Water-ethanol Mixed Solution Research Articles

Facile hydrothermal synthesis of Bi/BiOBr composites with enhanced visible-light photocatalytic activities for the degradation of rhodamine B

Bi/BiOBr photocatalysts with improved photodegradation performances were synthesized by a facile one-step hydrothermal method using ethanol–water mixed solution. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. The addition of ethanol results in the partial reduction of Bi3+ ions to metallic Bi, different morphology from pure BiOBr, and the formation of oxygen vacancies. The dosage of ethanol plays a vital role in the morphologies and photodegradation performances of as-obtained Bi/BiOBr. The Bi/BiOBr photocatalysts show improved photodegradation performances, which is attributed to the high surface area, narrow band gap, and inhibited recombination of electron–hole pairs .

The synthesis, structure and magnetic properties of a mononuclear cobalt compound with dipyrimidine sulfane ligand derived from 2-thio-barbituric acid

A new mononuclear compound named triaqua-(2,2′-di-thio-4,6,4′,6′-tetraoxo-5,5′-dipyrimidine-sulfanediyl-κ3O,O′,S)-cobalt(II) (1) was prepared by the solvothermal reaction of 2-thio-barbituric acid (TBA), CoCl2 and KOH in ethanol–water mixed solution. The supposed probable reaction mechanism shows that TBA desulfur coupling into 5,5’-dipyrimidine-sulfane is the key process of forming 1. Variable-temperature magnetic susceptibilities display intermolecular antiferromagnetic interactions in 1.

Synthesis, characterization and adsorption capability for Congo red of CoFe2O4 ferrite nanoparticles

CoFe2O4 ferrite nanoparticles are synthesized by an ethanol-assisted hydrothermal method, where the ethanol is mixed with water as the solution. In this synthesis, a rapid mixing of reducible metal cations with reducing agent and a simultaneous reduction process take place in a colloid mill. Synthesized ferrite samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and Raman spectroscopy. XRD patterns reveal the formation of CoFe2O4 ferrites with single spinel phase. SEM and TEM images show that the as-synthesized samples are with narrow size distribution. Raman spectroscopy studies clearly indicate the cation distribution in nanosized particles. Here, it is worthy to note that, with increasing ethanol content in ethanol–water mixed solution, an obvious superparamagnetic behavior of as-synthesized nanoparticles at room temperature is observed. The adsorption capability of the as-synthesized ferrite nanoparticles for Congo Red (CR) is examined. Enhancement of adsorption capability for CR with adding ethanol as the mixing solution is shown. The adsorption mechanism is discussed. This investigation reveals that the composition of ethanol/water mixed solution has great effects on the microstructure and magnetic properties as well as adsorption capacity of Congo Red (CR) dye of the as-synthesized CoFe2O4 ferrite samples.

One-step solvothermal process of In2O3/C nanosheet composite with double phases as high-performance lithium-ion battery anode

Single porous In2O3 nanosheets and In2O3/C nanosheet composite with double phases of c-In2O3 and rh-In2O3 were fabricated by a facile one-step solvothermal treatment of a mixture of d-fructose and In(NO3)3 using urea as a precipitating agent in water–ethanol mixed solution followed by calcination. The effect of solution on the fabrication of In2O3 nanosheets was investigated and a possible mechanism was proposed to explain the formation of nanosheets. In2O3/C nanosheet composite electrode exhibited a high lithium storage capacity of 869mAhg−1 after 100 cycles at 100mAg−1, excellent rate and long-term cycling performance. The superior electrochemical performance could be ascribed to the incorporation of carbon and the unique nanosheet architecture of the nanocomposite.

Potentiometric and Theoretical Studies of (2Z, 3Z)-2H-benzo[b][1,4]thiazine-2,3(4H)-dionedioxime with Some Divalent Transition Metal Ions

The protonation equilibria of (2Z, 3Z)-2H-benzo[b][1,4]thiazine-2,3(4H)-dionedioxime (BTDH2) together with the equilibria of its bis- binary complexes of Co(II), Ni(II), Cu(II) and Zn(II) were investigated potentiometrically. The investigation was carried out at 25 ± 0.1 °C, in aqueous solution, with a constant ionic strength of 0.100 mol·dm−3 NaCl. The protonation constants of the ligand together with the stability constants of a variety of complexes were determined potentiometrically in 10 % ethanol–water mixed solution using the SUPERQUAD computer program. Theoretical calculations were set up to assist in understanding the protonation sequence in the ligand molecule via the semi-empirical molecule orbital method of parameterized model number 3. Results are discussed in connection to the basicity of the donor atoms and structural arrangement of the ligand. Although BTDH2 has two dissociable protons, four protonation constants can be measured under the experimental conditions presented. These four protonation constants (as log10 βs) are 10.245, 19.397, 22.414 and 25.176.

Effect of solvent polarity on the assembly behavior of PVP coated rhodium nanoparticles

The rhodium nanoparticles (RhNPs) were prepared in aqueous, ethanol, and water–ethanol mixed solution using rhodium chloride, sodium borohydride and polyvinylpyrrolidone (PVP) as precursor, reducing agent and stabilizer, respectively. The effect of solvent polarity on the assembly behavior of PVP coated RhNPs was systematically investigated by varying the water-to-ethanol ratio in the solution. The main product changed from small separated RhNPs in ethanol to large spherical assemblies of RhNPs in water. The strong tendency for the RhNPs to form aggregates in high polarity solvent was clearly demonstrated by increasing the water-to-ethanol ratio in the reaction media. TEM characterization revealed a two-step formation process of the spherical RhNP assemblies in water: the initial rapid particle generation step followed by a slow particle aggregation step. A mechanism was proposed to elucidate the aggregation behavior of PVP coated RhNPs. The driving force for the aggregation of RhNPs is ascribed to the hydrophobic interaction of hydrocarbon chains of PVP, which can greatly reduce the surface energy of PVP coated RhNPs in high polarity solvents. This work shed light on how to control the formation of nanoparticle aggregates by modulating the polarity of solvent.

Controllable synthesis of hollow/flower-like BiOI microspheres and highly efficient adsorption and photocatalytic activity

Hollow/flower-like BiOI microspheres have been prepared through a facile precipitation route in a water–ethanol mixed solution with the assistance of PVP and citric acid (CA) at low temperature (70 °C). The obtained products were characterized by a range of methods such as XRD, FESEM, TEM, UV-vis, DRS, PL and nitrogen sorption. A three-stage growth mechanism of such hierarchical hollow/flower-like microstructures has been proposed by observing the XRD analysis and FESEM of the intermediate products at different reaction times. Interestingly, the structure of BiOI from hollow to flower-like could be obtained by only adjusting the different amounts of reagents in the reaction system. The photocatalytic activities of the hollow/flower-like microspheres were evaluated by the degradation of RhB under visible-light irradiation, compared with the nanoplate sample and P25. Although the hollow BiOI microspheres had a higher specific surface area, the flower-like BiOI microspheres exhibited much higher adsorption and photocatalytic activities than the former. This controllable morphology method and particular properties of BiOI hierarchical microstructures could be used to synthesize bismuth-based semiconductors or other structure-controllable materials and to explore remarkable potential applications of their photocatalytic degradation ability.

Synthesis and Characterization of Sr<sub>3</sub>MgSi<sub>2</sub>O<sub>8</sub>:Eu<sup>2+</sup>, Dy<sup>3+</sup> Phosphor Prepared by a Chemical Solution Method

A novel synthesis route for the production of Sr3MgSi2O8:Eu2+,Dy3+ sub-micron quasisphere phosphor powder is reported. Both the host and activator cations were co-precipitated in water-ethanol mixed solutions and precipitation was performed with analytical grade ammonium citratetribasic. As the dispersion media, optimum concentration for PEG in the precursor solution is determined to be 0.08 g/mL. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and fluorescence spectrophotometer were employed to characterize the phosphor. The effect of the calcining temperature on the crystalline particle and luminescence properties of Sr3MgSi2O8:Eu2+,Dy3+ is systematically discussed. Sr3MgSi2O8:Eu2+,Dy3+ single phased quasi-sphere phosphor was achieved by calcining the asprecipitated precursor at 1100°C. Sr2SiO4 was identified as the intermediate phase during the calcination process. Despite the small particle size, the emission intensities were higher by the present method. However, the afterglow characteristic was not better than that prepared by solidstate reaction in the comparable condition.

Solvothermal synthesis and characterization of tungsten oxides with controllable morphology and crystal phase

Tungsten oxides with various morphologies and crystal phases were synthesized by solvothermal reactions at 200 °C for 7–12 h using different solvents. The morphology and crystal phase of tungsten oxides changed depending on the solvents, i.e., spherical particles of ca. 1 μm in diameter consisting of nanowires, spindle shaped bundles of ca. 1 μm in length consisting of nanowires and accumulations consisting of micrometer sized plates and/or rods of tungsten oxides were obtained using ethanol, 1-propanol and water–ethanol mixed solution, respectively. When water–ethanol mixed solution was used, the crystallinity of tungsten oxide increased but the specific surface area greatly decreased. Crystallinity of tungsten oxides had more important effects on the NO degradation under light irradiation. The product using 42.9 vol.% water–ethanol mixed solvent consisted of the mixture of anhydrous tungsten oxide and hydrous tungsten oxide with preferential orientation of (0 0 2) plane and small band gap energy (2.43 eV), and showed higher photocatalytic degradation of NO even though it had a much smaller specific surface area than those prepared using ethanol and 1-propanol.

Template-free synthesis of mesoporous spinel lithium titanate microspheres and their application in high-rate lithium ion batteries

Mesoporous spinel lithium titanate Li4Ti5O12 microspheres were prepared by template-free hydrothermal process in ethanol–water mixed solution and subsequent heat treatment. The role of ethanol helps the formation of a mesoporous structure during the hydrothermal process. A mechanism analogous to the Kirkendall effect was proposed to account for the template-free formation of these mesoporous nanostructures. As anode materials for high-rate lithium ion battery, the Li4Ti5O12 mesoporous spheres exhibited superior high-rate performance of 114 mA h g−1 at 30C and good capacity retention of 125 mA h g−1 after 200 cycles at 20C, which indicates promising application in high-rate lithium ion batteries.

Fabrication and Gas-sensing Properties of Hollow SnO2 Microspheres

Abstract Hollow SnO2 microspheres with diameters ranging from 300–500 nm have been prepared via a simple template-free hydrothermal method in ethanol–water mixed solution. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to characterize the hollow microspheres. The gas-sensing properties of the hollow SnO2 microspheres have been investigated. The satisfactory gas response indicated that the hollow SnO2 microspheres have excellent potential application for ethanol sensors.

Hydrothermal synthesis and photocatalytic activity of nanocrystalline TiO 2 powders in ethanol–water mixed solutions

Bimodal mesoporous nanocrystalline TiO 2 powders were synthesized by a hydrothermal method using tetrabutylorthotitanate as precursor in ethanol–water mixed solutions. The as-prepared TiO 2 powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and N 2 adsorption–desorption measurements. The photocatalytic activity of the as-prepared TiO 2 powders was evaluated by the photocatalytic degradation of acetone under UV-light irradiation at room temperature in air. The effects of alcohol content on the microstructures and photocatalytic activity of the TiO 2 powders were investigated and discussed. The molar ratios of EtOH to H 2O obviously influenced the crystallization, crystallite size, BET specific surface areas and photocatalytic activity of the prepared TiO 2 powders. Hydrothermal treatment enhanced the phase transformation of the TiO 2 powders from amorphous to anatase and crystallization. It was found that the photocatalytic activity of TiO 2 powders prepared at 150–200 °C for 3–24 h in an ethanol–water mixed solution greatly exceeded that of Degussa P25. All TiO 2 powders after hydrothermal treatment showed bimodal pore-size distributions in the mesoporous region: one was intra-aggregated pores with maximum pore diameters of ca. 2–8 nm and the other inter-aggregated ones with maximum pore diameters of ca. 41–48 nm.

Synthesis and Characterization of Sulfide and Selenide Colloidal Semiconductor Nanocrystals

In this paper, we demonstrate the synthesis of sulfide and selenide nanocrystals in a water-ethanol mixed solution system. This synthetic way was based on the direct reactions between metal ions and S(2-)/Se. Linoleic acid was adopted to protect the nanocrystals from agglomeration. Without involving extreme experimental conditions, this less toxic synthetic route can be expected to bring more opportunities to nanocrystal-related research and application fields.

Preparation of monodispersed microporous SiO 2 microspheres with high specific surface area using dodecylamine as a hydrolysis catalyst

A novel and simple method for the synthesis of monodispersed microporous SiO 2 microspheres with high specific surface area was developed by hydrolysis of tetraethoxysilane (TEOS) in a water–ethanol mixed solution and using dodecylamine (DDA) as hydrolysis catalyst and template. The as-prepared products were characterized with differential thermal analysis–thermogravimetry, scanning electron microscopy, high-resolution transmission electron microscopy, small angle X-ray diffraction and nitrogen adsorption. The effects of experimental conditions including hydrolysis temperatures, calcination temperature and concentrations of TEOS and DDA on the morphology and pore parameters of the as-prepared SiO 2 microspheres were investigated and discussed. The results showed that hydrolysis temperature and concentrations of TEOS and DDA are important parameters for the control of size and morphology of particles. The specific surface area and specific pore volume of the as-prepared SiO 2 microspheres increased with increasing DDA concentration and calcination temperature. DDA may act not only as a good hydrolysis catalyst but also as a template for the formation of monodispersed SiO 2 microspheres with high specific surface area. This research may provide new insight into the synthesis of monodispersed microporous SiO 2 microspheres.

A novel approach for the synthesis of monodispersed porous silica microspheres with high surface area

Monodispersed porous silica microspheres are synthesized by the hydrolysis and condensation of tetraethoxysilane (TEOS) in a water–ethanol mixed solution containing 1-alkylamine as a template and hydrolysis catalyst. The as-prepared products were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle X-ray diffraction (SAXRD), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption, respectively. It was found that the alkyl chain length of 1-alkylamine and calcination temperature have an obvious influence on the particle size, morphology, specific surface area and pore structure of the as-prepared silica powder. The specific surface area, porosity and pore volume increased with increasing calcination temperature. Further observation showed that at 600°C, with increasing the alkyl chain length of template from C12 to C18, the specific surface area decreased and the pore size, porosity and pore volume increased. This research may provide new insight into the control of morphology and pore structures of oxide materials.

A water–ethanol mixed-solution hydrothermal route to silicates nanowires

In this manuscript, series of silicates nanowires, such as calcium silicate, strontium silicate, barium silicate, zinc silicate and cadmium silicate, etc., have been successfully prepared from a water–ethanol mixed solution system through a hydrothermal synthetic way. The formation process of these silicates nanowires has been studied in detail. Due to their rich sources and possible novel properties from reduced dimensionalities, we believe that the synthesis of these silicates nanowires may bring some new opportunity in the solid state chemistry and nanoscience and technology fields, etc.

Synthesis of monodisperse and spherical YAG nanopowder by a mixed solvothermal method

Yttrium aluminum garnet (YAG) powder was synthesized by a mixed solvothermal method under milder conditions with inexpensive aluminum and yttrium nitrates as the starting materials, and the low-cost ethanol–water mixed solution as the solvent. X-ray diffraction (XRD), DTA and TEM analysis showed that the powder synthesized was single-phase YAG, with well-dispersed fine spherical grains (80 nm average) and a relatively narrow grain size distribution. Moreover, the crystallization process of YAG grains was discussed.

Synthesis of monodisperse and spherical YAG nanopowder by a mixed solvothermal method

Yttrium aluminum garnet (YAG) powder was synthesized by a mixed solvothermal method under milder conditions with inexpensive aluminum and yttrium nitrates as the starting materials, and the low-cost ethanol–water mixed solution as the solvent. X-ray diffraction (XRD), DTA and TEM analysis showed that the powder synthesized was single-phase YAG, with well-dispersed fine spherical grains (80 nm average) and a relatively narrow grain size distribution. Moreover, the crystallization process of YAG grains was discussed.

The effect of photo-irradiation in hydrolysis and condensation of silicon alkoxide

A silicon alkoxide–water–ethanol mixed solution was irradiated with ultraviolet rays, and the change of the silicon alkoxide molecular structure was evaluated by 29Si nuclear magnetic resonance and Fourier transform infrared spectroscopies. Silicon alkoxide was hydrolyzed and the Si–OH bonds were produced by UV irradiation without any chemical catalyst for hydrolysis. The Si–O–Si bonds were also produced, and viscosity of the alkoxide solution became higher due to condensation of alkoxide.

A HIGH RESOLUTION ELECTRON MICROSCOPY INVESTIGATION OF CURVATURE IN MULTILAYER GRAPHITE SHEETS

Here we report a carbon sample generated by sonicating high oriented pyrolytic graphite (HOPG) in ethanol, water or ethanol-water mixed solution. High resolution transmission electron microscopy (HRTEM) revealed many multilayer graphite sheets with a total curved angle that is multiples of θ0(=30°). Close examination of the micrographs showed that the curvature is accomplished by bending the lattice planes. A possible explanation for the curvature in multilayer graphite sheets is discussed based on the conformation of graphite symmetry axes and the formation of sp3-like line defects in the sp2 graphitic network.