Electrochemical Analysis of Zirconiumin Aqueous and Organic Media

For the challenging nature of the zirconium environment analysis, this study consists to analyze the electrochemical behavior of Zirconium in both aqueous and organic media. To that end first the electrolytic media was selected on the basis of the Pourbaix potential-pH diagram, which provides informations on the predominance of Zr(IV) ion and Zr in aqueous media. In aqueous media, analyzes were first carried out in acidic media then in basic media. Studies have thus revealed that the acidic environment is not favourable for the electrochemical analysis of zirconium. Voltammograms obtained in an acidic environment show no zirconium detection signal;this is due to the strong presence of H+ ions in the solution. We have also observed in acidic media the phenomenon of passivation of the electrode surface. In aqueous alkaline media (pH = 13), we have drawn in reduction several Intensity-Potential curves by fixingsome technical parameterslike scanning speed, rotation speed of the electrode. The obtained voltammograms show cathodic waves, starting from -1.5 V/DHW and attributed to the reduction of Zr (IV) to Zr (0). The last phase of this study focused on the electrochemical analysis of zirconium in an organic media. In this media, several intensity-potential curves were plotted in reduction and in cyclic voltammetry with various parameters. Through several reduction analysis, the Zr (IV) was reduced to Zr (0) to the potential of -1.5 V/DHW. The electrochemical analysis of zirconium in organic media seems globally easier to achieve thanks to its large solvent window (i.e. dimethylformamide (DMF) solvent window > 6 V).

Effects of flaky rare earth oxide additives on the high temperature performance of nickel electrodes

Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached 96% at 60 oC for electrodes with 1 at.% flaky rare earth oxides.The high rate discharge performance for electrodes with flaky rare earth oxides were improved significantly,for example,discharge efficiency at 5C improved from 50% to 70%.The results showed that the end charging potential of the ...

Hydrothermal Synthesis,Crystal Structure and Properties of a Novel Polyoxometalate {[CuⅡ（1,10-phen）]2[PMoⅥ11MoⅤO40]} [CuⅠ（C8N4H6）（C9H6NO）（H2O）]

A new pseudo three-dimensional framework structure of the title compound {[CuⅡ（1,10-phen）]2[PMoⅥ11MoⅤO40]}[CuⅠ（C8N4H6）（C9H6NO）（H2O）]（1） has been prepared by the hydrothermal method for the first time and characterized by elemental analyses,X-ray single-crystal diffraction and IR spectra.1 consists of two building blocks,one {[CuⅡ（1,10-phen）]2[PMoⅥ11MoⅤO40]} and one [CuⅠ（C8N4H6）（C9H6NO）（H2O）] coordinated group.Singlecrystal X-ray diffraction revealed that 1 crystallizes in the monoclinic system,space group P2/c with a=13.498（4）,b=12.890（3）,c=21.465（8）,β=97.314o,V=3704（2）3,Mr=2693.61,Z=2,Dc=2.415 Mg/m3,μ=2.915 mm-1,F（000）=2562,S=1.009,the final R=0.0583 and wR=0.1406 for 5129 observed reflections with I2σ（I）.Furthermore,compound 1 shows strong fluorescent properties in the solid state at room temperature.The electrochemical behavior of 1 has also been studied by cyclic voltammograms.

Synthesis,Structure,Electrochemistry and Fluorescence Properties of a One-dimensional Coordination Polymer {[Cd[μ-(4,4′-dps)]_2(H_2O)_2]·(4-abs)_2(H_2O)_2}_n

A new cadmium（N） compound, {[ CdLu-（4,4＇-dps） ]2（H2O）2]＇（4＇abs ）2（H2O）2n 1 （4,4＇-dps = 4,4＇-dipyridylsulfide, 4-abs = deprotonated 4-amino benzenesulfonic acid）, has been synthesized and structurally characterized. It belongs to the orthorhombic system, space group Pbcn with a = 19.950（3）, b = 10.6381（13）, c = 18.055（2）A, V= 3831.8（8） A3, Z = 4, C32H36CdN6010S4, Mr = 905.31, F（000） = 1848, μ= 0.850 mm^-1, Dc = 1.569 Mg/m^3, the final R = 0.0238 and wR = 0.0589 for 3080 observed reflections with I 〉 2σ（I）. Complex I is a one-dimensional linear chain coordination polymer and the repeat unit is comprised of doubly charged cadmium complex cation, uncoordinated 4-aminobenzene sulfonate anions and water molecules. The cadmium（H） ion adopts a six-coordinate distorted octahedral geometry. Complex 1 is stabilized and linked into a three-dimensional layered structure through intermolecular O-H…O and N-H…O hydrogen bonds together with electrostatic force. The cyclic voltammograms and fluorescence spectrum of 1 were also measured. It shows one irreversible redox process and emits a very strong and sharp fluorescent band at about 341 nm.

Effect of Sb dopant amount on the structure and electrocatalytic capability of Ti/Sb-SnO_2 electrodes in the oxidation of 4-chlorophenol

Ti/Sb-SnO2 anodes were prepared by thermal decomposition to examine the influence of the amount of Sb dopant on the structure and electrocatalytic capability of the electrodes in the oxidation of 4-chlorophenol. The physicochemical properties of the Sb-SnO2 coating were markedly influenced by different amounts of Sb dopant. The electrodes, which contained 5% Sb dopant in the coating, presented a much more homogenous surface and much smaller mud-cracks, compared with Ti/Sb-SnO2 electrodes containing 10% or 15% Sb dopant, which exibited larger mud cracks and pores on the surface. However, the main microstructure remained unchanged with the addition of the Sb dopant. No new crystal phase was observed by X-ray diffraction （XRD）. The electrochemical oxidation of 4-chlorophenol on the Ti/SnO2 electrode with 5% Sb dopant was inclined to electrochemical combustion; while for those containing more Sb dopant, intermediate species were accumulated. The electrodes with 5% Sb dopant showed the highest efficiency in the bulk electrolysis of 4-chlorophenol at a current density of 20 mA/cm^2 for 180 min; and the removal rates of 4-chlorophenol and COD were 51.0% and 48.9%, respectively.

Preparation and electrochemical properties of Y-doped Li_3V_2(PO_4)_3 cathode materials for lithium batteries

Y-doped Li3V2（PO4）3 cathode materials were prepared by a carbothermal reduction（CTR） process.The properties of the Y-doped Li3V2（PO4）3 were investigated by X-ray diffraction（XRD） and electrochemical measurements.XRD studies showed that the Y-doped Li3V2（PO4）3 had the same monoclinic structure as the undoped Li3V2（PO4）3.The Y-doped Li3V2（PO4）3 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram（CV）, and electrochemical impedance spectra（EIS）.The optimal doping content of Y was x=0.03 in Li3V2-xYx（PO4）3 system.The Y-doped Li3V2（PO4）3 samples showed a better cyclic ability.The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through the Y-doping.The improved electrochemical perormances of the Y-doped Li3V2（PO4）3 cathode materials were attributed to the addition of Y3＋ ion by stabilizing the monoclinic structure.

Synthesis and Electrochemical Properties of Mg-doped LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 Cathode Materials for Li-ion Battery

The layered LiNi0.6Co0.2-xMn0.2MgxO2 （x=0.00,0.03,0.05,0.07） cathode materials were prepared by a co-precipitation method.The properties of the Mg-doped LiNi0.6Co0.2Mn0.2O2 were investigated by X-ray diffraction （XRD）,scanning electron microscopy （SEM）,and electrochemical measurements.XRD studies showed that the Mg-doped LiNi0.6Co0.2Mn0.2O2 had the same layered structure as the undoped LiNi0.6Co0.2Mn0.2O2.The SEM images exhibited that the particle size of Mg-doped LiNi0.6Co0.2Mn0.2O2 was finer than that of the undoped LiNi0.6Co0.2 Mn0.2O2 and that the smallest particle size is only about 1μm.The Mg-doped LiNi0.6Co0.2Mn0.2O2 samples were investigated on the Li extraction/insertion performances through charge/discharge,cyclic voltammogram （CV）,and electrochemical impedance spectra（EIS）.The optimal doping content of Mg was that x= 0.03 in the LiNi0.6Co0.2-xMn0.2MgxO2 samples to achieve high discharge capacity and good cyclic stability.The electrode reaction reversibility and electronic conductivity was enhanced,and the charge transfer resistance was decreased through Mg-doping.The improved electrochemical performances of the Mg-doped LiNi0.6Co0.2Mn0.2O2 cathode materials are attributed to the addition of Mg 2＋ ion by stabilizing the layer structure.

Preparation and Electrochemical Studies of Y-doped LiVPO_4F Cathode Materials for Lithium-ion Batteries

Y-doped LiVPO4F cathode materials were prepared by a carbothermal reduction（CTR） process. The properties of the Y-doped LiVPOaF samples were investigated by X-ray diffraction （XRD） and electrochemical measurements. XRD studies show that the Y-doped LiVPOaF samples have the same triclinic structure as the undoped LiVPO4F. The Li extraction/insertion performances of Y-doped LiVPO4F samples were investigated through charge/discharge, cyclic voltammogram （CV） , and electrochemical impedance spectra（EIS）. The optimal doping content of Y is x=0.04 in LiYxV1-xPO4F system. The Y-doped LiVPO4F samples show a better cyclic ability. The electrode reaction reversibility is enhanced, and the charge transfer resistance is decreased through the Y-doping. The improved electrochemical performances of the Y-doped LiVF＇OaF cathode materials are atlributed to the addidon of Y^3＋ ion by stabilizing the Iriclinic structure.

Electrochemical Study of Hypophosphite

Electrochemical behavior of hypophosphite was studied with cyclic voltammogram in acidic solution(pH = 4.6) at 80℃. Two anodic peaks were observed on gold electrode at - 0.44V and - 0.59 V (SCE),respectively, and no corresponding cathodic peaks were obtained. The one at - 0.44 V wits ascribed to the oxidation oftautomeric form of hypophosphite, the other at - 0.59 V was due to the oxidation of absorbed form of hypophosphite. The two oxidation reactions were believed to be the electron source of nickel ion reduction in electrolessnickel processes.

Synthesis and Electrochemical Behavior of Poly N, N′- Dithiobis(1,3- Phenylenediamine)

A novel organic disulfide, N, N′-dithiobis(3-nitroaniline)(1) was prepared by the reaction of 3-nitroaniline with sulfur monochloride in chloroform. Compound 1 was reduced by zinc powder to give N, N′-dithiobis(1,3-phenylenediamine) (2). Poly N, N′-dithiobis (1,3-phenylenediamine) (3) was prepared by electrochemical polymerization of compound 2 and its basic electrochemical behavior is discussed.

Synthesis and Electrochemical Properties of Cr-doped Li_3V_2(PO_4)_3 Cathode Materials for Lithium-ion Batteries

Cr-doped Li3V2（PO4）3 cathode materials Li3V2-xCr（PO4）3 were prepared by a carbothermal reduction（CTR） process. The properties of the Cr-doped Li3V2（PO4）3 were investigated by X-ray diffraction （XRD）, scanning electron microscopic （SEM）, and electrochemical measurements Results show that the Cr-doped Li3V2（PO4）3 has the same monoclinic structure as the undoped Li3V2（PO4）3, and the particle size of Cr-doped Li3V2（PO4）3 is smaller than that of the undoped Li3V2（PO4）3 and the smallest particle size is only about 1 1μm. The Cr-doped Li3V2（PO4）3 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram （CV）, and electrochemical impedance spectra（EIS）. The optimal doping content of Cr was that x=0.04 in the Li3V2-xCrx（PO4）3 samples to achieve high discharge capacity and good cyclic stability. The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through the Cr-doping. The improved electrochemical performances of the Cr-doped Li3V2（PO4）3 cathode materials are attributed to the addition of Cr^3＋ ion by stabilizing the monoclinic structure.

The Study of Anti-tumor Activity of Trichosanthin by Cyclic Voltammogram

The anti-tumor activity of Trichosanthin (TCS) has been frequently reported in recent years. In our experiments, electrochemical methods were applied to detect the effects of TCS on human leukemia cells U937. 50 mu g/ml TCS treatment for 40 hours can cause irreversible negative effects on the viability of U937 cells. This effect largely depends on the concentration of TCS and the time period of treatment.

Influence of Y^(3+) on Structure and Electrochemical Property of LiMn_2O_4

Li1.02YxMn2-xO4（x = 0, 0. 005, 0.01, 0.02, 0.04, 0. 1） were prepared by solid state reaction method with raw materials Li2CO3, electrolytic MnO2 and Y2O3. Li1.02YxMn2-x O4 with different Y^3＋ contents have good crystal structure, Y^3＋ doping makes the lattice parameter and crystal volume small. Cyclic vohammogram testing result shows that a small quantity of Y^3＋ doping has no influence on the Li^＋ deinsertion-insertion process, but Y^3＋ doping decreases the interacting force among Li^＋ , and then availably avoids the energy level splitting. The electrochemical property testing indicates that the initial discharge ca- pacity at x =0.02 is 117.2 mAh·g^-1 and remains 96.9% with 113.6 mAhg^-1 after 20 cycles, which explains that Y^3＋ doping effectively restricts Jahn-Teller effect and stabilizes the crystal structure. AC analysis shows that conductivity of the samples is clearly improved due to Y^3＋ doping.

A Simplified Microcontroller Based Potentiostat for Low-Resource Applications

A low component count, microcontroller-based potentiostat circuit was developed through the use of operational amplifiers arranged in different feedback configurations. This was developed to alleviate the cost burden of equipment procurement in low-cost and budget applications. Simplicity was achieved in the design by the use of the microcontroller’s native functionalities and a low-cost R/2R resistor ladder digital-to-analogue converter. The potentiostat was used to investigate the Ni2+/Ni(s) redox couple in a 3-electrode cell with a silver/silver chloride reference electrode and graphite counter and working electrodes. Linear sweep voltammograms were ob-tained at scan rates of 10, 20, 30 and 40 mV/s. The analysis of the peak current versus (scan rate)1/2 plot indicated that the Ni2+/Ni(s) reduction, though conforming to the Randles-Sevcik equation, was a non-reversible redox reaction.

Soft-Chemical Synthesis of Vanadium Oxide Nanostructures Using 3,3’,3”-Nitrilotripropionic Acid(NTP)as a Carrier

Vanadium oxide nanostructures were synthesized using NTP as a carrier through soft-chemical method. The influence of calcination temperature on the phase and morphology of obtained pristine product were characterized using X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). Cyclic voltammogram studies were conducted to examine the electrochemical performance of cathodes made of vanadium oxide nanostructures. X-ray diffraction results show that, the particle size of the nanomaterials is increases with the increasing of calcination temperature.

On the Criteria of Instability for Electrochemical Systems

Both cyclic-voltammetry-based and impedance-based experimental criteria thathave been developed recently for the oscil-latory electrochemical systems are critically appraisedwith two typical categories of oscillators. Consistent conclusions can be drawn by the two criteriafor the category of oscillators that involve the coupling of charge transfer mainly with surfacesteps (e.g. ad- and desorption) such as in the electrooxidation of C_1 organic molecules. Whereas,impedance-based criterion is not applicable to the category of oscillators that involve the couplingof charge transfer mainly with mass transfer (e.g. diffusion and convection) such as in theFe(CN)_6^(3-) reduction accompanying periodic hydrogen evolution. The reason is that the negativeimpedance cannot include the feedback information of convection mass transfer induced by thehydrogen evolution. However, both positive and negative nonlinear feedbacks, i. e., thediffusion-limited depletion and convection-enhanced replenishment of the Fe(CN)_6^(3-) surfaceconcentration, that coexist between the bistability, i. e., Fe(CN)_6^(3-) reduction with and withouthydrogen evolution at lower and higher potential sides respectively, are all reflected in thecrossed cyclic voltammo-gram (CCV). It can be concluded that the voltammetry-based criterion (intime domain) is more intuitive, less time-consuming and has a wider range of applications than theimpedance-based one (in frequency domain).

Investigation of flexible electrodes modified by TiN,Pt black and IrO_x

TiN, platinum （Pt） black and iridium oxide are introduced to the stimulating sites to improve the performance of the flexible electrode. Low temperature process is used to fabricate the modifying films. TiN is coated on the gold sites by magnetron sputtering while platinum black and iridium oxide are coated by electroplating and electrodeposifion, respectively. The impedance of the electrode decreases dramatically after modification. The combined analysis of surface morphology and cyclic voltammograms （CV） in phosphate buffer saline （PBS） solution indicates that the modified electrode sites have larger electrode-electrolyte capacitance and smaller faradic resistance than unmodified sites, thus they have smaller electrochemical impedances.

Influence of Nb^(5+) Doping on Structure and Electrochemical Properties of Spinel Li_(1.02)Mn_2O_4

The Li1.02NbxMn2-xO4 （x=0, 0.005, 0.01, 0.0：2, 0.04 and 0.1） materials were prepared by solid-state reaction method in which Li2CO3, electrolytic MnO2 and Nb2O5 were used as reactants. The influences of the Nb5＋ doping on structure, morphology and electrochemical performance were systemically investigated by means of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, cyclic voltammetry （CV） and AC impedance. XRD test showed that the prepared samples had single spinel structure although there was impurity phase of LiNbO3 existing in Li1.02NbxMn2-xO4 phase after Nb5＋ doping. The doped materials with Nb5＋ had smaller lattice parameters and crystal volume compared with pristine Li1.02Mn2O4. The endurance of overcharge was largely improved. In addition, the small amount of Nb5＋ doping could increase the material conductivity.

Inhibitory effect of H_(3+x)PMo_(12-x)V_xO_(40)-Ton the self-polymerization of methyl methacrylate

In this work,a series of molybdovanadophosphoric heteropoly acid quaternary ammonium salts H_（3＋x）PMo_（12 -x）V_xO40-T were synthesized and employed as a reaction inhibitor in the selfpolymerization of methyl methacrylate（MMA）.The polymerization inhibition effect of H_（3＋x）PMoPMo_（12 -x）V_xO40-T）with different number of vanadium atoms and reaction dosages was investigated using differential scanning calorimetry（DSC）.It shows that the inhibitory effect was improved with the increasing dosages of H_（3＋x）PMoPMo_（12 -x）V_xO40-T）,and the polymerization inhibition was also affected by the number of vanadium atoms in the H_（3＋x）PMo_（12 -x）V_xO40-T .Furthermore,cyclic voltammograms（CV）was used to probe the mechanism of the inhibition reaction with H3＋xPMo12xVxO40-T.The result of CV indicates that the inhibition reaction is an oxidation–reduction reaction.H_（3＋x）PMo_（12 -x）V_xO40-T can react directly with the MMA monomer radicals,which eliminated the MMA monomers,and therefore the self-polymerization of the MMA can be effectively inhibited by H_（3＋x）PMo_（12 -x）V_xO40-T.

Highly Sensitive Functionalized Conducting Copolypyrrole Film for DNA Sensing and Protein-resistant

In order to exploit the applications ofpolypyrrole （PPy） derivatives in biosensors and bioelectronics, the different immobilization mechanisms of biomolecules onto differently functionalized conducting PPy films are investigated. Pyrrole and pyrrole derivatives with carboxyl and amino groups were copolymerized with ω-（N-pyrrolyl）-octylthiol self-assembled on Au surface by the method of the chemical polymerization to form a layer of the copolymer film, i.e., poly[pyrrole-co-（N-pyrrolyl）-caproic acid] （poly（Py-co-PyCA）） and poly[pyrrole-co-（N-pyrrolyl）-hexylamine] （poly（Py-co-PyHA））, in which the carboxyl groups in poly（Py-co-PyCA） were activated to the ester groups. Based on the structure characteristics, the immobilization/hybridization of DNA molecules on PPy, poly（Py-co-PyCA） and poly（Py-co-PyHA） were surveyed by cyclic voltammograms measurements. For differently functionalized copolymers, the immobilization mechanisms of DNA are various. Besides the electrochemical properties of the composite electrodes of PPy and its copolymers being detected before and after bovine serum albumin （BSA） adsorption, the kinetic process of protein binding was determined by surface plasmon resonance of spectroscopy. Since few BSA molecules could anchor onto the PPy and its copolymers surfaces, it suggests this kind of conducting polymers can be applied as the protein-resistant material.