• Title, Summary, Keyword: Metal electrode

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Synthesis of Tridentate-Schiff Base Co(II) Complexes and Their Electrochemical Properties (세자리 Schiff Base Co(Ⅱ) 착물의 합성과 전기화학적 성질)

  • Chae, Hui Nam;Choe, Yong Guk
    • Journal of the Korean Chemical Society
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    • v.42 no.4
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    • pp.422-431
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    • 1998
  • Tridentate Schiff base ligands such as $SIPH_2,\;SIPCH_2,\;HNIPH_2,\;and\; HNIPCH_2$ were prepared by the reaction of salicylaldehyde and 2-hydroxy-l-naphthaldehyde with 2-aminophenol and 2-amino-p-cresol. The structures and properties of ligands and their Co(II) complexes were investigated by elemental analysis, $^1H$NMR, IR, UV-visible spectra, and thermogravimetric analysis. The molar ratio of Schiff base to the metal of complexes was found to be 1:1. Co(II) complexes were contemplated to be hexa-coordinated octahedral configuration containing three water molecules. The redox process of ligands and complexes in DMSO solution containing 0.1 M TBAP as a supporting electrolyte were investigated by cyclic voltammetry with glassy carbon electrode. The redox process of the tridentate Schiff base ligands was totally irreversible. The redox process of Co(II) complexes were irreversible and one electron processes by two steps in diffusion controlled reaction. The reduction potential of the Co(II) complexes was shifted to the positive direction in the order [Co(Ⅱ)$(HNIPC)(H_2O)_3$]>[Co(Ⅱ)$(HNIP)(H_2O)_3$]>[Co(II)$(SIPC)(H_2O)_3$]>[Co(Ⅱ)$(SIP)(H_2O)_3], and their dependence on ligands were not so high.

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Photoelectrochemical Characteristics for Cathodic Electrodeposited Cu2O Film on Indium Tin Oxide (음극전착법을 이용한 Cu2O 막의 광전기 화학적 특성)

  • 이은호;정광덕;주오심;최승철
    • Journal of the Korean Ceramic Society
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    • v.41 no.3
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    • pp.183-189
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    • 2004
  • Cuprous oxide (Cu$_2$O) thin films are cathodically deposited on Indium Tin Oxide (ITO) substrate. The as-deposited films were heat-treated at 30$0^{\circ}C$ to obtain Cu$_2$O. After the heat treatment, the film was changed from Cu metal into Cu$_2$O phase. The phase, morphology and photocurrent density of the films were dependent on the preparation conditions of deposition time, applied voltage, and the duration of heat treatment. The Cu$_2$O films were characterized by X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM). The apparent grain size of the films formed by the normal method was larger than those grown by the pulse method. The CU$_2$O film what was deposited at -0.7 V for 300 sec and then, calcined at 30$0^{\circ}C$ for 1 h showed the predominant photocurrent density of 1048 $\mu$A/$\textrm{cm}^2$. And the stability of Cu$_2$O electrodes were improved with chemically deposited TiO$_2$ thin films on Cu$_2$O.

The Effect of NH3 Concentration during Co-precipitation of Precursors from Leachate of Lithium-ion Battery Positive Electrode Active Materials (리튬이차전지 양극활물질의 암모니아 침출액에서 공침법에 의한 활물질 전구체의 합성에 대한 암모니아 농도의 영향)

  • Park, Sanghyuk;Ku, Heesuk;Lee, Kyoung-Joon;Song, Jun Ho;Kim, Sookyung;Sohn, Jeongsoo;Kwon, Kyungjung
    • Journal of the Korean Institute of Resources Recycling
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    • v.24 no.6
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    • pp.9-16
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    • 2015
  • In a recycling scheme of spent lithium ion batteries, a co-precipitation process for the re-synthesis of precursor is essential after the leaching of lithium ion battery scraps. In this study, the effect of ammonia as impurity during the co-precipitation process was investigated in order to re-synthesize a precursor of Ni-rich cathode active material $LiNi_{0.6}Co_{0.2}Mn_{0.2}O_2$ (NCM 622). As ammonia concentration increases from 1 M (the optimum condition for synthesis of the precursors based on 2 M of metal salt solution) to 4 M, the composition of obtained precursors deviates from the designed composition, most notably for Ni. The Ni co-precipitation efficiency gradually decreases from 100% to 87% when the concentration of ammonia solution increases from 1 M to 4 M. Meanwhile, the morphological properties of the obtained precursors such as sphericity, homogeneity and size distribution of particles were also investigated.

Spectral Induced Polarization Response Charaterization of Pb-Zn Ore Bodies at the Gagok mine (가곡광산 연-아연 광체의 광대역유도분극 반응 특성)

  • Shin, Seungwook;Park, Samgyu;Shin, Dongbok
    • Geophysics and Geophysical Exploration
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    • v.17 no.4
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    • pp.247-252
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    • 2014
  • Gagok Mine, which is skarn deposits, includes sulfide minerals such as sphalerite, galena, chalcopyrite, and pyrrhotite. To explore these minerals, spectral induced polarization (SIP) is relatively effective compared to other geophysical exploration methods because there is a strong IP effect caused by electrode polarization. In the SIP, the chargeability related to sulfide mineral contents and the time constant related to the grain size of the minerals are obtained. For this reason, we aim to compare difference in the mineralized characteristics between two orebodies in the Gagok Mine by using the chargeability and the time constant. For this study, we sampled ores from the south of Wolgok orebody and the north of Sungok orebody. In order to recognize the mineralization characteristics, the metal content of the samples was measured by a potable XRF and the SIP data of the samples were acquired by using a laboratory SIP measurement system. As a result, the metals in the samples such as Pb, Zn, Cu, and Fe were detected by the portable XRF measurement. In particular, the Fe and Zn contents were far higher than the other metals. The Fe and the Zn were caused by the sphalerite and the pyrrhotite through microscopy. The Wolgok orebody had higher sulfide mineral contents than the Sungok orebody and the result corresponded with the chargeability result. However, we considered that the Sungok orebody had a larger sulfide mineral grain size than the Wolgok orebody because the time constant of the Sungok orebody was larger.

Donor-π-Acceptor Type Diphenylaminothiophenyl Anthracene-mediated Organic Photosensitizers for Dye-sensitized Solar Cells

  • Heo, Dong Uk;Kim, Sun Jae;Yoo, Beom Jin;Kim, Boeun;Ko, Min Jae;Cho, Min Ju;Choi, Dong Hoon
    • Bulletin of the Korean Chemical Society
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    • v.34 no.4
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    • pp.1081-1088
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    • 2013
  • Two new metal-free organic dyes bridged by anthracene-mediated ${\pi}$-conjugated moieties were successfully synthesized for use in a dye-sensitized solar cell (DSSC). A N,N-diphenylthiophen-2-amine unit in these dyes acts as an electron donor, while a (E)-2-cyano-3-(thiophen-2-yl)acrylic acid group acts as an electron acceptor and an anchoring group to the $TiO_2$ electrode. The photovoltaic properties of (E)-2-cyano-3-(5-((10-(5-(diphenylamino)thiophen-2-yl)anthracen-9-yl)ethynyl)thiophen-2-yl)acrylic acid (DPATAT) and (E)-2-cyano-3-(5'-((10-(5-(diphenylamino)thiophen-2-yl)anthracen-9-yl)ethynyl)-2,2'-bithiophen-5-yl)acrylic acid (DPATABT) were investigated to identify the effect of conjugation length between electron donor and acceptor on the DSSC performance. By introducing an anthracene moiety into the dye structure, together with a triple bond and thiophene moieties for fine-tuning of molecular configurations and for broadening the absorption spectra, the short-circuit photocurrent densities ($J_{sc}$), and open-circuit photovoltages ($V_{oc}$) of DSSCs were improved. The improvement of $J_{sc}$ in DSSC made of DPATABT might be attributed to much broader absorption spectrum and higher molecular extinction coefficient (${\varepsilon}$) in the visible wavelength range. The DPATABT-based DSSC showed the highest power conversion efficiency (PCE) of 3.34% (${\eta}_{max}$ = 3.70%) under AM 1.5 illumination ($100mWcm^{-2}$) in a photoactive area of $0.41cm^2$, with the $J_{sc}$ of $7.89mAcm^{-2}$, the $V_{oc}$ of 0.59 V, and the fill factor (FF) of 72%. In brief, the solar cell performance with DPATABT was found to be better than that of DPATAT-based DSSC.

Characteristic of Ru Thin Film Deposited by ALD

  • Park, Jingyu;Jeon, Heeyoung;Kim, Hyunjung;Kim, Jinho;Jeon, Hyeongtag
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.78-78
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    • 2013
  • Recently, many platinoid metals like platinum and ruthenium have been used as an electrode of microelectronic devices because of their low resistivity and high work-function. However the material cost of Ru is very expensive and it usually takes long initial nucleation time on SiO2 during chemical deposition. Therefore many researchers have focused on how to enhance the initial growth rate on SiO2 surface. There are two methods to deposit Ru film with atomic layer deposition (ALD); the one is thermal ALD using dilute oxygen gas as a reactant, and the other is plasma enhanced ALD (PEALD) using NH3 plasma as a reactant. Generally, the film roughness of Ru film deposited by PEALD is smoother than that deposited by thermal ALD. However, the plasma is not favorable in the application of high aspect ratio structure. In this study, we used a bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)2] as a metal organic precursor for both thermal and plasma enhanced ALDs. In order to reduce initial nucleation time, we use several methods such as Ar plasma pre-treatment for PEALD and usage of sacrificial RuO2 under layer for thermal ALD. In case of PEALD, some of surface hydroxyls were removed from SiO2 substrate during the Ar plasma treatment. And relatively high surface nitrogen concentration after first NH3 plasma exposure step in ALD process was observed with in-situ Auger electron spectroscopy (AES). This means that surface amine filled the hydroxyl removed sites by the NH3 plasma. Surface amine played a role as a reduction site but not a nucleation site. Therefore, the precursor reduction was enhanced but the adhesion property was degraded. In case of thermal ALD, a Ru film was deposited from Ru precursors on the surface of RuO2 and the RuO2 film was reduced from RuO2/SiO2 interface to Ru during the deposition. The reduction process was controlled by oxygen partial pressure in ambient. Under high oxygen partial pressure, RuO2 was deposited on RuO2/SiO2, and under medium oxygen partial pressure, RuO2 was partially reduced and oxygen concentration in RuO2 film was decreased. Under low oxygen partial pressure, finally RuO2 was disappeared and about 3% of oxygen was remained. Usually rough surface was observed with longer initial nucleation time. However, the Ru deposited with reduction of RuO2 exhibits smooth surface and was deposited quickly because the sacrificial RuO2 has no initial nucleation time on SiO2 and played a role as a buffer layer between Ru and SiO2.

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Degradation of the Pd catalytic layer electrolyte in dye sensitized solar cells (염료감응태양전지에서 Pd 촉매층의 전해질과의 반응에 따른 특성 저하)

  • Noh, Yunyoung;Song, Ohsung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.4
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    • pp.2037-2042
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    • 2013
  • A TCO-less palladium (Pd) catalytic layer on the glass substrate was assessed as the counter electrode (CE) in a dye sensitized solar cell (DSSC) to confirm the stability of Pd with the $I^-/I_3{^-}$electrolyte on the DSSC performance. A 90nm-thick Pd film was deposited by a thermal evaporator. Finally, DSSC devices of $0.45cm^2$ with glass/FTO/blocking layer/$TiO_2$/dye/electrolyte(10 mM LiI + 1 mM $I_2$ + 0.1 M $LiClO_4$ in acetonitrile solution)/Pd/glass structure was prepared. We investigated the microstructure and photovoltaic property at 1 and 12 hours after the sample preparation. The optical microscopy, field emission scanning electron microscopy (FESEM), cyclic voltammetry measurement (C-V), and current voltage (I-V) were employed to measure the microstructure and photovoltaic property evolution. Microstructure analysis showed that the corrosion by reaction between the Pd layer and the electrolyte occurred as time went by, which led the decrease of the catalytic activity and the efficiency. I-V result revealed that the energy conversion efficiency after 1 and 12 hours was 0.34% and 0.15%, respectively. Our results implied that we might employ the other non-$I^-/I_3{^-}$electrolyte or the other catalytic metal layers to guarantee the long term stability of the DSSC devices.

A Study on Improving Electrical Conductivity for Conducting Polymers and their Applications to Transparent Electrodes (전도성 고분자의 전기전도도 향상 연구 및 이를 이용한 투명전극 응용)

  • Im, Soeun;Kim, Soyeon;Kim, Seyul;Kim, Felix Sunjoo;Kim, Jung Hyun
    • Applied Chemistry for Engineering
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    • v.26 no.6
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    • pp.640-647
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    • 2015
  • As the need for next-generation flexible electronics grows, novel materials and technologies that can replace conventional indium tin oxide (ITO) for transparent electrodes have been of great interest. Among them, a conducting polymer, especially poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS) is one of the most promising candidates because it is mechanically flexible, inexpensive, and capable of being processed in solution. Currently, there are a lot of research efforts on enhancing its electrical conductivity to the level of ITO or metal electrodes through chemical and/or physical processing. In this review article, we present various additives and pre-/post-deposition processing methods for improving the electrical conductivity of PEDOT : PSS. Some of representative reports are also introduced, which demonstrated the use of conductivity-enhanced PEDOT : PSS as transparent electrodes in electronics and energy conversion.

Investigating the Au-Cu thick layers Electrodeposition Rate with Pulsed Current by Optimization of the Operation Condition

  • Babaei, Hamid;Khosravi, Morteza;Sovizi, Mohamad Reza;Khorramie, Saeid Abedini
    • Journal of Electrochemical Science and Technology
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    • v.11 no.2
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    • pp.172-179
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    • 2020
  • The impact of effective parameters on the electrodeposition rate optimization of Au-Cu alloy at high thicknesses on the silver substrate was investigated in the present study. After ensuring the formation of gold alloy deposits with the desired and standard percentage of gold with the cartage of 18K and other standard karats that should be observed in the manufacturing of the gold and jewelry artifacts, comparing the rate of gold-copper deposition by direct and pulsed current was done. The rate of deposition with pulse current was significantly higher than direct current. In this process, the duty cycle parameter was effectively optimized by the "one factor at a time" method to achieve maximum deposition rate. Particular parameters in this work were direct and pulse current densities, bath temperature, concentration of gold and cyanide ions in electrolyte, pH, agitation and wetting agent additive. Scanning electron microscopy (SEM) and surface chemical analysis system (EDS) were used to study the effect of deposition on the cross-sections of the formed layers. The results revealed that the Au-Cu alloy layer formed with concentrations of 6gr·L-1 Au, 55gr·L-1 Cu, 24 gr·L-1 KCN and 1 ml·L-1 Lauryl dimethyl amine oxide (LDAO) in the 0.6 mA·cm-2 average current density and 30% duty cycle, had 0.841 ㎛·min-1 Which was the highest deposition rate. The use of electrodeposition of pure and alloy gold thick layers as a production method can reduce the use of gold metal in the production of hallow gold artifacts, create sophisticated and unique models, and diversify production by maintaining standard karats, hardness, thickness and mechanical strength. This will not only make the process economical, it will also provide significant added value to the gold artifacts. By pulsating of currents and increasing the duty cycle means reducing the pulse off-time, and if the pulse off-time becomes too short, the electric double layer would not have sufficient growth time, and its thickness decreases. These results show the effect of pulsed current on increasing the electrodeposition rate of Au-Cu alloy confirming the previous studies on the effect of pulsed current on increasing the deposition rate of Au-Cu alloy.