• 대한화학회지
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• 제36권1호
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• pp.107-112
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• 1992

rose bengal(RB)과 NaI를 각각 감응제 및 초감응제로 사용하여 광전기 화학쎌 ITO/$SnO_2$/RB, NaI, $NaClO_4$/Pt로부터 얻은 광전류는 광조사시간의 경과에 따라 비교적 서서히 감소하였다. RB 염료 용액을 광조사하여 분광학적인 방법으로 분석한 결과, 들뜬 RB 분자는 분자내에 있는 요오드에 의해 삼중항 상태, $^3RB^*$로 바뀌고 iodide를 산화시킨 후 환원된 상태가 되어 $SnO_2$ 반도체에 전자를 주입하는 것으로 확인되었다. NaI 대신 $I_2$가 포함되면 $^3RB^*$ 상태에서 전자를 주입하고 염료는 빠르게 분해되므로 광전류는 급격히 감소하였다.

• 대한화학회지
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• 제18권5호
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• pp.373-380
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• 1974

저자들에 의해서 이미 보고되어 있는 요오드화염으로부터 요오드산염$(I^-{\to}{IO_3}^-)$ 및 요오드산염으로 부터 과요오드산염$({IO_3}^-{\to}{IO_4}^-)$까지의 전해결과를 참작하여 무격막 전해조와 이산화납양극을 사용하여 요오드화염으로부터 과요오드산염$(I^-{\to}{IO_4}^-)$을 직접 전해제조하기 위한 최적 전해조건에 관하여 검토하였다. 0.5g/l의 환원방지제인 중크롬산칼륨을 함유함 1몰의 요오드화칼륨 수용액을 15A/$dm^2$의 양극전류밀도와 $60^{\circ}C$의 전해온도에서 전해한 결과, 요오드화칼륨으로 부터 과요오드산칼륨까지의 변화율 98%에서 전류효율이 84%이었다. 또한 각종 전해액중에서 이산화납 양극에 의한 분극곡선으로 부터 전극반응의 내용도 설명하였다.

• 한국세라믹학회지
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• 제50권6호
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• pp.480-484
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• 2013

Since SiOC was introduced as an anode material for lithium ion batteries, it has been studied with different chemical compositions and microstructures using various silicon based inorganic polymers. Poly(phenyl carbosilane) is a SiOC precursor with a high carbon supply in the form of the phenyl unit, and it has been investigated for film applications. Unlike any other siloxane-based polymers, oxygen atoms must be utilized in an oxidation process, and the amount of oxygen is controllable. In this study, SiOC anodes were prepared using poly(phenyl carbosilane) with different heat treatment conditions, and their electrochemical properties as an anode material for lithium ion batteries were studied. In detail, cyclic voltammetry and charge-discharge cycling behavior were evaluated using a half-cell. A SiOC anode which was prepared under a heat treatment condition at $1200^{\circ}C$ after an oxidation step showed stable cyclic performance with a reversible capacity of 360 mAh/g.

• Bulletin of the Korean Chemical Society
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• 제30권4호
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• pp.783-786
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• 2009

Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and ion chromatography(IC) were employed to analyze the thermal behavior of $Li_xCoO_2$ cathode material of lithium ion battery. The mass loss peaks appearing between 60 and 125 ${^{\circ}C}$ in TGA and the exothermic peaks with 4.9 and 7.0 J/g in DSC around 75 and 85 ${^{\circ}C}$ for the $Li_xCoO_2$ cathodes of 4.20 and 4.35 V cells are explained based on disruption of solid electrolyte interphase (SEI) film. Low temperature induced HF formation through weak interaction between organic electrolyte and LiF is supposed to cause carbonate film disruption reaction, $Li_2CO_3\;+\;2HF{\rightarrow}\;2LiF\;+\;CO_2\;+\;H_2O$. The different spectral DSC/TGA pattern for the cathode of 4.5 V cell has also been explained. Presence of ionic carbonate in the cathode has been identified by ion chromatography and LiF reported by early researchers has been used for explaining the film SEI disruption process. The absence of mass loss peak for the cathode washed with dimethyl carbonate (DMC) implies ionic nature of the film. The thermal behavior above 150 ${^{\circ}C}$ has also been analyzed and presented.

• 한국수소및신에너지학회논문집
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• 제3권2호
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• pp.25-33
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• 1992

With the aim to obtain $TiO_2$ films with an increased photorespones and absorbance in the visible region of the solar spectrum, the direct oxidation of titanium alloys were performed. In this study, $Ti-Ga_2O_3$ alloy was prepared by mixing, pressing and arc melting of appropriate amounts of titanium and $Ga_2O_3$ powder. Electrochemical measurements were performed in three electrode cell using electrolyte of 1M NaOH solution. The oxide films on $Ti-Ga_2O_3$ alloy was composed of $Ti_2O$, TiO, $TiO_2$, $Ga_2TiO_5$. The free energy efficiency (${\eta}e$) of $Ti-Ga_2O_3$ oxide films had 0.8~1.3 % and were increased with the increase of $Ga_2O_3$ content up to 10wt %. The onset potential ($V_{on}$) had -0.8V~0.9V ranges and were shifted to anodic direction with the increase of $Ga_2O_3$ content. The spectral response of Ti-$Ga_2O_3$ oxides were similar to the response of the $TiO_2$ and their $E_g$ were observed to 2.90~3.0eV. Variations of onset potential($V_{on}$) associated with electrolyte pH were -59mV/pH. This probably reflects the nature of the bonding of $OH^-$ ion to the $TiO_2$ surface, a common phenomena in the transition-metal oxides.

• 한국수소및신에너지학회논문집
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• 제26권5호
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• pp.416-422
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• 2015

Lithium Ion capacitor (LIC) is a new storage device which combines high power density and high energy density compared to conventional supercapacitors. LIC is capable of storing approximately 5.10 times more energy than conventional EDLCs and also have the benefits of high power and long cycle-life. In this study, LICs are assembled with activated carbon (AC) cathode and pre-doped graphite anode. Cathode material of natural graphite and artificial graphite kinds of MAGE-E3 was selected as the experiment proceeds. Super-P as a conductive agent and PTFE was used as binder, with the graphite: conductive agent: binder of 85: 10: 5 ratio of the negative electrode was prepared. Lithium doping condition of current density of $2mA/cm^2$ to $1mA/cm^2$, and was conducted by varying the doping. Results Analysis of Inductively Coupled Plasma Spectrometer (ICP) was used and a $1mA/cm^2$ current density, $2mA/cm^2$, when more than 1.5% of lithium ions was confirmed that contained. In addition, lithium ion doping to 0.005 V at 10, 20 and $30^{\circ}C$ temperature varying the voltage variation was confirmed, $20^{\circ}C$ cell from the low internal resistance of $4.9{\Omega}$ was confirmed.

• KSBB Journal
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• 제22권6호
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• pp.378-386
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• 2007

바이오센싱 디바이스는 본질적으로 생체인식소재와 신호전달장치로 구성된 집적화, 소형화된 분석시스템으로 많은 장점을 가지고 있다. 고민감도, 선택도, 단순성, 다성분 측정능력, 즉시측정능력 뿐 아니라 매우 작고, 고가의 장치가 필요없는 장점이 있다. 바이오센싱 디바이스의 개발을 위해서는 두 가지의 핵심요소기술이 필요하다. 이것은 생체인식소재모듈의 제작 (리셉터 개발 및 고정화기법)과 신호발생기술을 포함한 신호전달장치의 개발이다. 효소, DNA/RNA, 단백질, 세포 등의 다양한 생체인식소재가 바이오센싱 디바이스 제작을 위해 이용되어져 왔고, 신호전달시스템도 전기화학적, 광학적, mass sensitive transducer를 중심으로 매우 활발히 연구되어져 왔다. 본 고에서는 최근 개발된 바이오센싱디바이스에 대해 다루고, 향후 전망에 대해 논하고자 한다.

• 한국세라믹학회지
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• 제52권5호
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• pp.299-303
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• 2015

The electrolyte is an important component in determining the performance of Fuel Cells. Especially, investigation of the conduction properties of electrolytes plays a key role in determining the performance of the electrolyte. The electrochemical properties of Yttrium stabilized zirconia (YSZ) were measured to allow the use of this material as an electrolyte for solid oxide fuel cells (SOFC) in the temperature range of $700-1000^{\circ}C$ and in $0.21{\leq}pO_2/atm{\leq}10^{-23}$. A Hebb-Wagner polarization experimental cell was optimally manufactured; here we discuss typical problems associated with making cells. The partial conductivities due to electrons and holes for 8YSZ, which is known as a superior oxygen conductor, were obtained using I-V characteristics based on the Hebb-Wagner polarization method. Activation energies for holes and electrons are $3.99{\pm}0.17eV$ and $1.70{\pm}0.06eV$ respectively. Further, we calculated the oxygen ion conductivity with electron, hole, and total conductivity, which was obtained by DC four probe conductivity measurements. The oxygen ion conductivity was dependent on the temperature; the activation energy was $0.80{\pm}0.10eV$. The electrolyte domain was determined from the top limit, bottom limit, and boundary (p=n) of the oxygen partial pressure. As a result, the electrolyte domain was widely presented in an extensive range of oxygen partial pressures and temperatures.

• 세라미스트
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• 제23권2호
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• pp.200-210
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• 2020

Supported catalysts are at the heart of manufacturing essential chemical, agricultural and pharmaceutical products. While the longevity of such systems is critically hinged on the durability of metal nanoparticles, the conventional deposition/dispersion techniques are difficult to enhance the stability of the metal nanoparticles due to the lack of control over the interaction between metal-support. Regarding this matter, ex-solution has begun to be recognized as one of the most promising methodologies to develop thermally and chemically robust nanoparticles. By dissolving desired catalysts as a cation form into a parent oxide, fine and uniformly distributed metal nano-catalysts can be subsequently grown in situ under reductive heat treatment, which is referred to ex-solution. Over the several years, ex-solved analog has resulted in tremendous progress in the chemical-electrochemical applications due to the exceptional robustness coupled with ease synthesis. Herein, we describe the ex-solution process in detail which therein introducing the unique characteristics of ex-solved particles that distinguish them from conventionally dispersed nanoparticles. We then go through the history of science regarding the ex-solution phenomena and summarize several major research achievements which embrace the ex-solved nanoparticles to markedly promote the catalytic performances. In conclusion, we address the remaining challenges and the future perspectives of this rapidly growing field.

• 마이크로전자및패키징학회지
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• 제6권2호
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• pp.69-74
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• 1999

흑연 및 카본계 재료는 층상구조 내부로 리튬이온을 가역적으로 intercalation /deintercalation시킬 수 있는 특성을 지니고 있다. 리튬이온이 intercalation된 카본의 전기화학적 퍼텐셜은 리튬금속에 가까운 값이므로, 리튬이온전지의 부극용 재료로 많은 연구가 진행되고 있다. 본 연구에서는 petroleum pitch를 열분해시킨 후, 700~$1300^{\circ}C$의 서로 다른 온도에서 각각 3시간 동안 열처리한 카본을 사용하였다. XRD 측정 결과, 카본의 결정성은 열처리 온도와 함께 증가하였다. 충방전 특성 시험 및 전해질과 카본전극 표면 사이의 계면 반응특성은 각각 0.1C의 속도로 정전류법에 의한 충방전 시험과 순환전압전류법(CV)에 의해 평가하였으며, 열처리 온도와 충방전 횟수에 따른 용량과의 관계에 대하여 논의하였다. 가역용량(reversible capacity)은 열처리 온도가 증가함에 따라 $1000^{\circ}C$까지는 증가하지만, 그 이상의 온도에서는 약간 감소하는 경향을 보였다. 또한, 충방전 횟수가 증가할수록 충전용량은 감소하지만, 가역특성(reversibility)은 향상되었다.