Sonoemulsion Synthesis of Long CuO Nanorods with Enhanced Catalytic Thermal Decomposition of Potassium Perchlorate

A facile sonoemulsion route using suitable non-ionic surfactant, polyethylene glycol with molecular weight of 8000 (PEG8000) was developed to synthesize long CuO nanorods with average diameter of 15–20 nm and lengths up to 1.5 μm. The as-developed CuO nanorods were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, SAED and Raman spectroscopy. The Raman spectrum of as-synthesized nanorods was found to be red-shifted and broadened due to possible consequence of phonon confinement, electron–LO–phonon-coupling and internal compressive stresses. The dynamics of nanorod growth was elaborated in context of size aggregation effect fueled by ultra-sonication and steric hindrance effect imposed by PEG8000. The catalytic activity of CuO nanorods in thermal decomposition of potassium perchlorate was examined by thermogravimetric analysis technique. The CuO nanorods prepared by sonoemulsion route was found to be very effective in thermal decomposition of potassium perchlorate with significant reduction in thermal decomposition temperature.     

Different morphologies of ZnO nanostructures via polymeric complex sol–gel method: synthesis and characterization

Various morphologies of ZnO nanostructures, such as nanoparticles, nanorods and nanoflowers have been achieved controllably by polymeric sol–gel method. In this approach, zinc nitrate Zn(NO₃)₂·6H₂O, citric acid and ethylene glycol were used as the source of Zn²⁺, the chelating agent and the solvent agent, respectively. The microstructure of the ZnO nanostructures was characterized by X-ray diffractometry, scanning electron microscopy with the energy dispersive X-ray spectroscopy, transmission electron microscopy, thermogravimetric analysis and Fourier transform infrared spectroscopy. The effect of ethylene glycol to citric acid mole ratio on the morphology and structure of the products was discussed. The ZnO nanoparticles with diameter between 24 ± 2 nm was obtained with EG:CA mole ratio equal to 2:1. The optical properties of as-obtained power were investigated by ultraviolet–visible spectroscopy.     

Solvent-Free Synthesis of ZnO Nanoparticles by a Simple Thermal Decomposition Method

This paper reports on a novel processing route for producing ZnO nanoparticles by solid-state thermal decomposition of zinc(II) acetate nanostructures obtained by the sublimation of zinc(II) acetate powder. The sublimation process of the Zn(OAc)₂ powder was carried out in the temperature 150 °C for 2 h. In addition, nanoparticles of ZnO were obtained by solid-state thermal decomposition of the synthesized Zn(OAc)₂ nanostructures. The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, and energy dispersive X-ray spectroscopy. The sublimation process of the Zn(OAc)₂ powder was carried out within the range of 150–180 °C. The XRD studies indicated the production of pure hexagonal ZnO nanoparticles after thermal decomposition.     

Preparation and nonlinear optical properties of Au nanoparticles doped TiO2 thin films

Nano-sized noble metal nanoparticles doped dielectric composite films with large third-order nonlinear susceptibility due to the confinement and the enhancement of local field were considered to be applied for optical information processing devices, such as optical switch or all optical logical gates. In this paper, sol–gel titania thin films doped with gold nanoparticles (AuNPs, ~10 nm in average size) were prepared. AuNPs were firstly synthesized from HAuCl₄ in aqueous solution at ~60 °C, using trisodium citrate as the reducing agent, polyvinylpyrrolidone as the stable agent; then the particle size and optical absorption spectra of the AuNPs in aqueous solutions were characterized by transmitting electron microscopy and UV–Vis–NIR spectrometry. Sol–gel 2AuNPs–100TiO₂ (in %mol) thin films (5 layers, ~1 μm in thickness) were deposited on silica glass slides by multilayer dip-coating. After heat-treated at 300–1,000 °C in air, the AuNPs–TiO₂ thin films were investigated by X-ray diffraction, scanning electron microscopy and atomic force microscopy. The nonlinear optical properties of the AuNPs–TiO₂ thin films were measured with the Z-scan technique, using a femtosecond laser (200 fs) at the wavelength of 800 nm. The third-order nonlinear refractive index and nonlinear absorption coefficient of 2AuNPs–100TiO₂ films were at the order of 10^?12 cm²/W, and the order of 10^?6 cm/W, respectively, and the third-order optical nonlinear susceptibility χ⁽³⁾ was ~6.88 × 10^?10 esu.     

A Facile Sonochemical Method for Synthesis of Mercury Selenide Nanostructures

Mercury selenide (HgSe) nanostructures has been achieved from N–N′-bis(salicylaldehyde)-1,2-phenylenediimino mercury [Hg(salophen)] as a new precursor. Cubic phase HgSe nanoparticles with the size of mostly 20–40 nm were produced by sonication of the Hg(salophen) precursor. The products were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, photoluminescence, energy dispersive X-ray spectroscopy and Fourier transformed infrared spectroscopy. The results of this paper show that the shape and size of mercury selenide nanostructures can be controlled systematically by adjusting reaction parameters, such as the ultrasonic power, temperature, capping agent and reaction time.     

Synthesis and characterization of Na2O–CaO–SiO2 glass–ceramic

The Na₂O–CaO–SiO₂ ternary glass–ceramic with the composition of 49 mass% Na₂O, 20 mass% CaO, and 31 mass% SiO₂ was prepared by the conventional method. The ternary glass–ceramic was characterized using X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques. The Na₂CaSiO₄ phase, having the cubic crystal system, with the crystallite size of 25.14 nm and lattice parameter of 0.7506 nm was determined from the XRD pattern. The activation energy of the glass–ceramic calculated from the DTA curves was found to be 162.02 kJ mol^?1. The Avrami exponent was found to be ~2 indicating a one-dimensional growth process. The mass loss percent from ambient temperature to 1,173 K is less than 1 %. The density was calculated to be 2,723 kg m^?3. The fine-grained microstructure with the particle sizes less than 1 μm was confirmed by the scanning electron microscope micrograph.     

MnCo<Subscript>2</Subscript>O<Subscript>4</Subscript> nanoparticles with excellent catalytic activity in thermal decomposition of ammonium perchlorate

MnCo₂O₄ spinel nanoparticles (NPs) have been prepared using Aloe vera gel solution. The characterization of prepared spinel was performed applying Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron spectroscope, scanning electron microscope and dynamic light scattering. The results manifested that the prepared nanoparticles were mainly spherical plus minor agglomeration with average size distribution between 35 and 60 nm. The catalytic activity of the prepared nanoparticles upon thermal degradation of ammonium perchlorate (AP) was evaluated applying differential scanning calorimetry and thermogravimetry instruments. MnCo₂O₄ nanoparticles increased the released heat of AP from 450 to 1480 J g^?1 and decreased the decomposition temperature from 420 to 293 °C. The kinetic parameters obtained from Kissinger methods showed that the activation energy of AP thermal decomposition in the presence of MnCo₂O₄ NPs considerably decreased. Also, a mechanism has been proposed in the presence of catalyst for the process of thermal decomposition of AP.     

Perovskite-type ferromagnetic BiFeO3 nanopowder: a new magnetically recoverable heterogeneous nanocatalyst for efficient and selective transfer hydrogenation of aromatic nitro compounds into aromatic amines under microwave heating

Perovskite-type ferromagnetic BiFeO₃ nanopowder was readily synthesized via thermal decomposition of Bi[Fe(CN)₆]·5H₂O complex and characterized using thermal analysis (TGA/DSC), X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT–IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), magnetic measurement and Brunauer–Emmett–Teller (BET) specific surface area measurements. The magnetic measurements show a ferromagnetic behavior for the BiFeO₃ nanoparticles at room temperature. This nanosized ferromagnetic oxide with an average particle size of approximately 20 nm and a specific surface area of 48.5 m²/g was used as a new magnetically recoverable heterogeneous nanocatalyst for the highly efficient and selective reduction of aromatic nitro compounds into their corresponding amines by using propan-2-ol as the hydrogen donor under microwave irradiation. This method is regio- and chemoselective, clean, inexpensive and compatible with the substrates having hydrogenlyzable or reducible functional groups. As compared with conventional heating, this method is very fast and suitable for the large-scale preparation of different substituted anilines as well as other arylamines. The catalyst can also be reused without loss of activity.     

Preparation and Characterization of NiO Nanoparticles Via Solid-State Thermal Decomposition of Nickel(II) Schiff Base Complexes [Ni(salophen)] and [Ni(Me-salophen)]

This study focuses on the preparation and characterization of nickel oxide nanoparticles from nickel(II) Schiff base complexes as new precursors. At first nickel(II) complexes [Ni(salophen)] and [Ni(Me-salophen)] were synthesized and characterized by elemental analyses and FT-IR spectroscopy. Then NiO nanoparticles were prepared by solid-state thermal decomposition at 550 ºC for 3.5 h. The FT-IR spectrum confirmed the composition of products. The crystalline structures and morphology of products were studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD results revealed that the obtained products were nickel oxide. SEM and TEM images demonstrated that the NiO nanoparticles have uniform shape with size between 35 and 70 nm.     

Thermokinetic characterisation of tin(II) chloride

Thermokinetic behaviour of SnCl₂ was investigated using differential scanning calorimetry and thermogravimetry techniques under non-isothermal conditions in air, complemented by electron microscopy and Raman spectroscopy. According to the results obtained, the oxidation of SnCl₂ at the heating rates of 5 and 100 °C min^?1 leads to the in situ formation of highly crystalline SnO₂ nanostructures in the form of nanoparticles and nanorods, respectively. The oxidation of SnCl₂ was found to be a liquid–solid (LS) phase transition at the heating rates equal or lower than 10 °C min^?1 and a gas–solid phase transition at the heating rates equal or greater than 20 °C min^?1. The activation energy of melting, vaporisation and LS oxidation of SnCl₂ was determined to be 198, 93 and 91 kJ mol^?1, respectively.     

Studies on photocatalytic performance and photodegradation kinetics of zinc oxide nanoparticles prepared by microwave-assisted sol–gel technique using ethylene glycol

ZnO nanoparticles with an average particle size of 27 nm were fabricated using a microwave-assisted sol–gel method in the presence of ethylene glycol. The nanoparticles were characterized by X-ray diffraction, Monshi’s equation, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The band gap energy of the nanoparticles was measured to be 3.27 eV by UV–Vis absorption and reflection spectroscopy. Photocatalytic activity of the synthesized nanoparticles was assessed by degrading nitrophenol in aqueous solution under UV-C irradiation. The effects of initial nitrophenol concentration, amount of photocatalyst, and of pH on the photodegradation process were investigated. Degradation samples were analyzed by UV–Vis spectroscopy. Nitrophenol was removed by 98 % within 240 min. The degradation kinetics were studied and fitted well to pseudo-first-order and Langmuir–Hinshelwood models.     

Synthesis of mesoporous Stöber silica nanoparticles: the effect of secondary and tertiary alkanolamines

The effect of secondary (diethanolamine) and tertiary (triethanolamine) alkanolamines as catalysts on the formation of mesoporous Stöber silica nanoparticles by sol–gel method was studied. The particles were characterized by thermogravimetry and differential thermal analysis, Fourier transform infrared spectroscopy, N₂ physisorption measurements, and field emission scanning electron microscopy. By using ammonia and different alkanolamines as catalysts, the Brunauer–Emmet–Teller (BET) surface area and pore volume increased in the order of ammonia < diethanolamine < triethanolamine. A maximum BET surface area of 140.1 m² g^?1 and pore volume of 0.66 cm³ g^?1 were obtained from triethanolamine catalyzed silica particles. The average particle size of silica prepared by ammonia and different alkanolamines as catalysts decreased in the order of ammonia > diethanolamine > triethanolamine. The role of different alkanolamines on the textural properties and particle size of silica is explained in terms of their relative steric hindrance and basicity.     

Synthesis and Characterization of CdS Nanoparticles via Cyclic Microwave from Cadmium Oxalate

The present study reports synthesis and characterization of CdS nanoparticles prepared by cyclic microwave route with the use of [Cd(C₂O₄)·3H₂O] powder as a precursor. The products, with an average size ~15 nm, were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray microanalysis, thermogravimetric analysis, transmission electron microscopy and Fourier transform infrared spectroscopy. Optical property of obtained product was investigated by photoluminescence spectroscopy. The prepared nanostructures displayed a very strong luminescence at 528 nm (2.34 eV) at room temperature.     

Synthesis and characterization of metallic copper nanoparticles via thermal decomposition

Copper oxalate was used as a precursor to prepare metallic copper nanoparticles by thermal decomposition. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and UV–Vis spectroscopy. XRD analysis revealed broad pattern for fcc crystal structure of copper metal. The particle size by use of Debye–Scherrer’s equation was calculated to be about 40 nm.     

Synthesis and luminescence properties of Eu(III)-doped silica nanorods based on the sol–gel process

Uniform Eu³⁺-doped SiO₂ nanorods were synthesized through a simple sol–gel method using cetyltrimethylammonium bromide (CTAB) as surfactant template and tetraethylorthosilicate as silicon source. X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectrum, scanning electron microscope (SEM), transmission electron microscopy, and photoluminescence spectra were employed to characterize the products in detail. The nanorods have good uniformity and their diameters and lengths are in the range of 200–300 and 500–700 nm through the SEM images, respectively. The formation of the nanorods was studied by taking SEM images after different aging time. The experimental results indicate that CTAB plays a crucial role in the formation of the silica nanorods. The luminescence of Eu³⁺-doped SiO₂ nanorods is dominated by red-emission around 612 nm due to intra-atomic 4f → 4f (⁵D₀ → ⁷F₂₎ transition of Eu³⁺ ions. Furthermore, the effect of doping concentrations of Eu³⁺ ions on the luminescence was investigated.     

Organometallic polymer-functionalized Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles as a highly efficient and eco-friendly nanocatalyst for C–C bond formation

A magnetically recoverable biopolymer-based nanocatalyst was prepared through the covalent immobilization of a chitosan-bound 2-hydroxynaphthaldehyde Pd complex on the surface of superparamagnetic nanoparticles. The nanocatalyst was characterized by FTIR, X-ray powder diffraction and scanning electron microscopy, revealing an average particle size of 70 nm. The catalyst shows high thermostability by thermogravimetric analysis. Estimated Pd loading by inductively coupled plasma atomic emission analysis was found to be 0.348 mmol g^?1. The nanocatalyst exhibits excellent catalytic performance in Suzuki couplings of various aryl halides with phenylboronic acid, and Heck reactions of iodo- and bromoarenes with butylacrylate. The catalyst can be easily separated from the reaction mixture with an external magnet and reused consecutively four times without significant loss in activity.     

Water-in-oil microemulsion method preparation and capacitance performance study of Li4Mn5O12

Spinel Li₄Mn₅O₁₂ nanoparticles are successfully prepared by water-in-oil microemulsion method and characterized by X-ray diffraction and scanning electron microscopy. The Li₄Mn₅O₁₂ nanoparticles have sphere-like morphology with particle size less than 50 nm. The Li₄Mn₅O₁₂ and activated carbon (AC) were used as electrodes of Li₄Mn₅O₁₂/AC supercapacitor, respectively. The electrochemical capacitance performance of the supercapacitor was investigated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. The results showed that the single electrode was able to deliver specific capacitance 252 F g^?1 within potential range 0–1.4 V at a scan rate of 5 mV s^?1 in 1 mol L^?1 Li₂SO₄ solution, and it also showed high coulombic efficiency close to 100%. This material exhibited a good cycling performance.     

Time growing comparison for ZnO nanorod by using microwave irradiation method

In this study, zinc oxide (ZnO) nanorod were successfully prepared at different growth times (15, 30 and 60 min) using the microwave irradiation method. The ZnO nanorods were simply synthesized at a low temperature (90 °C) with low power microwave assisted heating (about 100 W) and a subsequent ageing process. The synthesized nanorod were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and Ultraviolet–Visible spectroscopy (UV–Vis). The FESEM images showed nanorods with diameter ranging between 50 and 150 nm, and length of 150–550 nm. The XRD results indicate that ZnO nanorods of different time of growth exhibits pure wurtzite structure with lattice parameters of 3.2568 and 5.2125 Å. UV–Vis characterization showed that energy gap decreases with increase in time. The result also shows that growth of ZnO at 60 min produces an energy band gap of 3.15 eV. In general, the results of the study confirm that the microwave irradiation method is a promising low temperature, cheap and fast method for the production of ZnO nanostructures.     

Synthesis and Catalytic Evaluation of Silver Nanoparticles Synthesized with <Emphasis Type="Italic">Aloysia triphylla</Emphasis> Leaf Extract

In this investigation, we report the biosynthesis of the silver nanoparticles using Aloysia triphylla leaves extract. The as-prepared silver nanoparticles were characterized by ultraviolet–visible (Uv–vis) spectroscopy, X-ray diffractometry, scanning electron microscopy and transmission electron microscopy The infrared spectroscopy (FTIR) and Raman spectroscopy techniques were also used to evaluate the chemical groups of the plant extract involved in the silver ions bioreduction. The results indicate that as the plant extract/precursor salt ratio increases, the size of the nanoparticles decreases. Also, as the reaction temperature increases, the reduction rate increased too, resulting in the formation of smaller nanoparticles-size ranges. Uv–vis spectroscopy illustrates absorption peaks in the range of wavelengths of 430–445 nm corresponding to surface plasmon resonance band of silver nanoparticles. The X-ray diffraction (XRD) confirmed the presence of silver solids with fcc structure type. The FTIR analysis showed that the bands corresponding to phenolic compounds and the amide group were involved in the synthesis and stabilization of silver nanoparticles, respectively. The Raman studies showed bands at 1380 and 1610 cm^?1, which correspond to the aromatic and amide compounds, confirming the FTIR results. The Uv–vis results indicate the capacity of silver nanoparticles to reduce the methylene blue.     

Synthesis and Characterization of H3PW12O40 and H3PMo12O40 Nanoparticles by a Simple Method

In this study H₃PW₁₂O₄₀·9H₂O and H₃PMo₁₂O₄₀·6H₂O (HPA) particles were changed into nano forms by heat-treatment in an autoclave as a simple, repaid, inexpensive and one step method. The particle size of these nanoparticles was around 25 nm. The as-synthesized nanostructures were characterized by dynamic light scattering, X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and inductively coupled plasma analyzer. Thermal stability of nanoparticles was surveyed by thermal gravimeter analyse. Acidity of prepared nanoparticles was investigated by pyridine adsorption method. Results showed rising acidity by declining particle size of HPA.