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Novel hierarchical hexagonal flower-like WO3·0.33H2O nanostructures (HHFWNs) have been successfully synthesized by hydrothermal method. We found that the hierarchical architectures of WO3·0...

Flower-like hierarchical ZnO nanostructures (FHZNs) have been successfully obtained through the hydrothermal method at the temperature of 120 °C for 7 h. The as-synthesized FHZNs was characterized by SEM, XRD, EDS, and XPS. Flower-like structure was formed by the simultaneous presence of urea and glycerol. A possible reaction mechanism was proposed based on a range of experiments. It could be described as nucleation, growth and self-assembly of nanosheets. Simultaneously, the photocatalytic properties of the product were also tested.

We present a one-step, environmentally-friendly and surfactant-free route to prepare the novel hierarchical hydrangea flower-like CuO nanostructures . The product simply uses copper acetate and sodium carbonate as the raw material, rather than any toxic and dangerous reagents, which is very important for safe, large-scale production. Based on the nucleation and self-assembly process, the possible formation mechanism is proposed. In addition, the product exhibits excellent photocatalytic activity in the catalytic degradation of toxic organic dyes and moreover, shows good stability and reusability under visible light irradiation. It can be expected to be used for dye-containing wastewater treatment.

In this paper, the erythrocyte-like Bi2WO6 structures were firstly synthesized and then were used as template, loading BiOI nanosheets on it. Then the erythrocyte-like BiOI/Bi2WO6 heterostructures were synthesized. Meantime, BiOI/Bi2WO6 heterostructures with different ratio of I/W were synthesized. The crystalline, morphology, chemical composition, and optical properties of BiOI/Bi2WO6 heterostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersion X-ray spectrum (EDX), UV-visible diffuse reflectance spectroscopy analysis (DRS), and X-ray photoelectron spectroscopy (XPS). In addition, the photocatalytic properties of degrading tetracycline (TC) were studied. The photocatalytic performance of erythrocyte-like BiOI/Bi2WO6 heterostructures with different BiOI content under visible-light irradiation showed that the erythrocyte-like BiOI/Bi2WO6 heterostructures were better than pure Bi2WO6. By optimizing the ratio of I/W, BWI-0.5 was almost completely degraded TC, and the photocatalytic mechanism of BiOI/Bi2WO6 has been proposed. Generally speaking, the erythrocyte-like BiOI/Bi2WO6 heterostructures greatly improved the photocatalytic performance.

A facile hydrothermal method is developed to prepare hierarchical dahlia-like SnO2 nanostructures (HDSNs). They have been successfully synthesized without using any templates or surfactants. We find that the hierarchical architectures of SnO2 are assembled by a number of regular-shaped nanosheets and nanoparticles, which are cross-linked in the interior of the micro-flower. Based on the nucleation and self-assembly process, a possible formation mechanism is proposed. The effect of NaCl on the product is also studied. In addition, the product exhibits excellent photocatalytic activity to Rhodamine B (RhB) aqueous solution and possess good stability and reusability under visible light. This study will provide valuable experimental data for further study of nanomaterials and their photocatalytic properties.

The hierarchical flower-like Zn-doped SnO2 (FLZn-SnO2) architectures composed of curved sheets are synthesized by a hydrothermal method at 180 °C for 8 h. We can obtain the morphological evolution of FLZn-SnO2 by a series of control experiments. Based on the nucleation and self-assembly process, a possible formation mechanism is proposed. The FLZn-SnO2 architectures exhibit higher photocatalytic activity in the degradation of Rhodamine B than pure SnO2 under visible light irradiation.

BiOBr hollow microspheres which were composed of BiOBr nanoslices were synthesized via a simple one-pot solvothermal method at 160 °C for 12 h without the addition of any spherical template. The resulted BiOBr hollow microspheres were regular in shape with external diameter of 1.4 μm in average. As a result, due to the highly hollow architecture, the resulted BiOBr hollow microsphere processed high BET surface area of 76.38 m2 g−1. Besides, a series of time-depended experiments had been listed, showing the morphological evolution for the formation and decomposition of the BiOBr hollow microspherical structure. SDS, which acted as a surfactant, played an important role in controlling the morphology of BiOBr. The obtained BiOBr hollow microspheres exhibited higher photocatalytic activity in the degradation of MB and RhB under visible-light irradiation.

Novel three-dimensional octagonal-like CuO micro-/nanostructures with diameters ranging from 10 to 15 μm have been successfully prepared by hydrogen peroxide-assisted hydrothermal method and subsequent calcination. The product morphology can be changed by simply ordering the amount of hydrogen peroxide (H2O2). When the amounts of H2O2 is increased, the length of the corner portion is increased and the width is narrower. The obtained octagonal CuO nanostructures were evaluated for their ability for the degradation of hazardous organic contaminants in water under visible-light irradiation. Comparing with commercial CuO and other CuO products, the CuO octagonal nanostructures exhibit excellent performance for photocatalytic decomposition of RhB (Rhodamine B). It is well established that effective photocatalytic performance results from its unique 3D octagonal nanostructures. We believe that the present work will provide some ideas for further fabrication of other novel nanostructures and exploration of their applications.

Novel hierarchical flower-like SnO 2 (HFL-SnO 2 ) nanostructures are successfully synthesized through the hydrothermal method. We find that the hierarchical architectures of SnO 2 is assembled by a number of regular-shaped nanosheets, which are cross-linked in the interior of the micro-flower. The product also has a high specific surface area of about 78.8 m 2 g −1 . Based on the nucleation and self-assembly process, a possible formation mechanism is proposed. The effects of SDS and NaCl on the product are also studied. Moreover, the product exhibits excellent photocatalytic activity and take possession of good stability and reusability under visible light. This study provides valuable experimental data for further study of nanomaterials and their photocatalytic properties.

The uniform hexagonal cone-like Cu2O nanostructures (HCCNs) which of the diameter is about 500 nm, have been successfully prepared via an ultrasound-assisted method. Due to the effects of sonication, the Cu2O nanostructures are composed of numerous nanoparticles. A possible growth mechanism is proposed as nucleation and growth of small primary nanoparticles through an oriented attachment mechanism. By investigating the effects of experimental conditions, it is found that the volume ratio of N,N-dimethylformamide (DMF)/deionized water and the time of sonication treatment turned out to be important parameters for the control of morphology of Cu2O. Moreover, compared with other Cu2O products, the HCCNs exhibits excellent photocatalytic activity for the photodegradation of hazardous organic contaminants in water such as phenol and Rhodamine B (RhB) under visible light irradiation. It is believed that this phenomenon is originated from the HCCNs unique nanostructure and its larger surface areas, leading to its high utilization rate of visible light. Based on the experimental results, mechanism for the degradation of phenol and RhB can be proposed.

3D hierarchical WO 3 ·0.33H 2 O microspheres have been successfully synthesized by one-pot solvothermal method at the temperature of 160 °C. The hierarchical WO 3 ·0.33H 2 O microspheres are composed of many slices with jagged edges, with side length of 100–300 nm and a thickness of about 50 nm. K 2 SO 4 , as a directing agent, plays an important role in controlling the morphology of WO 3 ·0.33H 2 O samples. In addition, a series of time-dependent tests have been listed, by which we can obtain the morphological evolution of hierarchical WO 3 ·0.33H 2 O microspheres. Moreover, the products exhibit excellent photocatalytic activity for the photodegradation of Rhodamine B (RhB) under visible light irradiation.

Hierarchical double-shell WO3 microspheres (HDS-WO3) have been successfully obtained through the thermal decomposition of WO3·H2O formed by metal salts as the templates. The products were characterized by X-ray diffraction (XRD), and the morphology was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, the HDS-WO3 microspheres were analyzed by the Thermogravimetric (TG) and Brunauer-Emmett-Teller (BET) analysis. The synthetic mechanism of the products with hierarchical structures was proposed. The obtained HDS-WO3 exhibits excellent photocatalytic efficiency (84.9%), which is much higher than other WO3 sample under visible light illumination.

Camellia-like WO 3 ·0.33H 2 O composed of nanosheets were successfully synthesized by the EDTA-assisted hydrothermal method. We find that the WO 3 ·0.33H 2 O of hierarchical architectures is assembled by a number of regular-shaped nanosheets, which are cross-linked in the interior of the micro-camellia. A possible formation mechanism is proposed, based on the nucleation and self-assembly process. Moreover, the products exhibit excellent photocatalytic activity and take possession of good stability and reusability under visible light.

Hollow copper oxide spheres with a diameter of 1.5–2 μm were prepared by hydrothermal reaction at 170 °C for 10 h in one step. The product was characterized by SEM, XRD, XPS, and EDX. We deduced the possible formation mechanism of the morphology through its nucleation process. Ostwald ripening process and NH3 produced by urea should be the main reason for the formation of hollow structure. We also explore the effects of different experimental conditions and find that the morphology is controllable. Finally, the photocatalytic experiments showed that the products have excellent photocatalytic activity and can be used in wastewater treatment.

Well-defined three-dimensional (3D) hierarchical flowerlike calcium molybdate (CaMoO4) microspheres were successfully synthesized via a facile ultrasound-assisted ethylenediaminetetraacetic acid (EDTA) chelation process. The structure and morphology were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). Time-dependent experiments with appropriate intervals have clearly disclosed that the self-assembly process of 3D flowerlike CaMoO4 microspheres is governed by a nucleation–dissolution–recrystallization growth mechanism. Moreover, the nitrogen adsorption–desorption isotherm indicated the presence of mesoporosity in the product. The room temperature photoluminescence (PL) properties of the products were then studied using a spectrophotometer and the samples exhibited green emission peaks centered around 470 nm, 485 nm and 493 nm with 280 nm excitation wavelength.

This work shows that a chemical bottom-up and successive top-down approach is a good synthetic strategy for nanoporous materials. The three-dimensional (3D) flower-like SrCO 3 nanocrystals have been prepared via a hydrothermal treatment process with a subsequently selective etching of the certain crystalline planes of SrCO 3 . Pores formed on the flowers owing to the loss of by-products of H 2 O and CO 2 . Accordingly, the original flower-like morphology of SrCO 3 was not preserved upon pore formation and during continuous stirring in the synthesis. Rearrangement of the SrCO 3 particles via a dissolution-recrystallization process occurred under our certain experimental conditions. Consequently, SrCO 3 particles with coarser surfaces and porous structures were obtained.

A novel Cu 2 O/Carbon Nanotubes (CNTs) hierarchical chrysanthemum-like nanocomposite has been successfully synthesized by a facile wet chemical method for the first time. This kind of nanostructure is made of three-dimensional (3D) ordered structures with an average diameter of about 80–120 nm. A possible growth mechanism of the Cu 2 O/CNTs chrysanthemum-like nanocomposites was proposed. Moreover, the novel chrysanthemum-like structure enlarged the range of absorbed light and enhanced the absorption intensity of light. The as-obtained Cu 2 O/CNTs samples were evaluated for their ability in the degradation of phenol under visible light irradiation. Compared with other as-prepared Cu 2 O/CNTs products, the Cu 2 O/CNTs chrysanthemum-like nanocomposite exhibited superior property on photocatalytic decomposition of phenol. It is believed that the efficient potocatalytic properties are originated from their unique 3D ordered nanostructures, which is highly beneficial to the reagent diffusion and mass transportation.

The shape-controlled crystallization of highly ordered three-dimensional (3D) hierarchical flower-like vaterite calcium carbonate (CaCO3) architecture was successfully prepared from a mild water–urea mixed system by a simple precipitation method. The mechanism of the crystal growth of CaCO3 was expounded according to the results, which is a step-by-step build process. It was found that the reaction time and the concentrations of carbonate and urea turned out to be important parameters for the control of morphology and polymorph of CaCO3. The detailed morphology and polymorph of the synthesized hierarchical CaCO3 nanostructures were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM) and electron diffraction (ED). This research may provide a promising route for the selective synthesis of other inorganic materials with different morphologies and polymorphs.

A novel Cu2O sedum rubrotinctum shaped architecture has been successfully synthesized in a water/oil (w/o) microemulsion. The obtained Cu2O sample was evaluated for its ability in the degradation of methylene blue under sunlight irradiation. It was found that a degradation of 98.94% was achieved in 90 min irradiation time.

A facile route was developed for the large-scale preparation of core–shell CuO nanostructures based on a solvothermal route with subsequent calcination. The CuO nanostructures show core–shell shape and are composed of numerous nanoparticles with high porosity resulting from the thermal decomposition of the Cu 2 O precursors. A possible growth mechanism of the CuO core–shell nanostructures was proposed. The novel core–shell structure enlarges the range of absorbed light and enhances the absorption intensity of light. The as-obtained CuO core–shell nanospheres were evaluated for the degradation of hazardous organic contaminants in water such as phenol and methylene blue (MB) under visible light irradiation. Compared with other CuO products, the as-prepared CuO core–shell nanosphere possesses superior property on photocatalytic decomposition of phenol and MB. It is believed that the efficient photocatalytic property of the as-prepared CuO core–shell nanosphere is originated from its unique openly core–shell nanostructure, which is highly beneficial to the reagent diffusion, mass transportation and the light reflection and absorption inside the CuO nanostructure.

Ag 3 PO 4 hollow microspheres (Ag 3 PO 4 -HMs) have been fabricated through a simple direct precipitation method in the presence of tartaric acid. The possible formation mechanisms of oriented aggregation and Ostwald ripening were proposed according to the time-dependent experimental results. Due to the high surface areas, the product of unique morphology exhibits high efficient photocatalytic activity for the photodegradation of Rhodamine B (RhB) under visible light irradiation.

A facile route was developed for the preparation of porous hexapod CuO nanostructures based on a solvothermal route with subsequent calcination. The CuO nanostructures are composed of numerous nanopaticles with high porosity resulting from the thermal decomposition of the Cu2O-CNTs precursors. The obtained CuO hexapod nanostructures were evaluated for their ability for the degradation of phenol under visible-light irradiation. Comparing with commercial CuO and P25, the as-prepared CuO hexapod nanostructures exhibit superior property on the photocatalytic decomposition of phenol. It is believed that the efficient photocatalytic property is originated from their unique 3D porous nanostructures which are highly beneficial to the reagent diffusion and mass transportation.

The porous cuprous oxide (Cu 2 O) dodecahedron nanocrystals have been successfully prepared via a solvothermal reduction process at a moderate temperature. The average dimensions of these Cu 2 O dodecahedron nanostructures were about 750 nm in diameter. The crystal growth mechanism of the novel architectures has been discussed. And then, the as-prepared Cu 2 O samples were used as photocatalysts in the degradation of methylene blue (MB). Due to the porous nature of the products, the photocatalytic performance has been significantly improved. We believe that the current work will offer some ideas for further fabricating porous nanostructures and exploring their applications.

Novel multishelled Cr 2 O 3 hollow microspheres (MCHMs) with diameters ranging from 1 to 3 μm have been successfully prepared through a simple, green and low-cost self-templating approach by simply modifying the post-calcination. The structure and morphology characteristics of the synthesized products were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Further experimental result reveals that the preheating program is vital to the formation of the multishelled architectures, and the formation process of the multishelled hollow microspheres was discussed in detail. More importantly, the multishelled Cr 2 O 3 hollow microspheres (MCHMs) exhibit enhanced gas sensitive activity to ethanol compared with single-shelled Cr 2 O 3 hollow structures.

Porous Cr 2 O 3 hollow microspheres assembled by nanoparticles have been successfully synthesized by thermal decomposition of a precursor which was prepared via a mild template-free hydrothermal approach. The average dimensions of these Cr 2 O 3 hollow microspheres were about 2.2 µm in diameter and 130 nm in thickness of spherical shell. The structures and morphologies of the synthesized products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). Moreover, the formation mechanism of the Cr 2 O 3 precursor hollow structure was suggested to be an inside-out formation mechanism process through tracking the morphology evolution with different reaction times.

In this study, complicated double-wall Cu2O hollow spheres have been successfully prepared by a facile hydrothermal process in a ternary solvent system including water, ethanol and glycerol. The obtained double-wall Cu2O hollow spheres have an average diameter of ∼15 μm and the spheres are assembled by irregular particles with an average diameter of ∼500 nm. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the structure of the synthesized products. The formation mechanism of the double-wall Cu2O hollow spheres is related to a self-assembly process accompanied by an Ostwald ripening process, during which the Cu2O spheres are first formed through the self-assembly of Cu2O nanoparticles and then gradually develop into double-wall hollow interiors by an Ostwald ripening process. Furthermore, the photocatalytic properties of the as-obtained samples were investigated. It is found that such unique double-wall hollow architecture exhibits excellent photocatalytic efficiency for the degradation of MO under visible-light illumination, which is up to 90.3% and this photocatalytic efficiency is higher than the Cu2O particles with irregular spherical structure (74.2%). The high photocatalytic performance of the double-wall Cu2O hollow spheres is associated with the fact that there are plenty of nanopores which exist in the spheres, serving as transport paths for small molecules.

Coupled twin-shaped hollow hemispherical calcium molybdate (CTHH-CaMoO4) microstructures were successfully synthesized via a facile ultrasound-assisted template-free route in the presence of absolute ethanol and ethylenediaminetetraacetic acid (EDTA). The oriented attachment and subsequent Ostwald ripening mechanism were responsible for the formation of this novel architecture.

α-MoO3 nanobelts with amphiphilic properties have been successfully fabricated via a hydrothermal method. The nanobelt membrane with a three-dimensional cross-linked nano-scale network structure was prepared on a filter paper surface by a suction filtration process. After being modified with water, the wetted membrane could be applied for the separation of nonpolar liquids and water, especially in emulsions. The separation process was simple, without employing any extra power, and the nanobelt membrane was easily recyclable. Based on this study, a separation mechanism was proposed. Our results suggest an innovative inorganic material that has excellent oil/water selectivity in the cleanup of oil from water.

Monodisperse ZnO hollow microspheres (ZnO–HMs) with average diameter about 2 μm and shell thickness about 300 nm were prepared through a facile template-free, glycerol-mediated hydrothermal route. Their structures and morphologies were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). A possible crystal growth and hollowing mechanism were suggested based on the detailed experimental results. Moreover, gas sensors were fabricated based on as-prepared hollow spheres and exhibited high response and good selectivity to ethanol at the optimum working temperature of 380 °C.

Cylindrical stacks WO3 (CSWs) have been successfully prepared by the reaction of Na2WO4·2H2O and HCl solution via a straightforward hydrothermal treatment in the absence of any template. And the flower-like WO3 (FLW) microstructures have been prepared by adding polyethylene glycol (PEG-1000). The structure and property of the products were characterized by various techniques (XRD, FTIR, SEM and UV–vis). The possible formation mechanism of the two superstructures was discussed in detail according to the experimental results. In addition, the photocatalytic activities of the samples were evaluated by the degradation of methylene blue (MB). The results showed that the photocatalytic performance of FLW was more efficient compared with CSWs, demonstrating that the degradation rate may be related to their different morphologies.

Pure vaterite CaCO3 microcrystals with an unusual spica-like hierarchical morphology were synthesized via a simple precipitation method, in which NaHCO3 and ethanol played a key role. The oriented attachment mechanism was responsible for the novel structure. An organic–inorganic composite membrane (PVDF/CaCO3) was prepared and its hydrophilicity was increased dramatically.

Vaterite calcium carbonate hierarchical structures with a flowerlike appearance have been successfully synthesized by means of a nanoparticle-mediated self-organization process in an ethanol/water mixed solution system under mild conditions without using any organic additives. A mechanism for the formation of vaterite crystal aggregates with flowerlike structures made of decussate “cigars” is presented. There are two points that play important roles in the regular organization of the terminal products: one is the concentration of carbonate, and the other is the volume ratio of ethanol/double-distilled water. In view of the results, a nanoparticle-mediated self-organization process is helpful in controlling the aggregation-driven formation of complex higher-order-structured materials and will provide new insights into biomineralization mechanisms. This study could provide an additional tool for designing advanced materials and could be used for the synthesis of more complex crystalline three-dimensional structures.

The uniform hierarchical sea urchin-like Cu 2 O architectures have been successfully prepared via an ultrasound-assisted method. The detailed morphology and structure of the synthesized hierarchical nanostructures were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). A series of observed intermediates disclose the possible process of forming hierarchical Cu 2 O architectures, and the possible chemical reactions involved in the construction of the Cu 2 O microstructures is proposed in order to gain a better control over their shape, crystallinity, and yield. The prepared sea urchin-like Cu 2 O particles exhibit higher adsorption ability and photocatalytic activity for photodegradation of methyl orange aqueous solution under visible-light illumination than other Cu 2 O particles with different morphologies (mesoporous spheres, star-like, meatball particles, broken flower-like).

The uniform hierarchical 3D flowerlike copper oxide (CuO) nanostructures, which were composed of interconnected nanowires, have been successfully prepared via a reverse microemuclsion method. The detailed morphology and structure of the synthesized hierarchical nanostructures were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). A series of observed intermediates disclose the possible process of forming 3D flowerlike CuO. An oriented aggregation growth process mediated by the microemulsion droplet building blocks might take place during the formation of initial 3D flowerlike CuO. And the novel 3D flowerlike and straw-like CuO nanostructures are produced as reaction time goes on, which might experience an Ostwald ripening process.

The synthesis of heteropoly compounds and preparation of the heteropoly acid zinc salt as photo-catalyst, and their characterizations are studied by IR, SEM. The dye wastewater (crystal violet) is investigated with the catalysts prepared under visible light for photocatalytic decoloration and degradation. The results showed that, the Zn-heteropoly salt prepared by sol- gel method as photocatalyst can crystal violet degradation very well in visible light. The efficiencies of photodegradation of the catalyst and oxidant dosage, as well as additive are closely related. The easy recovery of catalyst has a good reproducibility. It is energy saving and important to environmental protection. The application of them is promising.

Nanostructure manganese oxide shows very good catalytic activity in waste water treatment of dyeing industry. A few nano manganese oxides are prepared through different methods, Their catalytic degradation property of dyeing material (crystal violet solution) is tested with H2O2 as oxidizer. Besides, the influence of other parameters are also studied, including catalyst dosage, H2O2 dosage and catalyst circulation. After reaction of 60 minutes, degradation of crystal violet can reach over 99% for most catalyst samples.

Hollow metallic copper (0) spheres (HMCSs) about 2 to 6 μm in diameter were successfully synthesized via a mild template-free hydrothermal method. A possible formation mechanism, which was related to the Ostwald ripening process, is proposed. In addition, compression tests showed that these pure Cu hollow microspheres exhibit high compression plasticity.