• Journal of Electrochemical Science and Technology
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• v.3 no.1
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• pp.50-56
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• 2012

Nickel modified NiOOH electrodes were used for the electrocatalytic oxidation of ethanol in alkaline solutions where the methods of cyclic voltammetry (CV) and chronoamperometry (CA) were employed. In CV studies, in the presence of ethanol, an increase in the current for the oxidation of nickel hydroxide is followed by a decrease in the corresponding cathodic current. This suggests that the oxidation of ethanol is being catalysed through mediated electron transfer across the nickel hydroxide layer comprising of nickel ions of various valence states. Under the CA regime the reaction followed a Cottrellian behavior and the diffusion coefficient of ethanol was found to be $1{\times}10^7cm^2s^{-1}$.

• Journal of the Korean Electrochemical Society
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• v.1 no.1
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• pp.8-13
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• 1998

This work presents the way how to evaluate the degree of reversibility of the discharging process undergone by the nickel hydroxide film cathodically deposited on pure nickel as a positive electrode for electrochemical capacitor using the combined cyclic voltammetry and potential drop method, supplemented by galvanostatic discharge and open-circuit potential transient methods. The time interval necessary just to establish the current reversal of anodic to cathodic direction from the moment just after applying the potential inversion of anodic to cathodic direction, was obtained on cyclic voltammogram. The cathodic charge density passed upon dropping the applied potential, was calculated on potentiostatic current density-time curve. Both the time interval and the cathodic charge density in magnitude can be regarded as being measures of the degree of reversibility of the discharging process undergone by the positive active material for supercapacitor, i.e. , the longer the time interval is, the lower is the degree of reversibility and the greater the cathodic charge density is, the higher is the degree of reversibility. From the applied potential dependences of the time interval and cathodic charge density, discharge at $0.42 V_{SCE}$ was determined to be the most reversible.

• Resources Recycling
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• v.28 no.5
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• pp.51-59
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• 2019

This study focused on the synthesis of the nickel hydroxide using ammonium sulfate in leaching solution from waste nickel-cadmium batteries. The effect of pH, temperature and the input amount of ammonium sulfate in leaching solution was investigated. The ammonium nickel sulfate with high purity was obtained in acidic leaching solution and the solution temperature of $60^{\circ}C$. The suitable molar ratio of the input amount of ammonium sulfate to nickel in solution is 2:1. The impurity about 1.4 at.% of Cd was included in the nickel hydroxide precipitates when ammonium nickel sulfate was used. At the process using sodium sulfide which precipitates the cadmium in solution, nickel and iron compounds were precipitated together.

• Korean Journal of Materials Research
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• v.19 no.5
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• pp.270-275
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• 2009

Lotus-type porous nickel with cylindrical pores was fabricated by unidirectional solidification under an Ar gas atmosphere using the thermal decomposition method of the compounds such as sodium hydroxide, calcium hydroxide, calcium carbonate, and titanium hydride. The decomposed gas does form the pores in liquid nickel, and then, the pores become the cylindrical pores during unidirectional solidification. The decomposed particles from the compounds do play a rule on nucleation sites of the pores. The behavior of pore growth was controlled by atmosphere pressure, which can be explained by Boyle's law. The porosity and pore size decreased with increasing Ar gas pressure when the pores contain hydrogen gas decomposed from calcium and sodium hydroxide and titanium hydride, ; however it they did not change when the pores contain containing carbon dioxide decomposed from calcium carbonate. These results indicate that nickel does not have the solubility of carbon dioxide. Lotus-type porous metals can be easily fabricated by the thermal decomposition method, which is superior to the conventional fabrication method used to pressurized gas atmospheres.

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.710-718
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• 2021

Recently, due to high theoretical capacitance and excellent ion diffusion rate caused by the 2D layered crystal structure, transition metal hydroxides (TMHs) have generated considerable attention as active materials in supercapacitors (or electrochemical capacitors). However, TMHs should be designed using morphological or structural modification if they are to be used as active materials in supercapacitors, because they have insulation properties that induce low charge transfer rate. This study aims to modify the morphological structure for high cycling stability and fast charge storage kinetics of TMHs through the use of nickel cobalt hydroxide [NiCo(OH)₂] decorated on nickel foam. Among the samples used, needle-like NiCo(OH)₂ decorated on nickel foam offers a high specific capacitance (1110.9 F/g at current density of 0.5 A/g) with good rate capability (1110.9 - 746.7 F/g at current densities of 0.5 - 10.0 A/g). Moreover, at a high current density (10.0 A/g), a remarkable capacitance (713.8 F/g) and capacitance retention of 95.6% after 5000 cycles are noted. These results are attributed to high charge storage sites of needle-like NiCo(OH)₂ and uniformly grown NiCo(OH)₂ on nickel foam surface.

• Elastomers and Composites
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• v.50 no.3
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• pp.217-222
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• 2015

Carbon-nickel nanocomposites were prepared by the reaction of fullerene ($C_{60}$) and nickel hydroxide in an electric furnace at $700^{\circ}C$ for 2 h. The hybrid carbon-nickel nanocomposites were characterized by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. The kinetics and catalytic activity of the carbon-nickel nanocomposites in the reduction of 4-nitrophenol were confirmed by UV-vis spectroscopy.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.28.1-28.1
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• 2005

• Toxicological Research
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• v.27 no.1
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• pp.19-23
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• 2011

It has been proposed that acute phase response can be a mechanism by which inhaled particles exert adverse effects on the cardiovascular system. Although some of the human acute phase proteins have been widely studied as biomarkers of systemic inflammation or cardiovascular diseases, there are only a few studies that investigated the role of serum amyloid P (SAP), a major acute phase protein in mice. In this study, we investigated the changes in SAP, following inhalation exposure to nickel hydroxide nanoparticles (nano-NH). We conducted 1) acute (4 h) exposure to nano-NH at 100, 500, and $1000\;{\mu}g/m^3$ and 2) sub-acute (4h/d for 3d) exposure at $1000\;{\mu}g/m^3$, then measured serum SAP protein levels along with hepatic Sap mRNA levels. The results show that inhaled nano-NH can induce systemic acute phase response indicated by increased serum SAP levels and hepatic Sap mRNA levels. To the best of our knowledge, this is the first study showing induction of SAP in response to repeated particle exposure, and the results suggest that SAP can be used as a biomarker for systemic inflammation induced by inhaled particles.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.983-988
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• 2009

This study was performed to evaluate the toxicity and seek the control method of the wastewater in which nickel (Ni) was included into an industrial wastewater treatment plant. Nickel concentration of the wastewater, of which samples were taken every hour during 24hours, were various from 0.33 to 116.0 mg/L, with 24.0 mg/L of the average concentration. IC50 values against nitrosomonas and nitorbactor, a toxic level against bacteria which could inhibit 50% of nitrification bacteria in the wastewater, are 5.5 and 4.9 mg/L respectively. Nickel in this industrial wastewater can inhibit the 50% of nitrification bacteria even after diluting this wastewater 5 times. Also, this research, which reduced the nickel concentraion, forming nickel hydroxide compounds by increasing pH of the wastewater, shows that nickel concentraion can be obtained under 1.7 mg/L at pH 11 and 0.6 mg/L at pH 12. Consequently, the result of this study is that the nitrification efficiencies can be obtained from 83.8 to 99.4% with 97.6% of the average in the biological treatment after removing nickel in the wastewater by increasing the pH above 11~12, which is forming the nickel hydroxide compounds.

• Journal of the Korean institute of surface engineering
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• v.15 no.3
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• pp.146-151
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• 1982

The electrochemical reaction behavior of nickel electrode of the nickel-cadium battery system in potassium hydroxide solution has been studied by cyclic voltammetry, controlled potential electrolysis and X-ray diffraction method. It has been found that the reaction mechanism of positive nickel electrode for charging was assumed to be proten transfer step with a rate controlling diffusion process and char-ging state of positive electrode was amorphous $\beta$-NiOOH.