Inorganic and organic templates‐assisted solvothermal synthesis of trigonal selenium microrods

A facile and environment‐friendly solvothermal method has been developed for the controlled growth of nano‐ and micro‐structured trigonal selenium (t‐Se) by using green templates. And, the morphology of trigonal selenium can be tuned by using different kinds of templates. The as‐obtained products were characterized by X‐ray powder diffraction (XRD) and scanning electron microscope (SEM). Furthermore, the formation mechanism of trigonal selenium nano‐ and microcrystals was rationally suggested. This method will open a new avenue to synthesize other functional inorganic nano‐ and microcrystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Simple extraction‐solvothermal synthesis of single‐crystalline silver microplates

Single‐crystalline silver microplates, with average edge length of about 1.5 μm and thickness of 100 nm, have been synthesized by a simple extraction‐solvothermal method. Samples were characterized in detail by X‐ray diffraction (XRD), field‐emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM) and High‐resolution transmission electron microscopy (HRTEM) technologies. Extractant primary amine N1923 can also act as reducing agent. It has been found that microstructure of the silver can be controlled by the n‐octanol during the solvothermal treatment. Based on a series of experimental analysis, the possible formation mechanism of these microplates was discussed briefly. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Solvothermal growth of single‐crystal hexagonal prismatic SrCO3 microrods

Single‐crystal hexagonal prism SrCO₃ microrods have been prepared by a simple solvothermal route. The effects of the reaction time, the content of 1,2‐propanediol and the reactants mass on the products have been investigated, respectively. The as‐synthesized microrods were characterized by X‐ray powder diffraction (XRD), field‐emission scanning electron microscopy (FE‐SEM) and transmission electron microscopy (TEM). The results reveal that the products have uniform shape and excellent monodispersity. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Morphology‐controllable synthesis of ZnO nano‐/micro‐ structures by a solvothermal process in ethanol solution

Flower‐like ZnO nanostructures assembled by nanorods with bimodal size distribution have been synthesized by a solvothermal process in NaOH‐Et system. Various effects of the solvothermal parameters and assistant additives on the morphologies of ZnO nanostructures have been investigated. The directing effect of chloride ions have been observed in the formation of highly symmetrical 3D ZnO nanostructures. A possible mechanism has been proposed to explain the formation of ZnO nanoflowers in NaOH‐Et system. A strong near‐UV emission band centered at around 396 nm is observed in the photoluminescence spectrum of flower‐like ZnO nanostructures, indicating of their high crystal quality.     

Structural and catalytic properties of Cu2S microrods grown on a three‐dimensional substrate

We present a facile solution‐phase method for the synthesis of Cu₂S microcrystals with rod‐like morphologies by the reaction of sulfur with three‐dimensional substrate copper foam in a mixed solvent of ethylene glycol and deionized water. The lengths of Cu₂S microrods are between 80 and 150 μm and the diameter is among 3 to 8 μm. Monodisperse Cu₂S microrods self‐assemble into echinus structure. The samples were characterized by X‐ray powder diffraction and scanning electron microscopy. Energy dispersive X‐ray spectroscopy was further used to testifiy the purity of Cu₂S. Catalysis performance proved that the obtained Cu₂S materials possess superior catalytic efficiency on methylene blue with the assistance of H₂O₂. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Novel mixed–solvothermal synthesis of MoS2 nanosheets with controllable morphologies

MoS₂ nanosheets with controllable morphologies were successfully synthesized via a novel mixed–solvothermal approach based on interfusing organic solvent in the solution. The morphology of the MoS₂ nanosheets was lamellar–like using the mixed water/ethanol/N–Methyl pyrrolidone solvents, whereas that prepared with the mixed water/ethano/ethylene glycol solvents changes to fullerene–like. Because of the structure‐directing ability of organic molecules, the mixed solvents were proposed to be responsible for the formation of such different morphologies. The average size of MoS₂ nanosheets was approximately 90 nm, and the thickness was about 10–20 nm. The results indicated that the crystalline phase and morphology were largely influenced by calcination and reaction system.     

Additive‐free solvothermal synthesis of peanut‐like BiVO4 powders with enhanced photocatalysis activity

Monoclinic peanut‐like BiVO₄ products have been successfully synthesized by a solvothermal method. The volume of CH₃COOH and the concentration of NH₃·H₂O were found to play important roles in the formation of this morphology. The optimal condition for preparation of highly active peanut‐like BiVO₄ samples are the volume of CH₃COOH, which was 5 ml, and the concentration of NH₃·H₂O, which was 2 mol/L. The as‐prepared samples were characterized by XRD, SEM, TEM, DRS, BET, and their photocatalytic activity was evaluated by photocatalytic decolorization of a Rhodamine B (RhB) aqueous solution under visible‐light irradiation. The results demonstrated that BiVO₄ with peanut‐like morphology was better than that of other BiVO₄ samples for photodegradation of RhB.     

Dependence of photoluminescence properties on excitation power in ZnO and ZnCdO microrods

ZnO and ZnCdO microrods have been prepared through a chemical bath deposition method. The structure of microrods has been characterized using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Photoluminescence spectra were recorded for ZnO and ZnCdO microrods at different excitation powers. The intensity of UV emission is enhanced with increasing excitation power. The width of UV emission increases for spectra at higher excitation powers. In particular, the paper shows that the influence of excitation power on the shift of emission band for ZnCdO microrods is more remarkable than that of ZnO microrods with the increase of excitation power. The definite experimental evidence demonstrated that the temperature coefficient β of ZnCdO microrods is much larger than the temperature coefficient of ZnO microrods. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Well‐defined Sb2S3 nanostructures: citric acid‐assisted synthesis,electrochemical hydrogen storage properties

Well‐defined (three‐dimensional) 3‐D dandelion‐like Sb₂S₃ nanostructures consisted of numerous nanorods have been achieved via a facile citric acid‐assisted solvothermal process. The as‐prepared products were characterized by X‐ray diffraction (XRD), field‐emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high‐resolution TEM (HRTEM), respectively. The influence factors of the formation of the hierarchical Sb₂S₃ nanostructures are discussed in details based on FESEM characterizations. By simply controlling the quantity of citric acid, the nucleation and growth process can be readily tuned, which brings the different morphologies and nanostructures of the final products. On the basis of a series of contrastive experiments, the aggregation‐based process and anisotropic growth mechanism are reasonably proposed to understand the formation mechanism of Sb₂S₃ hierarchical architectures with distinctive morphologies including nanorods, and dandelion‐like nanostructures. Charge‐discharge curves of the obtained Sb₂S₃ nanostructures were measured to investigate their electrochemical hydrogen storage behaviors. It revealed that the morphology played a key role on the hydrogen storage capacity of Sb₂S₃ nanostructure. The dandelion‐like Sb₂S₃ nanostructures exhibited higher hydrogen storage capacity (108 mAh g⁻¹) than that of Sb₂S₃ nanorods (95 mAh g⁻¹) at room temperature.     

Solvothermal synthesis of mesoporous slabstone‐like TiO2 and its photodegradation preference in a methyl orange‐rhodamine B mixture solution

Mesoporous slabstone‐like anatase TiO₂ micro‐nanometer composite structure has been successfully synthesized by a facile solvothermal method at 180 °C using polyethylene glycol (PEG) as a structure‐directing agent, followed by calcination at 400 °C for 2 h. The crystal structure and morphology of the product were characterized by XRD, SEM, TEM and HRTEM. Its BET specific surface area was obtained from N₂ adsorption‐desorption isotherm measurement. Rhodamine B (RB) aqueous solution was used to evaluate the photocatalytic activity of the as‐prepared TiO₂ under simulated sunlight irradiation and compared with that of commercial TiO₂ (P25). A RB and methyl orange (MO) coexisting solution was chosen to investigate the photodegradation preference of the slabstone‐like TiO₂ on these two dyes. The results show that the photocatalytic activity of the as‐prepared TiO₂ is much higher than that of P25, and MO is the preferential degradation species in the MO‐RB mixture solution.     

Controllable synthesis of well‐aligned CuO nanotube arrays using porous alumina templates

In order to further enhance the performance of CuO in currently existing applications, well‐aligned CuO nanotube arrays with different diameters were fabricated. During the synthesis process, porous anodic alumina films were fabricated, and then the synthesis of CuO nanotube arrays was realized by using the obtained porous anodic alumina films as templates. The morphology and structure of the obtained products has been confirmed by field‐emission scanning electron microscopy, transmission electron microscopy and X‐ray diffraction measurements. Due to the large surface area of the synthesized products, the prepared CuO nanotube arrays may have potential applications in catalyzing and gas sensing area.     

Kinetically controlled synthesis of hollow Cu2O nanocubes under solvothermal condition

Hollow Cu₂O nanocubes have been fabricated under solvothermal condition using N,N ‐dimethylformamide (DMF) as solvent at 120 °C for 12 h. The products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray powder diffraction (XRD) and high‐resolution transmission electron microscopy (HRTEM). Series of experiment confirmed that the amount of water, the reaction time and temperature played important roles in the morphology evolution of hollow Cu₂O nanocubes. DMF is a relatively weak alkali solvent and could release a certain amount of OH^– under the given conditions. As the release speed of OH^– from DMF became substantially slow, the nucleation and growth of Cu₂O nanocubes turned into kinetically controlled process. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optical,photocatalytic properties of novel CuS nanoplate‐based architectures synthesised by a solvothermal route

CuS architectures were successfully prepared by a simple solvothermal route without any surfactant, in which copper nitrate trihydrate and element sulfur were used as reactants. The products were characterized by X‐ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The optical properties of CuS architectres were investigated by Raman spectrometer, ultraviolet‐visible spectroscopy, and fluorescence spectrophotometer. The results showed that the CuS architectures were hexagonal‐structured phase and composed of intersectional nanoplates. UV‐Vis absorption peaks of CuS architectures showed large blue shifts and PL spectrum exhibited a strong blue emission and a weak green emission. Photocatalytic activity of the CuS architectures was evaluated by measuring the decomposition rate of methylene blue solution under solar light. The CuS architectures show good photocatalytic activity. The effects of the molar ratio of Cu:S and the growth time on the synthesis of CuS crystalline were discussed and the growth mechanism of CuS nanoplate‐based architectures was also proposed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Morphological evolution of selenium micro‐crystals

A simple solution phase approach using dimethyl formamide (DMF) as solvent is utilized to obtain selenium (Se) microcrystals. Different morphological modifications of the products result from varied reaction environments. Solvothermal treatment of Se with DMF in an autoclave at 170°C yields rod‐like, and feather‐shaped microcrystalline structures while reduction of selenium dioxaide (SeO₂) by DMF generates microspheres at 30°C and 80°C, rods admixed with spherical particles at 120°C and predominantly micro rods at 150°C. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Template‐free synthesis of hierarchical zinc oxide with improved photocatalytic properties

Novel hierarchical nano materials possess tremendous latent force in many applications. In this paper, hierarchical flower‐like, spherical and bowl‐like zinc oxide was successfully synthesized by altering solvent ratio (absolute ethanol and diethylene glycol) via a simple and template‐free solvothermal synthetic route. The solvent ratio also plays a vital role in deciding the structure, crystalline, band gap energy and specific surface area of the as‐synthesized samples. The preparation mechanism of ZnO in mixed alcohols was discussed. The obtained samples were characterized by energy dispersive spectroscopy(EDS), X‐ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), N2 adsorption‐desorption, UV–vis diffuse reflectance spectroscopy (DRS). Photocatalytic activity of the as‐prepared ZnO nanocrystals was evaluated by the degradation of MB under UV irradiation. Among, the most effective photocatalyst was synthesized when the diethylene glycol was 10 ml.     

Solvothermal syntheses and crystal structures of two 4‐heterocyclic acylpyrazolone complexes

Many explorations of transition metal (M)‐L system under solvothermal condition, have led to the syntheses of two new 4‐heterocyclic acylpyrazolone complexes [Co(L)₂(CH₃OH)₂] (HL = 1‐phenyl‐3‐methyl‐4‐(2‐furoyl)‐5‐pyrazolone) ( 1 ) and [Cr(L)₃] ( 2 ). Single‐crystal X‐ray analyses reveal that crystal structures of compound 1 and 2 are respectively orthorhombic, Pbca, a = 15.0378(6) Å, b = 9.8405(4) Å, c = 20.7321(8) Å, V = 3067.9(2) ų, Z = 8 and triclinic, P‐1, a = 10.7966(18) Å, b = 13.023(2) Å, c = 15.520(3) Å, α = 73.011(4)°, β = 84.884(4)°, γ = 70.267(4)°, V = 1964.3(6) ų, Z = 2. Complex 1 has a two‐dimensional (2D) network structure that is formed by O–H···N H‐bonding interactions. Complex 2 makes a one‐dimensional (1D) zigzag chain structure by intermolecular π···π interactions, which is further interlinked via C–H···N H‐bonding interactions to generate a 2D sheet, and then a three‐dimensional (3D) supramolecular network structure is further linked by intermolecular C–H···π interactions. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A simple surfactant‐free route for preparation of flower‐like crystals of CoS with hierarchitectures

Hierarchical cobalt sulfide crystals with flower‐like microstructures were successfully prepared by a simple one‐pot solvothermal route, employing CoCl₂·6H₂O as a cobalt precursor and KSCN as a sulfur source. The morphology of these microstructures can be easily controlled by adjusting the molar ratio of glycol to DMF in the solvent. The products were characterized by XRD and SEM. Possible formation mechanisms of CoS hierarchical microspheres are proposed. The influences of the nature of reaction media on the morphological evolution were also investigated and it was found that the ratio of DMF to glycol was of great importance for the formation of CoS morphology.     

Solvothermal synthesis of flower‐like lanthanum tartrate and lanthanum oxide microspheres in ethanol‐water mixed system

Monodispersed lanthanum tartrate microspheres with flower‐like shape were synthesized by a mild solvothermal method using ethanol‐water mixed system as the solvent. Lanthanum oxide with reserved spherical shape was subsequently fabricated by a following calcination process. X‐ray diffraction analyses (XRD), X‐ray spectroscopy (EDS), scanning electron microscopy (SEM), thermogravimetry‐differential thermal analysis (TG‐DTA) were employed to characterize the composition, structure, and morphology of the products. The lanthanum tartrate microspheres were aggregated by nanosheets as petals. Size of the aggregation and thickness of the petal vary with the vol.% of ethanol. As the vol.% of ethanol increases the degree of aggregation and the thickness of the petal decrease, and other properties such as the size distribution, dispersion are also modulated. These alterations can be interpreted by the changing dielectric constant of mixed solvent. Such lanthanum tartrate can be applied to fabricate micro‐sphereshaped lanthanum oxide after calcination. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Controlled synthesis of selenium of different morphologies at room temperature

A facile and convenient chemical precipitation route has been developed for the controlled growth of selenium nanowires and hierarchical microspheres at room temperature, with Na₂SeO₃ and hydrazine hydrate as starting materials in the presence of 1,2,3‐trimethylimidazolium tetrafluoroborate (tmimBF₄). The surface morphology of microspheres can be tuned by adjusting the reaction media. The products were characterized by X‐ray powder diffraction (XRD) and scanning electron microscope (SEM). Possible formation mechanisms of selenium nanowires and microspheres are proposed, respectively. The influences of the nature of reaction media, agitation and tmimBF₄ on the morphologies development were experimentally investigated and it was found that these factors were of great importance for the formation of Se morphologies. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Solvothermal synthesis and growth mechanism of asymmetric ZnO hierarchical structures in diethylene glycol with ammonia solution

Several novel asymmetric ZnO hierarchical structures were synthesized in diethylene glycol (DEG) with different amount of ammonia solution via solvothermal process. The submicron‐rods or nanorods as the building units are distributed on the two sides in an asymmetric manner, resulting in formation of the shiitake‐like or bouquet‐like morphology. A possible formation mechanism was proposed on the basis of the experimental result. The consumption of the precursor could lead to a two‐step nucleation and growth process. The relative content of the [Zn(OH)₄]²⁻ and the [Zn(NH₃)₄]²⁺ precursors varies with the amount of ammonia solution, which affect the size and morphology of the asymmetric structures. The [Zn(OH)₄]²⁻ complex and the [Zn(NH₃)₄]²⁺ complex are absorbed on the positive (0001)‐Zn polar surface and the negative (000–1)‐O polar surface respectively, which lead to the alteration of growth rate of these polar surfaces.