• Journal of Electrochemical Science and Technology
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• 제7권1호
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• pp.27-32
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• 2016

Although the time dependences of the electrocatalytic activities of Pt and Pd nanoparticles during electrochemical operations have been widely studied, the time dependences under nonpolarized conditions have never been investigated in depth. This study reports the changes in the electrocatalytic activities of Pt and Pd nanoparticles with aging in air and in solution. Pt (or Pd) nanoparticle-modified electrodes are obtained by adsorbing citrate-stabilized Pt (or Pd) nanoparticles on amine-modified indium-tin oxide (ITO) electrodes, or by electrodeposition of Pt (or Pd) nanoparticles on ITO electrodes. The electrocatalytic activities of freshly prepared Pt and Pd nanoparticles in the oxygen reduction reaction slowly decrease with aging. The electrocatalytic activities decrease more slowly in solution than in air. An increase in surface contamination may cause electrocatalytic deactivation during aging. The electrocatalytic activities of long-aged Pt (or Pd) nanoparticles are significantly enhanced and recovered by NaBH₄ treatment.

• Journal of Electrochemical Science and Technology
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• 제10권2호
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• pp.170-176
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• 2019

Alkanethiol self-assembled monolayers (SAMs) and partially ferrocene (Fc) modifications were applied to the Au ultramicroelectrode (UME) rather than to standard sized electrodes with dimension of millimeters. The electron transfer mediation of the SAMs and Fc modified Au UME was investigated by using a p-aminophenol (p-AP) oxidation reaction via cyclic voltammetry. The electrocatalytic p-AP oxidation at the SAMs and Fc modified Au UME showed a much larger electrocatalytic current density than that at the standard sized electrode due to the fast mass transfer rate at the UME.

• Journal of Electrochemical Science and Technology
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• 제6권3호
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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.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.316-319
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• 2006

There is a worldwide interest in the development and commercialization of Polymer Electrolyte Membrane Fuel Cells (PEMFCs) for vehicular and stationary applications. One of the major objectives is the reduction of loaded electrode materials, which is comprise of the Pt-based noble metals. In this paper, a novel chemical strategy is described for the preparation and characterization of carbon-supported and surface-alloys, which were prepared by using a successive reduction process. After preparing Au colloid nanoparticles, the deposition of Au colloid nanoparticles occurred spontaneously in the carbon black-dispersed aqueous solution. Then nano-scaled active materials were formed on the surface of carbon-supported Au nanoparticles. The structural and electrochemical analyses indicate that the active materials were deposited on the surface of Au nanoparticles selectively and that an at toying process occurred during the successive reducing process The carbon-supported & surface-alloys showed the higher electrocatalytic activity than those of the particle-alloys and commercial one (Johnson-Matthey) for the reaction of methanol and formic acid oxidation. The increased electrocatalytic activity might be attributed to the effective surface structure of surface-alloys, which have a high utilization of active materials for the surface reaction of electrode.

• 신재생에너지
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• 제2권4호
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• pp.64-69
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• 2006

There is a worldwide interest in the development and commercialization of polymer electrolyte membrane fuel cells [PEMFCs] for vehicular and stationary applications. One of the major objectives is the reduction of loaded electrode materials, which is comprise of the Pt-based noble metals. In this paper, a novel chemical strategy is described for the preparation and characterization of carbon-supported and surface-alloys, which were prepared by using a successive reduction process. After preparing Au colloid nanoparticles, the supporting of Au colloid nanoparticles occurred spontaneously in the carbon black-dispersed aqueous solution. Then nano-scaled active materials were formed on the surface of carbon-supported Au nanoparticles. The structural and electrochemical analyses indicate that the active materials were deposited on the surface of Au nanoparticles selectively and that an alloying process occurred during the successive reducing process. The carbon-supported & surface-alloys showed the higher electrocatalytic activity than those of the particle-alloys and commercial one [Johnson-Matthey] for the reaction of methanol and formic acid oxidation. The increased electrocatalytic activity might be attributed to the effective surface structure of surface-alloys, which have a high utilization of active materials for the surface reaction of electrode.

• 한국결정성장학회지
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• 제31권2호
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• pp.96-101
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• 2021

Developing effective and earth-abundant electrocatalyst for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is critical for the commercialization of a water splitting system. In particular, the overpotential of the OER is relatively higher than the HER, and thus, it is considered that one of the important methods to enhance the performance of the electrocatalyst is to reduce the overpotential of the OER. We report effects of incorporation of metalloid into Ni(OH)2 microcrystal on electrocatalytic activities. In this study, Te incorporated Ni(OH)2 (��Te-Ni(OH)2) were grown on three-dimensional porous NF by a facile solvothermal method with �� = 1, 3 and 5. Homogeneous microplate structure on the NF was clearly observed for the Ni(OH)2/NF and ��Te-Ni(OH)2/NF samples. However, irregular and collapsed nanostructures were found on the surface of nickel foam when Te precursor ratio is (��) over 3. Electrocatalytic OER properties were analysed by Linear sweep voltammetry (LSV) and Electrochemical impedance spectroscopy (EIS). The amount of Te incorporation used in the electrocatalytic reaction was found to play a crucial role in improving catalytic activity. The optimum Te amount (��) introduced into the Ni(OH)2/NF was discussed with respect to their OER performance.

• Journal of Electrochemical Science and Technology
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• 제3권1호
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• pp.24-28
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• 2012

The electrocatalytic activities and surface roughness of indium-tin-oxide (ITO) electrodes have been investigated after thermal treatment at 100, 150, or $200^{\circ}C$ for 30 min, 2 h, or 8 h. To check electrocatalytic activities, the electrochemical behavior of four electroactive species (p-hydroquinone, $Ru(NH_3){_6}^{3+}$, ferrocenemethanol, and $Fe(CN){_6}^{4-}$) has been measured. The electron transfer rate for p-hydroquinone oxidation and ferrocenemethanol oxidation increases with increasing the incubation temperature and the incubation period of time, but the rate for $Ru(NH_3){_6}^{3+}$ is similar irrespective of the incubation temperature and period because $Ru(NH_3){_6}^{3+}$ undergoes a fast outer-sphere reaction. Overall, the electrocatalytic activities of ITO electrodes increase with increasing the incubation temperature and period. The surface roughness of ITO electrodes increases with increasing the incubation temperature, and the thermal treatment generates many towering pillars as high as several tens of nanometer.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.459-462
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• 2006

Formic acid recently attracted attention as an alternative fuel for direct liquid fuel cells(DLFCs) due to its high theoretical open circuit voltage(1.45V). In this paper, a novel chemical strategy is described for the preparation and characterization of carbon-supported and surface-alloys, which were prepared by using a successive reduction process. After preparing Au colloid nanoparticles, the deposition of Au colloid nanoparticles occurred spontaneously in the carbon black-dispersed aqueous solution. Then nano-scaled Pt layer were formed on the surface of carbon-supported Au nanoparticles. The Au-Pt[x] showed the higher electrocatalytic activity than those of the particle-alloys and commercial one (Johnson-Matthey) for the reaction of formic acid oxidation when the mass-specific currents were compared. The increased electrocatalytic activity might be attributed to the effective surface structure of surface-alloys, which have a high utilization of active materials for the surface reaction of electrode.

• 한국결정성장학회지
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• 제33권2호
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• pp.78-82
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• 2023

The oxygen evolution reaction (OER) is the primary challenge in renewable energy storage technologies, specifically electrochemical water splitting for hydrogen generation. We report effects of Mo doping into Ni layered double hydroxide (Ni-LDH) microcrystal on electrocatalytic activities. In this study, Mo doped Ni-LDH were grown on three-dimensional porous nicekl foam (NF) by a facile solvothermal method. Homogeneous LDH structure on the NF was clearly observed. However, the surface microstructure of the nickel foam began to be irregular and collapsed when Mo precursor is doped. Electrocatalytic OER properties were analyzed by Linear sweep voltammetry (LSV) and Electrochemical impedance spectroscopy (EIS). The amount of Mo doping used in the electrocatalytic reaction was found to play a crucial role in improving catalytic activity. The optimum Mo amount introduced into the Ni LDH was discussed with respect to their OER performance.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2000년도 추계 학술대회
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• pp.181-188
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• 2000

The electrocatalytic reduction of NAD$^{＋}$ using diaphorase was studied. methyl viologen (MV$^{2＋}$) mediator between an electrode and the enzyme. Steady-state currents could be obtained under the conditions of slow scan rate, low MV$^{2＋}$concentration, and high NAD$^{＋}$ concentration as the electrode reaction was converted to an electrochemical-catalytic (EC') reaction. The biomecular rate constant for the reaction of the reduced methyl viologen with the oxidized diaphorase was estimated as 7.5$\times$10$^3$M$^{-1}$ s$^{-1}$ from the slope of the current versus [MV$^{2＋}$] plot. And the optimal concentrations of diaphorase, MV$^{2＋}$ and NAD$^{＋}$ in the mediated electrocatalytic reduction of NAD$^{＋}$ were decided by applying the cyclic voltammetry. The optimal concentrations of the species were obtained by finding the conditions which gave the highest and steady-state current at a gold-amalgam electrode. The highest and steady-state catalytic current was achieved under the conditions of 1.5 U/ml diaphorase, 0.2 mM MV$^{2＋}$, and 4.8 mM NAD$^{＋}$ at the scan rate of 2 mV s$^{-1}$ , suggesting that the rate of the electrocatalytic reation is the higest under the former conditions. The electrochemical procedure under the conditions of 1.5 U/ml diaphorase,0.2 mM MV$^{2＋}$, and 4.8 mM NAD$^{＋}$ was used favorably to drive an enzymatic reduction of pyruvate to D-lactate.