Biomolecule-assisted synthesis and electrochemical hydrogen storage of porous spongelike Ni3S2 nanostructures grown directly on nickel foils

Nanothread-based porous spongelike Ni3S2 nanostructures were synthesized directly on Ni foil by using a simple biomolecule-assisted method. By varying the experimental parameters, other novel Ni3S2 nanostructures could also be fabricated on the nickel substrate. The electrochemical hydrogen-storage behavior of these novel porous Ni3S2 nanostructures was investigated as an example of the potential properties of such porous materials. The thread-based porous spongelike Ni3S2 could electrochemically charge and discharge with the high capacity of 380 mAh g(-1) (corresponding to 1.4 wt % hydrogen in single-walled nanotubes (SWNT)). A novel two-charging-plateaux phenomenon was observed in the synthesized porous spongelike Ni3S2 nanostructures, suggesting two independent steps in the charging process. We have demonstrated that the morphology of the synthesized Ni3S2 nanostructures had a noticeable influence on their electrochemical hydrogen-storage capacity. This is probably due to the size and density of the pores as well as the microcosmic morphology of different nickel sulfide nanostructures. These novel porous Ni3S2 nanostructures should find wide applications in hydrogen storage, high-energy batteries, luminescence, and catalytic fields. This facile, environmentally benign, and solution-phase biomolecule-assisted method can be potentially extended to the preparation of other metal sulfide nanostructures on metal substrates, such as Cu, Fe, Sn, and Pb foils.     

Development of one-dimensional nanostructures through the crystallization of amorphous colloids

In this paper we have demonstrated that the crystallization method of amorphous colloids is convenient and feasible in the large-scale production of one-dimensional (1D) nanostructures. For the crystals with highly anisotropic structures, such as orthorhombic, trigonal, and hexagonal crystals, the crystallization generally tends to occur along the (001) axis. The preparation of orthorhombic bismuth sulfide (Bi2S3) nanorods and trigonal selenium ( t-Se) nanowires by the crystallization route was used as typical examples to illustrate the process and mechanism of crystallization. The as-prepared products were characterized with transmission electron microscopy, field-emission scanning electron microscopy, X-ray diffraction, and selected area electron diffraction. Additionally, the detailed crystal growth processes involved in the crystallization of amorphous Bi2S3 colloid were investigated by studying the morphology and structure of intermediates. It demonstrates that the growth of the nanorods is through two key steps: (1) the formation of multiple activated sites on the surface of spherical Bi2S3 colloid and (2) the subsequent preferential growth along these sites.     

Biomolecule-assisted synthesis of highly ordered snowflakelike structures of bismuth sulfide nanorods

A biomolecule-assisted simple technique has been developed for the spontaneous ordering of the Bi2S3 nanorods into snowflakelike superstructures in high yield under microwave-hydrothermal conditions. In this method, glutathione (GSH) is used as both an assembling agent and a sulfur source. By controlling the molar ratio between bismuth nitrate and glutathione as well as the synthetic temperature, several kinds of Bi2S3 one-dimensional nanomaterials such as snowflakelike structures, nanowires constructed of particles, short nanorods, and fine and long nanowires have been controllably synthesized.     

生物分子辅助溶剂热合成硫化锑纳米棒

以SbCl3和L-胱氨酸为反应原料,采用溶剂热法在170℃反应12h,制得硫化锑(Sb2S3)纳米棒.X射线衍射(XRD)、能量分散光谱(EDS)和X射线光电子能谱(XPS)研究表明所得产物为典型的Sb2S3正交结构.场发射扫描电子显微镜(FESEM)和透射电子显微镜(TEM)研究显示,Sb2S3纳米棒长为3～6μm,平均直径约为150nm.讨论了不同反应时间对Sb2S3的形成及其形貌的影响,并根据实验结果对所合成的一维纳米棒可能的形成机理进行了简单的探讨.     

Electrodeposition of high-pressure-stable bcc phase bismuth flowerlike micro/nanocomposite architectures at room temperature without surfactant

Three-dimensional (3D) bismuth flowerlike micro/nanocomposite architectures were successfully prepared on Cu substrates by electrochemical self-assembly in aqueous solution at room temperature. The morphology, crystal structure, and composition were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). Results show that the synthesized 3D architectures are built with dozens of two-dimensional (2D) single crystal nanoscaled petals, which are high-pressure-stable bcc phase Bi. The thickness of the 2D petals is about 60 nm. The effects of the concentration of Bi³⁺ ions and the electric potential gradient on the evolution of the Bi flowerlike micro/nanocomposite architectures are discussed.     

Chemical conversion synthesis and optical properties of metal sulfide hollow microspheres

A facile chemical conversion method has been demonstrated to prepare various metal sulfide hollow microspheres. The present strategy utilizes the large difference in solubility between ZnS and other metal sulfides (Ag2S, PbS, CuS, Cu2S, Bi2S3, and Sb2S3) for the effective transformation and shows mild growth conditions and good reproducibility. The morphology, structure, and composition of the yielded hollow nanostructures have been confirmed by transmission electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction measurements. The optical properties of the metal sulfide hollow microspheres have been systematically investigated by absorption, micro-Raman, and photoluminescence spectroscopy. The results demonstrate that these metal sulfide hollow microspheres possess good optical quality with tunable band gaps and luminescence properties, which indicate their broad potential applications. This simple chemical conversion technique can be further extended to the synthesis of other semiconductors with various morphologies.     

Synthesis and characterization of bismuth single-crystalline nanowires and nanospheres

A facile solution-phase process has been demonstrated for the selective preparation of single-crystalline bismuth nanowires and nanospheres by reducing sodium bismuthate with ethylene glycol in the presence of poly(vinyl pyrrolidone) (PVP) or acetone. Bismuth nanobelts and Bi/Bi(2)O(3) nanocables could be also obtained by changing some reaction parameters. Various techniques such as XRD, EDXA, SEM, TEM, HRTEM, and FT-IR have been used to investigate the physical characteristics of these low-dimensional bismuth nanostructures.     

Bismuth sulfide nanoflakes and nanorods as high performance photodetectors and photoelectrochemical cells

Flake-like and rod-like bismuth sulfide nanostructures were synthesized via a facile polyol refluxing process. The rigid photodetectors based on both nanomaterials have the features of linear photocurrent characteristics and good sensitivity. Especially, the rigid bismuth sulfide nanoflakes photodetector has fast response time of 0.5 s and recovery time of 0.7 s. The flexible photodetectors were then fabricated on PET substrate, and this caused both the response time and the recovery time to increase by a factor of ∼2.5. Moreover, the photoelectrochemical (PEC) devices exhibited photosensitivity with the features of rapid response and recovery time, high on/off ratio and stable switching cycle performance. Our results imply that the two types of bismuth sulfide nanomaterials are prospective candidates for next generation photodetectors and optoelectronic switches.     

Controlling the morphology of ZnO nanostructures in a low-temperature hydrothermal process

ZnO nanostructures of different morphologies were grown in a controlled manner using a simple low-temperature hydrothermal technique. Controlling the content of ethylenediamine (soft surfactant) and the pH of the reaction mixture, nanoparticles, nanorods, and flowerlike ZnO structures could be synthesized at temperatures 80-100 degrees C with excellent reproducibility. High-resolution electron microscopy revealed the well crystalline nature of all the nanostructures with preferential growth along the [002] direction for linear structures. Photoluminescence spectra of the as-grown nanostructures revealed oxygen-vacancy-related defects in them, which could be reduced by air annealing at 250 degrees C. Possible mechanisms for the variation of morphology with synthesis parameters are discussed.     

离子液体中微波合成纳米结构的Bi2S3和Bi19Br3S27

在不同咪唑基离子液体中, 利用微波辅助法快速合成了不同形貌的Bi2S3纳米粒子和Bi19Br3S27纳米棒. 利用XRD, TEM和SEM对合成产物进行了结构和形貌的表征. 实验结果表明离子液体在合成过程中对产物的相结构和形貌发挥了重要的作用. 实验中还进一步考察了不同实验条件对产物形貌的影响. 对实验的合成机理进行了初步探讨. 对不同形貌和纳米结构的Bi2S3和Bi19Br3S27进行了UV-Vis光谱分析.     

Shape-controlled synthesis of 3D and 1D structures of CdS in a binary solution with L-cysteine's assistance

A facile L-cysteine-assisted route was designed for the selectively controlled synthesis of 1D and novel, interesting 3D CdS spherical nanostructures constructed from CdS nanorods (or nanopolypods) in a binary solution. By controlling reaction conditions such as the molar ratio between Cd(OAc)2 and L-cysteine and the volume ratio of the mixed solvents, the synthesis of various 3D architectural structures and 1D wirelike structures in large quantities can be controlled. This is the first reported case of the direct growth of novel 3D self-assemblies of CdS nanorods (or nanopolypods). The morphology, structure, and phase composition of the as-prepared CdS products were examined by using various techniques (X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), high-resolution TEM, and Raman spectroscopy). On the basis of the results from TEM studies and our analysis, we speculate that in the present synthesis the L-cysteine dominates nucleation growth and the ethylenediamine (en)-dominated, oriented-assembly process. Interestingly, the products obtained show a gradient evolution in color from light-yellow to dark-yellow, which implies that their intrinsic optical properties change, possibly due to variations in their special morphologies and structures. This facile solution-phase L-cysteine-assisted method could be extended for the controlled preparation of other metal chalcogenides nanostructures with complex morphologies.     

Single-crystal Bi2S3 nanosheets growing via attachment-recrystallization of nanorods

High-quality Bi(2)S(3) discrete single-crystal nanosheets with orthorhombic structure have been synthesized through the thermal decomposition of a single-source precursor, Bi(S(2)CNEt(2))(3), in amine media. The morphology evolution reveals that the Bi(2)S(3) nanosheets are developed through the assembly of nanorods, and an attachment-recrystallization growth mechanism is proposed for the formation of nanosheets with the use of nanorods as building blocks. High-resolution transmission electron microscopy studies reveal that the nanosheets have the largest exposed surface of (100) facets. The effects of experimental variables, such as the reaction temperature, time, precursor concentration, and media, on the morphology of the obtained nanocrystals have been systematically investigated in which the amine has served as the solvent, surfactant, and electron donor.     

Microwave-assisted synthesis of sulfide M2S3 (m = Bi, Sb) nanorods using an ionic liquid

Single-crystalline Bi(2)S(3) and Sb(2)S(3) nanorods have been successfully synthesized by the microwave-assisted ionic liquid method. The starting reagents were Bi(2)O(3) or Sb(2)O(3), HCl, Na(2)S(2)O(3), and ethylene glycol (EG) or ethanolamine, and the ionic liquid used was 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF(4)]). Our experiments showed that the ionic liquid played an important role in the morphology of M(2)S(3) (M = Bi, Sb). Single-crystalline Bi(2)S(3) nanorods could be prepared in the presence of [BMIM][BF(4)]. However, urchinlike Bi(2)S(3) structures consisting of nanorods were formed without using [BMIM][BF(4)]. Single-crystalline Sb(2)S(3) nanorods were obtained in the presence of [BMIM][BF(4)]. However, single-crystalline Sb(2)S(3) nanosheets could be prepared in the absence of [BMIM][BF(4)]. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and electron diffraction (ED).     

Controlled hydrothermal synthesis of bismuth oxyhalide nanobelts and nanotubes

Ternary bismuth oxyhalide crystalline nanobelts (such as Bi24O31Br10, Bi3O4Br, Bi12O17Br2, BiOCl, and Bi24O31Cl10) and nanotubes (such as Bi24O31Br10) have been synthesized by using convenient hydrothermal methods. The composition and morphologies of the bismuth oxyhalides could be controlled by adjusting some growth parameters, including reaction pH, time, and temperature. All the nanostructures were characterized by using various methods including X-ray diffraction, transmission electron microscopy, high-resolution TEM, electron diffraction, and energy-dispersive X-ray analysis. The possible reaction mechanism and growth of the crystals are discussed based on the experimental results.     

Self-assembly of flowerlike AlOOH boehmite 3D nanoarchitectures

In this work, a hydrothermal route using an ethanol-water solution to progressively synthesize a sequence of flowerlike three-dimensional gamma-AlOOH boehmite nanostructures without employing templates or matrixes for self-assembly is presented. The flowerlike boehmite nanoarchitectures exhibit three hierarchies of self-organization, i.e., single-crystalline nanorods, nanostrips, and bundles, which are characterized by scanning and transmission electron microscopy. The sequence of products obtained after different processing times indicates a self-assembly mechanism. The hydrogen bonding on the surface of nanorods or nanostrips possibly plays a key role, as identified by FTIR spectra of the products after they had been heated to 1000 degrees C. The specific surface area and pore-size distribution of the obtained product as determined by gas-sorption measurements show that the boehmite nanoarchitectures exhibit high BET surface area and porosity properties.     

Effect of polyvinylpyrrolidone as capping agent on Ce3+ doped flowerlike ZnS nanostructure

Nanoparticles of zinc sulfide doped with Ce³⁺ have been synthesized through a simple chemical precipitation method utilizing optimum dopant concentration (1.5 g) and employing various concentrations of polyvinylpyrrolidone (PVP, M.W: 40,000) as capping agent. The optical properties of the synthesized products were studied by UV–Vis absorption and photoluminescence measurements. The phase and size of the products were predicted by X-ray diffraction data. The existence of functional groups in the synthesized products was identified by Fourier transform infrared spectroscopy. Field emission scanning electron microscope results of Ce³⁺ doped ZnS show a uniform growth pattern of the nanorods with flowerlike structure. However, on surfactant assisted Ce³⁺ doped ZnS nanoparticles, the morphology of the products was changed from rod to spherical particles. The morphologies of the uncapped and PVP capped ZnS nanocrystals were confirmed by high resolution transmission electron microscopy.     

Ag/ZnO Catalysts with Different ZnO Nanostructures for Non‐enzymatic Detection of Urea

Silver coated ZnO nanorods and nanoflakes with different crystallographic orientations were synthesized by a combination of sputter deposition and solution growth process. Catalytic properties of morphology‐dependent Ag/ZnO nanostructures were then investigated for urea sensors without enzyme. Ag/ZnO nanorods on carbon electrodes exhibit a higher catalytic activity and an improved efficiency than Ag/ZnO nanoflakes on carbon electrodes. Ag/ZnO nanorod catalysts with more electrochemically surface area (169 cm² mg^?1) on carbon electrode facilitate urea electrooxidation due to easier electron transfer, which further promotes the urea electrolysis. The Ag/ZnO nanorod catalysts also show a significant reduction in the onset voltage (0.410 V vs. Ag/AgCl) and an increase in the current density (12.0 mA cm^?2 mg^?1) at 0.55 V vs Ag/AgCl. The results on urea electrooxidation show that Ag/ZnO nanostructures can be a potential catalyst for non‐enzymatic biosensors and fuel cells.     

Ultrafast growth of dendritic gold nanostructures and their applications in methanol electro-oxidation and surface-enhanced Raman scattering

A simple and rapid solution-phase synthesis of dendritic gold nanostructures with hyperbranched architecture is demonstrated in this report. Further investigations revealed that the morphology of the synthesized sample depended on proper parameters such as reagent concentration, reaction temperature, reagent addition sequence and stir. Moreover, the dendritic gold nanostructures exhibited a good electrocatalytic activity toward methanol electro-oxidation. When compared with sea-urchinlike and flowerlike gold nanostructures which were prepared by varying the parameters of experiment, dendritic gold nanostructures showed the highest surface-enhanced Raman scattering (SERS) sensitivity using 4-aminothiophenol (4-ATP) as probe molecules. The dendritic gold nanostructures may find potential applications in catalysis, SERS and biosensor.     

Bi2S3 nanomaterials: morphology manipulation and related properties

The Bi(2)S(3) nanomaterials with various morphologies such as nanorods, nanowires, nanowire bundles, urchin-like microspheres and urchin-like microspheres with cavities have been successfully synthesized through a simple hydrothermal method. Experimental results indicate that sulfur sources play crucial roles in determining the morphologies of Bi(2)S(3) products. Moreover, formation mechanisms of different Bi(2)S(3) nanostructures are discussed based on understanding of the growth habit of Bi(2)S(3) crystal. Finally, we also studied the morphologies-dependent electrochemical and optical properties of the as-synthesized Bi(2)S(3) nanomaterials.     

Bi2S3-sensitized TiO2 nanorods by bottom-up approach for photoelectrochemical solar cell

Journal of Solid State Electrochemistry - Bismuth sulfide (Bi2S3)-sensitized titanium dioxide (TiO2) nanorods have been successfully synthesized by a simple and cost-effective chemical deposition...