• Journal of Electrochemical Science and Technology
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• 제7권1호
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• pp.76-81
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• 2016

An anatase TiO₂ nanotube array (NTA) was fabricated by anodization and successive heat treatments. When the anatase TiO₂ NTA was cathodically polarized, its color changed to blue, and it could be used as an electrochemically active anode for an oxygen evolution reaction (OER) in alkaline water electrolysis. The structure of the blue anatase TiO₂ NTA was controlled by the anodization conditions and its catalytic activity increased with an increase of the surface area. The activity of the blue anatase TiO₂ NTA gradually reduced with the continued OER because of the partial oxidation of Ti³⁺ to Ti⁴⁺. However, an intermittent cathodic regeneration process could significantly slow its reduction rate. The blue anatase TiO₂ NTA could be an alternative anode for alkaline water electrolysis.

• 한국세라믹학회지
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• 제51권4호
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• pp.278-282
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• 2014

Due to high ionic conductivity and favorable oxygen electrocatalysis, doped $Bi_2O_3$ systems are promising candidates as solid oxide fuel cell cathode materials. Recently, several researchers reported reasonably low cathode polarization resistance by adding electronically conducting materials such as (La,Sr)$MnO_3$ (LSM) or Ag to doped $Bi_2O_3$ compositions. Despite extensive research efforts toward maximizing cathode performance, however, the inherent catalytic activity and electrochemical reaction pathways of these promising materials remain largely unknown. Here, we prepare a symmetrical structure with identically sized $Y_{0.5}Bi_{1.5}O_3$/LSM composite electrodes on both sides of a YSZ electrolyte substrate. AC impedance spectroscopy (ACIS) measurements of electrochemical cells with varied cathode compositions reveal the important role of bismuth oxide phase for oxygen electrocatalysis. These observations aid in directing future research into the reaction pathways and the site-specific electrocatalytic activity as well as giving improved guidance for optimizing SOFC cathode structures with doped $Bi_2O_3$ compositions.

• 전기화학회지
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• 제18권3호
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• pp.107-114
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• 2015

전기화학적인 방법으로 나노구조를 지니는 금 표면을 형성하는 방법에 관한 연구는 최근 많은 연구자들의 관심을 끌고 있다. 첨가된 금 전구체를 전기화학 석출에 의해 나노구조 금 표면을 형성하는 기존 연구와는 달리, 본 연구에서는 전구체를 외부에서 첨가하지 않고 금 표면을 전기 화학적으로 변형하여 표면에 나노구조체를 형성하는 방법을 제시하였다. $Br^-$이 존재하는 인산 완충용액 전해질 하에서 금 전극에 산화전위를 가해 주면 산화 용해된 금은 $Br^-$과 결합하여 전극 표면에 전구체를 형성하는데, 이렇게 형성된 표면상의 전구체를 연이어 환원시켜 주면 실시간으로 나노구조 금 표면을 형성하는 것이 가능함을 보였다. 전극에 가해주는 전위와 시간의 조절이 전극 표면에 형성되는 금 나노구조의 모양에 미치는 영향을 체계적으로 관찰한 결과 독특한 척추 모양의 금 나노구조가 형성이 되었다. 척추 모양의 금 나노구조는 표면증강 라만 분광 활성이 높은 것으로 나타났다. 본 연구에서 제시된 방법은 전구체 없이 전기화학적으로 금 전극 표면을 변형시키는 새로운 방법으로 금 나노구조 형성에 관한 연구에 도움이 될 것으로 기대한다.

• Korean Chemical Engineering Research
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• 제61권1호
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• pp.52-57
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• 2023

본 연구는 고성능 유연 전극 소재 개발을 위한 기초 연구로, 유연 전극 소재의 성능을 향상시키기 위해 금속 산화물 CuO nanoparticles (CuO NPs)를 도입하여 탄소나노튜브 섬유(carbon nanotube fiber; CNT fiber) 표면 위에 전기화학적 증착시켜 CNT fiber/CuO NPs 전극을 합성하고, 이를 전기화학적 비효소 글루코스 센서에 적용하였다. 이 전극의 표면 및 elemental composition 분석은 주사전자 현미경(SEM)과 에너지분산형 분광분석법(EDS)을 이용하였으며, 전극의 전기화학적 특성 및 글루코스에 대한 센싱 성능은 순환전압 전류법(CV)과 전기화학 임피던스법(EIS), 시간대전류법(CA)을 통해 조사되었다. CNT fiber/CuO NPs 전극은 CNT fiber의 우수한 특성과 함께 CuO NPs 도입에 따른 약 2.6배의 유효 전극면적(active surface area) 증가 효과와 11배 정도의 향상된 전자전달(electron transfer) 특성 및 우수한 전기적 촉매 활성(electrocatalytic activity) 덕분에 CNT fiber 유연 기반 전극의 글루코스 검출에 대한 성능이 개선되었다. 따라서, 본 연구를 기반으로 다양한 나노구조체를 활용한 고성능 유연 전극 소재 개발이 기대된다.

• Carbon letters
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• 제14권2호
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• pp.117-120
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• 2013

In this study, an electro-catalyst of Pt nanoparticles supported by polypyrrole-functionalized graphene (Pt/PPy-reduced graphene oxide [RGO]) is reported. The Pt nanoparticles are deposited on the PPy-RGO composite by chemical reduction of H2PtCl6 using NaBH4. The presence of graphene (RGO) caused higher activity. This might have been due to increased electro-chemically accessible surface areas, increased electronic conductivity, and easier charge-transfer at polymer-electrolyte interfaces, allowing higher dispersion and utilization of the deposited Pt nano-particles. Microstructure, morphology and crystallinity of the synthesized materials were investigated using X-ray diffraction and transmission electron microscopy. The results showed successful deposition of Pt nano-particles, with crystallite size of about 2.7 nm, on the PPy-RGO support film. Catalytic activity for methanol electro-oxidation in fuel cells was investigated using cyclic voltammetry. The fundamental electrochemical test results indicated that the electro-catalytic activity, for methanol oxidation, of the Pt/PPy-RGO combination was much better than for commercial catalyst.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1992년도 학술발표회 초록집
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• pp.39-40
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• 1992

This paper dealt with the manufacturing of binary alloy catalyst and showed simple electrochemical method for determing catalytic activity of oxygen reduction in acid or alkaline electrolyte. The catalyst was prepared by impregnating transition metal salts on platinum or silver particles adsorbed before on carbon paper substrate. The electrochemical characteristics of the catalysts was investigated with carbon paper electrode or PTFE-boned porous electrode and then cathodic current densities and tafel slopes were compared. As a result, of all binary catalysts utilized in this work, Pt-Fe, Pt-Mo showed better oxygen reduction activity than pure platinum catalyst in acid electrolyte and Ag-Fe, Ag-Pt, and Ag-Ni-Bi-Ti catalyst did than pure silver catalyst in alkaline electrolyte. The current density of Pt-Fe electrode in acid electrolyte was one and half times higher than that of Pt electrode(~500mA/$\textrm{cm}^2$ at 0.7VvsNHE).

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권6호
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• pp.505-509
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• 2005

For the purpose of developing a direct label-free electrochemical detection system, we have systematically investigated the electrochemical signatures of each step in the preparation procedure, from a bare gold electrode to the hybridization of label-free complementary DNA, for the streptavidin-modified electrode. For the purpose of this investigation, we obtained the following pertinent data; cyclic voltammogram measurements, electrochemical impedance spectra and square wave voltammogram measurements, in $Fe(CN)_6^{3-}/Fe(CN)_6^{4-}$ solution (which was utilized as the electron transfer redox mediator). The oligonucleotide molecules on the streptavidin-modified electrodes exhibited intrinsic redox activity in the ferrocyanide-mediated electrochemical measurements. Furthermore, the investigation of electrochemical electron transfer, according to the sequence of oligonucleotide molecules, was also undertaken. This work demonstrates that direct label-free oligonucleotide electrical recognition, based on biofunctional streptavidin-modified gold electrodes, could lead to the development of a new biosensor protocol for the expansion of rapid, cost-effective detection systems.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.243.1-243.1
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• 2010

Devices based on nanomaterials platforms are emerging as a powerful tool for ultrasensitive sensors for the direct detection of biological and chemical species. In this talk, we will report the preparation and the full characterization of electrochemical polymerization of biopolymers platforms and nano-structure formation for electrochemical detection of enzymatic activity and toxic compound in electrolyte for biosensor applications. Formation of an electroactive polymer film of two different compounds has been quantified by observing new redox peak at higher potentials in cyclic voltammogram measurements. RCT value of at various biopolymer concentration based hybrid films has been obtained from electrochemical impedance spectroscopy analysis and possible mechanism for formation of complexes during electrochemical polymerization on conducting substrates has been investigated. Biosensors developed based on these hybrid biopolymers have very high sensitivity.

• Journal of Electrochemical Science and Technology
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• 제8권4호
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• pp.307-313
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• 2017

In this paper we report an electrochemical sensor based on ZnO-functionalized graphene oxide nanocomposite (ZnO-GO) for the sensitive determination of the cabergoline. Cabergoline electrochemical behaviors were investigated by cyclic voltammetry (CV), chronoamperometry (CHA) and differential pulse voltammetry (DPV). The modified electrode shows electrocatalytic activity toward cabergoline oxidation in phosphate buffer solution (PBS) (pH 7.0) with a reduction of the overpotential of about 180 mV and an increase in peak current. The DPV data showed that the obtained anodic peak currents were linearly dependent on the cabergoline concentrations in the range of $1.0-200.0{\mu}M$, with the detection limit of $0.45{\mu}M$. The prepared electrode was successfully applied for the determination of cabergoline in real samples.

• Carbon letters
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• 제14권2호
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• pp.126-130
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• 2013

In this study, we present a more electrochemically enhanced electrode using activated carbon (AC)-sulfur (S) composite materials, which have high current density. The morphological and micro-structure properties were investigated by transmission electron microscopy. Quantity of sulfur was measured by thermogravimetric analysis analysis. The electrochemical behaviors were investigated by cyclic voltammetry. As a trapping carbon structure, AC could provide a porous structure for containing sulfur. We were able to confirm that the AC-S composite electrode had superior electrochemical activity.