Nickel Source Research Articles

Facile synthesis of ultrathin nickel hydroxides nanoflakes on nickel foam for high-performance supercapacitors

Ultrathin Ni(OH)2 nanoflakes grown on nickel foam have been prepared via a facile hydrothermal route without adding any additional nickel sources and further investigated as a binder-free electrode for high-performance supercapacitors. Benefiting from high conductivity and enough spaces between the nanoflakes in combination with high surface area, the Ni(OH)2 nanoflakes show high-capacitance performance with a specific capacitance of 2342Fg−1 at a charge and discharge current density of 2mAcm−2 and 1100Fg−1 at 8mAcm−2 with a good cycling ability (80.4% of the initial specific capacitance remains after 2000 cycles). These results show that Ni(OH)2 nanoflakes with this cost-effective synthesis route and distinguished electrochemical performance combined with the flexible nickel foam substrate are very promising for the next generation of high-performance supercapacitors.

Composto orgânico com altos teores de níquel e sua biodisponibilidade no sistema solo planta

A utilização de biossólidos industriais na agricultura pode proporcionar aumento de níquel no solo, porém sua biodisponibilidade é influenciada por diversos fatores e, muitas vezes, resíduos com elevados teores de níquel não estão associados à sua alta absorção pela planta. O objetivo foi avaliar a solubilidade do níquel no solo, sua biodisponibilidade e acumulação em plantas. O experimento foi conduzido em vasos em delineamento inteiramente casualizado com seis doses de níquel: 0, 9, 18, 36, 72 e 144 mg de níquel kg-1 de solo, via fonte orgânica (biossólido compostado) e mineral (cloreto de níquel) com 4 repetições. Utilizou-se um Cambissolo Háplico como substrato e o morangueiro como planta indicadora. Avaliaram-se os teores no solo pelos extratores: ácido nítrico + clorídrico concentrado (3:1), nitrato de cálcio a 0,5 mol L-1, ácido nítrico a 1,0 mol L-1 e o pirofosfato de sódio a 0,1 mol L-1 além, ainda, dos teores de níquel na raiz, coroa, parte aérea e fruto. As maiores e menores extrações de níquel no solo foram observadas pela aplicação da fonte orgânica e extração com o ácido nítrico e clorídrico concentrado e pelo nitrato de cálcio, respectivamente. Ambas as fontes aumentaram os teores de níquel nos tecidos avaliados, com menores aumentos para fonte orgânica. Os maiores teores foram observados em raiz e os menores em coroa.

Effect of Process Parameters on Tribological Properties of Ni‒P‒Al<sub>2</sub>O<sub>3</sub> Composite Coatings

The present study investigates the effect of different coating parameters along with heat treatment on the tribological properties of Ni–P–Al2O3 composite coating, deposited on mild steel substrate. The coefficient of friction and wear depth (μm) are optimized for increasing performance of the composite coating using Grey Taguchi analysis by considering three parameters, namely, concentration of nickel source, concentration of reducing agent, and concentration of alumina particles. Tribological properties of the composite coating after heat treatment at 400°C are evaluated by using plate-on-roller type of tribotester. It is observed that concentration of reducing agent and alumina particles have the significant influence on corrosion resistance at 400°C. Effects of operating parameters on microstructure, and crystallization are investigated using SEM and EDX techniques.

Taguchi -Grey Based Optimization of Friction and Wear of Electroless Ni-P Coatings in Acidic Environment

The present study describes the synthesis of electroless Ni-P (nickel-phosphorous) coatings on mild steel substrate and optimization of the coating process parameters for minimum friction and wear in acidic (1M H2SO4) solution using Taguchi based grey relation analysis. The study is carried out using different combinations of four coating process parameters, namely, concentration of nickel source, concentration of reducing agent, deposition temperature and annealing temperature with three levels each. The tribological tests are conducted with a pin-on-disk tribometer. Analysis of variance reveals that annealing temperature has the maximum contribution in controlling the friction and wear characteristics of Ni-P coating. The coating is characterized using scanning electron microscopy, energy dispersive X-ray and XRD analysis, respectively. It is found that Ni-P coating is amorphous in as-deposited condition but gradually turns crystalline with heat treatment. Moreover the wear mechanism is found to be abrasive in nature.

Influence of Na2CO3 on structure and electrochemical properties of nanometre Co substituted nickel hydroxide

Co substituted nanonickel hydroxide, which used NiCl2 and Na2CO3 as nickel source and buffer respectively, was synthesised by ultrasonic method. XRD, TEM, PSD and EDS were used to characterise the physical and electrochemical performance of the prepared samples respectively. The electrochemical performance affected by Co substituted ratio and buffer content were determined by cyclic voltammogram and discharge–charge test. The results demonstrated that the Co substituted nanonickel hydroxide was the mixed phase of α- and β-Ni(OH)2 and the increasing Co content led to the larger proportion of α-nickel hydroxide. An increase in Na2CO3 content was beneficial to form α-nickel hydroxide. The morphology of all samples was the needle-like and the length/diameter ratio decreased with increasing Na2CO3 content. Composite electrodes were made by mixing 8 wt-% nickel hydroxide with commercial β-nickel hydroxide. The discharge capacities of electrodes first increased and then decreased with the change of Na2CO3 content. When Ni2+ was 0·4 mol L−1 and Na2CO3 was 0·5 g, the electrode had the maximum discharge capacity, which reached 306·9 mAh g−1 at 0·5 C discharge/charge rate.

Metal Organic Chemical Vapor Deposition of nickel oxide thin films for wide band gap device technology

Epitaxial nickel oxide (NiO) thin films have been grown by Metal Organic Chemical Vapor Deposition on AlGaN/GaN heterostructures. Critical growth parameters have been studied in order to optimize the deposition process of NiO films suitable for applications in GaN-based devices. In particular, a second generation precursor has been used as nickel source, namely the N,N,N′,N′-tetramethylethylenediamine adduct of nickel bis 2-thenoyl-trifluoroacetonate, using different deposition temperatures and oxygen flow values. Optimized operative conditions allowed the growth of epitaxial thin films which exhibited a permittivity of 11.7, close to the bulk value. The electrical characterization of the obtained epitaxial films pointed out to promising dielectric properties for AlGaN/GaN transistor technology.

Phase and particle of Y-doped Ni(OH)2 prepared from different nickel sources and Na2CO3 amount

Multiple nano-sized α-Ni(OH)2 was synthesized by ultrasonic-assisted precipitation under different conditions. The crystal structure and particle size distribution of the sample were characterized with X-ray diffraction (XRD), infrared spectroscopy, and laser particle size analyzer (PSA). The results show that the samples are anisotropic polycrystalline of α and β Ni(OH)2, and the ratio of α and β changes with the difference of nickel source, resulting in the largest ratio of α-Ni(OH)2 using nickel nitrate as reactant. Larger amount of Na2CO3 is conducive to the formation of α-Ni(OH)2; while the resultant phases are all β with the same conditions but no doping. The results of PSD indicate that the samples are about 100–120 nm in size, and the sample with nickel sulfate as nickel source has the minimum particle size. The three ions of nickel source appear in the absorption peaks in the Fourier transform infrared spectrum showing that the ions change the crystal structure of Ni(OH)2. EDS testing shows that Y and anion distribute in the lattice of α-Ni(OH)2 uniformly.

Hexamethylenetetramine-induced synthesis of hierarchical NiO nanostructures on nickel foam and their electrochemical properties

Uniform NiO hierarchical nanostructures assembled by NiO nanosheets have grown directly on nickel foam substrate via a mild hydrothermal reaction between nickel salts and hexamethylenetetramine (HMT), followed by a subsequent calcinations process. HMT was employed as both alkaline source and complex agent. Several kinds of nickel salts (NiSO4, Ni(NO3)2, NiCl2 or Ni(CH3COO)2) were introduced as nickel source to investigate their effect on the morphology and electrochemical performances of NiO nanostructure. Cyclic voltammetry and constant current charge–discharge measurement illustrated these NiO electrodes presented good electrochemical performance. Especially the electrode with NiSO4 as nickel source gave a maximum specific capacitance of 349Fg−1 at a current density of 0.25Ag−1, which was superior to others owing to the smaller particle size that provided more active sites to ensure sufficient Faradaic reaction.

Effect of Ni Coated SiC on Mechanical Properties of SiC/Fe Composites

A facile onestep in situ chemical deposition method was introduced to synthesize Ni coated SiC composite powders, which used NiCl2·6H2O as nickel source and N2H4·H2O as reductant, respectively. SiC(Ni)/Fe composites were prepared by current-vacuum hot-pressed sintering at 850°C, 40MPa for 30min. Scanning electronic microscope (SEM) and X-ray diffraction (XRD) were used to characterize the structure, morphology and composition of the prepared Ni/SiC core/shell composite powders. It is found that the Ni coated SiC is favorable to improve the dispersion and compatibility of SiC(Ni)/ Fe composites. By a series of contrast experiments, it is shown that the sintering sample with 5wt% of SiC(Ni) has the best mechanical properties. The relative density, Vickers hardness and bending strength is 91.67%, 4.72GPa and 508MPa, respectively.

Effect of Nickel Sulphate to Hypophosphite Ratio on the Electroless Deposition of Ni-P Coatings on Aluminium

Electroless Ni-P alloy was deposited on commercial pure aluminium with different nickel source–reducing species ratios. Deposition time was fixed as two hours. The deposits were characterised for changes in morphology and crystallinity. It was observed that increase in nickel source to reducing species ratio produced a deposit with reduced mean nodule size. Also, nodule size distribution was narrow. Deposits with increased ratio showed higher levels of crystallinity

The impact of nickel source/doping elements/buffer on the structure of Ni(OH)2

The nano-nickel hydroxide samples were prepared by means of ultrasonic-assisted precipitation and the impact of source/doping element/buffer on the structure of Ni(OH)2 was studied. The results of XRD, IR and TEM testing clearly revealed that larger anionic radius of the nickel sources or the buffer solution was conducive to the formation of α-Ni(OH)2. The proportion of α-Ni(OH)2 samples doped with two elements was larger than that doped with single element. Additionally, speciation, valence as well as the radius of doping ions can directly affect the phase of Ni(OH)2.

Optimization of Electroless Ni–P–Al2O3 Composite Coatings based on Multiple Surface Roughness Characteristics

Electroless Ni–P–Al2O3 composite coatings are popular due to their excellent hardness, friction and wear resistance. The present study tries to investigate the influence of coating process parameters on the surface roughness of electroless Ni–P–Al2O3 composite coating with the help of Taguchi analysis. The different surface roughness parameters considered are, center line average roughness (Ra), root mean square roughness (Rq), skewness (Rsk), kurtosis (Rku), and mean line peak spacing (Rsm). Three parameters, namely, concentration of nickel sulphate as a nickel source, concentration of sodium hypophosphite as reducing agent, and concentration of Al2O3 particles as concentration of second phase particles are considered and fitted into an L27 orthogonal array to find out the optimized condition to minimize the surface roughness of the coating. It is observed that concentration of Al2O3 particles have the most significant influence on Ni–P–Al2O3 composite coating and concentration of reducing agent has moderate influence. The compositional, micro-structural, and phase structure analyses are conducted with the help of energy-dispersive X-ray analysis, scanning electron microscope, and X-ray diffraction analyzer, respectively.

Three-dimensional NiAl-mixed metal oxide film: preparation and capacitive deionization performances

A NiAl layered double hydroxide (NiAl-LDH) film was grown on the surface of a three-dimensional (3D) nickel foam by an in situ hydrothermal method using a nickel foam substrate as a nickel source, and boehmite (AlOOH) sol as an aluminium source.

Influence of Process Parameters on Multiple Roughness Characteristics of Ni–P–TiO2 Composite Coatings

The electroless nickel-phosphorus based composite coatings are popular because of their outstanding hardness, yield strength, better resistance to wear, frictional resistance, corrosion resistance, and good lubricity. In the present study attempts is made to investigate the influence of process parameters on the surface roughness of Ni–P–TiO2 composite coatings with the help of Grey analysis and the Taguchi method. Different surface roughness parameters considered in the analysis are Ra, Rq, Rsk, Rku and Rsm. The coating parameters considered nickel sulpahte as nickel source, sodium hypophosphite as a reducing agent and concentration of TiO2 particles as second phase particles are fitted into L27 orthogonal array to find out the optimum level of process parameters to minimize the surface roughness of the composite coatings. It is observed from the experimental result that the concentration of the second phase particles, i.e. titanium particles has significant influence and amount of reducing agent has moderate influence in controlling roughness parameters of composite coatings. The surface structure and compositional analysis with the phase structure of the composite coatings are analyzed by using SEM, EDAX and XRD analysis respectively. The experimental result confirmed that weight percentage of TiO2 particles increase with increase in TiO2 content in electrolysis bath. Similarly from SEM images it is confirmed that the composite particles are uniformly distributed over the coated surface. From the XRD analysis, it is observed that composite coating without heat treatment has single broad peak it means that the coating is amorphous in nature.

Wear Behavior of Electroless Ni-P Coatings in Brine Solution and Optimization of Coating Parameters

Abstract The present paper studies the wear behavior of electroless Ni-P coating in brine medium and optimization of the coating process parameters for minimum wear using Taguchi method based on L27 orthogonal array. The study is carried out using different combinations of four coating process parameters, namely, concentration of nickel source (A), concentration reducing agent (B), bath temperature (C) and annealing temperature (D). The wear tests are conducted with a pin-on-disk Wear & Friction Monitor. The optimum combination of process parameters for minimum depth of wear is obtained. ANOVA is performed to find out the significance of the coating parameters and their interactions. The surface morphology and composition of coatings are studied with the help of scanning electron microscopy (SEM), energy dispersed X-ray (EDX) analysis and X-ray diffraction (XRD) analysis. It is found that Ni-P coating is amorphous in as-deposited condition but gradually turns crystalline with heat treatment. The worn surface morphology reveals abrasive as well as corrosive wear mechanism.

Friction performance of electroless Ni-P coatings in alkaline medium and optimization of coating parameters

The present paper studies the friction performance of electroless Ni-P coating in alkaline medium (10% NaOH solution) and optimization of the coating process parameters is performed for minimum friction using Taguchi method based on L27 orthogonal array. The study is carried out using different combinations of four coating process parameters, namely, concentration of nickel source (A), concentration reducing agent (B), bath temperature (C) and annealing temperature (D). The friction tests are conducted with a pin-on-disk tribometer. The optimum combination of process parameters for minimum friction is obtained. Also, analysis of variance (ANOVA) is performed to find out the significant contribution of each coating process parameters and their interactions. ANOVA reveals that bath temperature has the maximum contribution in controlling the friction behaviour of Ni–P coating. The surface morphology and composition of coatings are studied with the help of scanning electron microscopy (SEM), energy dispersed X-ray (EDX) analysis and X-ray diffraction (XRD) analysis. It is found that the Ni-P coating is amorphous in as-deposited condition but gradually turns crystalline with heat treatment.

Improvement of Corrosion Resistance of Ni–P–Al2O3 Composite Coating by Optimizing Process Parameters Using Potentiodynamic Polarization Test

Electroless Ni–P based composite coatings are more popular due to their excellent hardness, yield strength, wear resistance, frictional resistance, corrosion resistance, and good lubricity. The present study deals with significance of various coating process parameters on the corrosion behavior of the Ni–P–Al2O3 composite coatings on mild steel substrate. Corrosion behavior of the composite coatings after heat treatment at various annealing temperatures (300 °C, 400 °C, and 500 °C) are investigated by potentiodynamic polarization test using 3.5% NaCl solution. For maximization of corrosion resistance, the electrochemical parameters, corrosion potential ( Ecorr ) and corrosion current density ( Icorr ), are optimized using Taguchi based grey relational analysis. For optimization four coating process parameters are considered, namely, concentration of nickel source, concentration of reducing agent, concentration of second phase particles (alumina particles), and annealing temperature, as main design factors. The optimum combinations of the said design factors are obtained from the analysis. Analysis of variance (ANOVA) reveals that the concentration of alumina particles and annealing temperature has the significant influence on the corrosion resistance of the composite coatings. The microstructure of the surface is studied by scanning electron microscopy (SEM) and chemical composition is studied by energy dispersive X–ray analysis (EDX). The X–ray diffraction analysis (XRD) is used to identify the phase transformation behavior of the composite coatings.

Effect of Process Parameters on Microhardness of Ni-P-Al2O3 Composite Coatings

Electroless Ni-P-Al2O3 composite coatings have found wide range of applications due to their high hardness and wear resistance. The present study triesto investigate the influence of coating process parameters on the microhardness of electroless Ni-P-Al2O3 composite coating with the help ofTaguchi analysis. Four parameters, namely, concentration of nickel sulphateas a nickel source, concentration of sodium hypophosphite as a reducing agent, concentration of Al2O3 particles as concentration of second phase particles, and annealing temperature, are considered and fitted into an L27 orthogonal array to find out the optimized condition for improvedhardness of the coating. The optimized condition is found to yield about 20.47% improvement in hardness of the coating comparedto the initial condition. The significance of the process parameters and their interactions on the hardness of electroless Ni-P-Al2O3 composite coating isstudied with the help of analysis of variance, which revealed that annealing temperature and concentration of second phase particles (Al2O3 particles) have significant influence on the hardness characteristics of electroless Ni-P-Al2O3 composite coating. The compositional, microstructural, andphase structure analyses are conducted with the help of energy-dispersive X-ray analysis, scanning electron microscope, and X-raydiffraction analyzer, respectively.

In situ functionalisation of mesoporous carbon electrodes with carbon nanotubes for proton exchange membrane fuel-cell application

In the work presented here, an attempt is made to study the effect of different carbon supports on the mesostructural properties as well as electrochemical behaviour of Pt/carbon supports.In this respect, the functionalised samples have been synthesised by using CMK-3, nickelocene as nickel source and the chemical vapour deposition (CVD) process for growth of carbon nanotubes. The platinum catalysts (Pt 20 wt.%) were obtained through a conventional wet impregnation method. All the materials have been characterised by XRD (small- and high-) angle, N2 adsorption–desorption isotherms, high-resolution transmission electron microscopy and high-resolution field emission scanning electron microscopy.The results showed that the mesostructural structure had been partially destroyed by functionalisation of CMK-3 with NiO and multiwalled carbon nanotubes (MWCNTs). Moreover, wide-angle X-ray diffraction (WAXRD) studies revealed the formation of smaller platinum crystallite sizes compared to Vulcan-supported samples. Furthermore, electrochemical evaluation indicates that CMK-3–CNT–20Pt gives a specific surface area of 58.9 m2 g−1. Finally, the polarisation curves for the fabricated membrane electrode assemblies (MEAs) with Pt loading of 0.5 mg cm−2 demonstrated that the CMK-3–CNT–20Pt catalyst shows better performance than industrial catalysts and even Vulcan–40% Pt.

Preparation of novel mesoporous Ce-Ni2P/SBA-15 catalysts and their catalytic performance for hydrodesulfurization of dibenzothiophene

Ni2P/SBA-15 precursors with Ni2P loadings of 25 wt% and initial P/Ni of 0.8 were prepared using nickel nitride as nickel source, diammonium hydrogen phosphide as phosphorus and mesopore molecular sieve SBA-15 as support. Then Ce was introduced into the Ni2P/SBA-15 precursor. The novel mesoporous Ce-Ni2P/SBA-15 catalysts were prepared after temperature-programmed reduction in flowing H2. The structure was characterized by X-ray diffraction, N2 adsorption–desorption isotherms, NH3 temperature-programmed desorption and X-ray photoelectron spectroscopy. The catalytic activities for the hydrodesulfurization (HDS) of dibenzothiophene (DBT) were evaluated. The results showed that only Ni2P phase was formed in Ce-Ni2P/SAB-15 catalysts with Ce loadings of 0–5 wt%. Ni2P and Ni12P5 phases were existed in 7 wt% Ce-Ni2P/SBA-15 catalyst. The surface area and pore volume increased when Ce was added to Ni2P/SBA-15 catalyst. The strength of the acid sites and total acid amount of Ce-Ni2P/SBA-15 catalysts increased with increasing Ce loadings. Ce existed in the form of Ce3+and Ce4+, Ni existed in the form of Ni2+ and Niδ+, and P existed in the form of Pδ− and P5+. The addition of Ce to the Ni2P/SBA-15 catalyst decreased Niδ+ concentration in Ni2P/SBA-15 catalyst. The activity for HDS of DBT over Ni2P/SBA-15 catalysts was affected by the addition of Ce at 300–340 °C. The catalysts exhibited a good catalytic performance of deep hydrodesulfurization of dibenzothiophene and the conversion of DBT can reach 98.9 % at 380 °C. Biphenyl was the main product over Ce-Ni2P/SBA-15 catalysts and cyclohexylbenzene was the main product over Ni2P/SBA-15 catalyst at 380 °C.