In Situ Heating TEM Study of Onion-like WS2 and MoS2 Nanostructures Obtained via MOCVD

2007

We report on the in situ heating transmission electron microscopy (TEM) study of WS2 and MoS2 nanoparticles obtained from metal–organic chemical vapor deposition (MOCVD). The general behavior of MoS2 and WS2 is similar: Round, amorphous particles in the pristine sample transform to hollow, onion-like particles upon annealing. A second type of particle with straight layers exhibits only minor changes. A significant difference between both compounds could be demonstrated in their crystallization behavior. The results of the in situ heating experiments are compared to those obtained from an ex situ annealing process under Ar.

Bismuth-Catalyzed Growth of SnS2 Nanotubes and Their Stability

2009

Synthesis of MoO3 Nanostructures and Their Facile Conversion to MoS2 Fullerenes and Nanotubes.

2007

The fast thermolysis of ammonium molybdate leads to a mixture of MoO3 and Mo5.3O14.5(OH)2.8(H2O)1.36 with spherical and rod-like morphologies. The oxide mixture can be converted in quantitative yield to inorganic fullerene-type (IF) MoS2 and MoS2 nanotubes (NT) by H2S reduction using a facile and quick procedure. The products were studied by X-Ray Diffraction (XRD) and by Transmission Electron Microscopy (TEM). TEM analysis reveals that the spherical and rod-like morphology of the oxide precursor is preserved during the H2S treatment.

From Layered Molybdic Acid to Lower-Dimensional Nanostructures by Intercalation of Amines under Ambient Conditions

2006

Nanostructures of varied dimensionality such as rods, scrolls, and disks of molybdenum oxide have been synthesized in gram quantities under ambient conditions using exfoliation of the layers as a synthetic tool. Intercalation of alkylamines (CnH2n+2NH2, where n = 3, 4, 8, 12, and 16) into yellow molybdic acid (MoO3·2H2O) and subsequent treatment with nitric acid resulted in molybdenum oxide nanorods, nanodisks, or oxide−amine composite nanorods. The sizes of the nanoparticles range from a few nanometers to micrometers in length and 10 to 200 nm in diameter. Detailed X-ray, scanning electron microscopy, and transmission electron microscopy analyses reveal an inverse relation between the size…

Superparamagnetic γ-Fe2O3 nanoparticles with tailored functionality for protein separation

2007

Polymer coated superparamagnetic gamma-Fe(2)O(3) nanoparticles were derivatized with a synthetic double-stranded RNA [poly(IC)], a known allosteric activator of the latent (2-5)A synthetase, to separate a single 35 kDa protein from a crude extract which cross reacted with antibodies raised against the sponge enzyme.

Magnetic transitions in double perovskiteSr2FeRe1−xSbxO6(0⩽x⩽0.9)

2006

The double perovskites ${\mathrm{Sr}}_{2}\mathrm{Fe}M{\mathrm{O}}_{6}$ $(M=\mathrm{Re},\mathrm{Mo})$ belong to the important class of half-metallic magnetic materials. In this study we explore the effect of replacing the electronic $5d$ buffer element Re with variable valency by the main group element Sb with fixed valency. X-ray diffraction reveals ${\mathrm{Sr}}_{2}{\mathrm{FeRe}}_{1\ensuremath{-}x}{\mathrm{Sb}}_{x}{\mathrm{O}}_{6}$ $(0lxl0.9)$ to crystallize without antisite disorder in the tetragonally distorted perovskite structure (space group $I4∕mmm$). The ferrimagnetic behavior of the parent compound ${\mathrm{Sr}}_{2}{\mathrm{FeReO}}_{6}$ changes to antiferromagnetic upon Sb subst…

Multifunctional polymer-derivatized γ-Fe2O3 nanocrystals as a methodology for the biomagnetic separation of recombinant His-tagged proteins

2008

Abstract Multifunctional polymer-derivatized superparamagnetic iron oxide (γ-Fe2O3) nanoparticles were prepared for biomagnetic separation of histidine-tagged recombinant proteins building up a faster and efficient method for protein separation by making use of their intrinsic magnetic properties. Using polymer bound γ-Fe2O3 nanocrystals, a 6× histidine-tagged recombinant protein (silicatein) with a molecular weight of 24 kDa has been isolated and purified. The supermagnetic iron oxide nanocrystals were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), SQUID and Mossbauer and the polymer functionalization of the γ-Fe2O3 nanocrystals was monitored by UV–vi…

Synthetic Approaches to Functionalized Chalcogenide Nanotubes

2008

Metal-Organic Chemical Vapor Depostion Synthesis of Hollow Inorganic-Fullerene-Type MoS2 and MoSe2 Nanoparticles

2005

Facile Large Scale Synthesis of WS2 Nanotubes from WO3 Nanorods Prepared by a Hydrothermal Route.

2005

Abstract Hexagonal WO 3 nanorods of 5–50 nm in diameter and 150–250 nm in length have been synthesised in gram quantities by a low temperature hydrothermal route using citric acid as a structural modifier and hexadecylamine as a templating agent. The ratio of [A]/[W] play an important role on WO 3 nanorods formation. These WO 3 nanorods were found highly suitable as a precursor for the synthesis of a good yield of multiwalled WS 2 nanotubes by reducing them with H 2 S at 840 °C for 30 min. The length and the wall thickness of the WS 2 nanotubes could be altered by controlled reduction of the oxide precursor. The morphology, structure and the composition of the WO 3 nanorods and WS 2 nanotub…

Metal—Organic Chemical Vapor Deposition Synthesis of Hollow Inorganic-Fullerene-Type MoS2 and MoSe2 Nanoparticles.

2005

VS2 nanotubes containing organic-amine templates from the NT-VOx precursors and reversible copper intercalation in NT-VS2.

2004

Selective Synthesis of Hollow and Filled Fullerene-like (IF) WS2 Nanoparticles via Metal–Organic Chemical Vapor Deposition

2007

The synthesis of WS2 onion-like nanoparticles by means of a high-temperature metal–organic chemical vapor deposition (MOCVD) process starting from W(CO)6 and elemental sulfur is reported. The react...

dsRNA-functionalized multifunctional gamma-Fe2O3 nanocrystals: a tool for targeting cell surface receptors.

2008

Hierarchical Assembly of TiO2 Nanoparticles on WS2 Nanotubes Achieved Through Multifunctional Polymeric Ligands

2007

Thefunctionalization of nanotubes is required in order to bene-fit from their outstanding properties, as any application inmaterials and devices is hindered by processing and manipu-lation difficulties. Only the attachment of appropriate chem-ical functionalities on the nanotube surface allows tailoringof the properties for the respective applications. As an ex-ample, the enhancement of the nanotube solubility is onemajor task since most pristine nanotubes are insoluble inboth water and organic solvents. Thus, the improvement ofthe solubility by chemical functionalization is an importantconcept for synthetic chemists and materials scientists. Tai-loring of the surface chemical bonds might a…

Enzyme-Mediated Deposition of a TiO2Coating onto Biofunctionalized WS2 Chalcogenide Nanotubes

2009

A chemically specific and facile method for the biofunctionalization of WS2 nanotubes (NT-WS2) is reported. The covalent modification strategy is based on the affinity of the nitrilotriacetic acid (NTA) side chain, which serves as a ligand for the surface binding to NT-WS2 and simultaneously as an anchor group for the binding of His-tagged proteins to the polymer backbone. The polymer functionalized WS2 nanotubes can be solubilized either in water or organic solvents; they are stable for at least one week. The probes were characterized by FT-IR and UV-vis spectroscopy. The immobilization of silicatein, a hydrolytic protein encountered in marine sponges, was visualized by scanning force micr…

Molybdenum blue: Binding to collagen fibres and microcrystal formation

2005

Collagen fibres have been shown by transmission electron microscopy to progressively bind the polyoxomolybdate ring-complex, termed molybdenum blue. Nucleation of cuboidal molybdenum blue microcrystals occurs on the surface of the collagen fibres, leading eventually to extensive coating of the fibres with microcrystals.

ChemInform Abstract: Large Scale MOCVD Synthesis of Hollow ReS2Nanoparticles with Nested Fullerene-Like Structure.

2008

Overcoming the Insolubility of Molybdenum Disulfide Nanoparticles through a High Degree of Sidewall Functionalization Using Polymeric Chelating Ligan…

2006

From Single Molecules to Nanoscopically Structured Functional Materials: Au Nanocrystal Growth on TiO2 Nanowires Controlled by Surface-Bound Silicate…

2006

VS2-Nanoröhren mit Amin-Templaten der VOx-Vorstufen und reversible Cu-Einlagerung in NT-VS2

2004

Bismut-katalysiertes Wachstum von SnS2-Nanoröhren und deren Stabilität

2009

Synthesis of Hierarchically Grown ZnO@NT-WS2 Nanocomposites

2009

A chemically specific and facile method for growth of ZnO nanorods on WS2 nanotubes (NT-WS2) is reported. The modification strategy is based on the chalcophilic affinity of Zn, which serves as an anchor to immobilize ZnO colloids onto the WS2 nanotubes. The surface bound ZnO colloids have been used as a seed to grow ZnO nanorods on WS2 nanotubes. The immobilization of ZnO colloids was monitored by UV−vis spectroscopy and photoluminescence spectroscopy whereas the growth of ZnO nanorods was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Raman imaging and spectroscopy of heterogeneous individual carbon nanotubes

2003

Isolated single-walled carbon nanotubes (CNTs) were grown by chemical vapor deposition methods on Fe/Mo/Al2O3 catalysts, which were patterned by microcontact printing. The pattern allowed us to trace back and investigate the same isolated CNT by atomic-force (AFM) and confocal Raman microscopy with different excitation wavelengths. A change of the Raman intensity could be correlated with structural defects revealing that the molecular structure of the tubes is changing along the tube axis. By investigating the same tube segments with different excitation energies, we found that the D-line of isolated tubes shows a strong dispersive effect of 45−50 cm-1/eV. In contrast, the spectral position…

dsRNA-funktionalisierte γ-Fe2O3-Nanokristalle: ein Instrument zur gezielten Adressierung von Rezeptoren an der Zelloberfläche

2008

Fabrication of a Silica Coating on Magnetic γ-Fe2O3 Nanoparticles by an Immobilized Enzyme

2008

Silicatein, a hydrolytic protein encountered in marine sponges, was immobilized on maghemite (γ-Fe2O3) nanoparticles that were surface functionalized with a reactive mulfunctional polymer. This polymer carries an anchor group based on dopamine which is capable of binding to the γ-Fe2O3 surface and a reactive functional group which allows binding of various biomolecules onto inorganic nanoparticles. This functional nitrilotriacetic acid (NTA) group allows immobilization of His-tagged silicatein on the surface of the γ-Fe2O3 nanoparticles. The surface-bound protein retains its native hydrolytic activity to catalyze formation of silica through copolymerization of alkoxysilanes Si(OR)4. Functio…

Pathogen-Mimicking MnO Nanoparticles for Selective Activation of the TLR9 Pathway and Imaging of Cancer Cells

2009

Here, design of the first pathogen-mimicking metal oxide nanoparticles with the ability to enter cancer cells and to selectively target and activate the TLR9 pathway, and with optical and MR imaging capabilities, is reported. The immobilization of ssDNA (CpG ODN 2006) on MnO nanoparticles is performed via the phosphoramidite route using a multifunctional polymer. The multifunctional polymer used for the nanoparticle surface modification not only affords a protective organic biocompatible shell but also provides an efficient and convenient means for loading immunostimulatory oligonucleotides. Since fluorescent molecules are amenable to photodetection, a chromophore (Rhodamine) is introduced …

Synthesis of Fullerene- and Nanotube-Like SnS2 Nanoparticles and Sn/S/Carbon Nanocomposites

2009

SnS2 nested fullerene-type (IF) nanoparticles, nanotubes, and SnS2/C hybrid nanostructures were obtained by vapor transport starting from elemental tin and CS2. The reaction was carried out in a single-step process by heating elemental tin metal powder in a horizontal tube furnace at 800−1000 °C. TEM analysis allowed proposing a plausible mechanism for the formation of fullerene-like particles of SnS2 as well as tubes and scrolls from nanosheets of SnS2. Pure material could be obtained by optimizing the reaction based on a product analysis using powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) combined with energy-dispersive X-ray spectroscopy (EDX…

Crystallization of Vaterite Nanowires by the Cooperative Interaction of Tailor-Made Nucleation Surfaces and Polyelectrolytes

2005

The concepts of template-induced crystallization on self-assembled monolayers (SAMs) and the use of polymer additives are combined into a new strategy, where, through the cooperative interaction of a SAM matrix involved in the nucleation process, poly(acrylic acid), a dissolved polyelectrolyte, and the dissolved ions, hierarchically ordered mineral structures are formed. The adsorption of poly(acrylic acid) to the SAM is monitored using a quartz microbalance. Transmission electron microscopy measurements on samples that are taken from polyacrylate solution in short intervals after the start of the reaction reveals that nanometer-sized particles pre-formed in solution are being attached to t…

Large Scale MOCVD Synthesis of Hollow ReS2 Nanoparticles with Nested Fullerene-Like Structure

2008

The synthesis of ReS2 onionlike nanoparticles by means of a high-temperature MOCVD process starting from Re2(CO)10 and elemental sulfur is reported. The reaction is carried out in a two-step proces...

Morphosynthesis of Strontianite Nanowires Using Polyacrylate Templates Tethered onto Self-Assembled Monolayers

2005

Strontianite nanowires have been synthesized on self-assembled monolayers (SAM) in the presence of polyacrylate templates. The morphology of this product exhibits characteristic differences from that of products obtained in the absence of polyacrylate. It is demonstrated that the template-induced crystallization process involves the interaction between the SAM surface, polyacrylate (a dissolved polyelectrolyte), and the cations/anions in solution. By the combination of these components, hierarchically ordered mineral hybrid structures are formed.

From Single Molecules to Nanoscopically Structured Functional Materials

2006

AbstractThe synthesis of MS2 (M = Mo, W) onion-like nanoparticles by means of a high temperature MOCVD process starting from W(CO)6 and elemental sulfur is reported. The reaction can also be carried out in two steps where the intermediate amorphous WS2 nanoparticles formed through the high temperature reaction of tungsten and sulfur in the initial phase of the reaction are isolated and converted in a separate annealing step to onion-type WS2 nanoparticles. Based on a study of the temperature dependence of the reaction a set of conditions could be derived where onion-like structures were formed in a one-step reaction. Onion-like structures obtained in the single-step process were filled, whe…