• Journal of the Korean Ceramic Society
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• v.55 no.1
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• pp.50-54
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• 2018

This study investigated the long-term durability of catalyst(Pd or Fe)-infiltrated solid oxide cells for $CO_2$/steam co-electrolysis. Fuel-electrode supported solid oxide cells with dimensions of $5{\times}5cm^2$ were fabricated, and palladium or iron was subsequently introduced via wet infiltration (as a form of PdO or FeO solution). The metallic catalysts were employed in the fuel-electrode to promote $CO_2$ reduction via reverse water gas shift reactions. The metal-precursor particles were well-dispersed on the fuel-electrode substrate, which formed a bimetallic alloy with Ni embedded on the substrate during high-temperature reduction processes. These planar cells were tested using a mixture of $H_2O$ and $CO_2$ to measure the electrochemical and gas-production stabilities during 350 h of co-electrolysis operations. The results confirmed that compared to the Fe-infiltrated cell, the Pd-infiltrated cell had higher stabilities for both electrochemical reactions and gas-production given its resistance to carbon deposition.

• Journal of the Korean Electrochemical Society
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• v.22 no.3
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• pp.104-111
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• 2019

Metal halide perovskite materials are considered as promising semiconducting materials for next-generation solar cells due to their unique electrical and optical properties. Intensive progress in perovskite solar cell yielded a certified power conversion efficiency over 24%. However, most of highly efficient perovskite solar cells required Pb-based perovskite materials, which is a critical obstacle for their commercialization, and development of Pb-free perovskite materials is one of recent urgent issues in this field. In this paper, we will introduce recent research progress on Pb-free perovskite solar cells.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.12-27
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• 2018

Supercapacitors (SCs) has gained an impressive concentration by the researchers due to its advantages such as high energy and power densities, long cyclic life, rapid charge-discharge rates, low maintenance and desirable safety. Hence it has been widely utilized in energy storage and conversion devices. Among the different components of SC, electrodes play a vital role in the performances of SCs. In this review, we present the recent advances in 2-D nanostructured metal nitrides, carbides, and phosphides based materials for SC electrodes. Finally, the electrochemical stability and designing approach for the future advancement of the electrode materials are also highlighted.

• Composites Research
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• v.34 no.6
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• pp.345-349
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• 2021

The continued environmental pollution caused by fossil fuel consumption has prompted researchers around the world to develop environmentally friendly energy technologies. Electrochemical energy storage is the significant area of research in this development process, and the research significance of supercapacitors in this field is increasing. Herein, a simple electrodeposition synthetic route was explored to develop the MoP layered cathode material. The layered structure provided a highly ion-accessible surface for smooth and faster ion adsorption/desorption. After Fe was doped into MoP, the morphology of MoP changes and the electrochemical performance was significantly improved. Specific capacitance value of the binder-free FeMoP electrode was found to be 269 F g^-1 at 2 A g^-1 current density in 6 M aqueous KOH electrolyte. After adding Fe to MoP, an additional redox contribution was observed in the redox conversion from Fe³⁺ to Fe²⁺ redox pair, and the charge transfer kinetics of MoP was effectively improved. This research can provide guidance for the development of supercapacitor electrode materials through simple electrodeposition technology.

• Journal of Electrochemical Science and Technology
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• v.15 no.3
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• pp.421-426
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• 2024

Ru dye (Z-907) is a crucial photosensitizing material in dye-sensitized solar cells (DSSCs). To enhance the utilization of Ru dye's photosensitizing properties in bulk heterojunction solar cells, a method was developed to synthesize phenyl-C61-butyric acid methyl ester (PCBM) nanoparticles that are chemically linked to Ru dye. PCBM contains a methoxy (-OCH₃) group, whereas Ru dye incorporates a carboxyl group (-COOH) within its molecular structure. By exploiting these complementary functional groups, a successful bond between Ru dye and PCBM was established through an anhydride functional group. The coupling of PCBM with Ru dye results in a modification of the energy levels, yielding lower LUMO (3.8 eV) and HOMO (6.1 eV) levels, compared with the LUMO (3.0 eV) and HOMO (5.2 eV) levels of Ru dye alone. This configuration potentially facilitates efficient electron transfer from Ru dye to PCBM, alongside promoting hole transfer from Ru dye to the conducting polymer. Consequently, the bulk heterojunction solar cells incorporating this Ru dye-PCBM configuration demonstrate superior performance, with an open circuit voltage (V_oc) of 0.62 V, short circuit current (J_sc) of 0.63 mA cm^-2, fill factor (FF) of 65.6%, and a photovoltaic conversion efficiency (η) of 0.25%.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.72-80
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• 2004

Electrolytic dissolution study was carried out to evaluate the applicability of electrochemical decontamination process using a neutral salt electrolyte as a decontamination technology for the recycle or self disposal with authorization of large amount of metallic wastes contaminated with uranium compounds generated by dismantling a retired uranium conversion plant using SUS-304 and Inconel-600 specimen as the main materials of internal system components of the plant. The effects of type of neutral salt as an electrolyte, current density, and concentration of electrolyte on the dissolution of the materials were evaluated. On the basis of the results obtained through the basic inactive experiments, electrochemical decontamination tests using the specimens contaminated with uranium compounds such as $UO_2$, AUC (ammonium uranyl carbonate) and ADU (ammonium diuranate) taken from an uranium conversion plant were peformed in $Na_2SO_4$ and $NaNO_3$ solution. It was verified that the electrochemical decontamination of the dismantled metallic wastes was quite successful in $Na_2SO_4$ and $NaNO_3$ neutral salt electrolyte by reducing $\beta$ radioactivities below the level of self disposal with authorization within 10 minutes regardless of the type of contaminants and the degree of contamination.

• Journal of the Korean Electrochemical Society
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• v.9 no.1
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• pp.19-28
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• 2006

The phase-shift method for determining the Langmuir, Frumkin, and Temkin adsorption isotherms ($\theta_H\;vs.\;E$) of H for the cathodic $H_2$ evolution reaction (HER) at a Pt/0.1 M KOH solution interface has been proposed and verified using cyclic voltammetric, differential pulse voltammetric, and electrochemical impedance techniques. At the Pt/0.1 M KOH solution interface, the Langmuir and Temkin adsorption isotherms ($\theta_H\;vs.\;E$), the equilibrium constants ($K_H=2.9X10^{-4}mol^{-1}$ for the Langmuir and $K_H=2.9X10^{-3}\exp(-4.6\theta_H)mol^{-1}$ for the Temkin adsorption isotherm), the interaction parameters (g=0 far the Langmuir and g=4.6 for the Temkin adsorption isotherm), the rate of change of the standard free energy of $\theta_H\;with\;\theta_H$ (r=11.4 kJ $mol^{-1}$ for g=4.6), and the standard free energies (${\Delta}G_{ads}^{\circ}=20.2kJ\;mol^{-1}$ for $k_H=2.9\times10^{-4}mol^{-1}$, i.e., the Langmuir adsorption isotherm, and $16.7<{\Delta}G_\theta^{\circ}<23.6kJ\;mol^{-1}$ for $K_H=2.9\times10^{-3}\exp(-4.6\theta_H)mol^{-1}$ and $0.2<\theta_H<0.8$, i.e., the Temkin adsorption isotherm) of H for the cathodic HER are determined using the phase-shift method. At intermediate values of $\theta_H$, i.e., $0.2<\theta_H<0.8$, the Temkin adsorption isotherm ($\theta_H\;vs.\;E$) corresponding to the Langmuir adsorption isotherm ($\theta_H\;vs.\;E$), and vice versa, is readily determined using the constant conversion factors. The phase-shift method and constant conversion factors are useful and effective for determining the Langmuir, Frumkin, and Temkin adsorption isotherms of intermediates for sequential reactions and related electrode kinetic and thermodynamic data at electrode catalyst interfaces.

• Journal of the Korean Electrochemical Society
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• v.19 no.2
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• pp.39-44
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• 2016

Oxygen reduction reaction in the fuel cell (ORR) plays a dominant role in the overall reaction. In addition, the low compatibility between the membrane and the binder consisted of different materials, greatly reduces the efficiency of the fuel cell performance. In view of these two problems, geometrically modified copolymers with 9.9_Bis (4-hydroxyphenyl) were synthesized via condensation reaction instead of conventional biphenol and were adopted as hydrocarbon ionomer binders. By utilizing these binders, two kinds of MEAs using fluorinated Nafion membrane and hydrocarbon based membrane were manufactured in order to electrochemical performance evaluation. With current-voltage curves, there was no significant difference in the 0.6 V when two types of membrane were applied. Also, tafel slope became considerably lower as compared to the Nafion membrane. Thus, it is determined that the new hydrocarbon binder is expected to contribute the improvement in performance of fuel cells.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.86-86
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• 2012

The new approaches for silicon solar cell of new concept have been actively conducted. Especially, solar cells with wire array structured radial p-n junctions has attracted considerable attention due to the unique advantages of orthogonalizing the direction of light absorption and charge separation while allowing for improved light scattering and trapping. One-dimenstional semiconductor nano/micro structures should be fabricated for radial p-n junction solar cell. Most of silicon wire and/or pillar arrays have been fabricated by vapour-liquid-solid (VLS) growth because of its simple and cheap process. In the case of the VLS method has some weak points, that is, the incorporation of heavy metal catalysts into the growing silicon wire, the high temperature procedure. We have tried new approaches; one is electrochemical etching, the other is noble metal catalytic etching method to overcome those problems. In this talk, the silicon pillar formation will be characterized by investigating the parameters of the electrochemical etching process such as HF concentration ratio of electrolyte, current density, back contact material, temperature of the solution, and large pre-pattern size and pitch. In the noble metal catalytic etching processes, the effect of solution composition and thickness of metal catalyst on the etching rate and morphologies of silicon was investigated. Finally, radial p-n junction wire arrays were fabricated by spin on doping (phosphor), starting from chemical etched p-Si wire arrays. In/Ga eutectic metal was used for contact metal. The energy conversion efficiency of radial p-n junction solar cell is discussed.

• Journal of Korean Society on Water Environment
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• v.32 no.3
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• pp.297-302
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• 2016

Microbial electrochemical technology (MET) has recently been studied to improve the efficiency of a traditional anaerobic digestion (AD). The purpose of this study was to investigate the impact of MET in the system when MET was combined with traditional AD (i.e., AD-MET). Electrodes used in the MET were Cu coated graphite electrodes. They were supplied with a voltage of 0.3 V. AD started to generate methane in 80 days. But AD-MET started to generate methane from the initial operation after the system started. It was observed that AD-MET reached steady state faster and produced higher methane yield than AD. During the steady state, the average daily methane productions in AD and AD-MET were 2.3L/d and 4.9L/d, respectively. Methane yields were 0.07-CH₄/g‧CODre in AD and 0.25L-CH₄/g‧CODre in AD-MET. In AD-MET, the production rates of total volatile fatty acids (TVFAs) and soluble chemical oxygen demand (SCOD) were 0.12 mg TVFAs/mg VS‧d and 0.35 mg SCOD/mg VS‧d, respectively. They were significantly (p < 0.05) higher than those in AD. However, the concentrations of residual TVFAs in both systems were not significantly (p > 0.05) different from each other, confirming that methane conversion in AD-MET was greater than that in AD.