• Rapid Communication in Photoscience
• /
• v.2 no.3
• /
• pp.79-81
• /
• 2013

A novel method of fabricating polythiophene-gold nanoparticle composite film electrodes for photoelectric conversion is demonstrated. The method includes electrodeposition of gold and electropolymerization of 2,2'-bithiophene onto an indium-tin-oxide (ITO) electrode. First, electrodeposition of gold onto the ITO electrode was carried out with various repetition times of pulsed applied potential (0.25 s at -2.0 V vs. Ag/AgCl) in an aqueous solution of $HAuCl_4$. Significant progress of the number density of deposited gold nanoparticles was confirmed from scanning electron micrographs, from 4 (1 time) to 25% (15 times). Next, electropolymerization of 2,2'-bithiophene onto the above ITO electrode was performed under controlled charge condition (+1.4 V vs. Ag wire, 15 $mC/cm^2$). Structural characterization of as-fabricated films were carried out by spectroscopic and electron micrographic methods. Photocurrent responses from the sample film electrodes were investigated in the presence of electron acceptors (methyl viologen and oxygen). Photocurrent intensities increased with increasing the density of deposited gold nanoparticles up to ~10%, and tended to decrease above it. It suggests that the surplus gold nanoparticles exhibit quenching effects rather than enhancement effects based on localized electric fields induced by surface plasmon resonance of the deposited gold nanoparticles.

• Journal of the Korean Chemical Society
• /
• v.33 no.1
• /
• pp.37-45
• /
• 1989

Voltammetric behavior of alkylammonium ion was studied in the absence and in the presence of crown ether in propylene carbonate as solvent. The peak potentials and the peak currents, their dependency on the concentrations, the reversibility of the electrode reactions are described. In the presence of crown ether chemical reaction might be preceeded before the electron-transfer process, the peak potential for the reduction shifts at the negative direction as the concentration of crown ether to the electrolyte solution increases. The addition of crown ether(20mM 18CR6)to the electrolyte solution made it possible to determine voltammetrically the dialkylammonium ions($Me_2NH^{+}_{2};O.6{\sim}0.8mM$) in the presence of the monoalkylammonium ions ($EtNH^{+}_{3} ;1.6mM$) and the monoalkylammonium ions ($EtNH^{+}_{3} ; 0.5{\sim}2.5mM$) in the presence of the dialkylammonium ions($Me_2NH^{+}_{2};0.5mM$)

• Analytical Science and Technology
• /
• v.12 no.1
• /
• pp.34-39
• /
• 1999

Estrone such as estriol and estradiol can not be determined by votammetric methods, because these are electrochemically inactive in the potential windows for mercury drop electrode. Nitro-derivatives of estrone are electro active and nitration of estrone is accomplished by heating the solution involving estrone and sodium nitrite in a water-bath at $100^{\circ}C$ for 30 min. Such nitro-derivatives are determined directly by voltammetry. The electrochemical behavior for nitrated estrone was investigated by cyclic voltammetry. The trace estrone was determinated by differential pulse adsorptive cathodic stripping voltammetry. Nitrated estrone gives a well defined voltammetric wave at ca. - 0.61 V (vs. Ag/AgCl electrode). The electrochemical reaction was irreversible process in sodium borate buffer at pH 11 and nitrated estrone was strongly adsorbed on the surface of mercury electrode. The optimal experimental conditions for the determination of nitrated esterone were found to be 0.05 M sodium nitrate, 0.01 M sodium borate, pH 11.0, and an accumlation potential of 0.10 V (vs. Ag/AgCl). The detection limit was as low as $1{\times}10^{-9}M$ for estrone with 2 min accumulation time.

• Journal of the Korean Chemical Society
• /
• v.37 no.10
• /
• pp.874-880
• /
• 1993

Spectrophotometric enzymatic analysis and amperometric enzymatic analysis for the determinations of glucose and ethanol were studied utilizing glucose oxidase (GO) and alcohol oxidase (AO), respectively, which commonly consume $O_2$ and produce $H_2O_2$. For the determination of glucose, $H_2O_2$ were coupled to $K_4Fe(CN)_6$ via peroxidase producing $K_3Fe(CN)_6$ whose absorbance was measured at 418 nm or whose diffusion current was measured on the glassy carbon electrode at an applied potential of -55 mV vs. Ag/AgCl (sat. KCl) reference electrode. Amperometric analysis was 1000 times more sensitive as well as 10 times better in the linear concentration range than spectrophotometric analysis. For the determination of ethanol, AO only was used for the enzymatic analysis, since $K_3Fe(CN)_6$ was completely disappeared as soon as AO was added. Either rate of $H_2O_2$ produced was amperometrically measured at +0.900 V or rate of $O_2$ consumed was measured at -0.500 V vs. Ag/AgCl(sat. KCl) reference electrode.

• Analytical Science and Technology
• /
• v.20 no.5
• /
• pp.393-399
• /
• 2007

In principle, the blood galactose level may be determined conveniently with a strip-type biosensor similar to that for glucose. In this study, we describe the development of a disposable galactose biosensor strip for point-of-care testing. The sensor strip is constructed with screen-printed carbon paste electrode (SPCE) and sample amount (< $100{\mu}L$). The developed strip the galactose level in less than 90 s using bienzymatic system of galactose oxidase (GAO) and horseradish peroxidase (HRP). The effects of pH, mediator (1,1-ferrocenedimethanol) concentration, ratio of enzymes, and applied potential were determined preliminarily with glassy carbon electrodes, and optimized further with the strip-type electrodes. The sensor exhibits linear response in the range of $0{\sim}400{\mu}M$ ($r^2$ = 0.997, S/N = 3). Since a low working potential, in principle, the fabricated disposable galactose biosensor has -100 mV (vs. Ag/AgCl), it is applied for the detection of galactose, interfering responses from common interferents such as ascorbic acid, uric acid and acetaminophen could be minimized. The sensor has been used to determine the total galactose level in standard samples with satisfactory reproducibility (CV = 5 %).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05b
• /
• pp.43-46
• /
• 2002

We have investgated the photoisomerization using light irradiation 8A5H-phospholipid( L-$\alpha$-dimyristoylphosphatidylcholine[DMPC], L-$\alpha$-dilauroylphosphatidylcholine[DLPC]mixture LB film accumulated by monolayer on an ITO. We determined electrochemical measurement by using cyclic voltammetry with a three-electrode system, An Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode measured in $NaClO_{4}$ solution at a variable concentration and variable number layers LB film. The scan rate was 100mV/s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.459-462
• /
• 2001

We have investgated the photoisomerization using light irradiation 8A5H LB film accumulated by monolayer and three layers on an ITO. We determined electrochemical measurement by using cyclic voltammetry with a three-electrode system, An Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode measured in 0.1mol/L NaClO$_4$ solution. The scan rate was 100mv/s.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.370-373
• /
• 2003

A search for a new phosphor composition of excellent performance in systematic ways requires lots of research efforts, and often turns out to be very timeconsuming and difficult. Thus, usually practical ways are taken to improve the performance of phosphors. A few examples of practical surface treatments on phosphors such as $In_2O_3$ coating on $ZnGa_2O_4:Mn$, phosphoric acid treatment on ZnS:Ag,Cl, and base KOH treatment with ultrasonication on ZnS:Ag,Cl are presented. The reasons for the improvement of luminescence intensity or degradation properties after these treatments are discussed based upon careful analyses on the surface of the phosphors and a proposed model on charge carriers generated by electron beam excitation.

• Proceedings of the KIEE Conference
• /
• 2001.07c
• /
• pp.1911-1913
• /
• 2001

전위차 측정형 바이오 센서는 기준전극에 대한 센서 전극의 전기화학적 전위를 정확하게 측정하여야 하므로 기준전극의 안정성이 매우 중요하다. 기준전극의 전위는 전해질 용액 내의 염소 음이온 농도에 영향을 받으나 다행히도 혈액 내의 염소 음이온 농도는 거의 변화가 없으므로 혈액 속에서의 은/염화은 기준전극의 전위도 거의 변화가 없다. 본 연구에서는, 사진석판 (Photolithography) 공정을 이용하여 실리콘 표면 및 다공질 실리콘 표면에 은/염화은 박막 기준전극을 제작하고 시료 용액에서의 drift, 안정성, 재현성 등에 대한 특성을 고찰하였고, SEM, AES, EDX 스펙트럼 등을 이용하여 전극의 표면을 분석하였다. 시료 용액의 염소 음이온 농도를 $10^{-4}$M에서 1M까지 변화시켜가며 기준 전극의 전위를 측정한 결과 약 50mV/pCl의 기울기를 얻었으며 이것은 Nernst식을 잘 따르는 결과이다.

• Macromolecular Research
• /
• v.17 no.9
• /
• pp.714-717
• /
• 2009

Hole transport copolymers consisting of 3,4-ethylenedioxythiophene (EDOT) and N-4-butylphenyl-N,N-diphenylamine (BTPA) were synthesized by oxidative coupling reaction using $FeCl_3$ as an oxidant. These copolymers showed good solubility and their thin films showed sufficient morphological stability. The copolymers showed an absorption maximum around 320 nm. Copolymers had an oxidation peak at approximately $1.03{\sim}1.14V$ versus the Ag/AgCl electrode. The hole mobility increased with increasing portion of the EDOT unit. The hole mobility of the copolymer containing 57% of the EDOT unit showed the highest mobility of $3{\times}10^{-5}cm^2/V{\cdot}s$.