Synthesis and characterization of polyaniline nanorods/Ce(OH)3-Pr2O3/montmorillonite composites through reverse micelle template

Polyaniline (PANI) nanorods/Ce(OH)₃-Pr₂O₃/montmorillonite (MMT) nanocomposites were synthesized via in situ polymerization of aniline monomer through reverse micelle template (RMT) in the presence of montmorillonite and Ce(OH)₃, Pr₂O₃. In the experiment, sulphosalicylic acid was used as dopant, aniline was designated as oil phase and the aqueous solution comprising Ce³⁺ and Pr³⁺ as water phase. The nanocomposites were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) analysis, Fourier transform infrared (FT-IR) spectroscopy and thermogravimetry-differential thermal analysis (TG-DTA). The results showed that PANI nanorods were synthesized in the interlayer spaces of MMT with uniform spherical rare earth nanoparticles. The thermal stability of the nanocomposites prepared was enhanced drastically compared with pure polyaniline.     

Preparation of reduced graphene oxide-NiFe2O4 nanocomposites for the electrocatalytic oxidation of hydrazine

A reduced graphene oxide (RGO)-NiFe₂O₄ nanocomposite was synthesized by a simple one step hydrothermal approach and its application in the electrocatalytic oxidation of hydrazine was demonstrated. The as-synthesized nanocomposite was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, UV–visible spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Thermogravimetric analysis, Field emission-scanning electron microscopy (FE-SEM), and Transmission electron microscopy (TEM). The FE-SEM and TEM image analyses revealed that the NiFe₂O₄ nanoparticles were uniformly distributed on the RGO sheets with a diameter and length of ∼10 and ∼100 nm, respectively. The XPS analysis confirmed the ionic states of Ni and Fe to be Ni³⁺ and Ni²⁺, and Fe²⁺ and Fe³⁺, respectively. Further, the electrochemical activity of the RGO-NiFe₂O₄ nanocomposite was investigated by studying the oxidation of hydrazine. The RGO-NiFe₂O₄ modified glassy carbon electrode (GCE) showed an outstanding electrocatalytic activity towards the oxidation of hydrazine as compared to the NiFe₂O₄ and RGO modified electrodes. The enhanced electrocatalytic activity is due to the synergistic effect between RGO and NiFe₂O₄. Using amperometry, the lowest detection limit of 200 nM was achieved with the RGO-NiFe₂O₄ modified GCE. Therefore, the RGO-NiFe₂O₄ modified GCE can be used for the electrochemical oxidation of hydrazine.     

Synthesis, morphology and optical properties of multi-pods Au/FeO(OH) and Au/Fe2O3 nanostructures

Multi-pods Au/FeOOH nanostructures were synthesized by a hydrothermal treatment of an aqueous solution of mixed micellar formed by gold nanoparticles, hexadecyltrimethyl ammonium bromide (CTAB), and (NH₄)₃[FeF₆] at 160 °C for 48 h and sequential calcined at 290 °C for 1.5 h, resulting in the formation of multi-pods Au/Fe₂O₃ nanostructures. The as-obtained products were characterized by powder X-ray diffraction, transmission electron microscopy, selected area electron diffraction, field emission scanning electron microscopy, and UV-vis spectroscopy. Surface plasmon resonance band of gold nanoparticles was observed in the multi-pods Au/FeOOH nanostructures. However, a similar behavior was not seen with multi-pods Au/Fe₂O₃ nanostructures. The critical role of F⁻ ions and CTAB molecules in the formation of FeO(OH) multipods and the probable mechanism of the formation of multi-pods Au/FeOOH and Au/Fe₂O₃ nanostructures were discussed.     

Preparation and properties of nickel ferrite (NiFe2O4) nanoparticles via sol-gel auto-combustion method

Using nickel and ferric nitrates and citric acid, NiFe₂O₄ nanoparticles are prepared by a simple and cost-effective polyvinylpyrrolidone (PVP) assisted sol-gel auto-combustion method. The synthesised nanoparticles consist of single phase inverse spinel structure of NiFe₂O₄. The particles are in spherical shape with an average size of ∼8 nm. The vibrational properties show tetrahedral and octahedral sites of NiFe₂O₄ nanoparticles. The super-paramagnetism is observed with magnetic saturation (M_s) of 50.4 emug^−1.     

CTAB assisted immobilization of RuO2 nanoparticles on graphene oxide for electrochemical sensing of hydrazine

A novel method has been presented to modify glassy carbon electrode (GCE) with graphene oxide (GO) nanocomposite without introducing any electrode binder such as chitosan and Nafion. First, modify GCE with RuO₂ nanoparticles which have been dispersed in cetyltrimethyl ammonium bromide (CTAB) aqueous solution. Then, highly adhesive RuO₂/CTAB/GO nanocomposite membrane formed on GCE by immersing RuO₂/CTAB modified GCE in GO suspension. CTAB plays significant roles not only in the preparation of the nanocomposite but also in the immobilization of nanocomposite on GCE surface. First, CTAB was used as the dispersant of RuO₂ nanoparticles. Second, CTAB acted as the molecular linker to bind RuO₂ nanoparticles on graphene sheets. Third, CTAB formed CTAB/GO nanocomposite which is highly adhesive on the surface of electrodes such as GCE and ITO (indium tin oxide). The obtained RuO₂/CTAB/GO/GCE shows excellent electrocatalytic ability towards the oxidation of hydrazine. The oxidation of hydrazine on RuO₂/CTAB/GO/GCE is an adsorption-controlled process and the oxidation current is linear with the concentration of hydrazine in the range of 1 × 10^?5～1 × 10^?3 M with a detection limit of 2.3 × 10^?6 M. The application of this sensor in the sensing of hydrazine in real water samples confirmed its reliability and accuracy.     

Parametric study of cost-effective synthesis of crystalline copper nanoparticles and their crystallographic characterization

Pure and high-crystalline copper nanoparticles were synthesized at room temperature by reduction of copper nitrate with hydrazine hydrate in cetyltrimethyl ammonium bromide (CTAB) solution without using any extra gases. A parametric study has been carried out in terms of hydrazine concentration, solution pH, and stirring. Pure copper nanoparticles without oxidation were obtained at 0.1–0.2 M N₂H₄ and pH = 10. The growth mechanism of various shaped copper nanoparticles is discussed based on structural analysis by transmission electron microscopy and selected area electron diffraction.     

Formation process of silver nanoparticles in DTAB/SDBS/PVP aqueous solution

Silver nanoparticles were prepared from the nitrate silver solution in dodecyl trimethyl ammonium bromide (DTAB)/sodium dodecylbenzenesulfonate (SDBS)/polyvinyl pyrrolidone (PVP) complex solution with hydrazine as the reductant. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV–Vis spectroscopic analysis were conducted to investigate the role of anionic–cationic surfactants on the growth process of silver particles. The results showed that, before the formation of spherical silver nanoparticles, the cube and then tetrakaidecahedrons of AgBr were initially formed. It is concluded that the selective interaction of bow-like electric double-layer structure of anionic–cationic surfactants with certain crystallographic planes of crystals dominated the morphology evolvement of the reaction products. In addition; the PVP coverage finally encouraged the formation of well-dispersed spherical silver nanoparticles.     

Microwave-assisted synthesis of palladium nanocubes and nanobars

Microwave was employed in the shape-controlled synthesis of palladium nanoparticles. Palladium nanocubes and nanobars with a mean size of about 23.8 nm were readily synthesized with H₂PdCl₄ as a precursor, tetraethylene glycol (TEG) as both a solvent and a reducing agent in the presence of PVP and CTAB in 80 s under microwave irradiation. The structures of the as-prepared palladium nanoparticles were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and ultraviolet-visible (UV-vis) absorption spectroscopy. The formation of PdBr₄²⁻due to the coordination replacement of the ligand Cl⁻ ions in PdCl₄²⁻ ions by Br⁻ ions in the presence of bromide was responsible for the synthesis of Pd nanocubes and nanobars. In addition, a milder reducing power, a higher viscosity and a stronger affinity of TEG were beneficial to the larger sizes of Pd nanocubes and nanobars.     

Microwave-assisted synthesis of ceria nanoparticles

Nanocrystalline ceria (CeO₂) particles have been successfully prepared by microwave-assisted heating technique from an aqueous solution containing ammonium Ce(IV) nitrate and sodium hydroxide. Further thermal treatment of the as-prepared powder at 500 °C resulted in the formation of the well-crystallized CeO₂ nanoparticles with an average crystal size of about 8 nm, varying with the heating temperature. The as-prepared powder and the CeO₂ nanoparticles were examined using X-ray diffraction (XRD) and transmission electron microscope (TEM) techniques. It was found that the morphologies of the synthesized powder show from rod-like for the as-prepared sample to sphere-like for the heat-treated nanoparticles. Mechanism of CeO₂ nanocrystallite growth during annealing is primarily investigated.     

Photocatalytic hydrogen generation over porous ZnIn2S4 microspheres synthesized via a CPBr-assisted hydrothermal method

Hexagonal ZnIn₂S₄ porous microspheres were synthesized via a cetylpyridinium bromide (CPBr)-assisted hydrothermal method. The structure, morphology and optical property of these prepared products were characterized by wide angle X-ray diffraction (WAXRD), small angle X-ray diffraction (SAXRD), UV-Vis diffusive reflectance spectroscopy (DRS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analyzer (EDX) and nitrogen sorption analysis. The effects of CPBr and pH on the crystal structure, morphology and photocatalytic activity of ZnIn₂S₄ products were studied. The results demonstrated that the flowerlike ZnIn₂S₄ microspheres, which were composed of numerous nanosheets, performed higher visible-light photocatalytic activity than bulk ZnIn₂S₄ for hydrogen evolution. The CPBr addition influenced the crystal structure including the position and intensity of some peaks. Furthermore, the pH played a crucial role in the formation of ZnIn₂S₄ porous microspheres. The as-synthesized porous ZnIn₂S₄ microspheres possessed the specific surface area of 165.4 m² g⁻¹ and the slit-like porous configuration, which was beneficial to photocatalytic reaction.     

Synthesis of mesoporous silica materials (MCM-41) from iron ore tailings

Highly ordered mesoporous materials were successfully synthesized by using the iron ore tailings as the silica source and n-hexadecyltrimethyl ammonium bromide as the template. The samples were detail characterized by powder X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy and N₂ physisorption. The as-synthesized materials had high surface area of 527 m² g⁻¹ and the mean pore diameter of 2.65 nm with a well-ordered two-dimensional hexagonal structure. It is feasible to prepare mesoporous MCM-41 materials using the iron ore tailings as precursor.     

IF-WS2 nanoparticles size design and synthesis via chemical reduction

An innovative synthesis of inorganic fullerene-like disulfide tungsten (IF-WS₂) nanoparticles was developed using a chemical reduction reaction in a horizontal quartz reactor. In this process, first tungsten trisulfide (WS₃) was formed via a chemical reaction of tetra thiotungstate ammonium ((NH₄)₂WS₄), polyethylene glycol (PEG), and hydrochloric acid (HCl) at ambient temperature and pressure. Subsequently, WS₃ was reacted with hydrogen (H₂) at high temperature (1173-1373 K) in a quartz tube. The produced WS₂ nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), and transmission electron microscopy (TEM). The characterization results indicated that the high-purity (100%) IF-WS₂ nanoparticles were produced. Moreover, addition of surfactant (PEG) and higher operating temperature (1173-1373 K) decreased the particles agglomeration, and consequently led to the reduction of average diameter of WS₂ particles in the range of 50-78 nm. The developed method is simple, environmentally compatible, and cost-effective in contrast to the conventional techniques.     

Synthesis and structural features of Ni–Al nanoparticles by hydrogen plasma–metal reaction

Eight kinds of Ni–Al nanoparticles have been prepared by hydrogen plasma–metal reaction. The morphology, crystal structure and chemical composition of the nanoparticles obtained in this study were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and induction-coupled plasma (ICP) spectroscopy. The particle size was determined by TEM and BET gas adsorption. It was found that all the nanoparticles have spherical shapes, with average particle size in the range of 14∼62 nm. The crystal structures of Ni–Al nanoparticles vary with the composition of master alloys. Pure Al₃Ni₂ (D5₁₃), NiAl (B2) and Ni₃Al (L1₂) structures were successfully produced with 55.0, 58.3 and 72.6 at.% Ni in bulk, respectively. The analysis result about the phase equilibrium based on the crystal structures of nanoparticles is not consistent with those based on the equilibrium phase diagram.     

Hydrothermal synthesis and photoluminescence properties of nano-crystalline GdBO3:Eu phosphor

Nano-crystalline GdBO₃:Eu³⁺ was prepared by a hydrothermal method and the effects of some processing variables such as pH, temperature were investigated. The as-synthesized powders were spherical shaped agglomerates of nanoparticles. The luminescent properties were compared with samples synthesized by conventional solid-state reaction method. Both the photoluminescence intensity and chromaticity were improved and a red-shift in the CT band was observed for the hydrothermally synthesized samples. Possible mechanisms of phase formation were investigated and explanations for the changes in optical properties are proposed.     

La-doped ZnO nanoparticles: Simple solution-combusting preparation and applications in the wastewater treatment

La-doped ZnO nanoparticles have been successfully synthesized by a simple solution combustion method via employing a mixture of ethanol and ethyleneglycol (v/v = 60/40) as the solvent. Zinc acetate and oxygen gas in the atmosphere were used as zinc and oxygen sources, and La(NO₃)₃ as the doping reagent. The as-obtained product was characterized by means of powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry and X-ray photoelectron spectroscopy. Experiments showed that La-doped ZnO nanoparticles exhibited the higher capacities for the removal of Pb²⁺ and Cu²⁺ ions in water resource than undoped ZnO nanoparticles.     

Photoluminescence of Fe2O3 nanoparticles prepared by laser oxidation of Fe catalysts in carbon nanotubes

Iron oxide nanoparticles have been produced on the top surface of aligned multi-walled carbon nanotubes by CO₂ laser processing. They were characterized to be Fe₂O₃ nanoparticles by X-ray photoelectron spectroscopy, X-ray diffraction and high resolution scanning electronic microscopy. Absorption bands in the visible region were found to be redshifted compared with the absorption of Fe₂O₃ nanoparticles prepared by traditional chemical methods. Photoluminescence from these Fe₂O₃ nanoparticles shows a broad emission band in the near infrared region for both excitations at 514 and 633 nm. Particle size is considered to be responsible for the unique optical properties of the Fe₂O₃ nanoparticles.     

Hydrothermal routes to various controllable morphologies of nanostructural lithium aluminate

The α-LiAlO₂ powders have been successfully prepared by a hydrothermal route based on using the surfactant of heax-adecyltrimethyl ammonium bromide (CTAB) as the template. One-dimensional (1D) nanorods with higher and lower aspect ratio, 2D mesoporous microsheets were respectively observed with different concentration of the surfactants. A high specific surface area up to 151 m²/g was obtained by this method. The formation mechanism of the nanostructural lithium aluminate was proposed.     

Preparation of carbon nanotube-neodymium oxide composite and research on its catalytic performance

Carbon Nanotube-Neodymium Oxide (CNT-Nd₂O₃) composite was prepared by using acid treated carbon nanotubes (CNTs) and neodymium nitrate in the presence of sodium dodecyl sulfate and ammonia liquid. Techniques of transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and differential thermal analysis (DTA) are used to characterize the morphology, structure, composition and catalytic property of the CNT-Nd₂O₃ composite. The experimental results show that the Nd₂O₃ nanoparticles, which have an average diameter of about 30-40 nm, are loaded on the surface of carbon nanotube. Compared with pure Nd₂O₃ nanorods, the CNT-Nd₂O₃ composite can catalyze the thermal decomposition of ammonium perchlorate more effectively. The sampling methods of the experimental samples made a difference on the catalytic experiment results, and the best catalytic result was obtained when de-ionized water served as the solvent of ammonium perchlorate.     

Effect of process parameters on size,shape, and distribution of Sb<Subscript>2</Subscript>O<Subscript>3</Subscript> nanoparticles

Antimony trioxide (Sb₂O₃) nanoparticles with particle sizes ranging from 2 to 12 nm, spherical in shape, and well-distributed were successfully synthesized by chemical reduction method. The nanoparticles were synthesized in the presence of hydrazine as a reduction agent in ethylene glycol through the reaction between antimony trichloride and sodium hydroxide. Effects of reaction temperature, reaction time, precursor concentration and boiling temperature on the particle size, shape, and distribution of the Sb₂O₃ nanoparticles were investigated. Morphology of the nanoparticles was examined by transmission electron microscope (TEM). It was revealed that the particle size increased when reaction temperature, reaction time and concentration of precursor were increased. Moreover, the mixture needed to be boiled prior to the addition of hydrazine as a reduction agent, in order to obtain an optimum reduction. X-ray diffraction (XRD) was employed to study the crystallinity and phase of the nanoparticles. The nanoparticles were determined as cubic phase of Sb₂O₃ (ICDD file no. 00-043-1071) by XRD. Interrelation between UV–vis absorption spectra of the nanoparticles and their particle size were obtained.     

A facile water-based process for preparation of stabilized Bi nanoparticles

Stabilized bismuth nanoparticles have been prepared by reducing bismuth chloride with hydrazine hydrate in the presence of sodium oleate under a facile water-based process. The obtained samples are investigated by X-ray diffraction, transmission electron microscopy (TEM) and differential thermal analysis and thermogravimetry (DTA/TG). The present results indicate that the bismuth nanoparticles are spherical, small diameter and in a high purity. In addition, measurement of water contact angle indicates that Bi samples are hydrophobic, which gives defense to samples from further oxidation, samples are steady in 6 months without obvious oxidation.