2 nanoparticles by co-precipitation method in this study was initiated by mixing 15% TiCl 3 solution into distilled water while stirring at constant speed for some time. Then, pH is adjusted to 11-13 by dripping ammonia (NH 4 OH) solution while continuing to stir. The precipitate (white gel) is then dried in the oven and crushed to produce TiO 2 powder. The morphology of the TiO2 particles obtained is spherical and tends to agglomerate. The average particle size of TiO2 produced is 192.2 nm. The EDS results show that the percentage of Ti mass in TiO2 particles is 59.52%. Based on XRD analysis, there are two phases formed namely anatase and rutile with a tetragonal crystal system. Keyword s : Co-precipitation method , nanoparticle s , and rutile .

Physical and Electrochemical Properties of Pt-Hollow-Structured TiO2 Prepared at Different pH’s and Its Self-Humidifying Ability in PEMFC

In this study, SiO2@TiO2 core–shell nanoparticles were prepared under different pH’s such as 5.0, 7.0, and 9.0. Under acidic and neutral conditions, silica nanoparticles are more agglomerated, while less agglomeration occurs under alkaline conditions. The latter case is attributed to repulsive forces between negatively charged silica nanoparticles because of the lack of protons under alkaline conditions. It was also observed that the individual particle size of hollow-structured TiO2 (HTiO2) is significantly affected by the pH. Below a pH of 7.0, the particle size of TiO2 is larger than that at pH 9.0 because of the hydrolysis and condensation of titanium tetrabutoxide via the sol–gel process. The smaller the particle sizes of SiO2 and HTiO2 are, the larger is the Brunauer–Emmett–Teller (BET) surface area, and the higher are the water uptake and electrochemical active surface area (ECSA). The ECSAs of Pt-HTiO2 for the water formation were determined to be 19.1, 13.8, and 25.0 m2/g, with the increase in pH. The cell performance is similar under high relative humidity. However, under zero humidity, a significant enhancement is observed at pH 9.0 (0.8 W/cm2) compared with 0.67 W/cm2 for pH 5.0 and 0.59 W/cm2 for pH 7.0, indicating an excellent self-humidifying ability.

Erosion Wear and Hardness of Glass Fiber / Epoxy with Nano and Micro TiO2 Hybride Composites

The objective of this research is to prepare and study (Glass Fiber / Epoxy) with nano and micro Titanium dioxide (TiO2) composites with different volume percentage of nano and micro TiO2 powder of 2%, 4%, and 6% volume fraction. Atomic force microscopy techniques was used to measure the grain size of nano TiO2 powder (average diameter was 46 nm) and particle size analyzer techniques was used. Erosive wear behavior of this composite under three different impingement angles of 30°, 60° and 90° and three angular silica sand abrasive particle sizes approximately 425, 600 and 850 μm and hardness (shore D) were studied. In general the erosion wear of micro composites have lower erosion resistance than other nano-based compounds. Erosion resistance increase as the volume fraction increase. Nano composites of GF / EP with TiO2 have many advantages over micro composites from the view point of wear and hardness tests. The worn surface features of unfilled and filled G-E composites were examined using scanning electron microscopy (SEM) and results indicates more severe damage to matrix and glass fiber in unfilled composite system as compared to TiO2 filled composites.

Surface modification of B–TiO2 by deposition of Au nanoparticles to increase its photocatalytic activity under simulated sunlight irradiation

Photocatalytic activity of TiO2 under visible light irradiation can be improved by doping with nonmetal atoms. However, inter-band energy states formed upon substitutional or interstitial doping can act as recombination centers, hindering the separation of the charge carriers. In this work, sol–gel synthesized TiO2 was doped with different loadings of boron, namely 0.25, 0.5, 1, 2, and 4 wt. %, and superficially modified by the deposition of Au nanoparticles (0.5, 1.0, and 1.5 wt. %). Particle size of doped TiO2 decreased with the increase of boron loading, while surface area increased accordingly. B2O3 was segregated from TiO2 when boron loading surpassed 1 wt. %. Light absorption of the doped materials was slightly blue shifted as the boron loading increased, more likely because of the quantization effect. Tiny and well dispersed Au nanoparticles were efficiently deposited on the B-TiO2 materials. Au nanoparticle size (3–5 nm) showed no modification as Au loading increased, although deposition rate slightly decreased with the boron loading. The complete mineralization of sulfamethoxazole under UV-A/visible light irradiation was obtained using the (0.5 wt. %) Au/(0.25 wt. %) B-TiO2 material. Electrochemical characterization showed how inter band energetic states increased the separation of the photo-produced charge carriers, while Au nanoparticles hampered the recombination rate via the electron trap effect. Photocatalytic materials displayed high stability. Photoactivity dropped when tap water was tested, because of the dissolved components in the liquid matrix. Some intermediates were identified via LC-MS/MS analysis, which displayed lower antibiotic activity than the parent compound.

Synthesis of TiO2 nanoparticles via a simple precipitation method and photocatalytic performance

Titanium dioxide nanoparticles were prepared by a simple precipitation method using titanium (IV) isopropoxide as a starting material. The precursor powder was calcined in air at temperatures ranging from 400 to 700 °C. XRD analysis results revealed that the crystallite size and crystallinity of the samples increased with increasing calcination temperature. The morphology and particle size of TiO2 particles were investigated with TEM images and the diameter of the particles was then calculated using the images. It was evident that the calcination temperature had a significant influence on the average particle size since the size increased from 11.3 to 27.4 nm when the temperature was raised from 400 to 700 °C. By extrapolating the graph of (αhv)n versus photon energy (hv) to the horizontal axis, the energy band gap (Eg) of the calcined TiO2 nanoparticles was in the range of 2.98–3.30 eV. Under UVA irradiation, photodegradation activity of methyl orange had the fastest kinetics as measured by areaction rate constant, k, using the pure anatase TiO2 nanoparticle calcined at 400 °C.

The effect mechanisms of pH, complexant and calcination temperature on the hydrophilicity of TiO2 films prepared by the sol-gel method

Nano TiO2 sols are prepared by the sol-gel method, and hydrophilic TiO2 films are deposited on stainless steel sheets by spin-coating technology. The effects of pH, complexant and calcination temperature on the hydrophilicity of TiO2 films are studied in this paper. In summary, they all affect the hydrophilicity of films by changing the hydroxyl content on the films surface. pH has a decisive influence on the size of holes in the film surfaces and also has a marked impact on the hydrolysis rate of Ti(OBu)4. When pH = 6, the film surfaces are covered with micro-Nano holes. The complexant is the critical factor of the hydrolysis rate of Ti(OBu)4. Double-complexants makes TiO2 sols more stability and films more hydrophilic. The calcination temperature determines the size, arrangement and crystal structure of TiO2 particles. When the temperature is 500 °C, the hydrophilicity of TiO2 films is the best. It is concluded from mechanism analysis that super hydrophilicity of TiO2 films is the combination of TiO2 particles and the surface morphology that work together.

The effect of TiO2 nanoparticles on color of cotton fabric dyed with reactive dye

PurposeThis paper aims to investigate the effect of titanium dioxide (TiO2) nanoparticle coating on the visible reflectance and color appearance of dyed cotton fabrics.Design/methodology/approachA Taguchi experimental design model was used to minimize the number of samples and for accurate prediction of possible responses. The governing parameters affecting the color change of dyed fabrics through the coating process were selected as shade of cotton fabrics, depth of shade, concentration and size of TiO2 nanoparticles and concentration of citric acid. The Taguchi model suggests the L18 orthogonal array. In the meantime, the lower response category was selected to determine the optimum conditions. According to obtained results, coating with TiO2 nanoparticles results in color change (ΔEab*) of all dyed cotton fabrics.FindingsThe obtained results indicate that the TiO2-coated fabrics had higher reflectance compared to raw fabrics. Furthermore, it was found that the TiO2 pigmented coating increases the brightness of samples and simultaneously decreases their chroma. On the other hand, analysis of variance reveals that the concentration of TiO2 nanoparticles together with shade of fabrics has the most significant impact on the color change of dyed fabrics through coating process. Dye concentration and size of TiO2 particles also, to the same extent, had influence over the color change. However, the effect of the concentration of citric acid on the color change was insignificant.Originality/valueThis research investigates the effect of TiO2 nanoparticles on the optical property of colored fabric by using a Taguchi experimental design model to minimize the number of samples.

Microstructural and optical properties of rare earth ions doped TiO2 for potential white LED applications

Nano ceramics of pure TiO2 and Dy3+, Eu3+ and Tb3+ doped TiO2 are prepared by hydrothermal method and these are characterized by using X-ray diffractometer (XRD), UV–Visible spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), and photoluminescence spectroscopy. XRD analysis revealed that the average particle size of the pure TiO2 and Dy3+, Eu3+ and Tb3+ doped TiO2 are in the range of 45–35 nm and confirms the anatase phase. The FESEM and HRTEM analysis confirm that the obtained ceramics are in nano regime. The absorption spectrum revealed that the bandgap of the TiO2 ceramics are in the range 3.14–3.2 eV. The PL analysis showed that the doping of Dy3+, Eu3+ and Tb3+ had improved the luminescence behavior than the pure TiO2 nanoparticles. Overall, by doping 0.5 mol% concentration of rare earth (RE) greatly alters the structural morphology and directly influence the luminescence behavior of TiO2 and suitable for advanced optoelectronic applications. The color purity of the studied samples is found to be 91% for Dy3+, 84% for Eu3+ and 73% for Tb3+ at the excitation of 345 nm, 376 nm and 350 nm respectively. The single-doped sample Eu3+: TiO2, Tb3+: TiO2 and Dy3+: TiO2 samples showed orange–red, blue–green and white emissions respectively.

Optimization of borosilicate glass/CaTiO3‐TiO2 composite via altering prefiring temperature and particle size

AbstractLow‐temperature co‐fired ceramic (LTCC) with middle permittivity is very crucial to the miniaturization of components. Based on our previous study on the glass/CaTiO3‐TiO2 composite, prefiring temperature and particle size of CaTiO3‐TiO2 ceramic were optimized in this study to promote the performance of the composites. Comparing with our previous study, after being sintered with 50 wt% glass at 875°C, CaTiO3‐TiO2 ceramic prefired at 1275°C with particle size of 3.38 μm showed excellent properties of sintering density = 3.33 g/cm3, εr = 30.2, tan δ = 0.0005 (7 GHz). In addition, surface roughness of green tapes was also improved after optimization. The material has a good chemical stability and shrinkage matching with silver, making it a very promising candidate material for LTCC applications.

Fabrication of TiO2/Cu hybrid composite films with near zero TCR and high adhesive strength via aerosol deposition

Room-temperature fabrication of TiO2/Cu composite films for embedded passive components were attempted via aerosol deposition process. XRD analysis and observation of internal microstructures revealed that TiO2/Cu composite films using 500 nm-sized TiO2 had further tight bonding between particles compared to 25 nm-sized TiO2, due to effect of initial TiO2 particle size on densification of internal microstructures. Then, to optimize their adhesive strength and temperature coefficient of resistance (TCR), electrical and mechanical properties of TiO2 (500 nm)/Cu composite films with different content of TiO2 were evaluated for applications as advanced composite film resistors. Results showed that TiO2/Cu (50 wt%/50 wt%) composite films had sufficient electrical resistivity (5.8 ×10−3 Ω cm), excellent near-zero TCR (−3 ppm/℃), and improved adhesive strength (~ 7.37 N/mm2) resulting from proper coexistence of anchoring bonds and mechanical interlocking formed during deposition.