锂离子电池Sn-Co-Zn合金负极材料电沉积及其储锂性能

运用电沉积技术制备出Sn-Co-Zn合金电极材料.采用X射线衍射(XRD)和扫描电子显微镜(SEM)分析了该合金材料的相结构和表面形貌.通过循环伏安和电位阶跃实验研究了Sn-Co-Zn合金的电沉积机理,实验表明,Sn-Co-Zn合金电沉积按扩散控制连续成核和三维生长方式进行.XRD结果表明,该合金由CoSn3、Co3Sn2和Zn组成.电化学性能测试表明:Sn-Co-Zn合金电极首次放电(脱锂)容量达751mAh·g-1,首次循环的库仑效率为88%;30周循环之后放电容量为510mAh·g-1.该Sn-Co-Zn合金电极良好的电化学储锂性能可能归因于材料的多相结构.     

Preparation of nanostructured Co–Mo alloy electrodes and investigation of their electrocatalytic activity for hydrazine oxidation in alkaline medium

Cobalt and cobalt–molybdenum alloy electrodes are prepared by galvanic deposition on copper substrates. In this paper, we report a study on the influence of alloying cobalt with molybdenum for the oxidation of hydrazine in 1 M NaOH aqueous solutions. The electrocatalytic properties of the electrodes are studied by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM), X‐ray diffraction (XRD), energy‐dispersive X‐ray spectroscopy (EDS,) and inductively coupled plasma (ICP) analysis demonstrate that the structural features and compositions of the as‐prepared Co–Mo coatings vary with the deposition conditions. Electrochemical characterization indicates that the electrochemical properties and the electrocatalytic activity of the investigated alloys were strongly dependent on the microstructural features obtained under different deposition conditions. The overall experimental data indicate that alloying cobalt with molybdenum metal leads to an increase of the electrocatalytic activity in hydrazine electroxidation compared to when using the pure cobalt electrode. High catalytic efficiencies were achieved on Co/25 at.% Mo and Co/33 at.% Mo electrodes, the latter being the best electrocatalyst for hydrazine electroxidation.     

Carbon aerogels with modified pore structures as electrode materials for supercapacitors

Carbon aerogels (CA) with uniform pore structures were prepared by the polycondensation of phloroglucinol, resorcinol, and formaldehyde, using carboxylated chitosan as a soft template. The CA were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and surface area analysis. When carboxylated chitosan was added, the time for wet gel formation was reduced by 60%, and the CA showed a more uniform pore structures. The electrochemical performance of the CA was measured in a three-electrode electrochemical cell. The CA prepared with added carboxylated chitosan showed lower charge transfer resistance on the electrode surface, and the specific capacitances were also enhanced, showing a specific capacitance as high as 135 F/g at a resorcinol-to-carboxylated chitosan mass ratio of 250:1 at a current density of 0.5 A/g. This specific capacitance is much higher than that of the CA without carboxylated chitosan. The capacitance retention under increasing discharge current density was also enhanced by the addition of carboxylated chitosan. The electrochemical performance of the CA in different electrolytes (1 M LiOH, 1 M NaOH, 1 M KOH, 3 M KOH, 6 M KOH, and 9 M KOH) was investigated. The results show that the electrochemical performance in 6 M KOH was better than those in other electrolytes.     

Self-assembled biotinylated disulfide derivative monolayer on gold electrode for immobilizing enzymes

Based on self-assembled biotinylated disulfide derivative monolayer on gold electrode, the sensors immobilized monolayer or multilayer membranes composed of avidin and biotinlabeled glucose oxidase (B.GOD) or of avidin-B.GOD complex (ABC) and B.COD were prepared. The present technique may be useful for controlling the enzyme content of the sensors in molecular level by repeating the deposition of enzyme layers. The sensors have the characteristics of shorter response time, higher sensitivity. The linear range is from 6.0 x 10(-6) - 5.0 x 10(-3) M. The sensor can be used for more than 1 month and can be reactivated. The sensor was used to determine glucose in human blood serum, and the results are satisfactory.     

Sensitive and Facile Determination of Catechol and Hydroquinone Simultaneously Under Coexistence of Resorcinol with a Zn/Al Layered Double Hydroxide Film Modified Glassy Carbon Electrode

A stable dihydroxybenzene sensor was fabricated by electrochemical deposition of Zn/Al layered double hydroxide film on glassy carbon electrode (LDHf/GCE). The sensitive and facile electrochemical method for the simultaneous determination of catechol (CA) and hydroquinone (HQ) under coexistence of resorcinol (RE) has been achieved at the LDHf/GCE in phosphate buffer solution (pH 6.5). Under the optimized conditions, the differential pulse voltammetry response of the modified electrode to CA (or HQ) shows a linear concentration range of 0.6 μM to 6.0 mM (or 3.2 μM to 2.4 mM) with a correlation coefficient of 0.9987 (or 0.9992) and the calculated limit of detection is 0.1 μM (or 1.0 μM) at a signal‐to‐noise ratio of 3. In the presence of 50 μM isomer, the linear concentration ranges for CA and HQ are 3.0 μM to 1.5 mM and 12.0 μM to 0.8 mM, respectively. The detection limits are 1.2 μM and 9.0 μM. Further, the proposed method has been performed to successfully detect dihydroxybenzene isomers in analysis of real samples, such as water and tea.     

Cyclopentanone thiosemicarbazone, a new complexing agent for copper determination in biological samples by adsorptive stripping voltammetry.

A selective and sensitive stripping voltammetric method for the determination of trace amounts of copper(II) with cyclopentanone thiosemicarbazone (CPTSC) is presented. The method is based on the adsorptive accumulation of the resulting copper-CPTSC complex on a hanging mercury drop electrode, followed by the stripping voltammetric measurements at the reduction current of the adsorbed complex at -0.37 V vs. Ag/AgCl. The optimal conditions for the stripping analysis of copper include pH 9.3, deposition time of 120 s, and a deposition potential of -0.1 V (vs. Ag/AgCl). The peak current is linearly proportional to the copper concentration over a range 3.14 x 10(-9) M to 1.57 x 10(-6) M with a limit of detection of 1.57 x 10(-9) M. The technique has been applied to the determination of copper in biological samples, like urine and whole blood.     

Rapid Method for Differentiation of Carbonic Anhydrase I from Carbonic Anhydrase II Activity

ABSTRACT

A simple method for differentiation of carbonic anhydrase (CA) I, from CA II, is described based on using the nicotinates as specific CA I inhibitors. Nicotinates inhibit the activity of CA I activity; at a concentration of 5x10^?1M 100% inhibition is complete. But no effect on CA II activity is observed. In vivo administration of xanthinol nicotinate in doses of 20 mg/kg b.w. completely inhibited erythrocyte CA I activity. Association in ex vivo of methyl-nicotinate at a concentration of 5x10^?1M did not further modify erythocyte CA activity that had already been reduced by i.v. administration of xanthinol nicotinate. The nicotinate class could be used as a test for an accurate differentiation of CA I from CA II activity in vitro, in vivo and in ex vivo; by subtraction of I from total CA activity, one could also find the erythrocyte CA II activity. The ex vivo assays, using the test with nicotinates we call Nicosilvanil, would easily allow monitoring of CA I and II activity changes under physiological, pathological and experimental conditions, in response to various endogenous or therapeutical stimuli with either activating or inhibitory effects. Considering convenience, simplicity, and cost effectiveness of the reagents for the Nicosilvanil Test, this assay has the potential of being useful in routine analysis and differentiation of CA I from CA II activity in erythrocyte samples, as well as in other tissues and organs.     

Growth of nanocrystalline MoO3 on Au(111) studied by in situ scanning tunneling microscopy

The growth of nanocrystalline MoO3 islands on Au(111) using physical vapor deposition of Mo has been studied by scanning tunneling microscopy and low energy electron diffraction. The growth conditions affect the shape and distribution of the MoO3 nanostructures, providing a means of preparing materials with different percentages of edge sites that may have different chemical and physical properties than atoms in the interior of the nanostructures. MoO3 islands were prepared by physical vapor deposition of Mo and subsequent oxidation by NO2 exposure at temperatures between 450 K and 600 K. They exhibit a crystalline structure with a c(4 x 2) periodicity relative to unreconstructed Au(111). While the atomic-scale structure is identical to that of MoO3 islands prepared by chemical vapor deposition, we demonstrate that the distribution of MoO3 islands on the Au(111) surface reflects the distribution of Mo clusters prior to oxidation although the growth of MoO3 involves long-range mass transport via volatile MoO3 precursor species. The island morphology is kinetically controlled at 450 K, whereas an equilibrium shape is approached at higher preparation temperatures or after prolonged annealing at the elevated temperature. Mo deposition at or above 525 K leads to the formation of a Mo-Au surface alloy as indicated by the observation of embedded MoO3 islands after oxidation by NO2. Au vacancy islands, formed when Mo and Au dealloy to produce vacancies, are observed for these growth conditions.     

Role of the anion in the underpotential deposition of cadmium on a Rh(111) electrode: probed by voltammetry and in situ scanning tunneling microscopy

In situ scanning tunneling microscopy (STM) and cyclic voltammetry (CV) were employed to examine the underpotential deposition (UPD) of cadmium on a rhodium(111) electrode in sulfuric and hydrochloric acids. The (bi)sulfate and chloride anions in the electrolytes played a main role in controlling the number and arrangement of Cd adatoms. Deposition of Cd along with hydrogen adsorption occurred near 0.1 V (vs reversible hydrogen electrode) in either 0.05 M H2SO4 or 0.1 M HCl containing 1 mM Cd(ClO4)2. These coupled processes resulted in an erroneous coverage of Cd adatoms. The process of Cd deposition shifted positively to 0.3 V and thus separated from that of hydrogen in 0.05 M H2SO4 containing 0.5 M Cd2+. The amount of charge (80 microC/cm2) for Cd deposition in 0.5 M Cd2+ implied a coverage of 0.17 for the Cd adatoms, which agreed with in situ STM results. Regardless of [Cd2+], in situ STM imaging revealed a highly ordered Rh(111)-(6 x 6)-6Cd + HSO4- or SO42- structure in sulfuric acid,. In hydrochloric acid, in situ STM discerned a (2 x 2)-Cd + Cl structure at potentials where Cd deposition commenced. STM atomic resolution showed roughly one-quarter of a monolayer of Cd adatoms were deposited, ca. 50% more than in sulfuric acid. Dynamic in situ STM imaging showed potential dependent, reversible transformations between the (6 x 6) Cd adlattices and (square root 3 x square root 7)-(bi)sulfate structure, and between (2 x 2) and (square root 7 x square root 7)R19.1 degrees -Cl structures. The fact that different Cd structures observed in H2SO4 and HCl entailed the involvement of anions in Cd deposition, i.e. (bi)sulfate and chloride anions were codeposited with Cd adatoms on Rh(111).     

Simultaneous analysis of sulfur-containing excitatory amino acids using micellar electrokinetic chromatography with diode array and laser-induced fluorescence detection

The suitability of micellar electrokinetic chromatography (MEKC) coupled with diode array or laser-induced fluorescence (LIF) detection to analyze the four sulfur-containing excitatory amino acids (SEAA), homocysteine sulfinic acid (HCSA), homocysteic acid (HCA), cysteine sulfinic acid (CSA), and cysteic acid (CA) was investigated. 5-Carboxy-fluorescein succinimidyl ester was chosen as fluorescent reagent to derivatize HCSA, HCA, CSA, and CA. During method development, the yield of reaction dependent on pH and incubation time as well as the stability of the products were analyzed. The maximum yield was obtained after 30 min using a 0.1 M borate buffer (pH 8.9) as derivatization buffer. Each labeled amino acid exhibited high stability at room temperature over a period of 5 days. Baseline separation of labeled HCSA, HCA, CSA, and CA was obtained using a buffer consisting of 0.1 M borate, 50 mM sodium dodecyl sulfate (SDS), and 5% v/v methanol (pH 9.0). By applying LIF detection, limits of detection ranged from 0.9 x 10(-10) M for HCSA to 6.0 x 10(-10) M for CA, respectively. Slightly modified separation conditions enabled the analysis of SEAA in cerebrospinal fluid in the presence of the neurotransmitters glutamate and aspartate. In conclusion, MEKC coupled with LIF detection is a suitable technique for the simultaneous and sensitive analysis of SEAA. Further work will focus on the validation of the method with cerebrospinal fluid as sample matrix.     

Nb(x)()Ru(6)(-)(x)()Te(8), New Chevrel-Type Clusters Containing Niobium and Ruthenium(,)

Phases of composition Nb(x)()Ru(6)(-)(x)()Te(8) were prepared by reacting stoichiometric mixtures of the elements at high temperature in evacuated silica ampules. The structure of Nb(3.33)Ru(2.67)Te(8) was refined from X-ray powder data using the Rietveld method. Nb(3.33)Ru(2.67)Te(8) crystallizes isotypic with Mo(6)Q(8) (Q = S, Se, Te) in the rhombohedral space group R&thremacr; with the hexagonal lattice parameters a = 10.34106(5) ?, c = 11.47953(7) ?, and Z = 3. Its structure consists of M(6)Te(8) mixed-metal clusters (M = Nb, Ru) which are connected by intercluster M-Te bonds to form a three-dimensional network. Metal-metal bonding in these phases is analyzed in terms of Pauling bond orders and found to be weaker compared to that in related cluster compounds. Nb(x)()Ru(6)(-)(x)()Te(8) are the first representatives of Chevrel-type cluster phases with complete substitution of Mo by other metals. The chemical perspectives arising from this substitution are discussed.     

柠檬酸对Ni2P/TiO2-Al2O3催化剂加氢脱硫性能的影响

采用溶胶-凝胶法制备了TiO2-Al2O3复合载体,以柠檬酸(CA)为络合剂采用浸渍法制备了Ni2P负载的TiO2-Al2O3复合载体催化剂,并用X射线衍射(XRD)、N2吸附比表面积测定、H2程序升温氢还原(H2-TPR)、程序升温氧化(TPO)、X射线光电子能谱(XPS)技术对催化剂的结构和性质进行了表征,考察了CA/Ni摩尔比对在Ni2P/TiO2-Al2O3催化剂上进行的二苯并噻吩(DBT)加氢脱硫(HDS)性能的影响.结果表明:适量的CA可以丰富催化剂的孔道,提高催化剂的比表面积.当n(CA)/n(Ni)=2:1时,催化剂的比表面积达到126.75m2·g-1,与不加CA时相比,提高了57.05m2·g-1.调节n(CA)/n(Ni)能够改善活性相的分布,改变活性相的种类;引入CA使Ni和P前驱体的还原温度明显降低,促进活性相Ni2P的生成,一定程度上能够抑制催化剂表面炭的形成和沉积,提高其稳定性.n(CA)/n(Ni)=2:1时,催化剂具有最好的加氢脱硫活性,在360°C,3.0MPa,氢油比为500(V/V),液时体积空速为2.0h-1的条件下,二苯并噻吩转化率为99.5%,可将模拟油中硫含量由2%(w)降低到0.01%(w).     

Simultaneous determination of phenylglycidol enantiomers and cinnamyl alcohol in asymmetric epoxidation processes by chiral liquid chromatography

A high-performance liquid chromatographic method has been developed for the simultaneous determination of phenylglycidol enantiomers and cinnamyl alcohol (CA). Separations were achieved on an amylose tris(3, 5-dymethylphenylcarbamate) chiral stationary phase (Chiralpak AD). The effect of concentration of organic modifier (2-propanol and ethanol) in the mobile phase and flow-rate was studied. The mobile phase selected consisted of a mixture of n-hexane-ethanol (85:15, v/v) with a flow-rate of 1.2 ml/min. The UV-vis detector was set at 254 nm. Resolution for the phenylglycidol enantiomers in the suitable chromatographic conditions was 2.4 with an analysis time of 12 min. The method developed was validated and was found to be linear in the range from 5 x 10(-4) to 3 x 10(-2) M, for phenylglycidol enantiomers and in the range from 5 x 10(-5) to 1 x 10(-3) M, for CA (r > 0.999 for the three compounds). Repeatability and intermediate precision for the three analytes at three different concentrations were below 3.6 and 2.8% R.S.D., respectively. This method has been applied to study the asymmetric epoxidation of CA with titanium(IV) alkoxide compounds as catalysts in order to evaluate their catalytic activity and stereoselectivity of the epoxidation processes.     

Reversible solid-state reaction between 18-Crown[6] and M[H2PO4](M = K, Rb, Cs) and an investigation of the decomplexation process

On heating the hydrated complexes 18-Crown[6].M[H(2)PO(4)].xH(2)O (x= 2 for M = K, Rb; x= 1.5 for M = Cs), quantitatively prepared by mechanical mixing of crystalline 18-Crown[6] and M[H(2)PO(4)], to ca. 60 degrees C, water loss takes place, accompanied by the extrusion of the crown ether from the crystalline complex and followed by reconstruction of the inorganic phase M[H(2)PO(4)](M = K, Rb, Cs); the resulting solid mixture reverts to 18-Crown[6].M[H(2)PO(4)].xH(2)O (x= 2 for M = K, Rb; x= 1.5 for M = Cs) upon grinding in air.     

Amplified detection of DNA and analysis of single-base mismatches by the catalyzed deposition of gold on Au-nanoparticles

A novel amplification route for DNA detection based on the deposition of gold on a 10 nm Au-colloid/avidin conjugate label acting as a 'seeding' catalyst, is described. Microgravimetric quartz-crystal-microbalance measurements are employed to transduce the catalyzed deposition of gold on the piezoelectric crystals. Three different DNA detection schemes are described: (i) analysis of a 27-base nucleic acid fragment; (ii) analysis of the entire M13phi DNA (7229 bases); and (iii) detection of a single-base mismatch in a DNA. Ultrasensitive detection of DNA is accomplished by the catalyzed deposition of gold, detection limit approximately 1 x 10(-15) M.     

Structure and thermoelectric properties of the new quaternary bismuth selenides A(1-x)M(4-x)Bi(11+x)Se21 (A = K and Rb and Cs; M = Sn and Pb)--members of the grand homologous series Km(M6Se8)m(M(5+n)Se(9+n))

Several members of the new family A(1-x)M(4-x)Bi(11+x)Se21 (A = K, Rb, Cs; M = Sn, Pb) were prepared by direct combination of A2Se, Bi2Se3, Sn (or Pb), and Se at 800 degrees C. The single-crystal structures of K(0.54)Sn(3.54)Bi(11.46)Se21, K(1.46)Pb(3.08)Bi(11.46)Se21, Rb(0.69)Pb(3.69)Bi(11.31)Se21, and Cs(0.65)Pb(3.65)Bi(11.35)Se21 were determined. The compounds A(1-x)M(4-x)Bi(11+x) Se21 crystallize in a new structure type with the monoclinic space group C2/m, in which building units of the Bi2Te3 and NaCl structure type join to give rise to a novel kind of three-dimensional anionic framework with alkali-ion-filled tunnels. The building units are assembled from distorted, edge-sharing (Bi,Sn)Se6 octahedra. Bi and Sn/Pb atoms are disordered over the metal sites of the chalcogenide network, while the alkali site is not fully occupied. A grand homologous series Km(M6Se8)m(M(5+n)Se(9+n)) has been identified of which the compounds A(1-x)M(4-x)Bi(11+x)Se21 are members. We discuss here the crystal structure, charge-transport properties, and very low thermal conductivity of A(1-x)M(4-x)Bi(11+x)Se21.     

Determination of gallium by square-wave voltammetry anodic stripping, based on the electrocatalytic action of 2,2'-bipyridine in dimethylsulphoxide: comparison with an aqueous NaSCN/NaClO(4) electrolyte

Deposition potential, deposition time, square-wave frequency, 2,2'-bipyridine concentration, and gallium concentration have been studied in detail, for the determination of trace concentration levels of the metal by square-wave voltammetry anodic stripping analysis, in dimethylsulphoxide. Optimum conditions have been found for gallium(III) determination and results compared to those obtained in 0.5M NaSCN + 4.2M NaClO(4) aqueous electrolyte by obtaining calibration graphs for the range 1 x 10(-8)M-1 x 10(-5)M gallium. Accuracy (+/- 3%) and precision (4-6% SD) of this method were assessed with both 4 x 10(-8)M and 4 x 10(-7)M gallium solutions used as synthetic samples. The efficiency of solvent extraction of gallium with di-isopropyl ether was found to be 99.98% at a 4 x 10(-7)M gallium concentration. The proposed method was applied to the determination of the gallium content in rock mineral samples (using the above mentioned solvent extraction procedure), are compared to those obtained with the NaSCNNaClO(4) based electrolyte. No statistically significant difference was observed. Analytical procedures followed are given in detail.     

Anodic stripping voltammetric determination of trace lead with a nafion/crown-ether film electrode

An electrode for the anodic stripping voltammetric determination of trace lead has been made by coating glassy carbon with a film of Naflon in which a crown ether is incorporated. The sensitivity is increased because of continuous transfer of lead from solution to the electrode surface by complexation with the crown ether and reduction during the deposition period. A detection limit of 5 x 10(-10)M has been obtained by electrodeposition for 3 min. The method is sensitive, simple and relatively rapid, with a relative standard deviation of 8% at the 2 x 10(-9)M level.     

Preparation and characterization of electrophoretically deposited high-temperature superconductor coatings

The high-temperature superconductor, YBa₂Cu₃O_7–x (x = 0.1–0.2) [YBCO], was prepared using an optimized calcination and sintering process. Thin layers of a few microns of this material were deposited on a silver substrate by applying a simplified electrophoretic deposition technique in a suspension of the fine, < 10 m, superconductor powder in a non-aqueous liquid. To get a uniform and strongly adherent coating, the deposition process is repeated several times, followed by an appropriate sintering procedure. The initially prepared YBCO powder and the coatings produced were characterized for their superconducting properties by X-ray diffraction analysis (XRD), magnetization measurements with a Superconducting Quantum Interference Device (SQUID) and electrical resistivity measurements. By scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) the grain size of the YBCO film, its thickness and impurity content, respectively, were estimated.     

Heterometallic modular metal-organic 3D frameworks assembled via new tris-β-diketonate metalloligands: nanoporous materials for anion exchange and scaffolding of selected anionic guests

The modular engineering of heterometallic nanoporous metal-organic frameworks (MOFs) based on novel tris-chelate metalloligands, prepared using the functionalised β-diketone 1,3-bis(4'-cyanophenyl)-1,3-propanedione (HL), is described. The complexes [M(III)L(3)] (M=Fe(3+), Co(3+)) and [M(II)L(3)](NEt(4)) (M=Mn(2+), Co(2+), Zn(2+), Cd(2+)) have been synthesised and characterised, all of which exhibit a distorted octahedral chiral structure. The presence of six exo-oriented cyano donor groups on each complex makes it a suitable building block for networking through interactions with external metal ions. We have prepared two families of MOFs by reacting the metalloligands [M(III)L(3)] and [M(II)L(3)](-) with many silver salts AgX (X=NO(3)(-), BF(4)(-), PF(6)(-), AsF(6)(-), SbF(6)(-), CF(3)SO(3)(-), tosylate), specifically the [M(III)L(3)Ag(3)]X(3)·Solv and [M(II)L(3)Ag(3)]X(2)·Solv network species. Very interestingly, all of these network species exhibit the same type of 3D structure and crystallise in the same trigonal space group with similar cell parameters, in spite of the different metal ions, ionic charges and X(-) counteranions of the silver salts. We have also succeeded in synthesising trimetallic species such as [Zn(x)Fe(y)L(3)Ag(3)](ClO(4))((2x+3y))·Solv and [Zn(x)Cd(y)L(3)Ag(3)](ClO(4))(2)·Solv (with x+y=1). All of the frameworks can be described as sixfold interpenetrated pcu nets, considering the Ag(+) ions as simple digonal spacers. Each individual net is homochiral, containing only Δ or Λ nodes; the whole array contains three nets of type Δ and three nets of type Λ. Otherwise, taking into account the presence of weak Ag-C σ bonds involving the central carbon atoms of the β-diketonate ligands of adjacent nets, the six interpenetrating pcu networks are joined into a unique non-interpenetrated six-connected frame with the rare acs topology. The networks contain large parallel channels of approximate hexagonal-shaped sections that represent 37-48% of the cell volume and include the anions and many guest solvent molecules. The guest solvent molecules can be reversibly removed by thermal activation with retention of the framework structure, which proved to be stable up to about 270°C, as confirmed by TGA and powder XRD monitoring. The anions could be easily exchanged in single-crystal to single-crystal processes, thereby allowing the insertion of selected anions into the framework channels.