• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.562-564
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• 2002

In recent years, environments of our globe has been getting worse as a result of rapid growth of socioeconomic activities. The global environmental issues of acid rain, green house effect and ozone depletion are caused by various chemical pollutants, emitted from industries, automobiles and home. Most of these pollutants are produced by combustion processes. CO2 as a chief criminal of the greenhouse effect is a main combustion product of fossil fuels. Development of solid-state electrochemical devices for detecting CO2 is demonstrated based on various combination of solid electrolytes and auxiliary sensing materials. The object of this research is to develop various sensor performance for solid electrolyte gas sensor, and to test gas sensor performance manufactured. So we try to present a guidance for developing potential type gas sensor. We concentrated on development of manufacturing process and performance test.

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.204-210
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• 2014

The nitrogen doped porous carbon nanopolyhedrons (N-PCNPs)-multi-walled carbon nanotubes (MWCNTs) hybrid materials were prepared for the first time. Combining the excellent catalytic activities, good electrical conductivities and high surface areas of N-PCNPs and MWCNTs, the simultaneous determination of hydroquinone (HQ), catechol (CC) and resorcinol (RE) with good analytical performance was achieved at the N-PCNPs-MWCNTs modified electrode. The linear response ranges for HQ, CC and RE are 0.2-455 ${\mu}M$, 0.7-440 ${\mu}M$ and 3.0-365 ${\mu}M$, respectively, and the detection limits (S/N = 3) are $0.03{\mu}M$, $0.11{\mu}M$ and $0.38{\mu}M$, respectively. These results are much better than that obtained on some graphene or CNTs-based materials modified electrodes. Furthermore, the developed sensor was successfully applied to simultaneously detect HQ, CC and RE in the local river water samples.

• Bulletin of the Korean Chemical Society
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• 제25권6호
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• pp.833-837
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• 2004

DeniLite$^{TM}$ laccase immobilized platinum electrode was used for amperometric detection of hydroquinone (HQ) and homogentisic acid (HGA) by means of substrate recycling. In case of HQ, the obtained sensitivity is 280 nA/ ${\mu}$M with linear range of 0.2-35 ${\mu}$M ($r^2$ = 0.998) and detection limit (S/N = 3) of 50 nM. This high sensitivity can be attributed to chemical amplification due to the cycling of the substrate caused by enzymatic oxidation and following electrochemical regeneration. In case of HGA, the obtained sensitivity is 53 nA/ ${\mu}$M with linear range of 1-50 $[\mu}M\;(r^2$ = 0.999) and detection limit of 0.3 ${\mu}$M. The response times ($t_{90%}$) are about 2 seconds for the two substrates and the long-term stability is 60 days for HQ and around 40-50 days for HGA with retaining 80% of initial activities. The very fast response and the durable long-term stability are the principal advantages of this sensor. pH studies show that optimal pH of the sensor for HQ is 6.0 and that for HGA is 4.5-5.0. This shift of optimal pH towards acidic range for HGA can be attributed to the balance between enzyme activity and accessibility of the substrate to the active site of the enzyme.

• 대한화학회지
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• 제53권6호
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• pp.683-692
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• 2009

본 연구는Isoniazid의 hydrazone으로부터 유도된 새로운 리간드를 갖는 몇 가지 새로운 니켈(II) 착물의 합성에 대해 보고한다. 착물의 조성은 [$Ni(L)_2X_2$] 또는 $[Ni(L)_3](ClO_4)_2$ {L = N-isonicotinamidofurfuraldimine(INH-FFL), N-isonicotinamido-3',4',5'-trimethoxybenzaldimine (INH-TMB) 또는 N-isonicotinamido-cinnamalidene (INH-CIN) 및 X=$Cl^-$, ${NO_3}^-$, $NCS^-$ 또는 $CH_3COO^-$} 이다. 리간드 hydrazone 은 카보닐 산소와 아조메틴 질소를 통해서 중성의 두 자리 (N및 O주개) 리간드로 작용한다. 육면체 구조를 갖는 새로운 착물들은 원소분석, 분자질량분석, 자화율, 열분석과 적외선 및 전기적 스펙트럼을 이용한 전기화학 및 분광학적 연구를 통해 규명하였다. 니트로벤젠($PhNO_2$) 에서의 전기 전도성 측정에 의하면 [$Ni(L)_2X_2$] 및 $[Ni(L)_3](ClO_4)_2$ 착물들은 각각 비전해질 및 1:2전해질임을 알았다. 착물의 기하구조를 알기 위한 열적특성도 역시 연구되었다. 니켈(II) 착물 및 약간의 표준 약품의 항균성 및 항진균성 또한 연구되었고, 이를 통해 착물이 적당한 향균성 활동을 하는 것을 알 수 있었다.

• Rapid Communication in Photoscience
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• 제2권2호
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• pp.42-45
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• 2013

Natural photosynthesis utilizes solar energy to convert carbon dioxide and water to energy-rich carbohydrates. Substantial use of sunlight to meet world energy demands requires energy storage in useful fuels via chemical bonds because sunlight is intermittent. Artificial photosynthesis research focuses the fundamental natural process to design solar energy conversion systems. Nicotinamide adenine dinucleotide ($NAD^+$) and $NADP^+$ are ubiquitous as electron transporters in biological systems. Enzymatic, chemical, and electrochemical methods have been reported for NADH regeneration. As photochemical systems, visible light-driven catalytic activity of NADH regeneration was carried out using platinum nanoparticles, molecular rhodium and cobalt complexes in the presence of triethanolamine as a sacrificial electron donor. Pt nanoparticles showed photochemical NADH regeneration activity without additional visible light collector molecules, demonstrating that both photoactivating and catalytic activities exist together in Pt nanoparticles. The NADH regeneration of the Pt nanoparticle system was not interfered with the reduction of $O_2$. Molecular cobalt complexes containing dimethylglyoxime ligands also transfer their hydrides to $NAD^+$ with photoactivation of eosin Y in the presence of TEOA. In this photocatalytic reaction, the $NAD^+$ reduction process competed with a proton reduction.

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.1973-1978
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• 2014

Here, we present a facile method to synthesize Pt nanoparticles (NPs) and graphene composite materials (Pt/G) via vacuum filtration. Anodic aluminum oxide (AAO) templates were used to separate Pt/G composite and liquid phase. This method can be used to easily tune the mass ratio of Pt NPs and graphene. Pt NPs, graphene, and carbon nanotubes (CNTs) as building blocks were characterized by a variety of techniques such as scanning electron microscopy, UV-Vis spectroscopy, and Raman spectroscopy. We compared the electrocatalytic activities of Pt/G with Pt NP and CNT films (Pt/CNT) by cyclic voltammetry (CV), CO oxidation, and methanol oxidation. Pt/G was much more stable than pure Pt films. Also, Pt/G had better electrochemical activity, CO tolerance and methanol oxidation than Pt/CNT loaded with the same amount of Pt NPs due to the better dispersion of Pt NPs on graphene flakes without aggregation. We further synthesized Au@Pt disk/G and Pt nanorods/G to determine if our synthetic method can be applied to other NP shapes such as nanodisks and nanorods, for further electrocatalysis studies.

• 분석과학
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• 제23권2호
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• pp.165-171
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• 2010

글루코스 옥시다아(GOx)제 고정화 바이오센서를 두 가지 방법으로 제조 하였다. 첫 번째 방법은 폴리(maleic anhydride) 그래프트 탄소나노튜브(PMAn-g-MWCNT) 전극에 감마선 조사법으로 제조 된 Au 나노입자를 물리적으로 흡착시킨 후, GOx을 고정화 시켜 바이오센서를 제조한 경우이고, 다른 하나는 PMAn-g-MWCNT 전극에서 Au 이온을 전기화학적으로 환원시켜 Au 나노입자를 코팅 시키고, 그 위에 GOx을 고정화 시켜 바이오센서를 제조 한 경우이두. 제조된 바이오센서에 대해 효율 평가를 수행 하였는데, 물리적 흡착법으로 제조된 전극의 경우 검출 범위는 $30\;{\mu}M\sim100\;{\mu}M$이었으며, 검출한계는 $15\;{\mu}M$이었다. 또한 ascorbic acid와 uric acid에 대한 검출한계는 7.6%이었다. 물리적으로 Au 나노입자가 흡착된 전극의 경우가 글루코스 측정에 매우 우수한 전극임을 확인 하였다.

• 대한화학회지
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• 제59권2호
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• pp.142-147
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• 2015

Two new chitosan derivatives, polyamine grafted chitosan copolymers have been synthesized for corrosion protection of carbon steel in acidic medium. First, methyl acrylate graft chitosan copolymer (CS-MAA) was prepared by the reaction of chitosan (CS) and methyl acrylate (MAA) via the Michael addition reaction. Then, CS-MAA was reacted with ethylene diamine (EN) and triethylene tetramine (TN) respectively to synthesize ethylene diamine grafted chitosan copolymer (CS-MAA-EN) and triethylene tetramine grafted chitosan copolymer (CS-MAA-TN), and the structures were characterized by Fourier-transform infrared spectroscopy (FT-IR). At last, the corrosion inhibition activities on Q235 carbon steel were investigated by using gravimetric measurements, metallographic microscope, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The compounds CS-MAA-EN and CS-MAA-TN show an appreciable corrosion inhibition property against corrosion of Q235 carbon steel in 5% HCl solution at $25^{\circ}C$. It has been observed that CS-MAA-EN shows greater corrosion inhibition efficiency than CS-MAA-TN. The inhibition efficiency of CS-MAA-EN was close to 90% when the mass fraction concentration was 0.2%~0.3%; the inhibition efficiency of CS-MAA-TN was close to 85% when the mass fraction concentration was 0.02%. The present work provided very promising results in the preparation of green corrosion inhibitors.

• 한국수소및신에너지학회논문집
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• 제25권4호
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• pp.436-442
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• 2014

$LaCoO_3$ powders synthesized by Pechini process were pulverized by planetary ball-milling to decrease particle size and characterized as a catalyst in alkaline solution for oxygen reduction and evolution reaction (ORR & OER). The changes of physical properties, such as particle size distribution, surface area and electric conductivity, were analyzed as a function of ball-milling time. Also, the variations of the crystal structure and surface morphology of ball-milled powders were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electrochemically catalytic activities of the intrinsic $LaCoO_3$ powders decreased with increasing ball-milling time, but their electrochemical performance as an electrode improved by the increase of the surface area of the powder.

• 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.