Thermal analysis for generating phase diagrams of systems alkali metal chloride/divalent metal chloride

After a historical survey of the application of differential thermal analysis (DTA) for the generation of phase diagrams, particularly those of pseudobinary halide systems, the authors' research work on the systems ACl/MCl₂ (A = NaCs) is reported. In addition to DTA measurements the thermodynamic properties of the ternary compounds A_nMCl_n+2 are investigated by solution calorimetry and EMF measurements dependent on temperature with a newly developed galvanic cell for solid electrolytes. This method is also a useful tool for elucidating phase diagrams, especially for reactions occurring in the solid state.     

Electrochemical fabrication of metal/organic/metal junctions for molecular electronics and sensing applications

A simple electrochemical approach was used for fabricating electrode/metal nanowire/(molecule or polymer)/electrode junctions for sensing or molecular electronics applications. The procedure for fabricating these molecule-based devices involves electropolymerization of phenol or chemisorption of alkanethiols on one set of electrodes (E1) and electrodeposition of Ag metal nano/microwires on a second electrode (E2) which is ～5 μm away from E1. Under appropriate deposition conditions, Ag nanowires grow from E2 and cross over to E1, forming a E1/(molecule or polymer)/Ag nanowire (NW)/E2 junction. The junction resistance was controlled by (1) electrodepositing polyphenol of varied densities on E1 and (2) assembling alkanethiols of different chain lengths on E1. Ag NWs at high resistance E1/polyphenol/Ag NW/E2 junctions functionalized with Pd monolayer protected clusters (MPCs) responded fast and reversibly to H(2) concentrations as low as 0.11% in a nitrogen carrier gas by a resistance decrease, likely due to volume expansion of the Pd nanoparticles, demonstrating the use of these electrochemically fabricated junctions for gas sensing applications.     

Choline chloride – Urea deep eutectic solvent an efficient media for the preparation of metal nanoparticles

Metal nanoparticles are nanosized structures that have different potential applications in biological, chemical, medical, and agricultural fields because of their exotic characteristics. Their size ranges from 1 to 100 nm. Metal nanoparticles are either purer forms of metals (eg: Gold, Silver, Copper, Iron, etc.) or their compounds (eg: sulfides, hydroxides, oxides, etc.). Ionic liquids are generally used in the extraction of nanoparticles but they are challenging because of their indigent bio-degradability, bio-compatibility, and sustainability. So Deep Eutectic Solvent (DES) is reported as an alternative to ionic liquids in the formation of nanoparticles. The DESs are a complex of quaternary ammonium salts and hydrogen donors or metal salt. DESs contain higher non-symmetric ions which have lower lattice energy and hence they have a lower melting point. This research utilizes a novel DES (choline chloride – urea) as an effective solvent to produce mercuric sulfide (HgS), zirconium oxide (ZrO), manganese oxide (MnO), and copper oxide (CuO) nanoparticles. As a result, the production of these metal nanoparticles using Choline Chloride (C₅H₁₄ClNO) – Urea DES can be treated as a promising way in chemical manufacturing. The nanoparticles have been analyzed using Ultra Violet Spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD) and Energy Dispersive X-Ray Analysis (EDAX).     

Graphene nucleation on transition metal surface: structure transformation and role of the metal step edge

The nucleation of graphene on a transition metal surface, either on a terrace or near a step edge, is systematically explored using density functional theory calculations and applying the two-dimensional (2D) crystal nucleation theory. Careful optimization of the supported carbon clusters, C(N) (with size N ranging from 1 to 24), on the Ni(111) surface indicates a ground state structure transformation from a one-dimensional C chain to a 2D sp(2) C network at N ≈ 10-12. Furthermore, the crucial parameters controlling graphene growth on the metal surface, nucleation barrier, nucleus size, and nucleation rate on a terrace or near a step edge are calculated. In agreement with numerous experimental observations, our analysis shows that graphene nucleation near a metal step edge is superior to that on a terrace. On the basis of our analysis, we propose the use of graphene seeds to synthesize high-quality graphene in large area.     

Using electroless deposition for the preparation of micron sized polymer/metal core/shell particles and hollow metal spheres

Uniform and stable core-shell microspheres composed of a poly(methyl methacrylate) (PMMA) core and a thin metallic shell of nickel-phosphorus, cobalt-phosphorus, or mixed metal alloys (CoNiP, NiFeP, CoFeP) were prepared by dispersion polymerization of methyl methacrylate followed by electroless plating. The presence of the metallic shell around the particles was confirmed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and photoelectron spectroscopy. Transmission electron microscopy images of the cross-section of individual particles show that the thickness of the metal/alloy can be precisely tuned by adjusting the immersion time of the microspheres in the electroless bath. Depending on the deposited metallic material, various magnetic properties, from paramagnetic to ferromagnetic, are achieved. Finally, uniform hollow metallic spheres composed of nickel, cobalt, or nickel-cobalt alloy are obtained by dissolving the polymer core.     

Synthesis,characterization and thermodynamic data of compounds with NZP structure

Data on synthesis, thermal behavior and thermodynamic properties for the NZP phosphates NaMe₂(PO₄)₃ and Na₅Me(PO₄)₃ (Me=Ti, Zr, Hf) are reported. The compounds were synthesized by sol-gel method and solid-state reactions and characterized by X-ray powder diffraction, IR spectroscopy, electron microprobe and chemical analysis. Their thermal behavior was studied by the DTA measurements. The heat capacities of the phosphates were measured between temperatures 7 and 650 K. The fractal dimensions for the phosphates were calculated. The obtained thermodynamic characteristics of these phosphates and also literature data for the compounds of NZP type structure are summarized.     

N,N-二甲氨基磺酰氯合成工艺的优化

以磺酰氯和二甲胺盐酸盐为原料在三乙胺催化剂的作用下合成N,N-二甲氨基磺酰氯,并进行了单因素实验,在此基础上运用响应面法对N,N-二甲氨基磺酰氯合成工艺进行了优化,优化调整后的工艺条件为:反应温度9℃,二氯乙烷用量250 mL,n(二甲胺盐酸盐):n(磺酰氯)=1.0:1.2.在该工艺条件下重复实验,N,N-二甲氨基磺...     

1,2-Diisophthalimidoethane. X-ray diffraction evidence for the structure of the product of acylation of 1,2-diaminoethane with phthaloyl chloride

It was demonstrated by x-ray diffraction investigation of the product of the reaction of 1,2-diaminoethane with phthalic acid dichloride that the resulting compound has the 1,2-diisophthalimidoethane structure. An improved method for its synthesis is proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1320–1323, October, 1987.     

Electrochemical dehydrochlorination initiation for vinylidene chloride-vinyl chloride copolymers

Direct electrochemical initiation of dehydrochlorination is possible for polyvinylidine chloride VDC and copolymers of VDC with vinyl chloride VC. The ratio of the VDC and VC links in the initial polymer affects the rate of the dehydrochlorination and the structure of the products. Institute for Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, 50 Kharkovskoe Shosse, 252660 Kiev-94, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 3, pp. 180–183, May–June, 1997.     

Electrochemical transformation of biomass-derived oxygenates

Replacing conventional fossil resources with renewable raw materials for chemical production and energy generation is crucial for achieving the carbon-neutral goal and alleviating the emerging energy crisis.Biomass has been considered as one of the most promising candidates for this purpose owing to its great natural abundance and inherent ability to fix CO2in the form of multicarbon compounds.Particularly,biomass conversion through an electrochemical route is intriguing because of its operabili...     

湿法合成尿素-氯化胆碱低共熔溶剂中铜锰氧化物的制备

研究了尿素-氯化胆碱低共熔溶剂DES的制备方法.通过监控制备过程中折光率、电导率和密度等性质指标的变化,考察了尿素-氯化胆碱DES合成规律及影响因素.采用红外光谱表征了所合成DES的分子结构.使用AMS软件中COSMO-RS模块对DES其中的尿素和氯化胆碱分子中的表面电荷密度分布进行了模拟,剖析了氢键作用机制.比较了干...     

Electrochemical investigation of the chloride effect on hemoglobin

Direct electron transfer between hemoglobin and gold electrode is achieved at both a bare and a 4, 4'-bipyridine-modified gold electrode in the presence of chloride ions. The addition of chloride to hemoglobin solution also increases the reversibility of the direct electrochemistry and shifts the formal potential of hemoglobin to the negative direction. While the existence of chloride does not significantly change the tertiary structure of the protein, it might induce a slight variation of the structure, which is beneficial to the electrochemical response. It is suggested that the chloride binding to hemoglobin is a combination of specific and unspecific bindings.     

Study on the preparation and structure of positive sol composed of mixed metal hydroxide

Using precipitation method mixed metal hydroxide (MMH) positive sol was prepared. The preparation process and the properties of the sol were studied with powder XRD, TEM, particle size distribution determination system and microelectrophoresis instrument.The preparation of MMH was made as follows: Diluted ammonia water was added to the mixed solution of aluminum and magnesium chlorides which was prepared in the molar ratio of 1 1 or 1 2, or 1 3; then the pH values of the suspension at different amounts of ammonia water were measured. After that, the precipitate was aged for 5 h in the mother solution at room temperature, and washed after filtering. Finally, the filter cake was peptized at constant temperature of 333 K.The results showed that 1) preparation reaction was completed in three steps, 2) pH value was decisive factor, and 3) both the contents of magnesium and the -potential of MMH sol particles increased with pH values and finally remained constant. The mechanism of the reaction was that magnesium ions intercalated Al(OH)₃ crystal lattice, forming mixed metal hydroxide. The results also showed that positively charged MMH colloidal particle belonged to hexagonal system and three-layer superposition structure.     

One-pot metal templated synthesis for the preparation of 2-quinoxalinol salen metal complexes

Metal complexes of 2-quinoxalinol salen (salqu) ligands can be prepared in a one-pot metal templated synthesis resulting in significantly enhanced yields than if the ligand were prepared and isolated prior to introducing the metal for complexation. Using this method, 12 salqu metal complexes have been prepared and characterized from +2 metal ions.     

Electrochemical preparation of ZnS/CdS superlattice and its photoelectrochemical properties

Superlattice electrodes composed of three molecular layers of CdS and one to three molecular layers of ZnS were prepared on gold (111) film by using electrochemical atomic layer epitaxy. The prepared electrodes exhibited similar behavior to those of n-type semiconductor electrodes. The energy gap was not changed at all by changing the number of molecular layers of ZnS and by increasing the number of periods in the superlattice structure up to four. The magnitude of the anodic photocurrent was, however, influenced by these variables. It increased with an increase in the number of periods in the superlattice structure and decreased with increasing number of molecular layers of ZnS.     

Au-PtNPs/SWNT复合材料修饰电极的电化学制备及其应用

在室温条件下,利用恒电位吸附法和多电位阶跃法制备了金-铂纳米粒子(Au-PtNPs)/单壁碳纳米管(SWNT)复合材料修饰电极,并利用电化学方法和原子力显微镜(AFM)对其进行了表征。结果表明:Au-Pt-NPs可很好的结合在SWNT表面,在该电极的最佳修饰条件下(SWNT分散液中电沉积30 s,H2PtO6中浸泡10 min,循环阶跃沉积金纳米粒子45次(葡萄糖)或30次(甲醇))可以较好的电催化氧化碱性环境中的葡萄糖及甲醇,有望在葡萄糖无酶传感器及甲醇燃料电池中得到应用。     

Electrochemical behavior of metal hydrides

Metal hydride electrodes are of particular interest owing to their potential and practical application in batteries. A large number of hydrogen storage materials has been characterized so far. This paper deals with the effect of the chemical nature and stoichiometry of specific alloy families (AB₅, A₂B, AB/AB₂ and AB₂) on the hydride stability, hydrogen storage capacity and kinetics of hydrogen sorption-desorption in the solid phase/gas and solid phase/electrolyte solution systems. Special attention has been paid towards the electrochemical properties of metal hydrides in terms of their performance in Ni-MH rechargeable alkaline cells. Electronic Publication