Synthesis of molybdenum (IV) disulfide using a single-source method

Molybdenum(IV) disulfide was prepared by the thermalysis of the single molecule precursor [Mo₂O₄(S₂CNEt₂)₂] (Et: ethyl group). The thermalysis was monitored by thermogravimetric analysis and FT-infrared spectroscopy. The MoS₂ materials obtained during the thermalysis experiments were characterized in terms of their morphological and optical characteristics.     

Synthesis and physicochemical properties of titanium(IV)- and cobalt(II)-Based photocatalytic oxide composites

We have studied the phase transitions, morphology, and photocatalytic activity of composites based on titanium(IV) and cobalt(II) oxides at Co doping levels from 0.5 to 60 wt % and heat-treatment temperatures from 80 to 1150°C. The highest photocatalytic activity under illumination in the spectral range λ ≥ 670 nm is offered by mesoporous X-ray amorphous and multiphase (X-ray amorphous phase, anatase, rutile, and CoTiO₃) nanomaterials containing 5–20 wt % Co, whereas two-phase materials (rutile + CoTiO₃) have the lowest photocatalytic activity.     

Synthesis of molybdenum disulfide (MoS2) for lithium ion battery applications

This paper reports the use of a rheological phase reaction method for preparing MoS₂ nanoflakes. The characterization by powder X-ray diffraction indicated that MoS₂ had been formed. High resolution electron microscopy observation revealed that the as-prepared MoS₂ nanoflakes had started to curve and partly form MoS₂ nanotubes. The lithium intercalation/de-intercalation behavior of as-prepared MoS₂ nanoflake electrode was also investigated. It was found that the MoS₂ nanoflake electrode exhibited higher specific capacity, with very high cycling stability, compared to MoS₂ nanoparticle electrode. The possible reasons for the high electrochemical performance of the nanoflakes electrodes are also discussed. The outstanding electrochemical properties of MoS₂ nanoflakes obtained by this method make it possible for MoS₂ to be used as a promising anode material.     

Synthesis and crystal structure of Th(IV), U(IV), and Np(IV) tribromoacetates

Actinide(IV) tribromoacetates of the composition [An(CBr₃COO)₄(H₂O)₂]₂ (An = Th, U, Np) were synthesized and studied. Their structural feature is the formation of electrically neutral dimeric complexes. The surrounding of the An(IV) atoms in the dimers is formed by the oxygen atoms of six CBr₃COO^? anions and two water molecules; the coordination number of An(IV) is 9, and the coordination polyhedron can be described as distorted base-monocapped tetragonal antiprism. Four independent CBr₃COO^? anions in the structure are coordinated to the An(IV) atoms in different fashions: monodentate, bidentate chelate, and bidentate bridging. Hydrogen bonding links the dimers in infinite chains along [010] direction. The hydrogen bonding noticeably influences the geometric characteristics of the coordination surrounding of the An(IV) atoms.     

Synthesis and photocatalytic properties of nanomaterials based on titanium(IV) and cerium(IV) oxides

We have studied the phase transitions, morphology, and photocatalytic activity of titanium(IV) oxide–cerium(IV) oxide materials at Ce doping levels from 1 to 20 wt % and heat-treatment temperatures from 80 to 1150°C. The highest photocatalytic activity under illumination in the spectral range λ ≥ 670 nm is offered by mesoporous X-ray amorphous and multiphase (X-ray amorphous phase + anatase + rutile + CeO₂) nanomaterials, whereas the two-phase materials (rutile + CeO₂) have the lowest photocatalytic activity.     

Photoelectrochemical and photocatalytic properties of titanium (IV) oxide nanoparticulate layers

Titania nanostructured particles were produced by the sol-gel method in the reverse micelle environment treated thermally and by various extraction steps including supercritical carbon dioxide, subcritical water and their combinations. Thin films comprised of the organized nanoparticles were tested in photoelectrochemical and photocatalytic experiments. The former were configured for the open circuit potential measurements and evaluation of polarization curves and the corresponding photocurrents. Photocatalytic activities of the layered films were assessed by following decomposition of the methyl ester of stearic acid. Attention was also paid to evaluation of the extent of the surface wettability of the layers. The effect of content of residual surface carbon, extent of hydrophilic properties and presence of anatase structure were identified as essential parameters responsible for the enhanced photoactivity of the tested layers. On the other hand also layers treated without any thermal steps revealed certain level of photoactivity that might be of special importance in some specific applications.     

Synthesis of molybdenum oxide hollow microspheres by ethanol and PEG assisting hydrothermal process

Molybdenum oxide hollow microspheres were successfully synthesized via a combination of a hydrothermal method with ethanol and PEG assisting technique. The as-obtained products were characterized by SEM, XRD. The SEM results showed that the sizes of molybdenum oxide hollow spheres were 1-2 μm, and the spherical shape of the hollow microsphere products remained almost unaltered after calcination at 500 °C for 2 h. The XRD results showed that a purity phase of α-MoO₃ could be obtained after calcination. It was also found that the reaction temperature played a key role in the formation of hollow microshphere structure.     

Adsorption characteristics and separation of Cr(III) and Cr(VI) on hydrous titanium(IV) oxide

A hydrous titanium(IV) oxide was prepared to study the adsorption characteristics and the separation of chromium species. Batch sorption studies have been carried out to determine the effect of pH on the sorption of Cr(III) and Cr(VI) on hydrous TiO2. An excellent separation efficiency of Cr(III) and Cr(VI) was obtained at pH 2. The adsorption percentage of Cr(VI) was above 99%, whereas that of the Cr(III) was less than 1% at this pH. The adsorption isotherm of Cr(VI) on hydrous TiO2 at pH 2 was in good agreement with the Langmuir isotherm. The maximum adsorption capacity of Cr(VI) on TiO2 was 5 mg g(-1). The rate of adsorption of Cr(VI) by hydrous TiO2 with average particle diameter 250 and 500 microm has been studied under particle diffusion controlled conditions. The diffusion coefficients of Cr(VI) for both hydrous TiO2 having average particle diameter of 250 and 500 microm was calculated at pH 2 as 3.84 x 10(-10) m2 s(-1) and 8.86 x 10(-10) m2 s(-1), respectively.     

Laser-induced molybdenum oxide formation by low energy (nJ)-high repetition rate (MHz) femtosecond pulses

Experimental results on femtosecond (fs) laser-induced oxidation of molybdenum (Mo) thin films are presented. The Mo thin films were deposited on fused silica substrates by the magnetron DC-sputtering technique. The as-deposited thin films were characterized by X-ray diffraction, which indicates that bbc-molybdenum was grown. The films were irradiated in ambient air, using a femtosecond Ti:Sapphire laser (800 nm, 60 fs pulse duration, 70 MHz and 6.5 nJ per pulse). The molybdenum thin films were laser scanned in the form of several millimeters long straight line traces, by using a per pulse laser fluence well below the (previously reported) ablation threshold. Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) were used to study the laser-induced optical and morphology changes on the exposed zone. Energy Dispersive Spectrometry (EDS) and Micro-Raman Spectroscopy (MRS) were used to determine the degree of oxidation and the phase change across the laser irradiated paths on the Mo thin film. Under the above described experimental conditions our results show that it is possible to laser-induce a specific oxide phase from the molybdenum starting material. Our micro-Raman results clearly demonstrate that the fs-laser irradiation induces the m-MoO₂ and o-Mo₄O₁₁ crystalline phases at the directly laser irradiated trace and its close proximity.     

Synthesis of nanocrystalline molybdenum carbide (Mo2C) by solution route

Nanocrystalline molybdenum carbide (Mo₂C) of less than 10 nm size was synthesized by solution route. The process temperature and composition of raw materials were optimized by thermodynamic equilibrium calculation. The raw materials as well as synthesized nanocrystalline molybdenum carbide were characterized by X-ray diffraction (XRD) and thermogravimetric analysis/differential thermal analysis (TGA/DTA).     

High-mobility molybdenum doped indium oxide

The effects of molybdenum doping (0-12 at.%) on the optical and electrical properties of In₂O₃ were investigated using combinatorial sputter deposition in combination with combinatorial analysis techniques. The electrical properties are highly dependent on the deposition temperature and the molybdenum doping concentration. A minimum temperature between 300 °C and 400 °C is needed to activate the carriers. The maximum mobility is observed at a Mo concentration of 4.4 at.% and is 65.3 cm² V^− 1 s^− 1. The maximum conductivity is observed at 5.9 at.% molybdenum doping and is equal to 5000 Ω^− 1 cm^− 1. The carrier concentration increases with increasing molybdenum doping to a maximum value of 6.6·10²⁰ cm^− 3 at a doping concentration of 8.6 at.%. The optical transparency is high (> 80%) in a wide spectral range that is dependent on the process parameters.     

Growth of nano-needles of manganese(IV) oxide by atomic layer deposition

Needles of manganese (IV) oxide in the nanometer range have been synthesised using the atomic layer deposition technique. Traditionally the atomic layer deposition technique is used for the fabrication of thin films, however, we find that needles of beta-MnO2 are formed when manganese (IV) oxide is deposited as relatively thick (ca. 800 nm) thin films on substrates of alpha-Al2O3 [(001) and (012) oriented]. There is no formation of needles when the film is deposited on substrates such as Si(100) or soda lime glass. The film is formed using Mn(thd)3 (Hthd = 2,2,6,6-tetramethylheptane-3,5-dione) and ozone as precursors. While thin films (ca. 100 nm) consist of epsilon'-MnO2, the same process applied to thicker films results in the formation of nano-needles of beta-MnO2. These needles of beta-MnO2 have dimensions ranging from approximately 1.5 microm at the base down to very sharp tips. The nano-needles and the bulk of the films have been analysed by atomic force microscopy, scanning electron microscopy, X-ray diffraction, and transmission electron microscopy.     

Tin(IV) oxide coatings from hybrid organotin/polymer nanoparticles

Tin dioxide coatings are widely applied in glasses and ceramics to improve not only optical, but also mechanical properties. In this work, we report a new method to prepare SnO(2) coatings from aqueous dispersions of polymer/organotin hybrid nanoparticles. Various liquid organotin compounds were encapsulated in polymeric nanoparticles synthesized by miniemulsion polymerization. Large amounts of tetrabutyltin and bis(tributyltin) could be successfully incorporated in cross-linked and noncross-linked polystyrene nanoparticles that served as sacrificial templates for the formation of tin oxide coatings after etching with oxygen plasma or calcination. Cross-linked polystyrene particles containing bis(tributyltin)--selected for having a high boiling point--were found to be especially suited for the oxide coating formation. The content of metal in the particles was up to 12 wt %, and estimations by thermogravimetrical indicated that at least 96% of the total organotin compound was converted to SnO(2). The resulting coatings were mainly identified as tetragonal SnO(2) (cassiterite) by X-ray diffraction, although a coexistence of this phase with orthorhombic SnO(2) was observed for samples prepared with bis(tributyltin).     

Synthesis and characterization of stable iron-iron oxide core-shell nanoclusters for environmental applications

Iron-iron oxide core-shell nanoclusters are of great interest due to their potential applications as a remedy for environmental contamination. We report the room-temperature synthesis of core-shell iron-iron oxide nanoclusters using our novel cluster deposition system. Various types of measurements such as Transmission Electron Microscopy, X-ray Diffraction, X-ray Photon Spectroscopy, and Electron Energy Loss Spectroscopy are conducted in characterizing nanoclusters. Stable, monodispersive iron-iron oxide core-shell nanocrystals are identified.     

Synthesis and characterization of tin(IV) phenyl phosphonate in nano form

An inorgano-organic ion exchanger, Sn(IV) phenyl phosphonate, has been synthesized in amorphous form. Further, an attempt has been made to synthesize Sn(IV) phenyl phosphonate in the nano form. The materials have been characterized for elemental analysis (ICP-AES), thermal analysis (TGA), X-ray analysis and FTIR spectroscopy. Chemical resistivity of these materials has been accessed in acidic, basic and organic solvent media. Catalytic activity has been studied and compared by using esterification of ethylene glycol as a model reaction wherein glycoldiacetate has been prepared. The transport properties of these materials have been explored by measuring specific proton conduction at different temperatures using SOLARTRON DATASET impedance analyser over a frequency range 1 Hz-1 MHz. It has been observed that Sn(IV) phenyl phosphate in the nano form behaves as a better Bronsted catalyst and proton conductor as compared to the amorphous form.     

Synthesis and photocatalytic properties of nanomaterials based on titanium(IV) and zinc(II) oxides

We have synthesized materials based on titanium(IV) and zinc(II) oxides, containing 1 to 60 wt % Zn, at heat-treatment temperatures from 80 to 1150°C, with the formation of multiphase compositions (X-ray amorphous phase, anatase, rutile, ZnTiO₃, and/or Zn₂TiO₄) and studied their phase transitions, morphology, and photocatalytic activity. Increasing the Zn content of the materials is favorable for their spectral sensitization, including the range λ ≥ 670 nm.     

Synthesis,structure, and morphology of bifunctional catalysts based on zirconia modified by molybdenum oxide

The preparation of Pt/MoO _x -ZrO₂ materials has been carried out by polymeric precursor method and with molybdenum loadings in the range 10–20 wt %. The synthesized samples were calcined at 600, 700, and 800°C. The structure and texture of the calcined Pt/MoO _x -ZrO₂ materials were characterized by x-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy, and N₂ adsorption measurements. XRD of the calcined samples revealed the formation of crystalline ZrO₂, Pt metal, and Zr(MoO₄)₂. Crystalline Zr(MoO₄)₂ was also detected by FTIR spectra. A decrease in the specific surface area was observed by nitrogen adsorption experiments when the temperatures of calcination and molybdenum loading increased. The text was submitted by the authors in English.     

Synthesis and characterization of poly(butylene oxide) grafted carbon nanofibers

The grafting of polybutylene oxide onto purified and functionalized carbon nanofibers is reported. Grafting was possible after the insertion of 2-(formyloxy)ethyl 2-bromo-2-methylpropanoate onto the carbon nanofibers. The polymerization of tetrahydrofuran was mediated by copper(I) bromide and 1,1,4,7-pentamethyl diethylenetriamine. The polymer-grafted carbon nanofibers were characterized by Raman spectrsocopy, Transmission Electron Microscopy, and Thermogravimetric Analysis. TEM images of CNF-COOH (A), CNF-PBO (B), completely open tip of CNF-COOH, and coated tip of CNF-PBO (D) are shown in the left panel. The right panel depicts the distribution of bromine (blue), and carbon (red) atoms inside and in the vicinity of CNF-Br (as obtained by Electron Energy Loss Spectroscopy). The bottom shows the actual doped CNF. Preliminary data showed that these modified fibers have potential applications as smart (electrorheological) fluids.