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     

Exfoliated nickel hydroxide nanosheets for urea electrolysis

Two-dimensional nickel hydroxide nanosheets were synthesized by exfoliating surfactant intercalated layered nickel hydroxides and developed as electrocatalysts for urea electro-oxidation. The electro-oxidation of urea on Ni(OH)₂ nanosheet modified electrodes shows a decrease of 100 mV in overpotential and an enhancement in current density, which reaches ca.154 mA cm^{− 2} mg^{− 1}, by a factor of ca. 170 compared to bulk Ni(OH)₂ powder modified electrodes. The Ni(OH)₂ nanosheets have promising applications in urea-rich wastewater remediation, hydrogen production, electrochemical sensors, and fuel cells due to their ability to promote the urea electrolysis reaction.     

超声波处理对球形β-Ni(OH)2结构及电化学性能的影响

A method of ultrasonic treatment （UST） was first used to modify the structure and electrochemical performance of nickel hydroxide for the active material of nickel series alkaline batteries. The experimental results showed that UST was an effective method to improve the electrochemical performance of β-Ni（OH）2 such as specific discharge capacity, discharge potential, electrochemical reversibility and oxygen evolution over-potential. The results of electrochemical impedance spectroscopy, powder X-ray diffraction and particle size distribution indicated that the improvement of the performance of β-Ni（OH）2 through UST was attributed to the reduction of the charge-transfer resistance （Rt） and the diffusion impedance （Zw）, which resulted from the decrease of the crystallite and particle size and the increase of interlayer spacing. Diffusion coefficient of proton DH of ultrasonic treated β-Ni（OH）2 gained by CV tests was 1.13 × 10^-11 cm^2/s, and the average discharge specific capacity of ultrasonic treated β-Ni（OH）2 electrode was 301 mAh/g.     

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.     

Al掺杂Ni(OH)2的结构及电化学性能

用化学共沉淀法合成了A l掺杂N i(OH)2,用XRD表征了合成样品的结构特征:研究了合成样品的循环伏安性能,以及用A l掺杂N i(OH)2为正极活性物质的Zn/N i试验电池的充放电性能。研究结果表明:所合成的A l掺杂N i(OH)2为具有α-型晶体结构的材料,A l掺杂N i(OH)2具有优良的电化学可逆性、良好的充放电性能和较好的电化学循环性能;A l掺杂N i(OH)2作为正极活性物质的Zn/N i试验电池等250次充放电循环容量保持率130.1%,最高放电比容量为420.5mAh/g。     

Nanocrystalline nickel cobalt hydroxides/ultrastable Y zeolite composite for electrochemical capacitors

A novel nanocomposite of Co(OH)₂−Ni(OH)₂ and ultrastable Y molecular sieves was synthesized by an improved chemical precipitation method for electrochemical capacitors. The Co(OH)₂−Ni(OH)₂/ultrastable Y zeolite (USY) composite and its microstructure were characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Electrochemical characterization was performed by cyclic voltammetry and galvanostatic charge–discharge measurements. The results show that Co(OH)₂−Ni(OH)₂/USY microstructure applied for the electrochemical energy storage has displayed superior capacitive performance. The effect of heat treatment conditions on specific capacitance properties was also systemically explored. Upon annealing at 250 °C, the maximum specific capacitance was up to 479 F/g (or 1,710 F/g after correcting for the weight percent of Co(OH)₂−Ni(OH)₂ phase). Annealing temperatures higher than 250 °C may cause the hydroxide to form oxide phase and decrease the surface activity of the oxide, thereby leading to a decline of the specific capacitance.     

Ni(OH)2纳米管的制备、表征及电化学性能

以多孔氧化铝为模板, 在不同溶液浓度下, 用化学沉积法制备了氢氧化镍纳米管. 采用XRD, SEM, TEM和HRTEM等手段, 对产物的物相、表面形貌及微结构进行了表征. 结果表明所得产物是高纯度的氢氧化镍纳米管, 外径约为180～220 nm, 管壁厚20～30 nm. 将所制备的氢氧化镍纳米管制成电极, 其电化学性能测试表明, Ni(OH)₂纳米管的中空结构特点, 能够有效地提高镍电极的充电效率、放电比容量、高倍率及高温放电性能. 机理分析表明中空结构的Ni(OH)₂纳米管对于提高碱性二次电池的综合性能有着极为重要的意义.     

Direct Growth of Cobalt Hydroxide Rods on Nickel Foam and Its Application for Energy Storage

The present work reports synthesis of cobalt hydroxide (Co(OH)₂) rods on nickel foam and its supercapacitor application. Hierarchical Co(OH)₂ rods with length of approximately 3.5 μm and diameter of approximately 400 nm were prepared by one‐step, simple, and inexpensive chemical‐bath‐deposition method. The direct growth of Co(OH)₂ rods on the Ni foam gave three dimensional (3D) structure for easy access of electrolyte throughout material surface. Also, well‐adhered interface between Co(OH)₂ rods and Ni‐foam surface gave better conduction channels. Detailed electrochemical study was performed by using cyclic voltammetry and galvanostatic charge/discharge measurements. The results demonstrate that Co(OH)₂ rods on Ni foam are efficient electrodes for supercapacitor application.     

Oxygen electroreduction on anthraquinone-modified nickel electrodes in alkaline solution

The electrochemical reduction of oxygen has been studied on anthraquinone (AQ) modified nickel electrodes in 0.1 M KOH solution using the rotating disk electrode (RDE) technique. Modification of the Ni electrode surface with AQ by electrochemical reduction of the corresponding diazonium salt was carried out in two different media (in acetonitrile and in aqueous acidic solution). The AQ-modified Ni electrodes showed a good electrocatalytic activity for O₂ reduction. The RDE data indicate that the reduction of oxygen on Ni/AQ electrodes proceeds by a two-electron pathway in alkaline solution. The O₂ reduction results obtained for Ni/AQ electrodes are compared with those of AQ-modified glassy carbon electrodes.     

Chemical deposition and exfoliation from liquid crystal template: Nickel/nickel (II) hydroxide nanoflakes electrocatalyst for a non-enzymatic glucose oxidation reaction

This work reports the synthesis of nickel/nickel hydroxides nanoflakes (Ni/Ni(OH)₂-NFs) at room temperature via a novel chemical deposition and exfoliation from a liquid crystal template mixture. The nickel ions dissolved in the interstitial aqueous domain of the Brij®78 hexagonal liquid crystal template were deposited by a reducing agent of sodium borohydride that concurrently reduces the nickel ions and generates extreme hydrogen gas bubbles, that exfoliated the nickel/nickel hydroxide layers. The Ni/Ni(OH)₂-NFs crystal structure, morphology, and surface area characterizations revealed the formation of semi-crystalline α-Ni(OH)₂ nanoflakes with a thickness of approximately 10 nm and a specific surface area of about 135 m²/g. The electrochemical measurements of cyclic voltammetry, chronoamperometry, and impedance analysis showed that the Ni/Ni(OH)₂-NFs exhibited significant performance for the glucose non-enzymatic oxidation in an alkaline solution in comparison to the bare-nickel hydroxide (bare-Ni(OH)₂) deposited without surfactant. The Ni/Ni(OH)₂-NFs electrode showed superior glucose oxidation activity over the bare-Ni(OH)₂ catalyst with a sensitivity of 1.078 mA mM^?1 cm^?2 with a linear concentration dependency range from 0.2 to 60 mM and a detection limit of 0.2 mM (S/N = 3). The enhanced electrochemical active surface area and mesoporosity of the 2D nanoflakes make the Ni/Ni(OH)₂-NFs a promising catalyst in the application of glucose non-enzymatic sensing.     

Electrodeposition of three-dimensional Ni(OH)<Subscript>2</Subscript> nanoflakes on partially crystallized activated carbon for high-performance supercapacitors

Three-dimensional Ni(OH)₂ nanoflakes were prepared via a facile and cost-effective electrodeposition method using commercial activated carbon (AC) as substrate. Nitric acid treatment (NT) and partial crystallization (PC) by metal nickel catalysis were applied for AC. The effects of the oxygen-containing functional groups and the degree of crystallization on the electrochemical performance of the electrode were investigated. The resulting Ni(OH)₂/PC–NT–AC/nickel foam electrode exhibits distinct performance with a specific capacitance of 2971 F/g (scaled to the mass of active Ni(OH)₂) at a current density of 6 A/g. A high capacitance of 1919 F/g was still achieved even at 40 A/g, which is much higher than Ni(OH)₂/AC/nickel foam electrode and Ni(OH)₂/NT–AC/nickel foam electrode. The excellent performance of Ni(OH)₂/PC–NT–AC/nickel foam electrode can be attributed to the presence of large surface area and highly conductive PC–NT–AC network on nickel foam. This study presents an effective method to improve the dispersion and rate capability of Ni(OH)₂ nanostructure electrodes.     

Melting and thermodestruction processes in the poly(ethylene)-nanocrystalline nickel system

Composite materials (CM) based on poly(ethylene) (PE) and nanocrystalline nickel (Ni) have been produced. The effect of the content of nanocrystalline Ni and processes of structure formation of its particles on a melting temperature (T _m), interval of melting, true melting heat (ΔH _m), degree of crystallinity (χ) as well as characteristics of CM thermodestruction have been determined by DTA and thermogravimetry techniques. It was found that these characteristics are changed non-linearly when the content of nanocrystalline Ni increases. The most efficient influence of Ni on the above mentioned characteristics was observed for its low content (0.01 volume part of Ni). It was shown that a formation of a branched multifractal cluster of nickel above a percolation threshold favored a decrease in T _m, ΔH _m, χ of filled PE and a majority of thermal characteristics of CM thermodestruction as well. This revised version was published online in August 2006 with corrections to the Cover Date.     

The Inherent Electrochemistry of Nickel/Nickel‐Oxide Nanoparticles

The direct detection of nanoparticles is at the forefront of research owing to their environmental and toxicological applications. Herein, we studied the inherent electrochemistry of Ni and NiO nanoparticles and proposed a simple and direct electrochemical method for the determination of the concentrations of both nickel (Ni) and nickel oxide (NiO) nanoparticles in alkaline solution. A highly sensitive voltammetry technique was used to measure the oxidative signal of Ni(OH)₂ that formed spontaneously on the surface of Ni and NiO nanoparticles in alkaline media. Detection limits of 220 μg mL^?1 for Ni and 13 μg mL^?1 for NiO nanoparticles were obtained. Ni and NiO nanoparticles are used as electrode modifiers or as electrochemical signal labels in various biosensing applications. Therefore, methods to rapidly quantify the amount of Ni and NiO nanoparticles are of widespread potential use.     

Fabrication of a Hierarchical Ni(OH)2@Ni3S2/Ni Foam Electrode from a Prussian Blue Analogue-Based Composite with Enhanced Electrochemical Capacitive and Electrocatalytic Properties

Developing high-efficiency, cost-effective, and durable electrodes is significant for electrochemical capacitors and electrocatalysis. Herein, a 3D bifunctional electrode consisting of nickel hydroxide nanosheets@nickel sulfide nanocubes arrays on Ni foam (Ni(OH)₂@Ni₃S₂/NF) obtained from a Prussian blue analogue-based precursor is reported. The 3D higher-order porous structure and synergistic effect of different compositions endow the electrode with large specific surface area, facile ion/electron transport path, and improved conductivity. As a result, the Ni(OH)₂@Ni₃S₂/NF electrode exhibits a high specific capacity of 211 mA h g⁻¹ at a current density of 1 A g⁻¹ and 73 % capacity retention after 5000 cycles at 5 A g⁻¹. Moreover, the Ni(OH)₂@Ni₃S₂/NF electrode has superior electrocatalytic activity for the hydrogen evolution reaction with low overpotentials of 140 and 210 mV at current densities of 10 and 100 mA cm⁻², respectively. The synthetic strategy for the unique higher-order porous structure can be extended to fabricate other composite materials for energy storage and conversion.     

Facile In Situ Synthesis of Hierarchical Porous Ni/Ni(OH)2 Hybrid Sponges with Excellent Electrochemical Energy‐Storage Performances for Supercapacitors

Herein, we report the in situ growth of single‐crystalline Ni(OH)₂ nanoflakes on a Ni support by using facile hydrothermal processes. The as‐prepared Ni/Ni(OH)₂ sponges were well‐characterized by using X‐ray diffraction (XRD), SEM, TEM, and X‐ray photoelectron spectroscopy (XPS) techniques. The results revealed that the nickel‐skeleton‐supported Ni(OH)₂ rope‐like aggregates were composed of numerous intercrossed single‐crystal Ni(OH)₂ flake‐like units. The Ni/Ni(OH)₂ hybrid sponges served as electrodes and displayed ultrahigh specific capacitance (SC=3247 F g^?1) and excellent rate‐capability performance, likely owing to fast electron and ion transport, sufficient Faradic redox reaction, and robust structural integrity of the Ni/Ni(OH)₂ hybrid electrode. These results support the promising application of Ni(OH)₂ nanoflakes as advanced pseudocapacitor materials.     

Enhanced electrochemical performance of nano-MnO2 modified by Ni(OH)2 as electrode material for supercapacitor

Ni(OH)₂ was compounded to MnO₂ in an easy liquid phase process to improve the diffusion process of the electrode. The as-prepared materials were a mixture of amorphous and nanocrystalline with aggregated nanoparticles forming slit-shaped pore structures. The composite has higher specific surface area and smaller pore volume compared with pristine MnO₂. Electrochemical properties of the electrodes were carried out with cyclic voltammetry (CV), galvanostatic charge–discharge tests, and electrochemical impedance spectroscopy (EIS). The MnO₂/Ni(OH)₂ composites exhibited enhanced electrochemical properties than that of pristine MnO₂. Remarkably, the composite which contains 3 % Ni(OH)₂ exerted the best discharged specific of 408 F g^?1 under 0.2 A g^?1, much higher than 247 F g^?1 of pristine MnO₂ at the same current density. Better rate capability and cycling stability were also realized by the same composite in comparison.     

Selective oxidation of ethylbenzene by dioxygen. The effect of chelate center on catalysis by bicyclic nickel complexes

The effect of the nature of the chelate center in Ni^II complexes on their catalytic activity in the selective oxidation of ethylbenzene by dioxygen to α-phenylethyl hydroperoxide in the presence of nickel bis(acetylacetonate) (chelate center Ni(O,O)₂) and nickel bis(enaminoacetonate) (chelate center Ni(O,NH)₂) was studied. The efficiency of selective oxidation of ethylbenzene increases substantially in the presence of the chelate with the Ni(O,NH)₂ active center as a catalyst, which is mainly due to the transformation of the catalyst into more active species during the oxidation process. The mechanism of transformation of nickel bis(enaminoacetonate) under the action of dioxygen was suggested. The sequence of formation of the reaction products at different stages of the catalytic process was determined. The activity of the nickel complex with the Ni(O,NH)₂ chelate center and the products of its transformation in the elementary stages of chain oxidation of ethylbenzene is discussed. Translated fromIzvestiya Akedemii Nauk. Seriya Khimicheskaya, No. 1, pp. 55–60, January, 1999.     

Complex study of nickel skeleton catalysts: V. Study of novel non-pyrophoric nickel skeleton catalysts by derivatograph

The structure and properties of non-pyrophoric skeleton catalysts prepared from NiSi, NiAlSi, NiMg and NiZn alloys have been studied—apart from other thermal methods—by means of the derivatograph.Our experimental results have contributed to the explanation of the non-pyrophoric behaviour of these catalysts. We demonstrated that the desorption of the hydrogen content in our catalysts is not accompanied by the oxidation of active nickel. This oxidation takes place only at higher temperatures, above 200°C, at a rate proportional to the amount of active nickel.Other constituents of the catalysts (adsorbed water, hydroxide content) were also determined from the experimental data. The outstandingly high Mg(OH)₂ content of the NiMg catalyst indicates that its structure is dissimilar: Mg(OH)₂ also acts as support for the catalyst.     

Synthesis of nickel sulfide and nickel–iron sulfide nanoparticles from nickel dithiocarbamate complexes and their photocatalytic activities

[ Ni(dtc)₂] (dtc = N-(pyrrole-2-ylmethyl)-N-thiophenemethyldithiocarbamate ( 1 ), N-methylferrocenyl-N-(2-phenylethyl)dithiocarbamate ( 2 ), N-furfuryl-N-methylferrocenyldithiocarbamate ( 3 ), and (N-[pyrrole-2-ylmethyl]-N-thiophenemethyldithiocarbamato-S,S′)(thiocyanato-N)(triphenylphosphine)nickel(II) ( 4 ) complexes were prepared and characterized by elemental analysis, infrared, ultraviolet–visible, and nuclear magnetic resonance (¹H and ¹³C) spectroscopies. The data were consistent with the formation of square planar nickel(II) complexes, which was confirmed by single-crystal X-ray diffraction studies on 2 and 4 . Fe···Fe interactions exhibited by complex 2 led to supramolecular aggregation. The structure of 4 reveals intermolecular and intramolecular C-H···Ni anagostic interactions. The anion-sensing properties of 2 were studied with halide ions by cyclic voltammetry. It was observed that 2 acts as sensor for bromide. Complexes 1 , 2 , and 3 , were utilized to prepare nickel sulfide, nickel–iron sulfide-1, and nickel–iron sulfide-2, respectively. The composition, structure, morphology, and optical properties of nickel sulfide and nickel–iron sulfides were examined using powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, ultraviolet–visible, fluorescence, and infrared spectroscopy. Powder X-ray diffraction patterns of nickel sulfide, nickel–iron sulfide-1, and nickel–iron sulfide-2 indicate the formation of orthorhombic Ni₉S₈, cubic NiFeS₂, and cubic Ni₂FeS₄, respectively. The photocatalytic activities of as-prepared nickel sulfide and nickel–iron sulfide-1 nanoparticles were investigated for photodegradation of methylene blue and rhodamine-B under ultraviolet irradiation. Nickel–iron sulfide-1 nanoparticles show slightly higher photodegradation efficiency compared with the nickel sulfide nanoparticles.     

Hybrid porous Ni(OH)2-MnO2 nanosheets/plasma-grafted MWCNTs for boosted supercapacitor performance

The utilization of nickel hydroxide and manganese dioxide solely as high-performance supercapacitive materials is hindered by their low capacitance retention and electrical conductivity. As Ni(OH)₂ and MnO₂ give a synergistic effect, porous Ni(OH)₂-MnO₂ nanosheets with a thickness of 9 nm are successfully grown on carbon fiber (CF) via a single-step hydrothermal co-deposition method. Multi-walled carbon nanotubes (CNT) are grafted with maleic anhydride (MA) through plasma-grafted process, followed by thiol-ene reaction to synthesize CNT-MA−S (CMS) to increase their aqueous dispersion behavior. The electrochemical properties of Ni(OH)₂-MnO₂ are further enhanced by dip-coating CMS on nanosheets. The composition and morphology of CMS and Ni(OH)₂-MnO₂ nanosheets are characterized using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), electron spectroscopy for chemical analysis (ESCA), transmission electron microscopy (TEM), thermogravimetric analyses (TGA), nuclear magnetic resonance (NMR), and Raman spectroscopy. The electrochemical characteristics of fabricated electrodes are analyzed using cyclic voltammetry and chronopotentiometry methods. CF−Ni(OH)₂-MnO₂/CMS electrode is successfully synthesized without using any binder, exhibited ultrahigh specific capacitance (2049 F g⁻¹ at a current density of 1 A g⁻¹), and excellent capacitance retention (>80 %) at 2 A g⁻¹ charge/discharge rate after 5000 cycles.