Showing papers on "Sol-gel published in 2014"
TL;DR: A novel and inexpensive route for the preparation of spinel magnesium aluminate nanoparticles (MgAl2O4) is proposed by synthesizing via sol-gel auto combustion method using oxalic acid, urea, and citric acid fuels at 350°C.
153 citations
TL;DR: In this paper, a sol-gel processed semi-transparent, durable and self-cleaning super-hydrophobic coatings on glass using a silica-PMMA composite are presented.
Abstract: Optically transparent, mechanically durable, and self-cleaning superhydrophobic coatings are greatly awaited for applications in daily life. An attempt has been made to develop sol–gel processed semi-transparent, durable and self-cleaning superhydrophobic coatings on glass using a silica–PMMA composite. A water drop acquires a near spherical shape on the coating exhibiting a water contact angle of ∼159° and immediately rolled off under small disturbance. A 10 μl water drop could individually collect around 10 mg of dirt particles along the way whilst rolling off the coating surface. The superhydrophobicity of the coatings remained intact under the impact of a water jet. A water jet hits the superhydrophobic coating and was repelled straightaway off the surface, without leaving any trace of water. These coatings showed both strong superhydrophobicity and superoleophilicity. We observed an improvement in mechanical stability, as well as optical transparency of the coatings in the visible range after low loadings of PMMA polymer (2 vol%) in silica. The prepared coatings maintained excellent superhydrophobicity even after 6 months storage under normal conditions in air.
151 citations
TL;DR: In this paper, the effect of annealing temperature on the structural and optical properties of titania nanoparticles was investigated by means of X-ray diffraction, Raman spectroscopy, UV-visible spectrograph, and photoluminescence.
Abstract: Titania nanoparticles have been prepared using different surfactants such as, acetic acid (AA), oleic acid (OA), oley amine (OM), and a mixture of OA + OM at room temperature by sol–gel method. TiO2 nanoparticles were collected by centrifugation of the precipitate obtained during gel formation. The collected samples were annealed at 550 and 950 °C to study the effect of annealing temperature on the structural and optical properties. The crystal structure and optical properties of titania nanoparticle is investigated by means of X-ray diffraction, Raman spectroscopy, UV–visible spectroscopy, and photoluminescence. After heat treatment at 950 °C, the mixed rutile and anatase phase of TiO2 was revealed for the sample prepared with AA, whereas pure rutile phase was observed for the sample prepared in presence of OA, OM and the mixture of OA + OM. The energy band gap and transmittance of measured for titania nanoparticles was found to be systematically reduced with increase in annealing temperature for each surfactant. The ideality factor decreases with increase in annealing temperature for all surfactants could be related to the voltage dependence of the standard deviation of the distribution of barrier heights.
107 citations
TL;DR: A novel core-shell magnetic nano-sorbent with surface molecularly-imprinted polymer coating was prepared via a sol-gel process and successfully applied to solid phase extraction followed by spectrophotometric determination of DMZ in real samples.
92 citations
TL;DR: In this article, a robust, super-hydrophobic, and transparent polysilicon-coated glass substrate was fabricated on glass substrates by a sol-gel method at a temperature of 80°C.
90 citations
TL;DR: In this article, the microstructure and surface morphology of the TiO2 films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), with respect to the film thickness.
Abstract: Transparent semiconducting thin films of titanium oxide (TiO2) were deposited on glass substrates by the sol–gel method and spin-coating technique. The physical properties of the prepared films were studied as a function of the number of spun-cast layers. The microstructure and surface morphology of the TiO2 films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), with respect to the film thickness. The XRD analysis reveals that the films are polycrystalline with an anatase crystal structure and a preferred grain orientation in the (101) direction. The morphological properties were investigated by AFM, which shows a porous morphology structure for the films. The optical properties of the films were characterized by UV–Visible spectrophotometry, which shows that the films are highly transparent in the visible region and their transparency is slightly influenced by the film thickness, with an average value above 80 %. The dependence of the refractive index (n), extinction coefficient (k), and absorption coefficient (α) of the films on the wavelength was investigated. A shift in the optical band gap energy of the films from 3.75 to 3.54 eV, as a function of the film thickness, has been observed.
89 citations
TL;DR: In this article, platelet-shaped lithium orthosilicate particles synthesized by a sol-gel approach employing the precursors lithium nitrate and colloidal silica displayed enhanced absorption kinetics for CO2 compared to the powders prepared by a solid-state reaction process involving Li2CO3 and silica.
Abstract: Platelet-shaped lithium orthosilicate particles synthesized by a sol–gel approach employing the precursors lithium nitrate and colloidal silica displayed enhanced absorption kinetics for CO2 compared to the powders prepared by a solid-state reaction process involving Li2CO3 and silica. The sol–gel samples showed a CO2 absorption capacity of 350 mg g−1 at an absorption rate of 22.5 mg g−1 min−1, a value 70% higher than the rate of 13.2 mg g−1 min−1 measured with the solid-state samples under similar conditions. The higher sorption kinetics of CO2 by the sol–gel derived lithium orthosilicate could be attributed to the unique platelet morphology of the particles, which have a very small thickness. A porous carbon mesh coated with the sol–gel based particles exhibited CO2 absorption capacity of 150 mg g−1 at an absorption rate of 37.5 mg g−1 min−1. This supported absorbent also showed stable absorption and desorption performance for the 8 cycles examined in this study. The excellent absorption characteristics of the sol–gel prepared powders, more specifically the coated strips, provide a successful pathway for the commercialisation of these materials.
84 citations
TL;DR: A facile sol-gel method has been developed to create a superhydrophobic surface on aluminum substrate with tetraethylorthosilicate (TEOS) and vinyltriethoxysilane (VTES) as co-precursor at room temperature as mentioned in this paper.
Abstract: A facile sol–gel method has been developed to create a superhydrophobic surface on aluminum substrate with tetraethylorthosilicate (TEOS) and vinyltriethoxysilane (VTES) as co-precursor at room temperature. Firstly, nanometer sized silica particles were self assembled on the substrate through the hydrolysis of TEOS. Then, the silica particles were modified with vinylsiloxane through the hydrolysis and condensation polymerization of VTES. The emphasis was focused on investigating the influence of the molar ratio between NH3·H2O and ethanol on the surface morphology and wetting property. The surface morphology was observed by scanning electron microscopy (SEM), the chemical composition and bonding state of the surface were explored by energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectra (XPS), and the wetting property of the surface was investigated by water contact angle measurement (WCA). The modified silica-based surface possessed the greatest static contact angle of 154.9°, exhibiting excellent superhydrophobic property. A hierarchical microstructure with spherical microparticles of around 2 μm decorated with nanoparticles of around 450 nm was observed on the film surface. The surface was covered by hydrophobic vinyl groups via the decoration of silica microparticles with vinyl-terminated siloxane nanoparticles as evidenced by EDS, FTIR and XPS. The corrosion resistant performance and durability of the superhydrophobic silica-based surface formed on aluminum substrate in corrosive NaCl solution were estimated by electrochemical impedance spectroscopy (EIS) measurements. The appropriate equivalent circuit model was put forward to fit and analyze the EIS data. The electrochemical result revealed that the corrosion resistant performance of aluminum was improved greatly by the superhydrophobic treatment.
82 citations
TL;DR: In this article, the formation mechanisms of different ZnO morphologies were also investigated based on the experimental results, and the results indicated that the flower-like morphologies possessed superior photocatalytic activity compared to other morphologies, which could be attributed to the morphology, surface defects, band gap and surface area.
81 citations
TL;DR: The ability to use readily available cheap raw materials, for the synthesis of such well-defined crystallites of hydroxyapatite, is an added advantage of this method, which may be explored further for the scaling up of the procedures to suit to industrial scale synthesis.
81 citations
TL;DR: In this paper, a pH sensor based on polymethylmethacrylate (PMMA) optical fibers has been developed for on-body monitoring in biological fluids, which relies on evanescent wave absorption in a thin film deposited on the fiber core.
Abstract: A pH sensor based on polymethylmethacrylate (PMMA) optical fibers has been developed for on-body monitoring in biological fluids. Detection relies on evanescent wave absorption in a thin film deposited on the fiber core. The sensitive film was prepared using sol–gel technology from a mixture of tetraethyl orthosilicate (TEOS) and methyltriethoxysilane (MTES) or phenyltriethoxysilane (PTES), forming a porous hybrid organic–inorganic layer upon drying. The so-called ORMOSILs (organically modified silicate) were doped with bromophenol blue (BB) and the formulation was optimized to suppress dye leaching by varying the fraction of organic precursor, the sol aging time and the drying conditions. The molecular structure of the films was examined by Fourier-transformed infrared (FTIR) spectroscopy, and their optical responses characterized with UV–VIS absorption spectroscopy. Homogeneous crack-free films were obtained with an optimal MTES content of 50%. Leaching from these films was greatly reduced, with more than 80% of dyes remaining after 2 months in phosphate buffered saline (PBS) buffer. The entrapped indicator showed pronounced increase of apparent pKa and a broader response range compared to the free form in solution. The sensor demonstrated good sensitivity from pH 3 to 9, with an optical signal variation of 3.5 dB. It showed sensitivity to ionic strength variations, but not to temperature in the range between 20 and 50 °C. Reversible pH monitoring between pH 5 and 8 with a precision of 0.2 pH unit was demonstrated in human serum as a model biological fluid, without degradation of the sensing fiber over 24 h. This simple and low cost device will be particularly valuable to support diagnosis and the evaluation of therapies for wound healing.
TL;DR: In this paper, pure and transition metal (TM = Ni, Mn, Co, Co) doped zinc oxide (ZnO) thin films were prepared by sol-gel spin coating method with a concentration of 003 Mol% of transition metals X-ray diffraction studies revealed the polycrystalline nature of the films with the presence of hexagonal wurtzite structure UV transmittance spectra showed that all the films are highly transparent in the visible region and in the case of doped ZnO thin films, d-d transition was observed in
TL;DR: In this article, a sol-gel method was proposed to synthesize pure TiO 2 and ZrO 2 -TiO 2 samples using titanium oxychloride as a precursor and zirconyl nitrate hydrate as a source in the presence of the surfactant.
TL;DR: In this article, the effect of the annealing temperature on the structural and optical properties of NiO thin films was studied and the results showed that 600°C is the optimum anneal temperature for NiO films with p-type conductivity and high optical transparency.
TL;DR: In this paper, optically transparent Al 2 O 3 thin films have been successfully synthesized by combining a sol-gel spin-coating process with one of two different annealing methods.
TL;DR: A novel, scaled-up sol-gel synthesis which enables one to produce 20 g batches of highly active and stable carbon supported PtCu3 nanoparticles as cathode materials for low temperature fuel cell application is presented.
TL;DR: In this article, an 80nm-thick ZnO film was prepared via the sol-gel method at 500°C using zinc acetate, 2-methoxyethanol, and monoethanolamine as precursors.
TL;DR: In this paper, the two-step dip coating via a sol-gel process to prepare super-hydrophobic silica films on the glass substrate was studied and the water repellency was controlled by surface silylation method using isooctyltrimethoxysilane (iso-OTMS) as a surface modifying agent.
TL;DR: In this article, the anatase structure of titanium dioxide was obtained after calcination using a Scanning Electron Microscope (SEM) and an X-ray diffractometer (XRD).
Abstract: 4 ABSTRACT: Nanosized Titanium dioxide (TiO2) powder was synthesized via sol-gel method using titanium tetraisopropoxide (TTIP) as the precursor. The as prepared nano powder was used for further characterization. The phase transformation was investigated by an X-ray diffractometer (XRD). The anatase structure of titanium dioxide was obtained after calcination. The microstructure was characterized by a Scanning Electron Microscope (SEM).
TL;DR: In this article, Nanocrystalline NiO-CeO2 binary oxide was synthesized via glycol assisted citrate sol-gel method for ultracapacitor and the observed electrochemical measurements further reveal the strong pseudocapacitance features of the mixed oxides at different current density.
Abstract: Nanocrystalline NiO–CeO2 binary oxide as a novel electrode material for ultracapacitor was synthesized via glycol assisted citrate sol–gel method. Unique cubic phases with aggregated crystalline microstructure of NiO–CeO2 mixed oxides were examined by X-ray diffraction and transmission electron microscope. The observed electrochemical measurements further reveal the strong pseudocapacitance features of the mixed oxides at different current density. Binary oxide annealed at 500 °C shows an optimum specific capacitance (Cs) of 305 Fg−1 at the constant current density of 1 Ag−1. The achieved Cs value undoubtedly certifies that in combination with NiO the structural stability and redox property of CeO2 have been enhanced. Especially, increasing the calcination temperature binary oxide has shown well reversible redox features which confirm the high chemical and thermal stability of CeO2 and it could be involve in the charge storage process effectively by their strong Ce3+/Ce4+ redox couples. Capacity retention and cyclic stability of the electrode was quite good, only ∼5 % capacity fading was observed after 1,000 cycles. Moreover, binary oxide calcined at 700 °C exhibits a specific capacitance of 167 Fg−1 at the constant current density of 1 Ag−1 which states that presence of CeO2 with NiO have controlled the grain growth and maintains their porous microstructure even at 700 °C. This facilitates to the redox process at both NiO and CeO2 active surfaces at elevated temperature significantly.
TL;DR: In this paper, a survey of the synthesis of nanocomposites and organic-inorganic hybrids from sol-gel chemistry under polymer processing is presented, and the potential for in situ synthesis of functional nanofillers using appropriate inorganic precursors is demonstrated.
TL;DR: The colloidal ZnO/PVP/methanol solution, apart from the most intense PL band at 356 nm coming from the PVP, exhibits a strong PL band which corresponds to the emission of the free exciton recombination in Zn O nanoparticles.
Abstract: We propose a method for the synthesis of a colloidal ZnO solution with poly(N-vinylpyrrolidone) (PVP) as stabilizer. Stable colloidal solutions with good luminescence properties are obtained by using PVP as stabilizer in the synthesis of ZnO nanoparticles by a sol–gel method assisted by ultrasound. Nanoparticles with sizes of 30–40 nm in a PVP matrix are produced as a solid product. The colloidal ZnO/PVP/methanol solution, apart from the most intense PL band at 356 nm coming from the PVP, exhibits a strong PL band at 376 nm (3.30 eV) which corresponds to the emission of the free exciton recombination in ZnO nanoparticles.
TL;DR: In this article, the morphologies, phase composition, open porosity, pore size distribution and mechanical strength of porous ceramics were examined as a function of alumina sources (calcined nano-sized alumina powder and alumina sol prepared from hydrolysis of aluminum isopropoxide) and contents.
Abstract: In the present work, mullite-bonded porous SiC ceramics were fabricated using reaction bonding techniques. The morphologies, phase composition, open porosity, pore size distribution and mechanical strength of porous ceramics were examined as a function of alumina sources (calcined nano-sized alumina powder and alumina sol prepared from hydrolysis of aluminum isopropoxide) and contents. It was found that the addition of alumina in powder form effectively enhanced the strength and decreased the porosity. In contrast, when alumina was added in sol form, a reverse effect was observed. Moreover, it was revealed that when a portion of calcined alumina was replaced by alumina sol, the mechanical properties improved significantly (more than 30%) as well as porosity compared to the traditional method. Pore size distribution analysis showed that the dispersion of nanosize alumina powder and SiC micro-particles in alumina sol is strongly improved compared to mixing in ethanol.
TL;DR: In this article, a shape-stabilized phase change material composite was prepared by impregnating the mixture of hydrated salts into porous silica matrix obtained by sol-gel process and further coated with polyvinylpyrrolidone to improve the thermal cycling performance.
TL;DR: In this article, crack-free nanostructured barium titanate thin films are prepared by a sol-gel processing method, where very thin films (thickness = 26nm) are deposited on fused silica substrates.
TL;DR: In this paper, the TiO 2 nanoparticles were synthesized by sol-gel method initiating titanium isopropoxide-propanol mixture as a precursor solution, and the obtained TiO2 nanoparticles are then deposited onto the glass substrate using dip-coating method under optimized conditions.
Abstract: The TiO 2 nanoparticles were synthesized by sol–gel method initiating titanium isopropoxide–propanol mixture as a precursor solution. The obtained TiO 2 nanoparticles were then deposited onto the glass substrate using dip-coating method under optimized conditions. The ethanol sensing behaviour of the prepared TiO 2 thin film was studied by chemiresistive method at room temperature (∼30 °C). The nanoparticle of TiO 2 as thin film formed exhibited good sensing response of 535% with response–recovery times of 5 s and 52 s, respectively, in the presence of 50 ppm of ethanol vapour. The effect of electrical resistance hysteresis was also discussed to emphasize the reversible nature of the TiO 2 film.
TL;DR: In this article, a simple sol−gel method was used to obtain a blue-shift of the band gap of the TiO 2 −MgO mixed metal oxide nanoparticles with variable MgO content.
TL;DR: The effects of La substitution on the microstructure, morphology, and carrier density of BLSO films have been investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy, and Hall effect measurement as discussed by the authors.
Abstract: Perovskite-structured Ba1–xLaxSnO3 (BLSO, x = 0–0.10) films have been directly deposited on (0001) sapphire substrates by a sol–gel method. The effects of La substitution on the microstructure, morphology, and carrier density of the BLSO films have been investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and Hall-effect measurement. XRD analysis shows that all of the films are of a single perovskite phase and the calculated lattice constants agree well with the theoretical lattice parameters. The AFM and SEM pictures show that the BLSO films do not contain cracks with the root-mean-square surface roughness of 2 nm. Temperature dependent conductivity behavior suggests that BLSO films do have a metallic-like conduction, but the resistivity in poly samples is dominated by grain boundary scattering and ionized-dopant scattering. The films exhibit high transparency with more than 80% in the visible region, which is due to the prohibition of electron trans...
TL;DR: In this article, the effect of Fe3+-doping on the optical properties and photocatalytic activity were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), ultraviolet-visible spectroscopy, spectroscopic ellipsometry and the degradation of methylene blue.
TL;DR: In this article, the effect of coating thickness and pore sizes of SiC foam supports on the photocatalytic performance was studied, and a synergistic effect between the p-type semiconductive SiC Foam supports and the n-type TiO2 coating was proposed to account for this enhanced performance.
Abstract: Structured TiO2–SiC photocatalysts were prepared by coating TiO2 nanoparticles on Si incorporated SiC foam supports, and their photocatalytic activities toward degradation of organic contaminant under UV light irradiation were evaluated by taking 4-aminobenzenesulfonic acid (4-ABS) as a model contaminant. In comparison to SiC foam support and TiO2 nanoparticles the TiO2–SiC photocatalysts exhibited significantly enhanced photocatalytic performance. The effects of coating thickness of TiO2 and pore sizes of the SiC foam supports on the photocatalytic activities were studied. A synergistic photocatalytic effect between the p-type semiconductive SiC foam supports and the n-type TiO2 coating was proposed to account for this enhanced photocatalytic properties.