• Journal of Electrochemical Science and Technology
• /
• v.11 no.4
• /
• pp.379-383
• /
• 2020

The novel voltammetry using a semi-circular potential wave for quasi-reversible charge transfer system on electrode is theoretically investigated. Compared with conventional voltammetry based on linear sweep such as linear sweep voltammetry (LSV), semi-circular potential sweep voltammetry (SCV) may decrease the charging current outside the center of potential range and increase the faradaic current at the midpoint due to variable scan rate. In this paper, we investigate the system based on macroelectrode where simple 1 dimensional (1 D) diffusion system is valid with various charge transfer rate constant (k₀). In order to observe the amplification at midpoint, voltammetric response with different midpoint ranging from -200 mV to 200 mV are studied. SCVs shows both the shift of peak potential and the amplification of peak current for quasi-reversible electrode reaction while only higher peak current is observed for reversible reaction. Moreover, the higher current at midpoint enable the amplification of current at low overpotential region which may assist the determination of onset potential as a figure-of-merit in electrocatalyst.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.123-123
• /
• 2008

본 논문에서는 Cu의 ECMP 적용을 위해 $HNO_3$ 전해액의 active, passive, transient, trans-passive 영역을 I-V 특성 곡선을 통해 알아보았고, LSV (Linear sweep voltammetry)와 CV (Cyclic voltammetry)법을 통하여 전기화학적 특성을 비교 분석하였다.

• Carbon letters
• /
• v.26
• /
• pp.88-94
• /
• 2018

This manuscript explains the effective determination of urea by redox cyclic voltammetric analysis, for which a modified polypyrrole-graphene oxide (PPY-GO, GO 20% w/w of PPY) nanocomposite electrode was developed. Cyclic voltammetry measurements revealed an effective electron transfer in 0.1 M KOH electrolytic solution in the potential window range of 0 to 0.6 V. This PPY-GO modified electrode exhibited a moderate electrocatalytic effect towards urea oxidation, thereby allowing its determination in an electrolytic solution. The linear dependence of the current vs. urea concentration was reached using square-wave voltammetry in the concentration range of urea between 0.5 to $3.0{\mu}M$ with a relatively low limit of detection of $0.27{\mu}M$. The scanning electron microscopy was used to characterize the morphologies and properties of the nanocomposite layer, along with Fourier transform infrared spectroscopy. The results indicated that the nanocomposite film modified electrode exhibited a synergistic effect, including high conductivity, a fast electron-transfer rate, and an inherent catalytic ability.

• Journal of the Korean Electrochemical Society
• /
• v.15 no.3
• /
• pp.165-171
• /
• 2012

Here is implemented MATLAB program to analyze the characteristic curves of cyclic voltammetry which involves the multi-electron electrode reaction considered as key processes in electrochemical systems. For the electrochemical mass-transfer system, Fick's concentration equation subject to semi-infinite diffusion model for the boundary condition was discretized and solved by the explicit finite difference method. The resulting concentration values were converted into currents at each node by using Butler-Volmer equation. Based on the good agreement between the present numerical solution and the existing experimental results, effects of kinetic constants and CV scan rates on the reaction mechanism in multi-electron transfer processes were investigated effectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.05b
• /
• pp.269-272
• /
• 2000

Spinel $LiMn_2O_4$ samples are prepared by heating a $LiOH{\cdot}H_2O/MnO_2$ mixture in air at $800^{\circ}C$ for 36h, and their structure and electrochemical performance are studied by using X-ray diffraction, Cyclic Voltammetry, AC Impedance, and Charge-discharge measurements. It was found that the electrochemical properties of the $LiMn_2O_4$ samples are very sensitive to substituted volume of lithium. Initial impedances of all cathode was similar. Initial resistance was $60{\sim}70{\Omega}$. Reaction peak of Cyclic voltammetry was weak by increase of substituted volume of lithium. $Li[Li_{0.08}Mn_{1.92}]O_4$ and $Li[Li_{0.1}Mn_{1.9}]O_4$ cathode materials showed the charge and discharge capacity of about 125mAh/g at first cycle, and about 95mAh/g after 70th cycle. It showed excellent property in sample revealed good structure and other electrochemical property.

• Applied Chemistry for Engineering
• /
• v.20 no.6
• /
• pp.700-704
• /
• 2009

The electrochemical properties of porous carbon electrodes as a function of their internal electrolyte concentration were investigated. Cyclic voltammetry, chronoamperometry, and impedance spectroscopic analysis were conducted for carbon electrodes equilibrated with 0.01, 0.05, 0.1, and 0.5 M KCl solution and covered with a cation-exchange membrane. The specific capacitance of the electrodes increased as the internal electrolyte concentration increased, due to a decrease in charging resistance. Experimental results indicated that the salt removal efficiency of the membrane capacitive deionization process could be enhanced by increasing the internal electrolyte concentration, even for an influent with a low salt concentration.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.18 no.1
• /
• pp.1-18
• /
• 2020

Molten salt solutions consisting of eutectic LiCl-KCl and concentrations of samarium chloride (0.5 to 3.0 wt%) at 500℃ were analyzed using both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The CV technique gave the average diffusion coefficient for Sm³⁺ over the concentration range. Equipped with Sm³⁺ diffusion coefficient, the Randles-Sevcik equation predicted Sm³⁺ concentration values that agree with the given experimental values. From CV measurements; the anodic, cathodic, and half-peak potentials were identified and subsequently used as a parameter to acquire EIS spectra. A six-element Voigt model was used to model the EIS data in terms of resistance-time constant pairs. The lowest resistances were observed at the half-peak potential with the associated resistance-time constant pairs characterizing the reversible reaction between Sm³⁺ and Sm²⁺. By extrapolation, the Voigt model estimated the polarization resistance and established a polarization resistance-concentration relationship.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.12
• /
• pp.3993-3997
• /
• 2012

Three-dimensional porous nickel foam was used as a current collector to prepare a Co-Ni oxide/Ni foam electrode for a supercapacitor. The synthesized Co-Ni oxide was proven to consist of mixed oxide phases of $Co_3O_4$ and NiO. The Co-Ni oxide/Ni foam electrode prepared was characterized by morphological observation, crystalline property analysis, cyclic voltammetry, and impedance spectroscopy. Cyclic voltammetry for the electrode showed high specific capacitances, such as 936 F $g^{-1}$ at 5 mV $s^{-1}$ and 566 F $g^{-1}$ at 200 mV $s^{-1}$, and a comparatively good cycle performance. These improved results were mainly due to the dimensional stability of the nickel foam and its high electrical contact between the electrode material and the current collector substrate.

• Journal of the Korean Chemical Society
• /
• v.54 no.1
• /
• pp.13-22
• /
• 2010

The photophysical properties of 7-diethylaminocoumarin (DEAC) laser dye have been measured in different solvents. The emission spectrum of DEAC has also been measured in cationic (CTAC) and anionic (SDS) micelles. The laser parameters have been calculated in different solvents namely acetone, dioxane, ethanol and dimethylforamide(DMF). The photoreactivity of DEAC has been studied in $CCl_4$ solvent using 366 nm light. The values of photochemical yield (${\Phi}_c$) and rate constant (k) are determined. The interaction of organic acceptors such as picric acid (PA), tetracyanoethylene (TCNE) and 7,7,8,8-tetracynoquinonedimethane (TCNQ) with DEAC are also studied using fluorescence measurements in acetonitrile ($CH_3CN$). The electrochemical investigation of (DEAC) has been carried out using cyclic voltammetry and convolutive voltammetry combined with digital simulation technique at a platinum electrode in 0.1 mol $L^{-1}$ tetrabutyl ammonium perchlorate (TBAP) in $CH_3CN$ solvent. The electrochemical parameters of the investigated compound were determined using cyclic and convolutive voltammetry. The extracted electrochemical parameters were verified and confirmed via digital simulation method.

• Toxicological Research
• /
• v.25 no.4
• /
• pp.231-235
• /
• 2009

Trace lead detection for cyclic voltammetry (CV) and square-wave (SW) stripping voltammetry was performed using mercury immobilized onto a carbon nanotube electrode (HNPE). Using the characteristics of mercury and the catalytic carbon nanotube structure, a modified technique, the $0.45{\mu}g/l$ detection limit of lead ion was attained. The developed method can be applied to pond water, fish tissue, plant tissue, and in vivo direct assay.