Influence of synthesis route on the properties of doped lanthanum cobaltite and its performance as an electrochemical reactor for the partial oxidation of natural gas

La(0.6)Sr(0.4)Co(0.2)Fe(0.8)O(3-delta)(LSCF) perovskite powders have been synthesised by solid-state reaction, co-precipitation, drip pyrolysis and citrate gel routes, and characterised using XRF, XRD, SEM and BET. Co-precipitation using oxalic acid or aqueous ammonia as precipitant failed to achieve the correct chemical composition. Perovskite structures were achieved in all other cases. Surface areas ranging from 0.6 to 17.4 m(2) g(-1) were obtained, which was reflected in the different microstructures observed. The citrate gel product exhibited a convoluted network morphology resulting in its large surface area. Thin-walled (approximately 200 microm) tubular membranes have been manufactured from the LSCF powders using viscous plastic processing. The tubes have been characterised using a custom-built gas analysis rig with on-line mass spectrometry. Porosity levels of the membranes were found to be very low (<0.1%). The spontaneous oxygen flux across the tubular membranes was determined as a function of temperature. Oxygen permeation rates ranged from 0.1 to 0.3 micromol cm(-2) s(-1) at 1273 K. The catalytic behaviour of the LSCF tubes towards methane oxidation has been studied using temperature programmed reaction and conventional catalytic measurements. The tubes favoured combustion reactions, with smaller amounts of partial oxidation and oxidative coupling products observed. Powder coatings have been incorporated to establish the effect of increasing surface area.     

Hydrothermal synthesis and electrochemical performance of Fe-doped Co hydroxide electrode materials

Journal of Solid State Electrochemistry - In order to meet the growing energy demand, it is of great significance to develop high-performance electrochemical energy storage materials. In this...     

New synthesis route for the preparation of pomalidomide

A new route for the preparation of pomalidomide is described in the study. The synthetic procedure starts from 4-nitroisobenzofuran-1,3-dione and 3-aminopiperidine-2,6-dione hydrochloride via a three-step reaction resulting in a total yield of 65% with a high-performance liquid chromatographic (HPLC) purity of 99.56% and a low palladium residue level of 2 ppm. This method can be deemed as an efficient, practical, and environmentally friendly synthetic route for the preparation of pomalidomide.     

The development of a new route to the synthesis of strontium orthosilicate

Journal of Thermal Analysis and Calorimetry - A new route including precipitation combined with calcination has been developed for the synthesis of strontium orthosilicate (Sr2SiO4) nano-sized...     

Dendritic cavitands: preparation and electrochemical properties

A new series of dendrimers containing a central cavitand core with four appended Fréchet-type dendrons, linked to the core through 4,4'-bipyridinium (viologen) subunits, have been synthesized, characterized and their electrochemical properties investigated using cyclic voltammetric measurements.     

Aqueous sol-gel synthesis route for the preparation of YAG: Evaluation of sol-gel process by mathematical regression model

Yttrium aluminium garnet (Y₃Al₅O₁₂, YAG) polycrystalline samples have been prepared by a simple aqueous sol-gel methodology. The influence of nineteen sol-gel processing variables on the formation of YAG has been investigated. Effects of different fabrication parameters on the phase purity and morphological properties of the compounds were studied by energy-dispersive spectrometry (EDS), X-ray powder diffraction (XRD) analysis and scanning electron microscopy (SEM). The parameters of the sol-gel processing such as pH of starting solution, concentration and nature of complexing ligand, temperature and duration of gelation, powder rehomogenization during annealing, duration and temperature of the final heat treatment were found to be the most significant. For the evaluation and verification of the experimental results the Brandon's model of a multiple regression was successfully used.     

Oligothiophene-functionalized CdSe nanocrystals: preparation and electrochemical properties

The preparation of new molecular hybrids consisting of CdSe semiconductor nanocrystals, surface-functionalized with conductive and electrochemically active oligothiophene ligands, is described. Specially synthesized aniline-terminated oligoalkylthiophenes containing one, two, or four thiophene units were used for the grafting on CdSe nanocrystals, previously surface-functionalized with 4-formyldithiobenzoate. The electrochemical activity of both the inorganic and the organic parts of the hybrid was investigated by cyclic voltammetry. The oxidative doping of the organic part of the hybrid is irreversible, contrary to the case of the “free” non-grafted ligand which shows reversible doping. Furthermore, the electrochemical doping of the surface ligands, occurring at lower potentials than the oxidation of the nanocrystals, perturbs the latter process via charging of the ligands followed by slow relaxation processes. The first two authors contributed equally to this work Correspondence: Peter Reiss, Adam Pron, DSM/DRFMC/SPrAM (UMR 5819 CEA-CNRS-Université Joseph Fourier 1)/LEMOH CEA Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France     

Twenty second synthesis of Pd nanourchins with high electrochemical activity through an electrochemical route

A rapid, templateless, surfactantless, electrochemical route is reported to synthesize uniform and clean Pd nanoparticles (～350 nm in diameter) with a substructure of sharp nanospikes (～95 nm in length). The effects of electrodeposition potential, PdCl(2) concentration, and supporting electrolyte were explored for the formation of the Pd nanourchins. The systematic studies revealed that the concentration of Pd(II) greatly affects the density of the nanospikes on the Pd nanourchins in this short-time synthesis. The substructure of the nanospikes on the nanourchins was examined to be a single-crystal quadrangular pyramid. Further investigation of the Pd nanourchins by cyclic voltammetry (CV) showed their high electrochemical activity toward formic acid oxidation.     

Allyl strontium compounds: synthesis, molecular structure and properties

The synthesis and attempted isolation of neutral bis(allyl)strontium [Sr(C(3)H(5))(2)] (1) resulted in the isolation of potassium tris(allyl)strontiate K[Sr(C(3)H(5))(3)] (2). In situ generated 1 shows a pronounced Br?nsted basicity, inducing polymerisation of THF. Ate complex 2 crystallises as [K(THF)(2){Sr(C(3)H(5))(3)}(THF)](∞) (2·(THF)(3)). The salt-like solid state structure of 2·(THF)(3) comprises a two-dimensional network of (μ(2)-η(3):η(3)-C(3)H(5))(-) bridged potassium and strontium centres. Synthesis of allyl complexes 1 and 2 utilised SrI(2), [Sr(TMDS)(2)] (3) (TMDS = tetramethyldisilazanide), and [Sr(HMDS)(2)] (HMDS = hexamethyldisilazanide) as strontium precursors. The solid state structure of previously reported [Sr(TMDS)(2)] (3) was established by X-ray single crystal analysis as a dissymmetric dimer of [Sr(2)(TMDS)(4)(THF)(3)] (3·(THF)(3)) with multiple Si-HSr agostic interactions. The presence of ether ligands (THF, 18-crown-6) influenced the Si-HSr resonances in the NMR spectra of the amido complex 3.     

微波作用下2,3,5-三取代噻吩的合成及光电性质的研究

含硫芳香化合物可用于有机半导体、电致发光器件,电致变色器件和场效应管。噻吩是一种富电子的五元芳杂环,电子的流动性大,有望成为较好的电子注入／传输材料。我们利用微波辐射在噻吩环的2,3,5位引入了芳基,产物的结构经元素分析、质谱、^1H NMR表征,采     

Effect of mechanical activation on the synthesis and electrochemical properties of lithium-vanadium bronze

An original technique for production of a lithium-vanadium bronze was developed. It includes mechanical activation of a mixture of vanadium oxide with lithium hydroxide in the course of plastic flow under twisting.     

Radiation-induced synthesis of Fe-doped TiO2: Characterization and catalytic properties

Fe-doped TiO₂ catalyst was prepared by wet impregnation, using TiO₂ P25 Degussa as a precursor and Fe(NO₃)₃ as a dopant, followed by irradiation with an electron beam or γ-rays. Surface properties of Fe/TiO₂ samples were examined by BET, XRD, ToF-SIMS, and TPR methods. The photocatalytic activity towards destruction of the anionic surfactant, sodium dodecylbenzenesulfonate (SDBS), in aqueous solutions was higher for the irradiated Fe/TiO₂ catalysts than for bare TiO₂ P25 or that calcined at 500 °C. The results show that irradiated catalysts exhibit a more uniform texture with high dispersion of iron species. An enhancement of the activity of irradiated Fe/TiO₂ systems can be attributed to the synergetic effects of small crystallite size and homogenous distribution of iron species including FeTiO₃ phase.     

New synthesis route to and physical properties of lanthanum monoiodide

A fast procedure to produce LaI by reduction of LaI2 or LaI3 in a Na melt under argon at 550 degrees C is given. The structural studies performed by means of powder X-ray diffraction as well as transmission electron microscopy are consistent with previous single-crystal results. Measurements of the electrical resistance on polycrystalline samples reveal metallic behavior for LaI in the range 10-300 K. Upon cooling, a small maximum in the resistivity has been observed at 67 K. This anomaly disappears upon heating a sample, however, yielding a hysteresis in rho(T) above 70 K. From the Pauli susceptibility, an electron density of states at the Fermi level of about 0.3 eV(-1).formula unit(-1) has been estimated, as compared with a value of 1.0 eV(-1).formula unit(-1) derived from ab initio LMTO band structure calculations.     

The preparation and properties of strontium zirconate ceramics for channels of open-cycle MHD generators

A two-stage procedure of preparation of dense strontium zirconate ceramics capable of being used as electrically insulating material in MHD generators is described. A small addition of TiO₂ was introduced at the first stage to favour development of the properties, especially low apparent porosity, required for MHD purposes. The effect of TiO₂ on sintering temperature, phase composition and microstructure of the bodies is described. Properties of the resulting ceramics i.e. porosity, cold crushing strength, microhardness as well as electrical conductivity over the temperature range of 20–2000°C were measured. The results of successful testing of these ceramics in the channel of an experimental MHD generator are presented.     

Graphene preparation and process parameters by pre-intercalation assisted electrochemical exfoliation of graphite

Journal of Solid State Electrochemistry - Among all the preparation methods, electrochemical exfoliation of graphite in neutral aqueous solution to prepare high-quality graphene is a hot research...     

Stepwise synthesis, characterization, and electrochemical properties of ordered mesoporous carbons containing well-dispersed Pt nanoparticles using a functionalized template route

A stepwise method is described for the accurately controlled growth of Pt nanoparticles supported on ordered mesoporous carbons (Pt-OMC) by the nanocasting of carbon and metal precursors in the pore channels of mesoporous silicas functionalized with Si-H groups. Results obtained from N₂ adsorption/desorption isotherms and transmission electron microscopy showed well-dispersed Pt nanoparticles (2-3 nm) on Pt-OMC with high surface area (837 m² g⁻¹) and regular pore channels (2.9 nm), which facilitate reactant/product diffusion. X-ray diffraction and X-ray photoelectron spectroscopy indicated that Pt nanoparticles in the Pt-OMC sample were mostly present in the metallic form of a face-centered cubic (fcc) crystalline structure. The Pt-OMC catalyst was found to have superior electrocatalytic properties during oxygen reduction reaction as compared to typical commercial electrocatalysts.     

An additive-free electrochemical route to rapid synthesis of large-area copper nano-octahedra on gold film substrates

We report the first fabrication of large-area Cu nano-octahedra with well-defined shape, good monodispersity and uniform distribution on a gold film substrate (GFS) by a very simple, rapid and cost-effective low-potential electrodeposition (LPED) technique. Different from general surfactant-assisted electrochemical approaches, LPED is an additive-free strategy that exploits the subtle surface energy differences among various crystallographic planes of metals themselves. The size of the octahedra depends on deposition time and is adjustable over a wide range. The shape evolution is found to be remarkably different from that of octahedral particles formed in solution. A formation mechanism is proposed for the unique evolution of Cu octahedra as resulting from the anisotropic growth under appropriate applied potentials.     

Metallic nitride endohedral fullerenes: synthesis and electrochemical properties

Metallic nitride endohedral fullerenes (MNEFs) are one of the most interesting types of metallofullerenes due to their high yields and interesting electronic properties. The synthesis of these compounds allows the encapsulation of different metals inside fullerenes making it possible to combine the properties of the metal with those of the fullerene. Their interesting electrochemical and optical features make them potential candidates for several applications such as molecular electronics, biomedical imaging, non-linear optical devices, and MRI agents. We report herein the synthesis, isolation, and electrochemical properties of the larger MNEFs including Gd₃N@C₈₂ and Gd₃N@C₈₆, reported here for the first time.     

Core-extended terrylene diimide on the bay region: synthesis and optical and electrochemical properties

Two novel core-extended terrylene diimides on the bay region (CETDIs) were synthesized via annulation of the four additional ethylene units or benzene units on the bay region of the terrylene diimide core. The optical and electrochemical properties of the two compounds were investigated. These CETDIs exhibited broad absorption spectra with high extinction coefficients, which span a wide range in the ultraviolet and visible spectrum from 300 to 700 nm. Furthermore, the redox process of the CETDIs increased from two waves to four waves, and the lowest unoccupied molecular orbital (LUMO) levels were enhanced from -4.00 to -3.59 eV.     

Ultrasonic route synthesis,characterization and electrochemical study of graphene oxide and reduced graphene oxide

Research on Chemical Intermediates - In this study, an efficient route for graphene oxide (GO) and reduced GO (RGO) synthesis was developed by using an ultrasonic probe and bath alternatively. RGO...