Coprecipitation-assisted hydrothermal synthesis of PLZT hollow nanospheres

Lanthanum-modified lead zirconate titanate Pb_1−xLa_x(Zr_1−yTi_y)O₃ (PLZT) hollow nanospheres have been successfully prepared via a template-free hydrothermal method using the well-mixed coprecipitated precursors and the KOH mineralizer. The structure, composition, and morphology of the PLZT hollow nanospheres were characterized by XRD (X-ray diffraction), ICP (inductive coupled plasma emission spectrometer), FTIR (Fourier transform infrared spectra), TG/DTA (thermogravimetric analysis and differential thermal analysis), TEM (transmission electron microscopy) and SEAD (selected area diffraction). The results show that the composition and the morphology control of the PLZT products are determined by the KOH concentration. The PLZT hollow nanospheres with uniform size of about 4 nm were synthesized in the presence of 5 M KOH. The crystalline nanoparticles can be prepared at dilute KOH, in contrast to the amorphous powders prepared at concentrated KOH. Formation mechanisms of the PLZT hollow nanospheres are also discussed.     

Preparation of hollow carbon nanospheres via explosive detonation

Hollow carbon nanospheres were prepared via a rapid detonation technique, by using negative-oxygen balance explosive trinitrotoluene and nickel powder as starting materials and inorganic acid as solvent. The carbon/metal nanocomposite particles precursor with core-shell structure was engendered firstly during detonation, and then the metal nickel core was dissolved through inorganic acid to attain the hollow carbon nanospheres. High-Resolution Transmission Electron Microscope, X-ray diffraction and Raman spectrum were used to characterize the precursor and the as-synthesized samples respectively. The results show that the external diameter of the hollow carbon nanospheres is 25-150 nm and the thickness of the wall is about 2-10 nm. The surface of hollow carbon nanosphere displays multilayer wall in structure with 0.35 nm space between the layers. Based on the experimental results, possible formation mechanism was also proposed.     

Selective synthesis of copper nanoplates and nanowires via a surfactant-assisted hydrothermal process

A facile solution-phase process has been demonstrated for the selective preparation of single-crystalline Cu nanoplates and nanowires by reducing Cu⁺ with ascorbic acid (VC) in the presence of cetyltrimethylammonium bromide (CTAB) or cetyltrimethylammonium chloride (CTAC). To study the formation process of nanoplates and nanowires, samples obtained at various stages of the growth process were studied by TEM and XRD. The possible mechanism was discussed to elucidate the formation of different morphologies of Cu nanostructures. UV–vis spectra of the Cu nanoplates and nanowires were recorded to investigate their optical properties, which indicated that the as-prepared Cu nanostructures exhibited morphology-dependent optical property.     

Facile synthesis of hollow carbon nanospheres from hollow chitosan nanospheres

Hollow carbon nanospheres (HCNS) with large surface area were synthesized from hollow chitosan nanospheres by one-step pyrolysis with a relatively low temperature (550 degrees C). The resulted HCNS is fully carbonized and partially graphitized under the experiment conditions. It is an important and facile method to prepare the uniform, shape- and size-controlled carbon nanomaterials by carbonization of the natural polysaccharide compounds and their derivatives. The as-prepared HCNS has a narrow size distribution in hollow carbon nanospheres (about 53 nm). The structure and size of HCNS are reproducible and could be tunable by changing the preparation conditions. The characterizations to estimate the composition, decompose properties, crystalline form, structure and surface property of the HCNS were investigated using FT-IR spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction measurement (XRD), transmission electron microscopy (TEM) analysis, and the N2 adsorption-desorption isothermal process. The present preparation method makes it feasible to synthesize carbon nanospheres in abundance in the lab, and the synthesized HCNS could be a promising support for metal catalysts, an ideal matrix connecting with DNA or other bioactive substances.     

Template-free hydrothermal synthesis and optical properties of ceria hollow nanospheres with rough surface

The large-scale uniform CeO₂ hollow nanospheres with diameter of about 600 nm and rough surface have been successfully synthesized via a simple template-free hydrothermal technology. The obtained samples were examined by XRD, SEM, TEM, XPS, Raman scattering and UV–Vis spectra. The results show that the samples have a cubic fluorite structure of CeO₂ with no crystalline impurity phase and many Ce³⁺ ions and oxygen vacancies exist in the surface of CeO₂ sample. A red-shifting of the band gap is observed for the CeO₂ hollow nanospheres contrasting with the bulk one, which is mainly attributed to the influences of the Ce³⁺ ions and oxygen vacancies.     

Preparation of CeO2 hollow spheres via a surfactant-assisted solvothermal route

In this study, CeO₂ hollow spheres were synthesized via a facile surfactant-assisted solvothermal route. The synthesized products were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, and N₂ adsorption–desorption. Different solvent species has been demonstrated as the key factor responsible for the controlled morphologies. Furthermore, both the water and the oleic acid were crucial to the formation of CeO₂ hollow spheres. The possible formation mechanism of CeO₂ hollow spheres has been preliminary discussed.     

Fabrication of hollow polyelectrolyte nanospheres via surface-initiated atom transfer radical polymerization

Novel polyelectrolyte-grafted core-shell organic/inorganic hybrid nanospheres which possess hard backbone of silica nanoparticles and soft shell of cross-linked poly(ionic liquids) (PILs) have been synthesized via a surface-initiated atom transfer radical polymerization (SI-ATRP). After removal of the core templates of the core-shell nanospheres, nearly monodispersed hollow polyelectrolyte nanospheres were obtained. Various characterization techniques including FT-IR, XPS, and TEM were used to characterize the resulting core-shell and hollow polyelectrolyte nanospheres. The results showed that the hollow nanosphere has a hollow core of an average diameter of ca. 200 nm with a shell thickness of ca. 25 nm. The obtained hollow polyelectrolyte nanospheres could be applied in release-control systems.     

Preparation and transformation to hollow nanospheres of wrapped CuS nanowires by a simple hydrothermal route

In this paper we reported the preparation of wrapped CuS nanowires via a simple hydrothermal reaction at 180 °C for 2 h, employing CuSO₄·5H₂O and thiourea as reactants in the absence of any structure-directing agent. SAED pattern showed that the wrapped CuS nanowires were polycrystalline, which was comprised of small nanoparticles. TEM observations showed that wrapped nanowires could grow and further transfer to hollow spheres with the prolonging of the reaction time from 2 h to 13. The UV-Vis spectra of CuS prepared at 180 °C for different times were studied. The possible transfer mechanism from wrapped nanowires to hollow spheres was suggested.     

Preparation of hollow CdSe nanospheres

Cadmium selenide (CdSe) hollow nanospheres (approximately 40–50 nm) have been successfully synthesized by γ-irradiating polyacrylamide (PAM) hydrogel template which contains CdCl₂ and Na₂SeO₃ aqueous solution at room temperature. The nanospheres were characterized by energy dispersive spectrum (EDS), field emission scanning electron micrograph (FESEM), transmission electron microscopy (TEM) and high-resolution transmission electron micrograph (HRTEM), respectively. EDS showed that nanospheres were composed of Cd and Se (atomic ratio, 1.15:1). A possible formation mechanism of CdSe hollow nanospheres through two-steps was presented.     

Synthesis and characterization of flower-like WS2 nanospheres via a facile hydrothermal route

Flower-like WS₂ nanospheres with high purity were successfully synthesized via a facile surfactant-assisted hydrothermal route. The products were characterized by X-ray powder diffraction and scanning electron microscopy. The flower-like WS₂ nanospheres, consisting of numerous aggregate nanosheets with the width of 300–500 nm, had uniform sizes with a mean diameter about 5 μm. Further comparative experiments showed that the surfactant cetyltrimethyl ammonium bromide (CTAB) played a critical role as templates to promote the growth of WS₂ nanosheets and accelerate the assembling of nanosheets into flower-like nanosphere. Interaction forces inside the CTAB made the flower-like nanospheres grow uniformly and dispersedly. Moreover, the WS₂ nanoflowers exhibited excellent visible-absorption ability and may have a potential application as a visible photocatalyst.     

NixCo0.85-xSe中空纳米球的溶液化学法合成、双功能特性及锌空电池应用（英文）

合成高活性、低成本、双功能特性的电催化剂是目前发展新能源材料的重要任务.过渡金属硒化物具有较高的电导特性、可调节的物理化学特性等,成为了开发高效氧还原和氧析出催化剂的研究热点.本文采用多元醇溶液化学法合成了具有较大比表面积的NixCo0.85-xSe中空纳米球.该催化剂的ORR起始电位达到0.89 V,OER在10 mA cm^-2电流密度下的过电位达到305 mV.以NixCo0.85-xSe中空纳米球为空气电极、锌片为阴极组成的锌空电池具有良好的比容量和循环稳定性.NixCo0.85-xSe中空纳米球优异的催化性能主要归因于较大的比表面积、Ni和Co的协同催化特性以及良好的导电性.本文为设计高效的锌空电池催化剂提供了良好的理论基础和实验支持.     

PEG based hyperbranched polymeric hollow nanospheres

The synthesis of a new PEG based hyperbranched copolymer of poly(ethylene glycol) methyl ether methacrylate-co-ethylene glycol dimethacrylate (PEGMEMA-co-EGDMA) was achieved via a one-step in situ deactivation enhanced atom transfer radical polymerization (DE-ATRP). Then, hollow PEG based nanospheres were fabricated from this polymer using a solvent evaporation method and post-stabilisation strategy. Furthermore, the analysis using a cellular metabolic activity assay proved that the copolymer did not affect cellular metabolism, indicating that this PEG based polymeric nanosphere has potential for use in drug delivery applications.     

Electrical and thermoelectric properties of surfactant-assisted calcium cobalt oxide nanoparticles

Journal of Materials Science: Materials in Electronics - We are in need of clean, cost-effective and renewable energy sources because of the energy crisis and global warming. Thermoelectric...     

Large-scale preparation of hollow graphitic carbon nanospheres

Hollow graphitic carbon nanospheres (HGCNSs) were synthesized on large scale by a simple reaction between glucose and Mg at 550 °C in an autoclave. Characterization by X-ray diffraction, Raman spectroscopy and transmission electron microscopy demonstrates the formation of HGCNSs with an average diameter of 10 nm or so and a wall thickness of a few graphenes. The HGCNSs exhibit a reversible capacity of 391 mAh g⁻¹ after 60 cycles when used as anode materials for Li-ion batteries.     

无机材料纳米空心球的制备方法研究进展

探索新的纳米结构已成为近年来物理、化学、材料等领域的研究热点之一.纳米空心球作为一种新的纳米结构,其特有的核-壳空心结构及纳米厚度的壳层使它具有许多优异的物理化学性能,从而在医学、制药学、材料学、染料工业等领域具有很好的应用前景.本文综述了模板法和由模板法发展而来的L-bL自组装法制备无机材料纳米空心球的一般过程及原理,最后展望了纳米空心球材料的发展前景,并探讨了目前在无机材料纳米空心球研究领域中存在的问题.     

The formation of WO3 nanorods using the surfactant-assisted hydrothermal reaction

Monoclinic tungsten oxide (WO₃) nanorods were grown using the hydrothermal method on a seeded W foil. The seed layer was formed by thermal oxidation of W foil at 400°C for 30 min. Cetyltrimethylammonium bromide (CTAB) or hexamethylamine (HMT) was used in the reactive hydrothermal bath, along with sodium tungstate dihydrate (Na₂WO₄.2H₂O) and hydrochloric acid (HCl). The concentration of CTAB was varied from 0.01 M to 0.07 M and the concentration of HMT was varied from 0.01 M and 0.05 M. The result showed that CTAB-assisted hydrothermal reaction produced WO₃ nanorods with 4–7 nm diameter, and provided that CTAB concentration was less than 0.07 M. WO₃ nanorods could not be obtained when CTAB concentration was 0.07 M. Columnar structured WO₃ was produced with the presence of HMT in the hydrothermal bath. This was due to decomposition of HMT to form hydroxyl ions (OH^?) that inhibited the growth of nanorods. Cyclic voltammetry (CV) analysis showed better electrochromic property of WO₃ nanorods compared to columnar structured WO₃.     

Fabrication of β-NiS hollow sphere consisting of nanoflakes via a hydrothermal process

Hexagonal structured β-NiS hollow spheres consisting of nanoflakes were successfully prepared by a dodecanethiol-assisted hydrothermal process at 180 °C for 12 h, employing l-cysteine and nickel sulfate hexahydrate as the precursors. The synthesized product was characterized by XRD, FESEM, TEM, HRTEM, and ED. The experiment results show that the sulfur source and dodecanethiol play key roles on the formation of the morphology of β-NiS hollow spheres. And the formation mechanism of nickel sulfide hollow spheres may be involved with dodecanethiol micelles as template and the Ostwald ripening process.     

Fabrication of hollow mesoporous NiO hexagonal microspheres via hydrothermal process in ionic liquid

The novel NiO hexagonal hollow microspheres have been successfully prepared by annealing Ni(OH)₂, which was synthesized via an ionic liquid-assisted hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), N₂ adsorption-desorption and Fourier transform infrared spectrometer (FTIR). The results show that the hollow NiO microstructures are self-organized by mesoporous cubic and hexagonal nanocrystals. The mesoporous structure possessed good thermal stability and high specific surface area (ca. 83 m²/g). The ionic liquid 1-butyl-3methylimidazolium tetrafluoroborate ([Bmim][BF₄]) was found to play a key role in controlling the morphology of NiO microstructures during the hydrothermal process. The special hollow mesoporous architectures will have potential applications in many fields, such as catalysts, absorbents, sensors, drug-delivery carriers, acoustic insulators and supercapacitors.     

Anionic surfactant-assisted hydrothermal synthesis of high-aspect-ratio ZnO nanowires and their photoluminescence property

ZnO nanowires with high-aspect-ratio of up to ca. 600 were synthesized in a quaternary reverse microemulsion containing sodium dodecyl sulfate (SDS) / water / heptane / n-hexane via a hydrothermal method. SDS, as an anionic surfactant, plays an important role in the formation of morphologies. Subsequently, we studied lots of key influencing factors including the molar ratio (w) value of NaOH to Zn(OAc)₂, the reaction temperature, and the instance without the quaternary reverse microemulsion. The selected-area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM) reveal the single-crystal nature of the ZnO nanowires. The morphologies and crystalline structure of the as-obtained products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and powder X-ray diffraction (XRD), respectively. Through this route, we can obtain a mass of products and the method is both convenient and reproducible. Finally, we measured the photoluminescence (PL) spectra and found that the ZnO nanowires exhibited green-orange emission at 525 nm and short ultraviolet emission at 380 nm and the ZnO nanomaterials with different aspect ratio (length to diameter) (L / D) showed PL intensity disciplinary change. Aiming at this phenomenon, we propose a reasonable mechanism to explain the PL spectra of the ZnO nanomaterials in detail.     

Immobilized CuO hollow nanospheres catalyzed alkyne-azide cycloadditions

An approach for gram-scale synthesis of uniform Cu2O nanocubes by a one-pot polyol process was used. The CuO hollow nanostructures were prepared by adding aqueous ammonia solutions with Cu2O nanocube colloidal solutions. CuO hollow nanospheres on acetylene black (CuO/AB), were synthesized and used for the catalytic [3+2] cycloaddition of azides with terminal alkynes to provide products in good yields with high regioselectivity. The CuO/AB was readily separated by centrifugation and could be reused ten times under the present reaction conditions without any loss of catalytic activity. Transition metals loaded onto acetylene black are useful reagents for a wide variety of organic transformations. Moreover, these heterogeneous systems are promising industrial catalysts.