• Journal of Electrochemical Science and Technology
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• v.10 no.3
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• pp.313-320
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• 2019

In this study, cobalt diselenide ($CoSe_2$) and the composites ($CoSe_2@RGO$) of $CoSe_2$ and reduced graphene oxide (RGO) were synthesized by a facile hydrothermal reaction using cobalt ions and selenide source with or without graphene oxide (GO). The formation of $CoSe_2@RGO$ composites was identified by analysis with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and scanning electron microscopy (SEM). Electrochemical analyses demonstrated that the $CoSe_2@RGO$ composites have excellent catalytic activity for the reduction of $I_3{^-}$, possibly indicating a synergetic effect of $CoSe_2$ and RGO. As a consequence, the $CoSe_2@RGO$ composites were applied as a counter electrode in DSSC for the reduction of redox couple electrolyte, and exhibiting the comparable power conversion efficiency (7.01%) to the rare metal platinum (Pt) based photovoltaic device (6.77%).

• Journal of Electrochemical Science and Technology
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• v.9 no.4
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• pp.260-275
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• 2018

The corrosion inhibition of cast iron in 1 M HCl by Phenanthroline (Phen) was investigated using potentiodynamic polarization (PDP) curves, electrochemical impedance spectroscopy (EIS), surface analysis and theoretical calculations. It is found that Phen exhibits high inhibition activity towards the corrosive action of HCl and its adsorption obeys the Langmuir adsorption isotherm model. The results showed that inhibition efficiency increases with Phen concentration up to a maximum value of 96% at 1.4 mM, and decreases slightly with the increase in temperature. The free adsorption energy value indicates that Phen adsorbs on cast iron surface in 1 M HCl via a simultaneous physisorption and chemisorption mechanism. Scanning electron microscopy (SEM) micrographs, atomic force microscopy (AFM) and FTIR analysis confirmed the formation of a protective film on cast iron surface, resulting in the improvement of its corrosion resistance in the studied aggressive solution. Quantum chemical calculations at the DFT level were achieved to correlate electronic structure parameters of Phen molecules with their adsorption mode.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.209-213
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• 2003

Self-assembled monolayers of spinach ferredoxin immobilized to Au substrate were investigated. Ferredoxin was immobilized onto the chemically modified Au surface. Au surface were modified to $NH^{3+}$ by the 4-aminothiphenol and then modified by N-succinimidyl-3-[2-pyridyldithio]propionate for the ferredoxin immobilization. To verify the electrochemical activity of immobilized ferredoxin molecules, cyclic-voltammetry was measured. Finally, to verify the memory application, reduction potential was applied to ferredoxin molecules as for the write function, and then current transients observed from the reduced ferredoxin layers were measured for the read function of memory applications.

• Journal of Electrochemical Science and Technology
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• v.6 no.3
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• pp.88-94
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• 2015

In this study we investigated the electrocatalytic oxidation of saccharose on conductive polymer- Nickel oxide modified graphite electrodes based on the ability of anionic surfactants to form micelles in aqueous media. This NiO modified electrode showed higher electrocatalytic activity than Ni rode electrode in electrocatalytic oxidation of saccharose. The anodic peak currents show linear dependency with the square root of scan rate. This behavior is the characteristic of a diffusion controlled process. Under the CA regime the reaction followed a Cottrellian behavior and the diffusion coefficient of saccharose was found in agreement with the values obtained from CV measurements.

• Journal of Microbiology and Biotechnology
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• v.14 no.5
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• pp.1043-1046
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• 2004

The stability and electrochemical properties of a self-assembled layer of spinach ferredoxin on a quartz substrate and on a highly oriented pyrolytic graphite electrode were investigated. To fabricate the ferredoxin self-assembly layer, dimyristoylphosphatidylcholine was first deposited onto a substrate for ferredoxin immobilization. Surface analysis of the ferredoxin layer was carried out by atomic force microscopy to verify the ferredoxin immobilization. To verify ferredoxin immobilization on the lipid layer and to confirm the maintenance of redox activity, absorption spectrum measurement was carried out. Finally, cyclic-voltammetry measurements were performed on the ferredoxin layers and the redox potentials were obtained. The redox potential of immobilized ferredoxin had a formal potential value of -540 mV. It is suggested that the redox-potential measurement of self-assembled ferredoxin molecules could be used to construct a biosensor and biodevice.

• Journal of Electrochemical Science and Technology
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• v.3 no.4
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• pp.178-184
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• 2012

A porous nickel (P-Ni) substrate was prepared by selective leaching of zinc from pressed pellets containing powders of Ni & Zn in 4 M NaOH solution. Anodic deposition of manganese oxide onto the porous Ni substrate ($MnO_x$/P-Ni) formed nano-flakes of manganese oxide layers as revealed in SEM studies. Pseudocapacitance of this oxide electrode was evaluated by cyclic voltammetry (CV) and chronopotentiometry (CHP) in 2 M NaOH solution. The specific capacitance of the Mn oxide electrode was as high as 1515 F $g^{-1}$, which was ten times higher than Mn oxide deposited on a flat Ni-ribbon. 80% of capacity was retained after 200 charge/discharge cycles. The system showed no loss of activity in dry form over period of days. The impedance studies indicated highly conducting $MnO_x$/P-Ni substance and the obtained specific capacitance from impedance data showed good agreement with the charge/discharge measurements.

• Journal of Electrochemical Science and Technology
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• v.5 no.2
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• pp.45-48
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• 2014

$TiO_2$ nanoparticles (NPs) with a diameter of 100 nm were synthesized by a simple hydrothermal route at $220^{\circ}C$ and then processed for a possible alternate cathode catalyst material in the lithium-oxygen batteries. It was found that when $TiO_2$ nanoparticles were utilized as cathodes, substantial improvements in the discharge capacity, cycle ability, rate capability and low overpotential were observed. This can be attributed to its high catalytic activity and large surface area.

• Journal of Electrochemical Science and Technology
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• v.5 no.4
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• pp.105-108
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• 2014

$TiO_2$ nanoparticles (NPs) with a diameter of 100 nm were synthesized by a simple hydrothermal route at $220^{\circ}C$ and then processed for a possible alternate cathode catalyst material in the lithium-oxygen batteries. It was found that when $TiO_2$ nanoparticles were utilized as cathodes, substantial improvements in the discharge capacity, cycle ability, rate capability and low overpotential were observed. This can be attributed to its high catalytic activity and large surface area.

• Journal of Electrochemical Science and Technology
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• v.4 no.3
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• pp.89-92
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• 2013

Poly (3,4-ethylenedioxythiophene) (PEDOT) polymers with different electric conductivities were synthesized directly on a FTO substrate via a chemical polymerization method and applied as a platinum (Pt)-free counter electrode for dye-sensitized solar cells (DSSCs). The catalytic properties of the PEDOT as a function of electrical conductivity were studied using cyclic voltammograms, J-V measurements and impedance spectroscopy. The PEDOT counter electrode with around 340 S/cm conductivity exhibited the best performance as a counter electrode for tri-iodide reduction. The ability to modulate catalytic activity of PEDOT with changes in conductivity shows one of promising routes for developing new counter electrode of Pt-free DSSCs.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.728-734
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• 1996

To obtain the relation in the electrochemical reduction of $CO_2$ in aqueous $KHCO_3$ colution between an activity for the product and the nature of Cu electrode, the electrode surface was characterized by using two methods: X-ray photoelectron spectroscopy (XPS) and photoelectron emission (PE) measurement. Electrolyses were performed with Cu electrodes pretreated in several ways. The distribution of the products changed drastically with electrolysis time and the pretreatment method. The features in XPS spectra were closely connected with the product distribution. The oxide film at the electrode surface was gradually reduced to bare Cu metal with electrolysis time, resulting in a variation of the product distribution. PE was measured by verying the wavelength of incident light at several temperatures. The dependence of PE on the measurement temperature changed greatly before and after electrolysis.