• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2689-2693
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• 2012

Single-walled carbon nanotubes (SWNTs) and $C_{60}$-encapsulated SWNTs ($C_{60}@SWNTs$) are introduced to Ru-sensitized photoelectrochemical cells (PECs), and photocurrents are compared between two cells, i.e., an $RuL_2(NCS)_2$/DAPV/SWNTs/ITO cell and an $RuL_2(NCS)_2$/DAPV/$C_{60}@SWNTs$/ITO cell. [L = 2,2'-bipyridine-4,4'-dicarboxylic acid, DAPV = di-(3-aminopropyl)-viologen, and ITO = indium-tin oxide] The photocurrents are increased by 70.6% in the presence of $C_{60}@SWNTs$. To explain the photocurrent increase, the reverse-field emission method is used, i.e., $RuL_2(NCS)_2$/DAPV/SWNTs/ITO cell (or $RuL_2(NCS)_2$/DAPV/$C_{60}@SWNTs$/ITO cell) as an anode and a counter electrode Pt as a cathode in the external electric field. The improved field emission properties, i.e., ${\beta}$ (field enhancement factor) and emission currents in the reverse-field emission with $C_{60}@SWNTs$ indicate the enhancement of the PEC electric field, which implies the improvement of the electron transfer rate along with the reduced charge recombination in the cell.

• 분석과학
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• 제29권1호
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• pp.35-42
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• 2016

A new nano-composite carbon ink for the development of disposable dopamine (DA) biosensors based on screen-printed carbon electrodes (SPCEs) is introduced. The method developed uses SPCEs coupled with a tyrosinase modified nano-composite carbon ink. The ink was prepared by an “in-house” procedure with reduced graphene oxide (rGO), Pt nanoparticles (PtNP), and carbon materials such as carbon black and graphite. The rGO-PtNP carbon composite ink was used to print the working electrodes of the SPCEs and the reference counter electrodes were printed by using a commercial Ag/AgCl ink. After the construction of nano-composite SPCEs, tyrosinase was immobilized onto the working electrodes by using a biocompatible matrix, chitosan. The composite of nano-materials was characterized by X-ray photoelectron spectroscopy (XPS) and the performance characteristics of the sensors were evaluated by using voltammetric and amperometric techniques. The cyclic voltammetry results indicated that the sensors prepared with the rGO-PtNP-carbon composite ink revealed a significant improvement in electro-catalytic activity to DA compared with the results obtained from bare or only PtNP embedded carbon inks. Optimum experimental parameters such as pH and operating potential were evaluated and calibration curves for dopamine were constructed with the results obtained from a series of amperometric detections at −0.1 V vs. Ag/AgCl. The limit of detection was found to be 14 nM in a linear range of 10 nM to 100 µM of DA, and the sensor’s sensitivity was calculated to be 0.4 µAµM⁻¹cm⁻².

• Carbon letters
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• 제26권
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• pp.18-24
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• 2018

Pollution of chloride ion-reinforced concrete can trigger active corrosion processes that reduce the useful life of structures. Multifunctional materials used as a counter-electrode by electrochemical techniques have been used to rehabilitate contaminated concrete. Cement-based pastes added to carbonaceous material, fibers or dust, have been used as an anode in the non-destructive Electrochemical Chloride Extraction (ECE) technique. We studied the performance of the addition of Carbon Fiber (CF) in a cement-graphite powder base paste used as an anode in ECE of concretes contaminated with chlorides from the preparation of the mixture. The experimental parameters were: 2.3% of free chlorides, 21 days of ECE application, a Carbon Fiber Volume Fraction (CFVF) of 0.1, 0.3, 0.6, 0.9%, a lithium borate alkaline electrolyte, a current density of $4.0A/m^2$ and a cement/graphite ratio of 1.0 for the paste. The efficiency of the ECE in the traditional technique using metal mesh as an anode was 77.6% and for CFVF of 0.9% it was 90.4%, with a tendency to increase to higher percentages of the CFVF in the conductive cement-graphite paste, keeping the pH stable and achieving a homogeneous ECE in the mass of the concrete contaminated with chlorides.

• 전기화학회지
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• 제15권2호
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• pp.101-108
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• 2012

본 연구에서는 탄소를 첨가하여 $Li_3V_2(PO_4){_3}$의 낮은 전기전도도를 개선시켜서 고율 방전특성, 충 방전 사이클 특성을 향상시키는 것을 목적으로 하고 있다. 탄소 첨가제로는 글루코스와 CNT (carbon nano tube)를 사용하였으며, 탄소의 첨가 여부와 탄소 원료의 종류에 따라 합성된 $Li_3V_2(PO_4){_3}$의 구조적 그리고 전기화학적 특성에 대해 연구를 하였다. $Li_3V_2(PO_4){_3}$와 $Li_3V_2(PO_4){_3}$/C의 $Li_3V_2(PO_4){_3}$/CNT의 합성방법으로는 고상법을 이용하였다. 합성된 물질을 수소환원방법을 통하여 600, 700, 800, $900^{\circ}C$에서 소성해주었다. 합성된 물질로 양극 집전판을 제작하여 상대전극을 리튬메탈로 한 Coin 2032 cell을 만들어 전기화학적 특성분석을 진행하였다. 전지테스트는 정전류법을 이용하여 3.0~4.8 V까지 충 방전 실험을 하였다.

• 한국재료학회지
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• 제7권10호
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• pp.856-862
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• 1997

박막형 CdTe/CdS 태양전지의 배면전극(back contacts)물질로서 Cu도핑된 ZnTe 박막(ZnTe:Cu)을 전착법(electroplating)으로 제조하는 연구를 수행하였다. Sulfate계의 전해질 수용액에서 CdTe 기판과 투명전극으로 코팅된 유리(In$_{2}$O$_{3}$: Sn, ITO)기판 위에 ZnTe 박막을 코팅하는 방법으로써 potentiostat와 기판(cathode), Pt counter electrode, Ag/AgCI 표준전극으로 구성된 장치를 사용하여 pH=2.5-4, T=70-8$0^{\circ}C$, 0.02M $Zn^{2+}$ 1x$10^{-4}$M TeO$_{2}$, 0.2M $K_{2}$SO$_{4}$조건에서 -0.800 Vs~-0.975 V 범위의 전압(V$_{a}$ )에 걸쳐 실험하였다. ITO박막을 기판으로 사용하여 cyclic voltammogram을 작성한 결과 약 -0.50 V 에서 Te환원 peak이 나타났다. Auger electron spectroscopy (AES)로 조성분석한 결과 표면에서 Zn signal이 강하게 나왔고 시편의 두께에 따라 Zn의 signal감소하는 반면 Cd signal은 증가하는 것이 확인되었다. SEM 사진으로부터 ZnTe의 표면이 작은 입자 (0.2$\mu\textrm{m}$ 이하)로 구성되어 있으며 낮은 V$_{a}$ 에서는 입자가 작아지면서 조직이 치밀해짐이 관찰되었다. Optical transmission방법에 의하여 ITO기판위에 입혀진 박막의 밴드갭은 2.5 eV으로 측정되었다. 수용액중의 Cu$_{2+}$와 triethanolamine(TEA)은 산성용액에서 착물형성이 이루어지지 않았으며 1,10-phenanthroline과는 pH=2에서도 착물이 형성되었다.

• 한국전기전자재료학회논문지
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• 제18권4호
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• pp.357-362
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• 2005

The tandem solar cell composed of a dye-sensitized solar cell (DSC) and a thermoelectric generator (TEG) was designed. In such new cell, the characteristics of DSC and TEG were investigated. DSC uses the wavelength range of 380∼750 nm and has the maximum efficiency of below 10 ％. If the solar light transmitted through DSC can be converted to heat energy, TEG can generate electric energy using this heat energy. By this means, it is possible to utilize most of solar energy in the wavelength range of 350∼3000 nm for electric generation and it can be expected to obtain higher solar energy conversion efficiency exceeding the known limit of maximum efficiency. For this purpose we suggest the tandem solar cell constructed with DSC and TEG. In this structure, DSC has a carbon nanotube film as a counter electrode of DSC in order to collect the solar light and convert it to heat energy. We measured the I-V characteristics of DSC and TEG, assembled to the tandem cell. As a result, it was shown that DSC with carbon nanotube and TEG had the efficiency of 9.1 ％ and 6.2 ％, respectively. From this results, it is expected that the tandem solar cell of the new design has the possibility of enhanced conversion efficiency to exceed above 15 ％.

• Transactions on Electrical and Electronic Materials
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• 제5권3호
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• pp.89-92
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• 2004

For improving solar efficiencies, down conversion of high-energy photons to visible lights is discussed. The losses due to thermalization of charge carriers generated by the absorption of high-energy photons, can largely be reduced in a solar cell if more than one electron-hole pair can be generated per incident photon. The solar cell was constructed of dye-sensitized anatase-based TiO$_2$, approximately 30nm particle size, 6$\mu\textrm{m}$thickness, and 6${\times}$6$\textrm{mm}^2$ active area, Pt counter electrode and I$_3$$\^$-/I$_2$$\^$-/ electrolyte. After correction for losses due to light reflection and absorption by the conducting glass, the conversion of photons to electric current is practically quantitative in the plateau region of the curves. The incident photon to current conversion efficiency(IPCE) of N3 used as a dye in this work is about 80% at around 590nm and 610nm which is the emission spectrum of Eu doped LGF. The Eu doped LGF powder was prepared by conventional ceramic process, and used as a down converter for DSC after spin coated on the slide glass and fired.

• 한국재료학회지
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• 제20권9호
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• pp.483-487
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• 2010

To fabricate $TiO_2$ nanoparticle-based dye sensitized solar cells (DSSCs) at a low-temperature, DSSCs were fabricated using hydropolymer and ZnO nanoparticles composites for the electron transport layer around a low-temperature ($200^{\circ}C$). ZnO nanoparticle with 20 nm and 60 nm diameter were used and Pt was deposited as a counter electrode on ITO/glass using an RF magnetron sputtering. We investigate the effect of ZnO nanoparticle concentration in hydropolymer and ZnO nanoparticle solution on the photoconversion performance of the low temperature fabricated ($200^{\circ}C$) DSSCs. Using cis-bis(isothiocyanato)bis(2,20 bipyridy1-4,40 dicarboxylato) ruthenium (II) bis-tetrabutylammonium (N719) dye as a sensitizer, the corresponding device performance and photo-physical characteristics are investigated through conventional physical characterization techniques. The effect of thickness of the ZnO photoelectrode and the morphology of the ZnO nanoparticles with the variations of hydropolymer to ZnO ratio on the photoconversion performance are also investigated. The morphology of the ZnO layer after sintering was examined using a field emission scanning electron microscope (FE-SEM). 60 nm ZnO nanoparticle DSSCs showed an incident photon-to-current conversion efficiency (IPCE) value of about 7% higher than that of 20 nm ZnO nanoparticle DSSCs. The maximum parameters of the short circuit current density ($J_{sc}$), the open circuit potential ($V_{oc}$), fill factor (ff), and efficiency ($\eta$) in the 60 nm ZnO nanoparticle-based DSSC devices were 4.93 mA/$cm^2$, 0.56V, 0.40, and 1.12%, respectively.

• 전기학회논문지
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• 제58권12호
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• pp.2425-2430
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• 2009

Dye-sensitized solar cell(DSC) is composed of a dye-adsorbed nanoporous $TiO_2$ layer on fluorine-doped tin oxide(FTO) glass substrate, electrolyte, and platinium doped counter electrode. Among these, a dye-absorbed nanoporous $TiO_2$ layer plays an important role in the performance of the DSC because the injected electrons from excited dye molecules move through this layer. And the condition of $TiO_2$ layer such as the morphology and thickness affects on the electron movement. Therefore, the performances and the efficiency of DSC change as the thickness of $TiO_2$ layer is different. Electrochemical Impedance Spectroscopy(EIS) is the powerful analysis method to study the kinetics of electrochemical and photoelectrochemical processes occurring in the DSC especially the injected electron movements. So we analyzed the DSCs with different $TiO_2$ thicknesses by using EIS to understand the influence of the $TiO_2$ thickness to the performance of the DSC clearly. Finally, we got the EIS analysis on the DSC with different $TiO_2$ thickness from the internal resistance of the DSC, the electron life time and the amount of dye molecules.

• 한국세라믹학회지
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• 제45권6호
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• pp.331-335
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• 2008

The purpose of this study is to characterize the photo-catalytic efficiency of $TiO_2$ nanotube with respect to the distribution of anatase phase which can be changed by the annealing temperature of $TiO_2$ nanotube. $TiO_2$ nanotube was fabricated by the anodization method in the 0.5 wt% HF electrolyte. And then the $TiO_2$ nanotube was annealed at temperatures ranging from $380^{\circ}C$ to $780^{\circ}C$ in dry oxygen ambient for 2 h. For the photo-catalytic water-splitting tests, the photocurrent density was measured as a function of applied potential with a potentiostat using a Ag/AgCl reference, Pt counter electrode, and 1 M KOH electrolyte under illumination of UV by a Xe arc lamp of 1 KW. According to the UV photo-catalytic water-splitting tests, the nanotube annealed at $560^{\circ}C$ was found to show the highest photocurrent density.