CHARACTERIZATION OF OXIDES AND HALOGENIDES OF CERIUM BY ESCA .2. AUGER PEAKS OF CE-M5N45N45

The larger chemical shift of cerium compounds was discoveried. The chemical states of the cerium compounds were identified by the chemical shifts of Auger energy. The changes in Anger energy and parameters are principally due to the changes in extra-atomic relaxation or polarization energy. The increase of the polarizable properties in anions of cerium compounds corresponds to the increase of Auger energy and parameter. The Auger parameter can be measured more accurately. Ce(CF3COO)(x)Cl-3-x was also studied by ESCA. It is shown that the electron density at cerium atom increases with the increase of x, while the electron density at oxygen atom decreases.

ELECTROCATALYTIC OXIDATION AND ION-CHROMATOGRAPHIC DETECTION OF BR-, I-, SO32-, S2O32- AND SCN- AT A PLATINUM PARTICLE-BASED GLASSY-CARBON MODIFIED ELECTRODE

A modified method for dispersing platinum particles on a glassy carbon (GC) electrode was investigated. The ultramicro Pt particle-modified electrode obtained exhibited high catalytic stability and activity towards the oxidation of some halide ions (Br-, I-) and inorganic sulfur species (S2O32-, SO32- and SCN-). These anions were separated and detected by using ion chromatography and electrochemical detection via this novel dispersed Pt particles-GC working electrode. The detection limits were 20 ng/ml for Br-, 1.0 ng/ml for I-, 10 ng/ml for SO32- and 4.0 ng/ml for SCN-. This method was employed for the analysis of industrial and environmental waste waters.

SYNTHESIS AND X-RAY STRUCTURE OF A SEMICONDUCTING ORGANOMETALLIC SALT [FECP(TOL)](2)[NI(MNT)(2)]

The compound [FeCp(Tol)](2)[Ni(mnt)(2)] has been prepared from [FeCp(Tol)]AlCl4 and Na-2[Ni(mnt)(2)]. This new organometallic radical ionic salt has been characterized by elemental analysis, IR, H-1 NMR and mass spectroscopy. The X-ray structure of the compound shows there are segregated cation and anion stacks in the perpendicular directions, The molecular anions form a zig-zag stacking along the b axis, and between every two neighbouring anion planes a methyl group of the cation is inserted. This gives rise to a long spacing of 6.87 Angstrom, between the anion planes. The cations stack along the c axis, with the closest spacing of 3.457 Angstrom between the cyclopentadienyl plane and the neighbouring toluene plane, which is shorter than the sum of Van der Wall's radii. Conductivity measurements showed the compound as a semiconductor with a room temperature conductivity of 1.6 X 10(-4) Scm(-1).

ELECTROCHEMICAL CONTROLLED-RELEASE OF ADENOSINE-TRIPHOSPHATE

Polypyrrole (PPy) film was synthesized by anodic polymerization of pyrrole onto the surface of platinum electrode in the solution of sodium p-toluene sulfonate (NaTsO). When this film was oxidized anodically in an aqueous solution of adenosine triphosphatle (ATP), the ATP anions were incorporated into the film. Release of ATP From the film could be accomplished by reduction of the film in aqueous electrolyte solution. The total amount of ATP released from the film was determined by UV spectroscopic method.

ELECTROCATALYTIC PROPERTIES OF MIXED-VALENCE MOLYBDENUM OXIDE THIN-FILM MODIFIED MICROELECTRODES

A compact blue conducting mixed-valence Mo (VI,V) oxide film was grown on the surface of a carbon fibre (CF) microelectrode by cycling the potential between +0.20 and similar to 0.70 V SCE in freshly prepared Na2MoO4 solution in H2SO4 (pH 2). The thicknes

PREPARATION AND PROPERTIES OF POLYPYRROLE FILM DOPED WITH A DAWSON-TYPE HETEROPOLYANION

The electropolymerization of pyrrole in the presence of Dawson-type tungstophosphate yields a polypyrrole (PPy) film doped with tungstophosphate anions on the electrode surfaces. The electrochemical behaviour of this film was described, and the stability

ALKYLATION OF ISOBUTANE WITH BUTENE OVER LAYERED DOUBLE HYDROXIDE PILLARED HETEROPOLYOXOMETALATE ACID-BASE CATALYSTS

[Si(W2O7)(6)](8-) pillared LDH structure hydroxides were synthesized by the method of restructuring of the thermally decomposed hydrotalcite-like compounds for Zn-Al and Mg-Al oxide systems. [P(W2O7)(6)](8-) pillared Ni-Al LDH structure hydroxide was synt

STUDY OF A 1/12 PHOSPHOMOLYBDIC ANION DOPED POLYPYRROLE FILM ELECTRODE AND ITS CATALYSIS

A phosphomolybdic anion doped polypyrrole (PMo12O403- + PPy) film electrode has been prepared by electrochemical polymerization of pyrrole in an aqueous solution of 0.5 mol l-1 H2SO4 or 0.5 mol l-1 KNO3 containing PMo12O403- anions, and characterized by scanning electron microscopy and in-situ UV-visible spectroelectrochemical methods. The film electrode obtained is very stable upon potential cycling in acidic solution, but not in neutral solution. The catalytic effect of the film electrode on the reduction of ClO3- and BrO3- was studied.

THE PREPARATION OF ELECTRODES MODIFIED WITH ISOPOLYMOLYBDIC ACID PLUS POLYANILINE FILM AND ITS CATALYTIC EFFECTS ON CHLORATE IONS

Electrodes modified with isopolymolybdic acid+polyaniline film, which exhibit high stability and activity in aqueous acidic solution, have been prepared successfully using two methods: one-step synthesis by electrochemical polymerization at a constant applied potential of +0.80 V/SCE or by cycling the potential at 100 mV/s between -0.12 and +0.85 V in 0.5 M H2SO4 containing 5.0x10(-2) M aniline and 5.0x10(-3) M H4Mo8O26, or two-step synthesis by doping the polyaniline film electrode with isopoly acid (IPA) under a cycling potential between -0.20 and +0.40 V in 0.5 M H2SO4 containing the H4Mo8O26 dopant. The thickness of the film and the amount of dopant in the polyaniline film can be controlled by experimental parameters such as the charge, time and the ratio of aniline to IPA in the solution. The experimental results show that electrodes modified with isopolymolybdic acid+polyaniline film using both methods have a strong catalytic effect on the reduction of chlorate anions. Comparison of the two methods of modification shows that the catalytic effect at the modified electrode prepared by the two-step method is greater than that at the electrode prepared by the one-step method.

THE SYNTHESIS AND CRYSTAL-STRUCTURE OF MOLYBDENUM-SILICON BLUE

The single crystal of heteropoly blue, HsSiMo12O40.12H2O, the reduced product of molybdenum-silicon heteropoly acid, was prepared by electrochemical reduction and evaporation in nitrogen atmosphere. The Crystal structure of the product was determined. The heteropoly blue H8SiMo12O40.12H2O, Crystallizes space group P1BAR a = 1.3769 (3) nm, b = 1.4346 (4) nm, c = 1.4134 (4) nm, alpha = 120.47 (2)-degrees, beta = 110.70 (2)-degrees, gamma = 66.11 (2)-degrees, Z = 2, R = 0.0608. The heteropoly blue anion was determined to have Keggin Structure and alpha-isomer and it remained the structure of the unreduced heteropoly acid anion. But the distortion of the structure and the changes of bond length and bond angle take place obviously. The four Mo5+ Positions were determined in the structure.

CRYSTAL-STRUCTURE OF 1, 10-DECANEDIAMMONIUM TETRACHLOROZINCATE

The crystal structure of the title compound has been determined from single crystal X-ray diffraction. The complex crystallizes in the triclinic space group P1 with Z=2. Lattice parameters are: a = 0.7296(1), b = 1.0110(3), c = 1.2814(4) nm; alpha = 90.84(2), beta = 101.17(2), gamma = 92.52(2)-degrees. Intensity data were collected on a Nicolet R3M/E four-circle diffractometer using MoK alpha (lambda = 0.071073 nm) radiation. The structure was solved by Patterson and Fourier techniques and refined by least-squares techniques to R = 0.065. The structure of the complex consists of tetrahedral ZnCl42- anions which form a two-dimensional sheets. Tetrahedral ZnCl42- anions are sandwiched between two hydrocarbon layers which consist of [NH3(CH2)10NH3]2+ cations. Each [NH3(CH2)10NH3]2+ group is in a gauche bond between C atoms near NH3 polar heads.

ELECTROCHEMICAL STUDY OF ISOPOLY AND HETEROPOLY OXOMETALLATE FILM MODIFIED MICROELECTRODES .5. PREPARATION AND ELECTROCHEMICAL-BEHAVIOR OF A 2/18-MOLYBDODIPHOSPHATE ANION MONOLAYER MODIFIED ELECTRODE

In this paper a carbon fibre (CF) microelectrode modified with the 2:18-molybdodiphosphate anion by simple adsorption is described and its electrochemical behaviour is reported. The 2:18-molybdodiphosphate anion (alpha-P2Mo18O626-), which is a Dawson structure, undergoes five successive multielectron reductions in acidic solution. The first three redox waves correspond to the two-electron process, and the last two waves are four-electron and six-electron processes respectively. On the basis of the experimental results it is shown that the electrode process of alpha-P2Mo18O626- on the CF electrode in acidic solution is simultaneously controlled by the diffusion and adsorption of alpha-P2Mo18O626- anions. When the concentration of the alpha-P2Mo18O626- in the solution is reduced, the electrode process mainly exhibits non-diffusion-controlled behaviour, and the diffusion-limited process takes over as the concentration of alpha-P2Mo18O626- becomes higher. The CF electrode modified with a thin film of alpha-P2Mo18O626- exhibits very good stability and redox behaviour in aqueous acidic solution. The alpha-P2Mo18O626- is reduced to heteropoly blue, with an accompanying protonation process. The addition of more than six electrons to the alpha-P2Mo18O626- anion in an aqueous solution does not result in its decomposition. The result obtained is not the same as that reported previously.

ELECTROCHEMICAL STABILITY AND ELECTROCATALYSIS BEHAVIORS OF POLY(3-METHYLTHIOPHENE) THIN-FILM MODIFIED ELECTRODES

The Electrochemical stability of poly(3-methylthiophene) (PMT) thin film modified glassy carbon electrodes was investigated experimentally with successive cyclic voltammetry(CV) The effects of electrolyte solutions on the stability were studied. In the presence of small hydrated anions (less-than-or-equal-to 3.5nm) in the solution, the electroactivity of PMT films decreased with the characteristics of second order kinetics. In a solution with large hydrated anions (greater-than-or-equal-to 4 nm), PMT films have good stability. PMT/GO electrode can electrocatalyse the oxidation of Br- and Cl- anions, and loses its electroactivity rapidly. X-ray photoelectron spectra (XPS) have demonstrated that chlorine has bonded covalently onto the PMT structure after OV cycles in NaCl solutions.

ELECTROCHEMICAL-BEHAVIOR OF N-METHYL-N'-HEXADECYLVIOLOGEN MONOLAYERS ON SILVER ELECTRODES - EFFECTS OF COUNTERIONS

N-Methyl-N'-hexadecylviologen (C16MV) has been the subject of several electrochemical and spectroelectrochemical studies which characterized the species present in various redox states for C16MV monolayers on silver electrode surfaces. Both self-assembled monolayers (SA) and Langmuir-Blodgett (LB) transferred systems have been studied. These indicated inconsistencies regarding the presence or absence of splitting of the first reduction peak in its cyclic voltammogram (CV). The present study demonstrates the important influence of the specific anionic species present in the supporting electrolyte. Splitting may or may not take place, depending on the size and relative strength of the adsorption of specific anions contributed by the supporting electrolyte. Small, strongly adsorbing anions such as iodide produced peak splitting in the CV of C16MV monolayers; bulky but weakly adsorbing anions such as perchlorate may disrupt the ordered structure of monolayers but produce no splitting. Ancillary data provided by surface enhanced Raman spectroscopy (SERS) was consistent with the electrochemical measurements.

AMPEROMETRIC GLUCOSE SENSOR WITH FERROCENE AS AN ELECTRON-TRANSFER MEDIATOR

A glucose oxidase (GOD) electrode with ferrocene (Fc) used as an electron transfer mediator has been described. Using Nafion, Fc was modified on a glassy carbon (GC) electrode surface, and glucose oxidase was then immobilized on the Fc-Nafion film, forming a GOD-Fc-Nafion enzyme electrode. The preparation method was quite simple and rapid. The enzyme electrode showed a reversible reaction of the redox couple (Fc+/Fc), used in a biosensor system, displayed a sensitive catalytic current response (response time was less than 20 s) on variation of the glucose concentration, with a wide linear range up to 16 mM and with good repeatability. The enzyme electrode showed almost no deterioration over the course of three weeks. There was little or no interference from electro-active anions, such as ascorbic acid, to the determination of glucose based on Nafion film and lower oxidizing potentials of the enzyme electrode.