Electrochemical Behaviour Of Nickel Research Articles

Electrochemical Behaviour of Nickel(II)-Rhenium(VII) And Electrodeposition of Nickel-Rhenium Alloy from Choline Chloride - Urea Deep Eutectic Solvent

The electrochemical behaviour of nickel(II)-rhenium(VII) and the electrodeposition of nickel-rhenium alloy using choline chloride: 2 Urea deep eutectic solvent (Reline DES) is reported. Speciation of nickel(II)-rhenium(VII) in Reline DES was studied using UV -Visible spectroscopy. Cyclic voltammetry of Ni2+-ReO4 − in Reline indicates the simultaneous reduction of two metal ions at glassy carbon electrode controlled by non-reversible diffusion process. Chronoamperograms obtained for the reduction of Ni2+-ReO4 − suggests nucleation and three-dimensional growth of bimetallic phase on electrode surface followed progressive nucleation. Electrodeposition of nickel—rhenium alloy was carried out on copper substrates under galvanostatic and potentiostatic conditions. Smooth and uniform deposits were obtained by galvanostatic deposition. X-ray diffraction analysis of the deposit confirmed it to be nickel-rhenium alloy (at −1.2 V) in amorphous form which upon annealing at 1000 °C crystallizes into hexagonal phase with concurrent morphology change from spherical particles to irregular polygons.

Electrochemical behavior of nickel containing passive oxide films on carbon steel in alkaline medium

The passive oxide film formed on the carbon steel surface in lithiated water was modified by the incorporation of nickel ions by hydrothermal deposition at 250°C. The aim was to verify to what extent the in-situ oxide films grown in presence of nickel ions improved the corrosion resistance of the carbon steel substrate in comparison to the films formed in the absence of nickel ions at different exposure times. Grazing incidence-X-ray diffraction studies confirmed the formation of the spinel phase in the passive oxide film. X-ray photoelectron spectroscopy revealed the presence of the nickel ions in the oxide lattice. The electrochemical behavior of the oxide films formed on the carbon steel surface was studied using electrochemical impedance spectroscopy and potentiodynamic anodic polarization methods. Tafel plot extrapolations from the potentiodynamic anodic polarization plots revealed a substantial difference in the corrosion resistance of the films formed on carbon steel substrate in the presence of nickel ions. The oxides grown in the absence and in the presence of nickel ions exhibited similar corrosion current densities but showed a higher polarization resistance value in the presence of nickel ions. The semiconductor properties of these oxides were characterized by Mott Schottky measurements and the results are presented in detail in this paper.

Electropolymerization and corrosion resistance of polypyrrole on nickel bipolar plate for PEM fuel cell application

Abstract Nickel has been considered advantageous as a bipolar plate for proton exchange membrane fuel cells (PEMFC). In fact, nickel presents high mechanical strength, good thermal and electrical conductivity in addition to its low cost. Nevertheless, the long-term exposure of nickel bipolar plate to the humid medium of PEMFC accelerates its corrosion kinetics which brings to PEMFC performance deterioration. The objective of this study is to improve the corrosion resistance of nickel bipolar plate by means of conductive polymer coating. Typically, polypyrrole film has been electrodeposited using chronopotentiometric technique at different current densities in aqueous sodium saccharin medium. The electrochemical behaviour of nickel in the presence of sodium saccharinate solution in the absence and the presence of the pyrrole monomer were investigated using cyclic voltammetry. Characterization of the polypyrrole coating was carried out using x-ray photoelectrons (XPS) and scanning electron microscopy (SEM). Corrosion behavior of the PPy coating has been studied in aggressive medium using 3.5% NaCl by OCP and EIS techniques.

Electrorefining of nickel from nickel–chromium alloy in molten LiCl–KCl

Electrorefining of nickel in LiCl–KCl melt was investigated using electrochemical techniques. Nickel products after electrorefining were characterized by X-ray diffraction, X-ray fluorescence, and scanning electron microscopy. Both cyclic voltammetry and square wave voltammetry results suggested that Ni2+ was directly reduced to Ni metal in LiCl–KCl. Based on a preliminary study on the electrochemical behavior of nickel and chromium, electrorefining was carried out under constant potential, whereupon deposits were formed on the cathode. The purity of nickel increased from 72.62% in the original alloy to 99.83% in cathodic deposits, as determined by inductively coupled plasma atomic emission spectroscopy analysis. Almost all the nickel in the alloy could be recovered during the electrochemical process with > 90% current efficiency. A lower concentration of NiCl2 in LiCl–KCl was found to be favorable for nickel electrorefining, as increased NiCl2 concentration caused severe corrosion of the nickel anode at the gas–liquid interface due to the accumulation of Cl2 gas.

Electrochemical Behavior of the Nickel/Oxide Tungsten Bronze System at Cyclic Potential Sweep

The electrochemical behavior of nickel in the K2WO4–Na2WO4 (1 : 1)–WO3 (35 mol %) and K2WO4–Na2WO4 (1 : 1)–WO3 (50 mol %) polytungstate melts was studied by the cyclic voltammetry. Based on a comparison of the obtained cyclic voltammograms with the data of SEM, EDS and XRD conclusions were drawn about the sequence of processes proceeding on the nickel substrate. Equations of the electrolysis products formation are proposed.

Electrochemical behavior of nickel–polyaniline electrode in 1 M LiClO4–propylene carbonate electrolyte

Doping of emeraldine-base (EB) with lithium salts involves the addition of lithium cations to nitrogen in imine groups and intercalation of counter ions i.e., proceeds similarly to doping with protonic acids. The results of studies show that doping of polyaniline (PANI) with a lithium salt proceeds relatively difficultly as compared with protonic doping. For a polyaniline electrode, to attain faster the stationary mode by repeated cycling (“electrode training”) in an organic lithium electrolyte and to reach the higher capacitance, the method of preliminary lithiation of the NiO surface layer on the nickel substrate with Li+ cations through the EB film is proposed. The studies show that preliminary cycling of the Ni/PANI electrode (7 cycles at 10 mV s–1) in the region of negative potentials (from 0 to–2.99 V vs. Ag/AgCl) leads to substantial increase in the capacitance characteristics of the PANI film in the region of its intrinsic redox activity from–0.4 to +1.1 V at high charge–discharge currents (2–5 A/g).

Monitoring of nickel(II) in biological samples using 4-(2-hydroxy-phenylethamino)benzene-1,3-diol by extractive differential pulse polarography

<p class="PaperAbstract"><span lang="EN-US">A novel analytical reagent, 4-(2-hydroxyphenylethamino)benzene-1,3-diol was synthesized for determination of nickel(II) in biological samples and plant materials by extractive differential pulse polarography. The analysis of nickel(II) was carried out by extracting the nickel(II)-(4-(2-hydroxyphenylethamino)benzene-1,3-diol) complex from chloroform prior to injecting into the instrument. The electrochemical behavior of nickel(II) complex was studied under optimum parameters like effect of pH, pulse amplitude, scan rate and choice of solvent. The calibration curve was constructed in the concentration range of 0.05-42 µg mL<sup>-1</sup> at pH 4.0 (acetate buffer) with a correlation coefficient of 0.992, respectively. Interference of diverse ions was also investigated during the analysis of nickel(II) to optimize the conditions. The accuracy and validity of the proposed method were checked by the analysis of Certified Reference Materials which is distributed by the National Institute of Standard Technology</span></p>

Electrochemical study of nickel from urea-acetamide-LiBr low-temperature molten salt

The electrochemical behavior of nickel was studied by cyclic voltammetry and chronoamperometry techniques at 353K using a tungsten electrode in urea-acetamide-LiBr low-temperature molten salt. The cyclic voltammograms indicate that the reduction of Ni(II) to Ni proceeds via a single-step, two-electron transfer process. Chronoamperometric measurements show that the electrodeposition of nickel on the tungsten electrode involves three-dimensional (3D) progressive nucleation under diffusion-controlled growth at 353K. Nickel coatings were prepared at different cathodic potentials (−0.70 to −0.85V) and different temperatures (343–373K) in urea-acetamide-LiBr molten salt. The deposits were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The SEM images reveal that uniform, dense, and compact deposits were obtained at more positive cathodic potentials within the temperature range of 343–363K. The EDS and XRD analyses confirm that the obtained deposits are pure nickel.

Electrochemical Behavior of Nickel in the EMIC Ionic Liquid with Glycol

Electrochemical Behavior of Nickel in the EMIC Ionic Liquid with Glycol

Electrochemical behavior of nickel and its oxides in concentrated sodium hydroxide solutions

By using the methods of cyclic voltammetry (the potential scan rates of 20 mV/s and 2–500 V/s) and preparative electrolysis at an ac frequency of 10 to 200 Hz, in 17 M sodium hydroxide, it is found that nickel oxidation proceeds with the formation of oxides of variable composition. It is shown that the dependence of nickel failure rate on the current frequency has a peak. The highest failure rate corresponds to a current frequency of 20 Hz.

Influence of the oxyanion nature of the electrolyte on the corrosion/passivation behaviour of nickel

The electrochemical behaviour of nickel in the presence of various electrolyte solutions at 0.1mol/L concentration exhibits a distinction according to the oxyanion nature of the investigated anions. Passivity is achieved with oxyanions whereas it fails with anions not containing oxygen. SIMS and XPS measurements performed from isotopic and non isotopic KNO3 electrolytes indicate that the oxygen and nitrogen atoms from nitrate oxyanions are incorporated into the passive film during anodic polarization and with evidence of a direct bonding between nitrogen and nickel surface.

Electrochemical behavior of nickel in electrolytes based on 1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid for capacitor applications

Electrochemical studies were performed using Ni electrodes in solutions of a mixture of ethylene glycol or of γ-butyrolactone with 1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid. The aim of the study was to evaluate the use of these systems in electrochemical double-layer capacitor. Cyclic voltammetry experiments showed a potential range at which the Ni electrode behaved as a polarizable electrode. Ni oxidizes at high anodic potentials. Inside the potential range without electrochemical activity, the capacitance and the solution resistance, which were evaluated by impedance electrochemical spectroscopy, were compared for the two solutions tested. Conductivity measurements of the electrolytes with different compositions were also acquired. The results of cyclic voltammetry indicated that the Ni has a wide electrochemical window and low current peak densities of oxidation in the γ-butyrolactone medium than in ethylene glycol medium. The γ-butyrolactone and 1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid solutions had the highest conductivity values. Decreased 1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid content in different solvent mixtures resulted in an increase in the capacitance value at the Ni/electrolyte interface. The highest capacitance values were obtained for Ni in ethylene glycol and 1-n-butyl-3-methylimidazolium tetrafluoroborate medium.

Electrochemical behavior of nickel in nitric acid and its corrosion inhibition using some thiosemicarbazone derivatives

Abstract The adsorption and corrosion inhibition behavior of three selected thiosemicarbazone derivatives, namely 3-pyridinecarboxaldehyde thiosemicarbazone (META), isonicotinaldehyde thiosemicarbazone (PARA) and 2-pyridinecarboxaldehyde thiosemicarbazone (ORTHO) at the nickel surface were studied electrochemically by Tafel and impedance methods and computationally by carrying out Monte Carlo searches of configurational space on nickel/thiosemicarbazone derivative system. Electrochemical measurements showed that the inhibition efficiency of these compounds increased with increase in their concentration. The recorded inhibition efficiencies of the three tested thiosemicarbazone increase in the order: META > PARA > ORTHO. Polarization studies showed that these compounds act as mixed-type inhibitors for nickel corrosion in 1.0 M HNO3 solutions. Results obtained from Tafel and impedance methods are in good agreement. Thiosemicarbazone derivatives have been simulated as adsorbate on Ni (1 1 1) substrate and the adsorption energy, binding energy and the low energy adsorption sites have been identified on nickel surface.

Transition metal complexes of pyrazole head 24-membered polyazamacrocyclic bimetal cores: synthesis, characterization, electrochemistry and spectral study

A series of new 24-membered macrocyclic CoII, NiII, CuII and ZnII complexes of the ligands L1H2 and L2H2 were prepared by the non-template and template methods respectively. The ligand L1H2 was formed by the condensation of pyrazole-3,5-dicarbohydrazide and glyoxal and all attempts to isolate the ligand L2H2 were unsuccessful. These, ligand and transition metal complexes were characterized on the basis of elemental analysis, IR, 1HNMR, UV–Visible, magnetic susceptibility measurements, ESR, conductivity measurements, FAB-mass and thermal analysis. The redox behavior of metal ions in the polyazamacrocyclic ligand field is also studied. Electroreduction of carbon dioxide to carbon monoxide is mainly focused on using polydentate azamacrocyclic ligands with amine and imine functionalities, based on the electrochemical behavior of nickel (II) ion in the macrocyclic territory.

Influence of temperature and applied potential on the electrochemical behaviour of nickel in LiBr solutions by means of electrochemical impedance spectroscopy

The effects of temperature, applied potential and hydrogen generation on the passive behaviour of nickel were investigated in lithium bromide aqueous solution using different electrochemical techniques: open circuit potential (OCP), potentiodynamic and potentiostatic measurements, and electrochemical impedance spectroscopy (EIS). From the polarization curves, it is observed that localised corrosion resistance decreases with temperature, the repassivation of nickel is more difficult at 75 °C and the hydrogen evolution reaction is favoured with an increase in temperature. Impedance results showed that the most suitable corrosion mechanism of nickel in LiBr solutions includes the double layer and the passive film formed on the nickel surface. The passive film of nickel partially disappears when a low cathodic potential is applied.

Electrochemical Behavior of Nickel in Acidic Sulfate Electrolytes

The electrochemical behaviour of Nickel in sulphuric acid electrolytes was studied by various electrochemical means. Under cathodic polarization, Nickel forms metastable hydrides under cathodic charging; the successive egress of hydrogen is controlled by solid state diffusion of hydrogen atoms. The nature of these hydrides evolves with electrochemical aging of the samples, as judged by their electrochemical signature. The nature of the (hydro)oxides formed during anodic polarization also evolves with aging. Anodic polarization and investigation of electrochemical oscillations in the transpassive region show that defect states which constitute preferred dissolution sites assume a wider energy range with increasing aging, indicating a high degree of inhomogeneity of the surface. The catalytic activity of Nickel increases after aging under both cathodic and anodic conditions, due to the formation of an inhomogeneous surface.

The effect of medium on the corrosion and electrochemical behavior of nickel

Electrochemical and corrosion properties of nickel in neutral, alkaline, and acidic solutions are studied. Chemical and phase composition of surface films and surface morphology are examined. The effect of electrolyte composition and concentration on the metal removal rate in the course of broaching is determined. Optical, electrochemical, and gravimetrical methods, x-ray diffraction analysis, and thermogravimetry were used in the work.

Electrochemical synthesis of nickel (cobalt)—molybdenum (tungsten) intermetallic compounds

We study the electrochemical behavior of nickel and cobalt in tungstate melts and the influence of the conditions of electrolysis on the composition and structure of deposits of nickel (cobalt)—molybdenum (tungsten) alloys and intermetallic compounds in oxide-tungstate melts. It is shown that, as the concentration of molybdenum (tungsten) in the melt increases and the concentration of nickel (cobalt) decreases, the phase composition of cathodic deposits includes nickel, cobalt, alloys and intermetallic compounds of nickel and cobalt with molybdenum and tungsten, molybdenum, and tungsten.

Electrochemical Behavior of Nickel in HNO<SUB>3</SUB> and the Effect of Chloride Ions

The electrochemical behavior of nickel in HNO3 solutions of varying concentrations was examined using the cyclic voltammetry and potentiodynamic anodic polarization techniques. The anodic branch of the cyclic voltammogram is characterized by one anodic dissolution peak and a passivation region before oxygen evolution. The cathodic branch shows only one cathodic reduction peak corresponding to the reduction of HNO3. Analysis of the anodic polarization data shows features of both reversible and irreversible reactions pointing to the complexity of the system. CT− ions enhance the active dissolution of nickel in HNO3 due to the adsorption on the bare metal surface and cause destruction of the passive film and initiation of pitting corrosion.

New insight in the cyclic voltammetric behaviour of nickel in molten Li 2CO 3–Na 2CO 3 at 650 °C

The electrochemical behaviour of nickel and its oxides in molten carbonates is very complex because of the continuous growth of the NiO layer and the material losses during the oxidation and reduction processes. Thus, cyclic voltammograms have been realised in molten Li 2CO 3+Na 2CO 3 at 650 °C at different electrodes (gold covered by NiO, fresh and aged nickel); they allowed us to identify, at different scan rates, the reactions associated with the peaks observed. In particular, thanks to a planar nickel disc electrode, with a well-defined surface, the principal reduction peak has been attributed to the transformation of NiO into Ni. Other reduction peaks, occurring at lower potentials, are probably due to the same reaction and their presence to phase transitions. Evidence was given for the existence of a Ni/Ni 2+ system and the formation of Ni(III), most probably NaNiO 2, by the oxidation of NiO at relatively high potentials.