• 한국재료학회지
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• 제10권12호
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• pp.831-837
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• 2000

고분자전해질형 연료전지에서 촉매의 활성을 증가시키기 위하여 기존에 사용되고 있는 백금과 전이금속인 chromium, nickel과의 합금을 제조하였다. XRD를 이용하여 합금의 구조가 $33^{\circ}$에서 superlattice line을 가지고 있는 것으로 보아 face centered cubic 구조를 가진 ordered alloy로 이루어졌다는 것을 알 수 있었다. 열처리 온도가 증가할수록 합금의 입자 크기는 증가하였으며, 결정 격자 상수는 감소하였다. 전지성능테스트, cyclic voltammogram 등을 통하여 mass activity, specific activity, Tafel slope, 개회로 전압을 측정한 결과, 합금촉매의 활성이 순수한 백금촉매보다 크게 향상되었음을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제30권8호
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• pp.1733-1737
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• 2009

A new cathode material based on Li$Ni_{0.8}Co_{0.15}Al_{0.05}O_2$ (LNCA)/polyaniline (Pani) composite was prepared by in situ self-stabilized dispersion polymerization in the presence of LNCA. The materials were characterized by fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Electrochemical properties including galvanostatic charge-discharge ability, cyclic voltammetry (CV), capacity, cycling performance, and AC impedance were measured. The synthesized LNCA/Pani had a similar particle size to LNCA and exhibited good electrochemical properties at a high C rate. Pani (the emeraldine salt form) interacts with metal-oxide particles to generate good connectivity. This material shows good reversibility for Li insertion in discharge cycles when used as the electrode of lithium ion batteries. Therefore, the Pani coating is beneficial for stabilizing the structure and reducing the resistance of the LNCA. In particular, the LNCA/Pani material has advantageous electrochemical properties.

• Journal of Electrochemical Science and Technology
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• 제1권2호
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• pp.75-80
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• 2010

We report Co-tetramethoxyphenylporphyrin on carbon particles (Co-TMPP/C) as a non-Pt catalyst for tri-iodide reduction in dye-sensitized solar cells (DSSCs). The presence of well-dispersed carbon and cobalt source in the catalyst surface is confirmed by transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray analysis. In the C 1s, Co 2p, and N 1s peaks measured by X-ray photoelectron spectroscopy, the C-N, Co-$N_4$, and N-C are assigned to the component at 285.7, 781.8, and 401 eV, respectively. Especially, the Co-TMPP/C shows improved current density, diffusion coefficient, and charge-transfer resistance in the ${I_3}^-/I^-$ redox reaction compared to conventional catalysts. Furthermore, in the DSSCs performance, the Co-TMPP/C shows increased short circuit current density, higher open circuit voltage, and improved cell efficieny in comparison with Pt/C.

• 한국재료학회지
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• 제26권5호
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• pp.250-257
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• 2016

Octahedral $Co_3O_4$/carbon nanofiber (CNF) composites are fabricated using electrospinning and hydrothermal methods. Their morphological characteristics, chemical bonding states, and electrochemical properties are used to demonstrate the improved photovoltaic properties of the samples. Octahedral $Co_3O_4$ grown on CNFs is based on metallic Co nanoparticles acting as seeds in the CNFs, which seeds are directly related to the high performance of DSSCs. The octahedral $Co_3O_4$/CNFs composites exhibit high photocurrent density ($12.73mA/m^2$), superb fill factor (62.1 %), and excellent power conversion efficiency (5.61 %) compared to those characteristics of commercial $Co_3O_4$, conventional CNFs, and metallic Co-seed/CNFs. These results can be described as stemmnig from the synergistic effect of the porous and graphitized matrix formed by catalytic graphitization using the metal cobalt catalyst on CNFs, which leads to an increase in the catalytic activity for the reduction of triiodide ions. Therefore, octahedral $Co_3O_4$/CNFs composites can be used as a counter electrode for Pt-free dye-sensitized solar cells.

• 분석과학
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• 제11권6호
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• pp.460-468
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• 1998

$SOPDH_2$, $SNDH_2$, $EBNH_2$, $PBNH_2$ Schiff base 리간드와 이들의 [$Co(II)(SND)(H_2O)_2$], [$Co(II)(SOPD)(H_2O)_2$], [$Co(II)(EBN)(H_2O)$], [$Co(II)(PBN)(H_2O)$] 착물들을 합성하였다. Co(II) 착물들에서 Schiff base 리간드와 Co(II)의 몰 결합 비는 1:1로 주어졌으며 6배위 결합을 합성하였다. Co(II) 착물이 수식된 유리질 탄소전극을 사용하여 1 M KOH 수용액에서 산소 환원 반응을 순환 전압전류법으로 알아보았다. Schiff base Co(II) 착물이 수식된 전극에서의 산소의 환원 전류는 알몸 유리질 탄소전극에서 보다 더 증가하였고 환원 전위는 양전위 방향으로 더 이동하였다. 산소 환원 반응에 관여한 전자수와 교환 속도 상수 값은 순환 전압전류 곡선으로부터 구하였다. 산소 환원 반응경로는 최종 생성물이 $H_2O_2$로 가는 $2e^-$ 전이 반응을 나타내었으며 촉매가 수식된 전극에서의 교환 속도 상수는 알몸전극의 값에 비해 약 2~10배 정도 증가하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.356.2-356.2
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• 2014

Spin Transfer Torque (STT) is of great interest in data writing scheme for the Magneto-resistive Random Access Memory (MRAM) using Magnetic Tunnel Junction (MTJ). Scalability for high density memory requires ferromagnetic electrodes having the perpendicular magnetic easy axis. We investigated CoZr as the ferromagnetic electrode. It is observed that interfacial magnetic anisotropy is preferred perpendicular to the plane with thickness dependence on the interfaces with Pt layer. The anisotropy energy (Ku) with thickness dependence shows a change of magnetic-easy-axis direction from perpendicular to in-plane around 1.2 nm of CoZr. The interfacial anisotropy (Ki) as the directly related parameters to switching and thermal stability, are estimated as $1.64erg/cm^2$ from CoZr/Pt multilayered system.

• 한국환경과학회지
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• 제11권2호
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• pp.131-137
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• 2002

The chemical behavior and properties on the redox state of environmental pollutant has been investigated by electrochemical methods. We carried out to measure the variations in the redox reaction of differential pulse polarogram and cyclic voltammogram. The results observed the influences on redox potential and current of various factors with temperature and pH. These were established factors as the effect of the redox reaction. It can be clearly recognized that the electrode reaction are from qusi-reversible to irreversible processes. Also, it was mixing with reaction current controlled. The bits-phenol A in the waste water was made to compound with cobalt ion and it take away from the separation into compound. The $Co(BPA)_2$ compound was not found to be dissociation in waste water. However, this compound is avery unstable(K=1.02) and for a while, it was to be a dissociation. Therefore, we believed that it was likely to a toxic substance.

• 전기화학회지
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• 제12권4호
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• pp.335-341
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• 2009

Organic-inorganic hybrid sol-gel matrices were used as hosts for chloro (5, 10, 15, 20-tetraphenylporphyrinato) cobalt (III) (Co[TPP]Cl), a known ionophore for nitrite. The sol-gel precursor was prepared by the reaction of (3-isocyanopropyl) triethoxysilane with 1,4-butanediol. An appropriate amount of the anion-exchanger, tridodecylmethylammonium chloride (TDMAC) and the plasticizer, tributylphosphate (DBP) were used as membrane additives. On mixing with an acidic catalyst, the sol-state precursors slowly gelled, yielding a membrane in which the active components, Co[TPP]Cl and TDMAC, were encapsulated. The performances of the sol-gel membrane-based electrodes were compared to those of Co[TPP]Cl-based poly(vinyl chloride) (PVC) membrane electrodes. Membranes with a molar ratio of Co[TPP]Cl: TDMAC (1 : 0.1) showed reasonable response slopes toward nitrite. The response slopes were typically 53 mV/decade between $10^{-5.4}$ and $10^{-1.0}\;M$. Selectivities toward nitrite over hydrophilic and small anions such as chloride were somewhat inferior to those observed with PVC-based membranes, but selectivities over lipophilic anions were quite similar. Reduced asymmetry potentials due to protein adsorption were found to occur with the sol-gel matrix relative to PVC-based films when the sensors were employed as a detector in flow-through configuration.

• 분석과학
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• 제15권2호
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• pp.97-101
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• 2002

Co(II)착물들을 세자리 Schiff base-NOIPH, 네자리 Schiff base-$NOTDH_2$ 및 $TNBPH_4$ 로부터 합성하였으며, 이 착물들의 산화-환원 과정 mecanism을 지지 전해질로서 0.1 M TBAP를 포함한 DMF용액에서 작업전극으로 유리질 탄소전극을 사용하여 순환 전압-전류법과 펄스 차이 전압-전류법에 의해서 알아 보았다. [Co(II)$(NOIP)_2$]와 [Co(II)(NOTD)$(H_2O)_2$] 착물의 환원은 Co(III)/Co(II)의 반응이 비가역적으로 진행되고 Co(II)/Co(I)의 반응이 준가역적으로 진행되는 일전자의 2단계반응이 확산 지배적으로 일어났다. 반면에 [$Co(II)_2$(TNBP)] 착물의 환원반응은 $Co(II)_2$가 Co(II)/Co(I)로 진행되는 준가역적이며 일전자 일단계의 반응이 확산지배적으로 일어났다.

• 한국표면공학회지
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• 제55권1호
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• pp.32-37
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• 2022

In a carbon-zero social atmospher, research is underway to reduce the use of fossil fuels. Interest in cleaner energy sources and their storage system is growing, and among them, research on effective energy storage is being actively conducted. Energy storage system(ESS) can be divided into secondary batteries, fuel cells, and capacitors, and the superiority of energy density of secondary batteries has a dominent influence on the ESS market. However, as problems with secondary batteries, charge/discharge speed, safety, and deterioration of electrodes are being highlighted. In this study, an electrode for supercapacitor with superior charge/discharge speed and specific capacitance is manufactured. The manufactured spinel nickel cobalt electrodes had specific capacitances of 1018.8 F/g, 690.8 F/g, and 475.1 F/g at 1 A/g in 1 M KOH electrolyte, and shows a performance retention rate of 77.48%, 63.30%, and 58.16% after 2000cycles at 7 A/g.