• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.4
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• pp.313-320
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• 2017

A spectroelectrochemical method has been applied to investigate the electrochemical behaviors and identify the kinds of samarium ions dissolved in high temperature molten LiCl-KCl eutectic. An optically transparent electrode (OTE) fabricated with a tungsten gauze as a working electrode has been used to conduct cyclic voltammetry and potential step chronoabsorptometry. Based on the reversibility of the redox reaction of $Sm^{3+}/Sm^{2+}$, which was determined from the cyclic voltammograms, the formal potential and the diffusion coefficient were calculated to be -1.99 V vs. $Cl_2/Cl^-$ and $2.53{\times}10^{-6}cm^2{\cdot}s^{-1}$, respectively. From the chronoabsorptometry results at the applied potential of -1.5 V vs. Ag/AgCl (1wt%), the characteristic peaks of absorption for samarium ions were determined to be 408.08 nm for $Sm^{3+}$ and 545.62 nm for $Sm^{2+}$. Potential step chronoabsorptometry was conducted using the anodic and the cathodic peak potentials from the voltammograms. Absorbance analysis at 545.63 nm shows that the diffusion coefficient of $Sm^{3+}$ is $2.15{\times}10^{-6}cm^2{\cdot}s^{-1}$, which is comparable to the value determined by cyclic voltammetry at the same temperature.

• Journal of the Korean Electrochemical Society
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• v.19 no.1
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• pp.1-8
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• 2016

Capacity of layered lithium nickel-cobalt-manganese oxide ($LiNi_{1-x-y}Co_xMn_yO_2$) cathode material can increase by raising the charge cut-off voltage above 4.3 V vs. $Li/Li^+$, but it is limited due to anodic instability of conventional electrolyte. We have been screening and evaluating various sulfone-based compounds of dimethyl sulfone (DMS), diethyl sulfone (DES), ethyl methyl sulfone (EMS) as electrolyte additives for high-voltage applications. Here we report improved cycling performance of $LiNi_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode by the use of dimethyl sulfone (DMS) additive under an aggressive charge condition of 4.6 V, compared to that in conventional electrolyte, and cathode-electrolyte interfacial reaction behavior. The cathode with DMS delivered discharge capacities of $198-173mAhg^{-1}$ over 50 cycles and capacity retention of 84%. Surface analysis results indicate that DMS induces to form a surface protective film at the cathode and inhibit metal-dissolution, which is correlated to improved high-voltage cycling performance.

• Journal of Sensor Science and Technology
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• v.11 no.3
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• pp.163-170
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• 2002

This paper proposes a $10\;{\mu}m$ thick oxide air-bridge structure which can be used as a substrate for RF circuits. The structure was fabricated by anodic reaction, complex oxidation and micromachining technology using TMAH etching. High quality films were obtained by combining low temperature thermal oxidation ($500^{\circ}C$, 1 hr at $H_2O/O_2$) and rapid thermal oxidation (RTO) process ($1050^{\circ}C$, 2 min). This structure is mechanically stable because of thick oxide layer up to $10\;{\mu}m$ and is expected to solve the problem of high dielectric loss of silicon substrate in RF region. The properties of the transmission line formed on the oxidized porous silicon (OPS) air-bridge were investigated and compared with those of the transmission line formed on the OPS layers. The insertion loss of coplanar waveguide (CPW) on OPS air-bridge was (about 2dB) lower than that of CPW on OPS layers. Also, the return loss of CPW on OPS air-bridge was less than about -20 dB at measured frequency region for 2.2 mm. Therefore, this technology is very promising for extending the use of CMOS circuitry to higher RF frequencies.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.711-716
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• 1993

The mechanism for electrochemical oxidation of natural alkaloid, ${\iota}$-sparteine (SP) was studied in acetonitrile solvent. The cyclic voltammogram of SP shows two irreversible anodic peaks at +0.75 V and +1.45 V vs. Ag/AgCl (0.1M AgNO$_2$ in acetonitrile) electrode. Coulometry reveals that the number of electrons involved in each oxidation peaks is in the range of 1.2∼1.3 respectively. Neutral imine radical was produced by fast deprotonation of SP radical cation formed by oxidation of one nitrogen atom in SP. Two pathways are possible for the reaction of the neutral radical: Due to the disproportionation of the radical, SP and enamine were mainly produced. Also, the 1,2-dehydrosparteinium cation was formed as minor product through the second one electron transfer oxidation of this radical. The (+)-lupanine was produced by treatment of sparteinium cation with potassium hydroxide. We have isolated and confirmed the electrolysis products using IR, GC-MS, UV-Vis, and thin-layer spectroelectrochemical method.

• Journal of the Korean Chemical Society
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• v.47 no.2
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• pp.121-126
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• 2003

Tris(2-cyclohexylaminoethyl)amine (L) was synthesized by the Schiff base condensation reaction of tris(2-aminoethyl)amine with cyclohexanone, followed by reduction. The thermodynamic characteristics, mole ratio and formation constant of [Zn(II)-L] complex were measured by the cyclic voltammetry and isothermal titration. In the case of Zn(II), well-defined cathodic and anodic peak were obtained at -1.02V and -0.48V vs Ag/AgCl , respectively. For the [Zn(II)-L] complex, both peaks were obtained at -1.19V and -0.45V vs Ag/AgCl, respectively. In addition, the peak height gradually increases as the scan rate increases, suggesting that the currents obtained were diffusion - controlled. The mole ratio and stability constant of the complex measured cyclic voltammerty were 1:1 and logK$_f$= 5.8, respectively. And the mole ratio and stability constant of the complexe calculated by isothermal titration method was 1:1 and logK =5.4, respectively. ${\Delta}$H, ${\Delta}$G and T${\Delta}$S for the complex formation were -53.0 kJ/mol, -31.1 kJ/mol, and -21.9 J/K at 25 ${\circ}$C, respectively.

• Resources Recycling
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• v.31 no.3
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• pp.61-72
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• 2022

We investigated the electrochemical behavior of Sn (93.0 %)-Ag (4.06 %)-Cu (0.89 %) during electrolysis of Pb-free solder waste to recover tin and silver. A thin strip of the solder waste produced by high-temperature melting and casting was used as a working electrode to perform electrochemical analysis. During anodic polarization, the current peak of an active region decreased with an increase in the concentration of sulfuric acid used as an electrolyte. This resulted in the electro-dissolution of the working electrode in the electrolyte (1.0 molL^-1 sulfuric acid) for a constant current study. The study revealed that the thickening of an anode slime layer at the working surface continuously increased the electrode potential of the working electrode. At 10 mAcm^-2, the dissolution reaction continued for 25 h. By contrast, at 50 mAcm^-2, a sharp increase in the electrode potential stopped the dissolution in 2.5 h. During dissolution, silver enrichment in the anode slime reached 94.3% in the 1 molL^-1 sulfuric acid electrolyte containing a 0.3 molL^-1 chlorine ion, which was 12.7% higher than that without chlorine addition. Moreover, the chlorine enhanced the stability of the dissolved tin ions in the electrolyte as well as the current efficiency of tin electro-deposition at the counter electrode.