PEG-300 assisted hydrothermal synthesis of 4ZnO·B2O3·H2O nanorods

4ZnO·B₂O₃·H₂O is commonly used as a flame-retardant filler in composite materials. The microstructure of the powder is of importance in its applications. In our study, for the first time, one-dimensional (1D) nanostructure of 4ZnO·B₂O₃·H₂O with rectangle rod-like shape has been synthesized by a hydrothermal route in the presence of surfactant polyethylene glycol-300 (PEG-300). The nanorods have been characterized by X-ray powder diffraction (XRD), inductively coupled plasma with atomic emission spectroscopy (ICP-AES), thermogravimetry (TG) and differential thermal analysis (DTA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with selected area electron diffraction (SAED) as well as high-resolution transmission electron microscopy (HRTEM). These nanorods are about 70 nm in thickness, 150-800 nm in width and have lengths up to a few microns. 4ZnO·B₂O₃·H₂O nanorods crystallize in the monoclinic space group P2₁/m, a = 6.8871(19) Å, b = 4.9318(10) Å, c = 5.7137(16) Å, β = 98.81(21)° and V = 191.779(71) Å³.     

Investigation of heterogeneous asymmetric dihydroxylation over OsO4-(QN)2PHAL catalysts of functionalized bimodal mesoporous silica with ionic liquid

A novel synthesis of the functionalized bimodal mesoporous silica with ionic liquid (FBMMs) was performed. After grafting 1-methyl-3-(trimethoxysilyl)propylimidazolium chloride onto the surface of bimodal mesoporous silicas, 1,4-bis(9-O-quininyl)phthalazine ((QN)₂-PHAL) and K₂Os(OH)₄·2H₂O were immobilized onto the modified FBMMs by adsorption or ionic exchange methods, and then, the asymmetric dihydroxylation reaction was carried out by using solid catalysts. Techniques such as X-ray diffraction, Fourier Transform Infrared spectroscopy, N₂ adsorption and desorption were employed to characterize their structure and properties. The results showed that the mesoporous ordering degree of bimodal mesoporous silica decreased after functionalization and immobilization of OsO₄-(QN)₂PHAL. Being very effective in asymmetric dihydroxylation with high yield and enantioselectivity, the prepared heterogeneous solid catalyst could be recycled for five times with little loss of enantioselectivity, with comparison of those results obtained in homophase system. Moreover, the effect of Osmium catalyst on asymmetric dihydroxylation was investigated.     

A solvothermal synthesis of ultra-fine iron phosphide

Powder iron phosphide (FeP) has been prepared via a benzene-thermal synthesis with the reaction of anhydrous iron chloride (FeCl₃) and sodium phosphide (Na₃P) at 180-190°C. The product was analyzed by X-ray photoelectron spectroscopy (XPS), and the results show the mole ratio of Fe:P is 1.12. X-ray diffraction (XRD) pattern can be indexed to the orthorhombic cell of FeP with the lattice constant a=5.191, b=3.101, and c=5.789 Å. Transmission electron microscope (TEM) images indicate that average particle size is about 200 nm in diameter.     

The preparation of silver sulfide nanoparticles in lamellar liquid crystal and application to lubrication

The silver sulfide (Ag₂S) nanoparticles were prepared by the reaction of AgNO₃ and Na₂S in the lamellar liquid crystal (LLC) formed by Triton X-100, n-C₁₀H₂₁OH and H₂O. The size of the particles is about 2-3 nm. The existence of Ag₂S nanoparticles can improve the lubrication of the lamellar liquid crystal.     

Fabrication of microspherical LiMnPO4 cathode material by a facile one-step solvothermal process

The microspherical LiMnPO₄ cathode material was successfully prepared for the first time by a simple one-step solvothermal process in the presence of critic acid. The reaction conditions (reactant concentration, reaction temperature) were used further to fabricate the size, surface coarseness and morphology of the microspherical LiMnPO₄. The as-prepared microspherical LiMnPO₄ at variant conditions exhibited remarkably different discharge capacity and rate capacity, indicating the potential of the suggested method in tuning the morphology and the structure of LiMnPO₄ to improve its electrochemical performance.     

Highly controllable and green reduction of graphene oxide to flexible graphene film with high strength

Graphene film with high strength was fabricated by the assembly of graphene sheets derived from graphene oxide (GO) in an effective and environmentally friendly approach. Highly controllable reduction of GO to chemical converted graphene (CCG) was achieved with sodium citrate as a facile reductant, in which the reduction process was monitored by XRD analysis and UV–vis absorption spectra. Self-assembly of the as-made CCG sheets results in a flexible CCG film. This method may open an avenue to the easy and scalable preparation of graphene film with high strength which has promising potentials in many fields where strong, flexible and electrically conductive films are highly demanded.     

Structural characterization and surface heterogeneity of bimodal mesoporous silicas functionalized with aminopropyl groups and loaded aspirin

Bimodal mesoporous materials were modified with different amount of 3-aminopropyltriethoxysilane and employed as aspirin carriers. The modified and drug loaded bimodal mesoporous materials were characterized with XRD, FT-IR, TEM and elemental analysis methods to explore the influence of amino groups and drug molecules on the mesoporous surface. Meanwhile, the mesoporous surface energy states was calculated by the density functional theory based on the N₂ sorption analysis. According to the surface energy distributions of samples including before and after modification and drug loading, it can be deduced that through superficial modification with amino groups, the surface energy moves to high state, implying the introduction of amino moieties could provide the mesoporous surface with much active sites. Besides, the interaction between the amino groups and drug molecules is weak, and hence the controlled drug delivery would be possible.     

The reaction of ceria coatings on mica with H2S: An in-situ X-ray diffraction study

Thin layers of ceria were deposited on the surface of mica platelets in solution. The reaction of such particles with hydrogen sulfide yields a red colored special effect pigment. The ceria layer reacts with H₂S to produce a variety of sulfide and oxysulfide phases. The reaction path discovered in situ by time and temperature resolved X-ray diffraction is CeO₂→CeS₂→C-Ce₂S₃→Ce₁₀S₁₄O. The reaction itself is extremely variable depending on gas flow, heating rates and decomposition atmospheres. Effects on the thin film are recorded by scanning electron microscopy (SEM) and revealed a destruction of the layer once red Ce₁₀S₁₄O was formed. The product layer then reveals the typical nonwetting behaviour of a liquid on a surface.     

Photocatalytic activity of nitrogen doped rutile TiO2 nanoparticles under visible light irradiation

This work provides the design and synthesis of nitrogen doped rutile TiO₂ nanoparticles working as efficient photocatalysts under visible light irradiation. Nitrogen doped rutile TiO₂ nanoparticles are synthesized through the surface nitridation of rutile nanoparticles, which have been prepared in advance. The experimental results show that the nitrogen element is easily doped into the lattice of TiO₂ nanoparticles and its doping amount increases with the decrease of nanocrystallite size. The photocatalytic activity of the nanoparticles under visible light irradiation is correlated not only with the amount of doped nitrogen element but also with the morphology and crystallinity of nanoparticles.     

Phase selection and visible light photo-catalytic activity of Fe-doped TiO2 prepared by the hydrothermal method

It is necessary to extend the absorption range of TiO₂ based materials from the ultraviolet to the visible light region for most photo-catalytic applications of TiO₂ under solar irradiance or indoor lighting. Also, the ability to control the structural evolution, particularly the competition and transformation between different phases (anatase or rutile), is extremely important for the preparation of high efficiency TiO₂ based photo-catalysts. In this work, we have systematically studied the effects of various processing factors on the phase selection process/outcome of nanocrystalline Fe-doped TiO₂, which includes the level of doping ions, annealing temperature, solution pH and the addition of acidic anions, using a low temperature hydrothermal method. Both Fe-doped rutile and anatase TiO₂ phases were obtained via varying the processing conditions. The visible-light photo-catalytic activity of doped materials was significantly improved over that of the pure TiO₂ nanopowders, which was demonstrated by effective degradation of methylene blue under visible light.     

Supported zirconium sulfate on carbon nanotubes as water-tolerant solid acid catalyst

A new solid acid of zirconium sulfate (CZ) was successfully supported on carbon nanotube (CNT) for esterification reaction. Preparation conditions of the supported CZ have been investigated, to obtain highest catalytic activity for esterification reaction. XRD, TEM, BET, X-ray photoelectron spectra (XPS) and in situ FTIR analysis has also been carried out to understand the characteristics of the catalyst. In the esterification of acrylic acid with n-octanol, the supported CZ exhibited high catalytic activity and stability. The catalytic activity was nearly unchanged during four times of reuse. XRD and TEM analysis indicated that CZ was finely dispersed on CNT. XPS analysis shows that the CZ species was preserved and the chemical environment of the CZ has changed after loaded on CNT. This finding show that CNT as CZ support is an efficient water-tolerant solid acid.     

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 of PbTe thermoelectric materials by alkaline reducing chemical routes

Binary PbTe thermoelectric compounds have been successfully synthesized by alkaline reducing solvothermal, hydrothermal and low-temperature aqueous chemical routes using Pb(CH₃COO)₂·3H₂O and pure tellurium as precursors, and NaBH₄ as the reductant. Compared to PbTe powders synthesized by solvothermal and hydrothermal routes, smaller PbTe nanopowders of about 20 nm have been obtained by low-temperature aqueous chemical route. Possible formation mechanisms of PbTe were discussed.     

Controllable synthesis and optical properties of NdOHCO3 dodecahedral microcrystals

NdOHCO₃ dodecahedral microcrystals with an orthorhombic structure have been successfully synthesized by the hydrothermal method used urea as the precipitator. Experimental parameters, such as the reaction temperature, the reaction time, and the molar ratio of the starting reagents were examined. The as-synthesized products were characterized by powder X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and photoluminescence. The possible growth process of NdOHCO₃ dodecahedral microcrystals was discussed.     

Microwave synthesis of Al-doped SiC powders and study of their dielectric properties

To improve the dielectric properties of β-SiC powders, microwave synthesis was applied to produce SiC powders doped with different amounts of Al from fine powders of Si, C and Al under Ar atmosphere. The dielectric properties of the as-synthesized Al-doped SiC powders were investigated, and the mechanism of dielectric loss by doping has been discussed. The presence of Al influenced the formation of secondary phases (α-SiC and Al₄SiC₄) and the microstructure of the resultant powders. The produced powders form Al-SiC solid-solutions, which seemingly favor defect polarization loss effect in the high frequency region. This is consistent with the measurements of dielectric properties, which showed that doping of SiC with Al causes increase of permittivity, both real and imaginary parts, and loss tangent, within 8.2-12.4 GHz. The results show that SiC doped with 30% Al has the highest real part ?′ and imaginary part ?″ of permittivity and also loss tangent.     

Preparation of nitrogen doped TiO2 photocatalyst by oxidation of titanium nitride with H2O2

Nitrogen doped anatase TiO₂ (N-TiO₂) were prepared by hydrothermally treating TiN with H₂O₂. The as-synthesized samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-vis diffuse reflectance spectrum (DRS), Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectroscopy (XPS) techniques. The results confirmed that the hydrothermal oxidation is an effective method to prepare N-doped TiO₂ anatase. The nitrogen concentration in TiO₂ could be controlled by the concentration of H₂O₂ solution. Photocatalytic degradation of methyl orange (MO) was carried out under visible light and UV-visible light irradiation, respectively. The as-prepared optimal N-TiO₂ showed higher photocatalytic activity than N-P25 and P25, and exhibited excellent reusability.     

CeO2 nanocrystals: Seed-mediated synthesis and size control

This work reports on seed-mediated synthesis and size control of monodispersed CeO₂ nanoparticles. CeO₂ nanoparticles of mean size smaller than 2 nm were first prepared by a simple mixing of aqueous solution of cerium (IV) sulfate and ammonia solution at ambient conditions. Using these as-prepared fine particles as the tiny seeds, tunable sizes of CeO₂ nanoparticles were achieved via a facile hydrothermal treatment. All samples were characterized by X-ray diffraction (XRD), infrared (IR) spectroscopy, UV-vis spectroscopy, and thermogravimetric analysis (TGA). It is shown that in comparison with other inorganic cerium salts such as cerium (III) nitrates, cerium (IV) sulfate appears more suitable for forming CeO₂ nanoparticles at room temperature. Sulfate groups are strongly thermodynamically adsorbed on CeO₂ nanoparticle surfaces. The formation mechanism, surface hydration and sulfation characteristics of the resulting CeO₂ nanoparticles are also discussed.     

Synthesis of nanocrystalline TiO2 with high photoactivity and large specific surface area by sol-gel method

Nano-TiO₂ powder was prepared by sol-gel method with modified precursor, tetrabutyl titanate (TBT), and photocatalytic oxidation was applied in removal of organics in the powder. The microstructure of as-prepared nano-TiO₂ was determined using UV-vis, TEM, XRD and BET. The results indicated that the nano-TiO₂, with grain size of 3.8 nm and specific surface area of 359.1 m²/g, was composed of anatase alone, and that it exhibited significant blue-shift in its UV-vis spectrum. The decomposition of organics in the sample was systematically investigated using FT-IR and TG-DTA. According to the testing results, we could conclude that organics in the samples were completely eliminated by means of photocatalytic oxidation. With photocatalytic decoloration of active brilliant red X-3B in aqueous solution as model reaction, the photocatalytic activity of as-prepared nano-TiO₂ was investigated and was compared with that of the samples experiencing heat treatment and Degussa P-25 as well. The experimental results indicated that the photoactivity of as-prepared nano-TiO₂ is much higher than that of the samples experiencing heat treatment.     

Ethanol-thermal synthesis of Cd1−xZnxS nanoparticles with enhanced photodegradation of 4-chlorophenol

Cd_1−xZn_xS nanoparticles were prepared by a one-pot solvothermal process from Zn(CH₃COO)₂, Cd(CH₃COO)₂ and NaS₂CNEt₂·3H₂O (sodium diethyldithiocarbamate, DDTC). The Cd_1−xZn_xS nanoparticles were characterized by X-ray powder diffraction, transmission electron microscope and high-resolution transmission electron microscope equipped with an energy-dispersive X-ray spectrometer. The absorption spectra of the Cd_1−xZn_xS nanoparticles can be tuned into visible region by modulating stoichiometric ratio between Zn and Cd. With the increase of Zn content, the Cd_1−xZn_xS nanoparticles showed an enhanced photocatalytic activity on degradation of 4-chlorophenol. The Cd_1−xZn_xS prepared under the optimal experimental condition (initial Zn/Cd = 3:1, 210 °C, 24 h, in ethanol) possessed the best photocatalytic activity. The conversion ratio could reach up to 84% after 12 h under irradiation of visible light for Cd_1−xZn_xS prepared in ethanol, which was obviously superior to those of products prepared in water. These results showed that both crystallinity and synthetic medium were responsible for the enhanced photocatalytic activity for 4-chlorophenol.     

Microwave irradiation assisted rapid synthesis of Fe-Ru bimetallic nanoparticles and their catalytic properties in water-gas shift reaction

Fe-Ru bimetallic nanoparticles were prepared by a microwave irradiation assisted glycol reduction method using poly-N-vinyl-2-pyrrolidone (PVP) as protective agent. The structure and morphology of the nanoparticles were characterized by X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDXA) and high-resolution transmission electron microscopy (HRTEM). EDXA and XRD analysis confirmed the presence of Fe and Ru. The bimetallic nanoparticles were subsequently loaded onto an MgAl₂O₄ supporter with K₂O as promoters and used as catalyst for water-gas shift reaction. The results indicated that the FeRu bimetallic nanoparticles exhibit high catalytic activity for water-gas shift reaction due to the synergistic effect between iron and ruthenium. Potassium oxide can enhance the CO selectivity of the catalyst significantly besides increasing the catalyst activity.