Phase TiO2 Nanoparticles Research Articles

Investigation of the Effects of Different Phases of TiO2 Nanoparticles on PVA Membranes

Introduction: PVA/TiO2 nanocomposite membranes are prepared by solution casting technique where different phases of TiO2 nanoparticles like brookite, brookiterutile and rutile are dispersed in PVA matrix. Sol-gel method was employed to prepare TiO2 nanoparticles, while different phases of TiO2 have been obtained by controlling the calcination temperature. Methods: PVA/TiO2 nanocomposite membranes were characterized by XRD, FTIR, AFM, TEM, UV-visible and PL techniques. XRD results confirmed the presence of different phases of TiO2, exhibiting 3.3 nm, 8.4 nm, and 35.7 nm mean crystalline size. The XRD studies also confirmed that TiO2 nanoparticles became properly dispersed to the PVA matrix, leading to increased PVA crystallinity after doping of different phases of TiO2 nanoparticles. UV-visible analysis revealed an increase in absorption intensity and peak position shifts slightly towards longer wavelengths, which indicates that nanofillers tuned the band gap of PVA. The doping of the TiO2 (brookite) phase in the PVA matrix results in a decreased in PL intensity. Results: This suggests that the PVA/TiO2 (brookite) membrane exhibits a greater degree of photocatalytic activity in comparison to the other two composites. According to the FTIR investigation, the hydroxyl (OH) groups present in PVA interact with the dopants Ti+ ions via intra- and intermolecular hydrogen bonds to produce charge transfer complexes (CTC). The AFM study shows surface roughness details for PVA and PVA/TiO2 composite membranes. The average grain size of TiO2 nanoparticles calculated from TEM images is in good agreement with the grain size calculated by XRD. Conclusion: By adjusting the phase of TiO2 nanoparticles into PVA matrix, composites can be developed that are optimized for a variety of applications such as water purification, UV protection, self-cleaning surfaces, lithium-ion batteries, and optoelectronic devices.

Catalytic synthesis and characterization of aryl benzimidazole and its interaction with TiO2 nanoparticles: ESIPT process

2-(1-phenyl-1H-benzo[d]imidazol-2-yl)-4-(trifluoromethyl)phenol(PBITP) has been synthesised and the compound structure was confirmed by proton NMR, carbon NMR, mass spectral studies and elemental analysis. The binding interaction between PBITP and different phases of TiO2 nanoparticles were investigated. We have observed surprising result. Synthesized PBITP enhanced the fluorescence of rutile phase of TiO2 on account of the lowering of frontier orbital levels of the PBITP. But the opposite trend was observed for anatase phase of TiO2. So that, we can identify the rutile and anatase phase. The mechanism of electron transfer was discussed in detail. Emission spectroscopy has been employed to probe on the process of excited state intra-molecular proton transfer (ESIPT) in hydroxy imidazole.An abnormal Stokes – shifted emission band, at shorter and longer wavelengths has been observed in the fluorescence spectra of the sample PBITP / dioxane, which is an indication towards the existence of two different forms of intra-molecular hydrogen bonded isomers.

The effect of TiO2 phase on the lubricating performance of sol–gel-derived TiO2 nanoparticles in fully formulated engine oil

This paper is devoted to investigate the friction-reducing and wear protection performance of TiO2 nanoparticles as lubricant additive in fully formulated engine oil. The phase of TiO2 nanoparticles, synthesized by a sol–gel process, was characterized by XRD. A four-ball tribometer was used to compare the friction coefficient and wear when lubricated by engine oil in absence and presence of TiO2 nanoparticles. The surface chemistry of tribofilm was observed by XPS. The experiments showed that phase of TiO2 nanoparticles plays great role in determining the friction-reducing and wear protection of engine oil containing TiO2 nanoparticles. TiO2 nanoparticles upon calcination at 300 °C are amorphous, showing lowest hardness and then best friction-reducing and wear protection performance in engine oil. Rutile nanoparticles obtained upon calcination at the temperature above 700 °C, on the contrary, act as abrasive in the sliding contact and present larger wear than the blank engine oil.

Optical characterization of Poly [2-methoxy-5-(2-ethylhexyloxy-p-phenylene vinylene] (MEH-PPV):C60, MEH-PPV:C60:TiO2 and MEHPPV:C60:ZnO Thin Films

In this work, ZnO and TiO2 nanoparticles were prepared separately by sol gel method. Structural, morphological and optical properties of both of them are studied. A hexagonal crystal structure of ZnO was formed, while different weight ratio of Anatase (85%) and rutile (15%) phases of TiO2 nanoparticles were formed as confirmed by the X-ray diffraction (XRD). In addition, The XRD and Raman spectroscopy showed that our materials are polycrystalline. The particles sizes were calculated by sheerer formula are found to be closed to that got from scanning electron microscope (SEM) and transmission electron microscope (TEM). The band gaps for both materials were calculated from Kubelka-Munk function using their measured diffuse reflection. The band gap for ZnO and TiO2 nanoparticles found to be 3.4 eV and 3.2 eV respectively. Poly [2-methoxy-5-(2-ethylhexyloxy-p-phenylene-vinylene] which named MEH-PPV with C60 were dissolved and spin coated on glass substrates to get thin film. Structural, morphological and optical properties of this thin film were studied. Also, the effects of adding any of our metal oxides nanoparticles (ZnO or TiO2) on the physical properties of MEH-PPV:C60 are studied. All results are correlated to check the applicability of using these layers as an absorber layer for solar energy applications.

Simultaneous photocatalytic and catalytic activity of p–n junction NiO@anatase/rutile-TiO2 as a noble-metal free reusable nanoparticle for synthesis of organic compounds

Photocatalytic and catalytic activity of NiO loaded on mixture of anatase/rutile phases of TiO2 nanoparticles were investigated for some organic reactions including selective oxidation of alcohols, synthesis of benzimidazoles and preparation of imines at room temperature. The p–n junction formed between NiO and TiO2 as well as difference between band gaps in anatase/rutile phases facilitated electron transfer to TiO2 and successfully promoted synthesis of compounds. The use of a reusable photocatalyst without noble metal co-catalysts, along with the mild reaction conditions and use of light energy, make this method as an environmentally benign and energy saving chemical procedure.

Synthesis of Titanium Dioxide Nanoparticles Using a Double-Slit Curved Wall-Jet Burner

ABSTRACTA novel double-slit curved wall-jet (DS-CWJ) burner was proposed and utilized for flame synthesis. This burner was comprised of double curved wall-jet nozzles with coaxial slits; the inner slit was for the delivery of titanium tetraisopropoxide (TTIP) precursor while the outer one was to supply premixed fuel/air mixture of ethylene (C2H4) or propane (C3H8). This configuration enabled rapid mixing between the precursor and reactants along the curved surface and inside the recirculation zone of the burner. Particle growth of titanium dioxide (TiO2) nanoparticles and their phases was investigated with varying equivalence ratio and Reynolds number. Flow field and flame structure were measured using particle image velocimetry (PIV) and OH planar laser-induced fluorescence (PLIF) techniques, respectively. The nanoparticles were characterized using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and nitrogen adsorption Brunauer–Emmett–Teller (BET) for surface area analysis. The flow field consisted of a wall-jet region leading to a recirculation zone, an interaction jet region, followed by a merged-jet region. The DS-CWJ burner revealed appreciable mixing characteristics between the precursor and combustion gases near the nozzle regions, with a slight increase in the axial velocity due to the precursor injection. The precursor supply had a negligible effect on the flame structure. The burner produced a reasonably uniform size (13–18 nm) nanoparticles with a high BET surface area (>100 m2/g). The phase of TiO2 nanoparticles was mainly dependent on the equivalence ratio and fuel type, which impact flame height, heat release rate, and high temperature residence time of the precursor vapor. For ethylene flames, the anatase content increased with the equivalence ratio, whereas it decreased in the case of propane flames. The synthesized TiO2 nanoparticles exhibited high crystallinity and the anatase phase was dominant at high equivalence ratios (ϕ > 1.6) for C2H4, and at low equivalence ratios (ϕ < 1.3) for the C3H8 flame.

Synthesis, microstructure, and properties of black anatase and B phase TiO2 nanoparticles

We report the preparation of black TiO2 nanoparticles by UV irradiation of monodispersed TiO2-B nanoparticles with an average size of 5.0nm. After heating, the light-induced electron doping (Ti3+) TiO2-B nanoparticles in argon, air-stable black TiO2-B nanoparticles were obtained by heating at 340°C and further transformed to black anatase TiO2 by heating at 360°C. A characteristic single electron signal of electron paramagnetic resonance indicates oxygen vacancies with trapped electrons in black TiO2-B and black anatase TiO2. HRTEM images demonstrate that the black TiO2 samples have TiO2/TiO2−x core-shell heterostructures. Both of the black TiO2-B and black anatase TiO2 show room temperature superparamagnetic behavior and efficient photocatalysis under visible light.

Effect of aging on the properties of TiO2 nanoparticle

Effect of aging on the properties of titanium dioxide nanoparticles produced by laser ablation process in water is investigated experimentally. The fundamental wavelength of a Q-switched Nd:YAG laser was employed to irradiate a high-purity Ti plate in distilled water at temperatures of 20, 35, 50 and 65 °C. Produced nanoparticles were diagnosed by UV–Vis–NIR spectroscopy, X-ray diffraction method, and dynamic light scattering device immediately after production and 1 week after. Bandgap energy of samples was extracted using Tauc method. Size of nanoparticles was increased after a week and their bandgap energy was decreased. Results show that the phase of TiO2 nanoparticles was transited from brookite to rutile after 1 week.

Formation and Characterization of TiO&lt;sub&gt;2&lt;/sub&gt; Scattering Layer Deposited by Spray Pyrolysis for DSSC

In this paper the TiO2 nanoparticle for scattering layers were prepared using hydrolytic and non-hydrolytic sol gel route. The TiO2 nanoparticles by hydrolytic sol gel were prepare by adding 5 ml of titanium (IV) isopropanol (TTIP) with 15 ml isopropanol. Then this TTIP mixture was added dropwise into 250 ml water with adjusted pH to 3 using nitric acids. For non-hydrolytic sol gel route 12 gram of acetylacetone, 12 gram of TTIP and 16 gram of ethanol anhydrous were mixed in a beaker under vigorous stirring. Then the prepared TiO2 nanoparticles solutions were deposited onto TiO2 mesoporous layer via spray pyrolysis and assemble into complete solar cell. From the XRD (X-ray diffraction) results show that the phase of TiO2 nanoparticles formed by hydrolytic sol gel route was amorphous and for non-hydrolytic route the phase formed was mixture of anatase and rutile. The efficiency of the solar cell shows that scattering layer prepare by hydrolytic route give higher efficiency, 6.0 x 10-5 %, as compare to scattering layer prepare by non-hydrolytic route, 4.9 x 10-5 %.

Simple Crystal Phase Control of TiO2Nanoparticles via Pulsed Laser Ablation in Nitric Acid

It has long been known that anatase, brookite, and rutile are the major crystalline structures of TiO2, of which the rutile phase is the most stable; whereas anatase and brookite phases are metastable and easily transformed to the rutile phase by heating above about 600-800 C. A number of investigations have been made on controlling the crystal structure and morphology of TiO2 using a variety of synthetic methods, such as by hydrolysis of Ti ions, hydrolysis of titanium alkoxides or titanium tetrachloride in the gas phase, sol-gel, hydrothermal hydrolysis, and precipitation. Furthermore, a variety of attempts have been made to enhance the photocatalytic effects of TiO2, including metallic and non-metallic doping, nano-size reduction, and its use in bi-metallic catalysis. However, there is no report on the selective synthesis of the different phases of TiO2 nanoparticles, involving different ratios of anatase and rutile, prepared in an ambient environment, i.e., through the variation of HNO3 concentration, without extreme temperature and pressure conditions. Here, we present an approach that differs from the previously mentioned methods for the synthesis of TiO2 nanoparticles. In our case we have employed a pulsed laser to ablate a Ti plate immersed in water. Pulsed laser ablation in liquid (PLAL) has been demonstrated to be a simple, versatile, and clean method for preparing metal and metal oxide nanomaterials due to the use of high purity starting materials, no requirement for a catalyst, and reduced byproducts, provided an appropriate metal and liquid is chosen. Recent studies have demonstrated that PLAL of metal plates employing different parameters, such as laser wavelength, power, and the presence of surfactants, can lead to different products, sizes, and/or morphologies. Nonetheless, there are few reports of the formation of TiO2 via PLAL. Furthermore, most studies have focused on the preparation of anatase and rutile TiO2 in the absence/presence of surfactants; however, the systematic preparation employing different ratios of anatase/rutile TiO2 has not been studied before. In this work, we have controlled the ratios of anatase/ rutile TiO2 nanoparticles by changing the concentration of HNO3. XRD measurements of the samples were employed in order to determine the crystal structure and the crystallinity of the prepared TiO2 samples prepared via PLAL. The XRD patterns illustrated in Figure 1 correspond to the crystalline phases of the TiO2 samples prepared via PLAL using various concentrated HNO3 solutions. Figure 1(a), (b), and (c) present XRD patterns over a scan interval from 10 to 90 for the as-is sample of TiO2 via PLA in DI water (a), 10 −3 M (b), and 1 M solution of HNO3 (c), respectively. It is seen that the XRD patterns for samples, (a) and (c), obtained via PLA in DI water and 1 M HNO3 solution match the standard anatase (JCPDS number: 00-021-1272) and rutile (JCPDS number: 00-021-1276) patterns, respectively. The XRD pattern shown in Figure 1 (b) indicates that mixed phases of TiO2, anatase and rutile are formed in 10 M HNO3 solution. While it is generally the case that rutile TiO2 is fabricated from calcination of anatase TiO2 above 600-800 C; in this work the rutile phase is simply and selectively obtained in 1 M HNO3 solution at ambient conditions. According to the XRD patterns shown in (a), (b), and (c), the peaks are broader than those in (d), (e), and (f). From the Scherrer equation, peak broadness is inversely related to the full width at half maximum of an individual peak; the broader peak, the smaller crystallite size. Thus, it is apparent that the TiO2 nanoparticles prepared at low concentrations of HNO3 (Figure 1(a)-(c)) were smaller than the particles produced at higher

The Size Effect of TiO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; Anatase Nanoparticles on Photon Correlation Spectroscopy

In this work, the anataze phase of TiO2 nanoparticles was prepared by sol gel method. We changed time and temperature of calcinations to change size and property of nanoparticles. The Transmission Electron Microscopy and Scanning Electron Microscopy were used for characterization of the TiO2 nanoparticles. The nanoparticle size was increased with time and temperature. We found that the average size of samples was changed from 30 to 46 nm with changing temperature from 450℃ to 650℃ and at fixed temperature (450℃) with changing of calcination times from 1 to 3 hours, the size was changed from 30 to 58 nm. For study the dynamic of nanoparticles, the TiO2 nanoparticles were added to water with 2.4 weights present of particles to the water. The different size of TiO2 nanoparticles was studied with photon correlation spectroscopy. The relaxation time was increased with increasing of nanoparticle size and so diffusion coefficient was decreased.

Formation of Spherical and Rod-Shaped TiO&lt;sub&gt;2&lt;/sub&gt; Nanocrystals Prepared by Reverse Micelle Method

Uniform spherical- and rod-shaped TiO2 nanoparticles of anatase phase were prepared using decanoic acid at 300°C by reverse micelle method. The nanoparticles were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffractometry (XRD) and FT-Raman spectroscope. The content of decanoic acid and operating temperature were noted as crucial parameters, controlling the shape, size and phase of TiO2 nanoparticles. RMS roughness (1.62 nm), measured by atomic force microscope (AFM), confirmed its superiority over other methods. The DCB photodegradation reaction rate constant (first order) TiO2 nanoparticles was found superior to that of commercial TiO2, Degussa P-25.