Ellipsometry of nickel hydroxide electrodes formed by ex situ chemical precipitation. Potential routine and time effects

Ellipsometric and reflectivity data combined with voltammetric data have been obtained at 546.1 nm for different nickel hydroxide electrodes in 0.01 M NaOH at 25°C. The electrodes were prepared by ex situ chemical precipitation on a polished platinum substrate. The influence of the potential routine applied to the nickel hydroxide electrode on the corresponding optical parameters and time effects for both the oxidized and reduced forms of the active material kept at constant potential have been investigated. The nickel hydroxide layer is described as a mixture of nickel(II) hydroxide, nickel(III) hydroxide and electrolyte—water domains. The kinetic effects are discussed through a complex reaction pathway involving different nickel(II) and nickel(III) hydroxide species, the processes starting preferentially at the borders of the different domains.     

Synthesis of Metallofullerenes by Electric-Arc Method with a Surface-Modified Electrode

A method for synthesis of metallofullerenes by electric-arc sputtering of graphite, in which lanthanum compounds are deposited on the surface of a graphite electrode, was suggested. The influence exerted by the amount of deposited lanthanum on the yield of lanthanum was studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 4, 2005, pp. 566–571.Original Russian Text Copyright © 2005 by Kuz’min, Borovkov, Kolker, Brazhyunas.     

Kinetics and Mechanism of Reactions Occurring in Electrodeposition of Silver from Thiosulfate Solutions

The kinetics and mechanism of processes occurring in reduction of silver thiosulfate complexes on stationary and rotating disc electrodes and on fluidized glass-bead electrode were studied voltammetrically.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 1, 2005, pp. 86–89.Original Russian Text Copyright © 2005 by Shvab, Gur’yanova, Omel’chuk.     

Obtaining Nickel Hydroxide from Half-Products of Hydrometallurgical Processing of Nickel-Iron Batteries

The possibility of obtaining nickel hydroxide from solutions produced in ammonia leaching of the active paste of positive electrodes of a nickel-iron battery was studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3, 2005, pp. 362–366.Original Russian Text Copyright © 2005 by Demidov, Krasovitskaya, Andreeva, Tolypin.     

Alkaline Decomposition of Cyclic Nitramines

Treatment of 1,3,5-trinitro-1,3,5-triazacyclohexane and 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclo-octane with potassium hydroxide gives dipotassium salt of methylenedinitramine.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 130–132.Original Russian Text Copyright © 2005 by Il’yasov, Lobanova.     

Electrocatalytic Hydrogenation of Nicotine

Electrocatalytic reduction of the nicotine alkaloid in the presence of skeletal nickel catalysts was studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 4, 2005, pp. 591–594.Original Russian Text Copyright © 2005 by Astaf’eva, Sidoikin, Krichevskii, Kagarlitskii.     

Specific Features of the Initial Stages of Oxidation of a Silver Electrode in Weakly Acidified Solutions of Sodium Fluoride

The behavior of a silver electrode, which is renewed in situ by mechanical cutting, in weakly acidified sodium fluoride solutions is studied with the aid of an impedance method and a method of cyclic voltammetry. The application of said procedures makes it possible to record time effects, which reflect the processes of electrochemical adsorption of oxygen at the interface between the silver electrode and the solution, in the potential region extending from −0.7 to 0.2 V (SCE). Approximate calculations of the effect of potential and the time of the electrode’s exposure (after its renewal) in contact with the electrolyte at given values of potential on the amount of adsorbed oxygen are performed on the basis of an analysis of the obtained experimental data. A comparison of the obtained results with the literature data makes it possible to put forth a substantiated opinion as to the reasons for the substantial difference in the intervals of potentials of ideal polarizability of the silver electrode/solution of a surface-inactive electrolyte system, which are presented in works of various authors.__________Translated from Elektrokhimiya, Vol. 41, No. 7, 2005, pp. 857–865.Original Russian Text Copyright © 2005 by Safonov, Choba, Oshkin.     

Surface modification of spherical nickel hydroxide for nickel electrodes

Electroless cobalt plating on spherical nickel hydroxide is tested in order to improve the conductivity of Ni(OH)₂ and the capacity of the electrode. The factors affecting the process of electroless cobalt plating are cobalt solution, temperature and pH, etc. The effects have been examined and the optimum process parameters have been obtained. The nickel hydroxide electrode which is made by nickel hydroxide deposited cobalt has excellent performance, the results showing that electroless cobalt plating on the surface of spherical nickel hydroxide particles is an effective method for modifying electrodes.     

Influence of Cobalt Intercalation on Processes in a Nickel-Zinc Battery with Nickel Oxide Electrode Fabricated from Spherical Nickel Hydroxide

The influence of cobalt on processes that occur in a nickel oxide electrode of a nickel-zinc battery, fabricated from spherical nickel hydroxide on foamed nickel support, was studied.     

氢氧化镍薄膜修饰玻碳电极的制备及其对L-赖氨酸氧化的电催化活性

采用恒电位沉积方法将氢氧化镍沉积到玻碳电极表面,得到稳定性高、催化活性好的氢氧化镍薄膜修饰玻碳电极;分析了影响薄膜形成过程的关键因素,确定了最佳薄膜制备方案;与此同时,将薄膜修饰玻碳电极用于生物样品L-赖氨酸的氧化测定,并探讨了其催化作用机理.结果表明,所制备的氢氧化镍薄膜修饰玻碳电极表面发生电化学反应[Ni(OH)2→NiOOH],从而促进电极表面的电子转移,实现对L-赖氨酸的电催化作用.当L-赖氨酸的浓度在1.0×10-4～4.0×10-7 mol/L范围内时,相应氧化峰电流与浓度呈线性关系,检出限达4.0×10-7 mol/L;据此可方便地制备稳定性好且灵敏度高的电流型传感器.     

Processes in a Nickel-Zinc Battery with Nickel Oxide Electrode Fabricated from Spherical Nickel Hydroxide

Processes occurring in a cycled nickel-zinc battery with positive nickel oxide electrode fabricated from spherical nickel hydroxide on foamed-nickel support and the influence exerted by its physicochemical parameters on changes in the electrolyte composition and on inter- and intraelectrode mass transfer of zinc was studied.     

Nickel oxide coated on ultrasonically pretreated carbon nanotubes for supercapacitor

Nickel oxide/carbon nanotubes (NiO/CNTs) composite materials for supercapacitor are prepared by chemically depositing nickel hydroxide onto carbon nanotubes pretreated by ultrasonication and followed by thermal annealing at 300 °C. A series of NiO/CNTs composites with different weight ratios of nickel oxide versus carbon nanotubes are synthesized via the same route. The high-resolution TEM and SEM results show that a lot of nicks, which favored the nucleation of the nickel hydroxide formed on the outer walls of carbon nanotubes due to ultrasonic cavitations, and then nickel oxide coated uniformly on the outer surface of the individual carbon nanotubes. The NiO/CNTs electrode presents a maximum specific capacitance of 523 F/g as well as a good cycle life during 1,000 cycles in 6 M KOH electrolyte. The good electrochemical characteristics of NiO/CNTs composite can be attributed to the three-dimensionally interconnected nanotubular structure with a thin film of electroactive materials.     

Voltamperometry of Aromatic Nitro Compounds Using a Multisensor System of Electrodes Modified with Poly(Arylene Phthalide Ketones)

Electrodes modified with poly(arylene phthalide ketones) were developed for the voltammetric determination of isomers of aromatic nitro compounds. A polynomial algorithm for processing analytical signals from a sensor array was tested in the analysis of ternary mixtures. It is shown that the sensor array offers promise for analyzing multicomponent mixtures in the case when analytical signals overlap.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 6, 2005, pp. 576–581.Original Russian Text Copyright © 2005 by Sidel’nikov, Maistrenko, Kudasheva, Kuz’mina, Sapel’nikova, Gileva.Presented at the VI All-Russia Conference (with international participation) on Electrochemical Methods of Analysis (EMA-2004, Ufa, May 23–27, 2004).     

Effect of the Electrolyte Concentration on the Reversibility of a Nickel Oxide Electrode in a Nickel-Zinc Battery

The degree of charging of a nickel oxide electrode composed of spherical nickel hydroxide in a nickel-zinc battery was studied in anodic oxidation of the electrode in KOH solutions of different concentrations, containing hydroxozincate ions.     

4-Functionally-substituted 3-Heterylpyrazoles: XV. 3-Aryl(heteryl)-1-phenyl-4-pyrazolylmethylamines and Heterocumulenes Obtained Therefrom

By reduction of 3-aryl(heteryl)-1-phenyl-4-azidomethyl-pyrazoles in the presence of Raney nickel or by hydrazinolysis of N-[3-aryl(heteryl)-1-phenyl-4-pyrazolylmethyl]phthalimides 4-pyrazolylmethylamines were obtained that in reaction with bis(trichloromethyl) carbonate afforded 3-aryl-(heteryl)-1-phenyl-4-pyrazolylmethyl isocyanates, and with carbon disulfide furnished 3-aryl-(heteryl)-1-phenyl-4-pyrazolylmethyl isothiocyanates.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 2, 2005, pp. 247–251.Original Russian Text Copyright © 2005 by Bratenko, Panimarchuk, Mel’nichenko, Vovk.     

沉积钴镀层的粘接式氢氧化镍电极电化学性能研究

研究了在碱性可充电电池正极活性物质－球型氢氧化镍粒子表面化学镀钴后氢氧化镍电极的性能。通过比较充放电曲线和循环伏安试验结果,讨论了电极的放电容量、活性物质利用率和Ｎｉ（ＯＨ）２／ＭｉＯＯＨ氧化还原可逆性。实验还发现镀钴后的氢氧化镍电极有更好的充放电性能和优良的电极特性。测定了化学镀钴前后氢氧化镍电极的交流阻抗,表明镀钴后氢氧化镍的基体之间的有较低接触电阻。此外,本文还对钴镀层改进氢氧化镍性能的机理     

Voltammetric Study and Detection of Methane on Nickel Hydroxide–Modified Nickel Electrode

Abstract

The nickel hydroxide–modified nickel (NMN) electrode was prepared by cyclic voltammetry. The modified electrode exhibited better catalytic effect toward electrochemical oxidation of methane in 1.0 mol · L^?1 NaOH solution. The catalytic activation of nickel hydroxide on the nickel electrode surface was investigated in different supporting electrolyte solutions by the cyclic voltammetry method in detail, and the related electrochemical oxidation of methane at the NMN electrode was first proposed by amperometric i‐t curve method under the experiment conditions. The results indicated that in the 1.0 mol · L^?1 NaOH solution, the anodic peak current increased with the increased concentration of methane.     

Electrocatalytic oxidation of thiosulfate on a modified nickel hexacyanoferrate film electrode

Summary A modified nickel hexacyanoferrate film glassy carbon electrode is prepared by the electrochemical deposition technique. The film is very stable upon voltammetric scanning in the potential range of 1.0 to –0.5 V (vs. SCE) and an oxidation peak occurs at 0.35 V (vs. SCE) (1 mol/l NaNO₃). The effects of electrolyte, solvent, coexisting ions and other variables on the voltammetric behaviour of the modified film have been studied. The thickness of the resulting film can be controlled by changing the number of voltammetric cycles and the concentrations of nickel(II) and hexacyanoferrate(III) ions. The film shows catalytic activity towards electrooxidation of thiosulfate with a peak potential +0.5 V (K^–-containing media). This oxidation potential of thiosulfate on the modified electrode is shifted negatively by about 550 mV as compared to the naked glassy carbon electrode. For practical application, the modified electrode can be used for the determination of thiosulfate in concentrations from 5.0×10^–5 to 1.0×10^–1 mol/l. This method has been successfully applied to the determination of thiosulfate in photographic waste effluents.     

Synthesis of Ozone in a Surface Barrier Discharge with a Plasma Electrode

The synthesis of ozone from oxygen in a cylindrical ozonizer operating under surface discharge conditions with a plasma electrode was studied. The conditions of ozone synthesis were optimized. The dependence of ozone concentration and specific energy consumption on gas pressure in the plasma electrode and on distance between the coils of a corona electrode was determined. The results were compared with data obtained with the use of classical surface barrier discharge.__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 4, 2005, pp. 307–311.Original Russian Text Copyright © 2005 by Alemskaya, Lelevkin, Tokarev, Yudanov.     

Ion and solvent transfer discrimination at a nickel hydroxide film exposed to LiOH by combined electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD) techniques

A combined electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD) instrument was used to monitor the mobile species transfers associated with the redox processes of thin (Γ100–150 nmol cm⁻²) α- and β-nickel hydroxide films exposed to aqueous LiOH solution. A comparison of the measured PBD signal with the predicted PBD profiles, calculated by temporal convolution analysis of the current and mass responses, enabled the contributions to redox switching of anion (OH⁻) and solvent (H₂O) transfers to be discriminated quantitatively. The responses from the combined instrument are reconciled in terms of H⁺ deintercalation/intercalation within the nickel hydroxide structure as OH⁻ ions enter/exit the film. Hydroxide ion movement is associated with a counterflux of water. Thin nickel hydroxide films show a gradual α→β phase transformation with continuous voltammetric cycling, especially when the films are exposed to high concentrations of electrolyte. α-Films are characterised by OH⁻ transfers that dominate the H⁺ and H₂O movements; β-films are characterised by an increased participation of water and protons to the exchange dynamics.