A simple route to synthesis of BaCO3 nanostructures in water/ethylene glycol mixed solvents

Barium carbonate (BaCO₃) nanostructures with different morphologies were synthesized using Ba(NO₃)₂ and (NH₄)₂CO₃ in the water/ethylene glycol (EG) mixed solvents by oil bath heating at 80 °C for 30 min. The molar ratio of water to EG had an effect on the morphology of BaCO₃. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM).     

Hydrothermal-polyol route to synthesis of β-Ni(OH)2 and NiO in mixed solvents of 1,4-butanediol and water

The β-Ni(OH)₂ with flower-like morphology assembled from nanosheets has been successfully synthesized by a hydrothermal-polyol method from Ni(CH₃COO)₂·4H₂O in mixed solvents of 1,4-butanediol and water at 200 °C for 24 h. The NiO with similar morphology was obtained by a simple thermal decomposition of the precursor (β-Ni(OH)₂) at 400 °C for 3 h in air. The products were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), thermogravimetric analysis (TG) and differential scanning calorimetric analysis (DSC). We expect that this hydrothermal-polyol method may be extended to the preparation of nanostructures of other kinds of metal oxides.     

Synthesis and characterization of WO3 nanostructures prepared by an aged-hydrothermal method

Nanostructures of tungsten trioxide (WO₃) have been successfully synthesized by using an aged route at low temperature (60 °C) followed by a hydrothermal method at 200 °C for 48 h under well controlled conditions. The material was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Specific Surface Area (S_BET) were measured by using the BET method. The lengths of the WO₃ nanostructures obtained are between 30 and 200 nm and their diameters are from 20 to 70 nm. The growth direction of the tungsten oxide nanostructures was determined along [010] axis with an inter-planar distance of 0.38 nm.     

Large-scale synthesis and characterization of fan-shaped rutile TiO2 nanostructures

Large-scale fan-shaped rutile TiO₂ nanostructures have been synthesized by means of a simple hydrothermal method using only TiCl₄ as titanium source and chloroform/water as solvents. The physicochemical features of the fan-shaped TiO₂ nanostructures are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), nitrogen absorption-desorption, diffuse reflectance ultraviolet-visible spectroscopy (UV-vis) and Fourier transform infrared spectroscopy (FTIR). Structural characterization indicates that the fan-shaped TiO₂ nanostructures are composed of several TiO₂ nanorods with diameters of about 5 nm and lengths of 300-350 nm. The average pore size and BET surface area of the fan-shaped TiO₂ nanostructures are 6.2 nm and 59 m²/g, respectively. Optical adsorption investigation shows that the fan-shaped TiO₂ nanostructures possess optical band gap energy of 3.11 eV.     

Hydrothermal synthesis and photoluminescence properties of SrCO3

Well-crystallized strontium carbonate (SrCO₃) nanoparticles were successfully synthesized by a simple hydrothermal method. The products were characterized by X-ray diffraction (XRD), which is in good agreement with orthorhombic SrCO₃. Raman spectrum is in accordance with its crystal structure. Field emission scanning electron microscopy (FE-SEM) characterization indicates that the as-synthesized SrCO₃ nanoparticles are of mean size about 80 nm. The band gap of SrCO₃ was estimated by Wood and Tauc method through UV-visible reflection spectrum, showing a band gap value of 3.17 eV (391 nm). The photoluminescence properties of the as-synthesized SrCO₃ were measured at room temperature, which shows excellent emissions with two emission centers ranging from ultraviolet to red. The ultraviolet emission center locates at 390 nm, and the green emission center locates at 523 nm, respectively.     

Characterization of SrCO3 and BaCO3 nanoparticles synthesized by sonochemical method

SrCO₃ and BaCO₃ nanoparticles were synthesized using Sr(NO₃)₂ or Ba(NO₃)₂ and Na₂CO₃ as starting materials in ethylene glycol by ultrasonic irradiation at 80 °C for 1-5 h. Their phases, vibration modes and morphologies were characterized using X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, selected area electron diffraction (SAED) and transmission electron microscopy (TEM). These products were found to be orthorhombic SrCO₃ and BaCO₃ nanoparticles with 20-50 nm and 40-100 nm ranges, respectively. Asymmetric stretching, symmetric stretching, and out of plane and in plane bending vibrations of CO₃²⁻ complexes were also detected.     

Synthesis and properties of β-Ga2O3 nanostructures

A novel method was utilized to synthesize one-dimensional β-Ga₂O₃ nanostructures. In this method, β-Ga₂O₃ nanostructures have been successfully synthesized on Si(111) substrates through annealing sputtered Ga₂O₃/Mo films under flowing ammonia in a quartz tube. The as-obtained samples were analyzed in detail using the methods of X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDX) attached to the HRTEM instrument. The results show that the formed nanostructures are single-crystalline Ga₂O₃. The annealing temperature has an evident influence on the morphology of the β-Ga₂O₃ nanostructures. The growth mechanism of the β-Ga₂O₃ nanostructures is also discussed by conventional vapor-solid (VS) mechanism.     

A facile hydrothermal route to spinel CoCo2O4 nanotubes and porous nanostructures without assisted surfactants and templates

Spinel CoCo₂O₄ nanotubes and porous nanostructures have been synthesized by a novel hydrothermal method from Co(NO₃)₂·6H₂O in mixtures of ammonia and cyclohexane at 220 °C. The morphology and phase of CoCo₂O₄ can be controlled by adjusting the experimental parameters that include the Co²⁺ concentration and the volume ratio of ammonia to cyclohexane. X-ray diffraction and transmission electron microscopy analyses were used to characterize the products. The formation mechanisms of CoCo₂O₄ nanostructures is proposed in detail. The electrochemical properties of the as-prepared samples have been investigated.     

Facile hydrothermal route to the controlled synthesis of α-Fe2O3 1-D nanostructures

Single-crystalline α-Fe₂O₃ 1-D nanostructures can be obtained via a facile one-step hydrothermal synthetic route. It was found that the introduction of SnCl₄ played a key role in determining the composition and morphology of α-Fe₂O₃. The addition of SnCl₄ favours the formation of Fe₂O₃ rather than FeOOH, and the morphology can be tuned from nanorod to double-shuttle as the increase of SnCl₄ concentration. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). This simple method does not need any seed, catalyst, or template, thus is promising for large-scale and low-cost production.     

Different morphologies of strontium carbonate in water/ethylene glycol and their photocatalytic activity

Three-dimensional SrCO₃ flower-like nanostructures self-assembly from nanocrystals have been successfully synthesized by solvothermal method at the temperature of 120?°C. In the presence of anionic surfactant sodium dodecyl sulfate, SrCO₃ is crystallized in different alcohols and aqueous solutions. X-ray diffraction (XRD) pattern reveals that needles and flakes flower-like SrCO₃ are orthorhombic phases. The product also has a high specific surface area of about 60.52 m² g^?1. Based on the nucleation and self-assembly process, a possible formation mechanism is proposed. The effects of SDS and alcohol on the product are also studied. Results suggest that –OH groups of alcohol play a key role in morphological controlling of SrCO₃. Moreover, the FCNS exhibits excellent photocatalytic activity for the photodegradation of RhB under visible light irradiation and the degradation rate approached to 90.32%.     

Rapid synthesis of TiO2 hollow nanostructures with crystallized walls by using CuO as template and microwave heating

In this paper, TiO₂ hollow nanostructures with anatase walls have been rapidly fabricated by using CuO as template and microwave heating. These TiO₂ hollow nanostructures have been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Experimental results showed that the TiO₂ shell transformed from amorphous to anatase phase in 3 min, induced by the hot CuO core under microwave irradiation. The diameter of TiO₂ hollow nanostructures is about 50-80 nm, and the length is about 200-300 nm. The thickness of the shell is about 3 nm. This method is promising to be used to synthesize other nanomaterials with a hollow nanostructure.     

Synthesis and characterization of novel flower-like CeF3 nanostructures via a rapid microwave method

Novel flower-like CeF₃ nanostructures with a mean diameter of 190 nm were successfully synthesized via a rapid and facile microwave irradiation route using ethylenediaminetetraacetic acid disodium as the complexing reagent. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and photoluminescence (PL). XRD patterns showed that the CeF₃ nanoflowers were hexagonal phase and had good crystallinity and purity. TEM and SEM images showed that the as-prepared CeF₃ samples displayed 3D flower-like nanostructures and had uniform sizes and morphologies. The experimental results revealed that the as-prepared CeF₃ nanoflowers might be assembled by nanodisks. The formation process of the CeF₃ nanoflowers was preliminarily investigated.     

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.     

Microwave synthesis and characterization of ZnO with various morphologies

ZnO micro- and nanostructures with a variety of morphologies have been synthesized using Zn(NO₃)₂·6H₂O and pyridine by a microwave-assisted aqueous solution method at 90 °C for 10 min. The pyridine has a significant influence on the morphology of ZnO. Various morphologies of ZnO (hexagonal columns, linked hexagonal needles, hollow structures, and hexagonal nanorings) were obtained by adjusting the concentration of pyridine. The effect of the type of other alkaline additive (aniline and triethanolamine) on the morphology of ZnO was also investigated. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM).     

Solvothermal synthesis of In(OH)3 nanorods and their conversion to In2O3

In this work, we demonstrate that monodisperse indium hydroxide (In(OH)₃) nanorods constructed with parallel wire-like subunits have been fabricated via a acrylamide-assisted synthesis route without any template. NH₃ from the hydrolysis of acrylamide acts as the OH⁻ provider. The structure and morphology of as-prepared products have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and thermogravimetric analysis (TG). A detailed mechanism has been proposed on the basis of time-dependent experimental results. Furthermore, by annealing In(OH)₃ precursors at 500 °C for 3 h in air, In₂O₃ samples were obtained with the designed morphology.     

Self-construction of SnO2 cubes based on aggration of nanorods

The SnO₂ cubes with the rutile structure have been successfully synthesized without using any catalyst. Their morphology and microstructure were studied by field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), and elected area electron diffraction (SAED). It is revealed that the SnO₂ nanocubes exhibit high crystalline quality. The size of the nanocubes ranges from 100 nm to 300 nm. The side surfaces of nanocubes are {110} planes, while their cube axes are [001] direction. The growth mechanism of SnO₂ nanocubes was discussed and we suggested vapor-solid process should dominate the growth. These SnO₂ nanostructures represent an important example of spontaneous organization.     

Fabrication of three-dimensional snowflake-like bismuth sulfide nanostructures by simple refluxing

Three-dimensional snowflake-like bismuth sulfide nanostructures were successfully synthesized by simple refluxing at 160 °C in ethylene glycol, using bismuth citrate and thiourea as reactants. The crystal structures and morphologies of the products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDX). The Bi₂S₃ nanostructure was built up by highly ordered one-dimensional Bi₂S₃ nanorods, which was aligned in an orderly fashion. Ethylene glycol plays a critical role in the creation of bismuth sulfide three-dimensional nanostructures, which serves as an excellent solvent and structure director. Bismuth citrate, a linear polymer, also makes for the formation of the three-dimensional nanostructures.     

Synthesis and characterization of bundle-like structures consisting of single crystal Ce(OH)CO3 nanorods

Bundle-like structures consisting of single crystal cerium hydroxide carbonate (Ce(OH)CO₃) nanorods have been synthesized successfully by a hydrothermal method at 100 °C using cerium nitrate (Ce(NO₃)₃·6H₂O) as the cerium source, aqueous carbamide both as an alkaline and carbon source and cetyltrimethylammonium bromide (CTAB) as surfactant. X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were used to characterize such bundle-like structures. SEM and TEM images show that Ce(OH)CO₃ bundle-like structures were composed of nanorods with diameters of ∼ 100 nm. The XRD pattern and electron diffraction (ED) pattern indicate that Ce(OH)CO₃ has a pure orthorhombic single crystal structure.     

Low-temperature hydrothermal synthesis of α-MnO2 three-dimensional nanostructures

Single-crystalline α-MnO₂ three-dimensional nanostructures were synthesized via a novel redox reaction of KMnO₄ and Cr(NO₃)₃ under hydrothermal conditions. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), and high-resolution transmission electron microscopy (HRTEM). The addition of HNO₃ into the reaction has a significant effect on the morphologies of the final products. The α-MnO₂ three-dimensional nanostructures were obtained under the acidic condition, while α-MnO₂ nanowires were obtained without the addition of HNO₃. A mechanism for the growth of α-MnO₂ three-dimensional nanostructures was proposed.     

Synthesis of uniform WO3 square nanoplates via an organic acid-assisted hydrothermal process

Two kinds of tungsten oxide (WO₃) square nanoplates have been prepared by a simple hydrothermal method using l(+)-tartaric acid or citric acid as assistant agents. The products are characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). XRD, SEM and TEM images of the products illustrate that WO₃ square nanostructures prepared in the presence of l(+)-tartaric acid have a hexagonal phase, length of ∼ 200 nm and thickness of ∼ 100 nm, while WO₃ nanostructures synthesized in the presence of citric acid have an orthorhombic phase, length of ∼ 500 nm and thickness of ∼ 100 nm. Selected area electron diffraction (SAED) suggests that both of the as-prepared WO₃ square nanoplates are single crystalline. The plausible growth mechanism for the formation of WO₃ square nanostructures is also proposed.