• Title, Summary, Keyword: Ni electrodes

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Conductance of a Single Molecule Junction Formed with Ni, Au, and Ag Electrodes

  • Kim, Taekyeong
    • Journal of the Korean Chemical Society
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    • v.58 no.6
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    • pp.513-516
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    • 2014
  • We measure the conductance of a 4,4'-diaminobiphenyl formed with Ni electrodes using a scanning tunneling microscope-based break-junction technique. For comparison, we use Au or Ag electrodes to form a metal-molecular junction. For molecules that conduct through the highest occupied molecular orbital, junctions formed with Ni show similar conductance as Au and are more conductive than those formed with Ag, consistent with the higher work function for Ni or Au. Furthermore, we observe that the measured molecular junction length that is formed with the Ni or Au electrodes was shorter than that formed with the Ag electrodes. These observations are attributed to a larger gap distance of the Ni or Au electrodes compared to that of the Ag electrodes after the metal contact ruptures. Since our work allows us to measure the conductance of a molecule formed with various electrodes, it should be relevant to molecular electronics with versatile materials.

Activated Carbon-Nickel (II) Oxide Electrodes for Capacitive Deionization Process

  • Gandionco, Karl Adrian;Kim, Jin Won;Ocon, Joey D.;Lee, Jaeyoung
    • Applied Chemistry for Engineering
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    • v.31 no.5
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    • pp.552-559
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    • 2020
  • Activated carbon-nickel (II) oxide (AC-NiO) electrodes were studied as materials for the capacitive deionization (CDI) of aqueous sodium chloride solution. AC-NiO electrodes were fabricated through physical mixing and low-temperature heating of precursor materials. The amount of NiO in the electrodes was varied and its effect on the deionization performance was investigated using a single-pass mode CDI setup. The pure activated carbon electrode showed the highest specific surface area among the electrodes. However, the AC-NiO electrode with approximately 10 and 20% of NiO displayed better deionization performance. The addition of a dielectric material like NiO to the carbon material resulted in the enhancement of the electric field, which eventually led to an improved deionization performance. Among all as-prepared electrodes, the AC-NiO electrode with approximately 10% of NiO gave the highest salt adsorption capacity and charge efficiency, which are equal to 7.46 mg/g and 90.1%, respectively. This finding can be attributed to the optimum enhancement of the physical and chemical characteristics of the electrode brought by the addition of the appropriate amount of NiO.

Understanding the Effect on Hydrogen Evolution Reaction in Alkaline Medium of Thickness of Physical Vapor Deposited Al-Ni Electrodes (Physical Vapor Deposition 방법으로 제조된 Al-Ni 전극의 두께가 알칼라인 수전해 수소발생반응에 미치는 영향 연구)

  • HAN, WON-BI;CHO, HYUN-SEOK;CHO, WON-CHUL;KIM, CHANG-HEE
    • Transactions of the Korean hydrogen and new energy society
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    • v.28 no.6
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    • pp.610-617
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    • 2017
  • This paper presents a study of the effect of thickness of porous Al-Ni electrodes, on the Hydrogen Evolution Reaction (HER) in alkaline media. As varying deposition time at 300 W DC sputtering power, the thickness of the Al-Ni electrodes was controlled from 1 to $20{\mu}m$. The heat treatment was carried out in $610^{\circ}C$, followed by selective leaching of the Al-rich phase. XRD studies confirmed the presence of $Al_3Ni_2$ intermetallic compounds after the heat treatment, indicating the diffusion of Ni from the Ni-rich phase to Al-rich phase. The porous structure of the Al-Ni electrodes after the selective leaching of Al was also confirmed in SEM-EDS analysis. The double layer capacitance ($C_{dl}$) and roughness factor ($R_f$) of the electrodes were increased for the thicker Al-Ni electrodes. As opposed to the general results in above, there were no further improvements of the HER activity in the case of the electrode thickness above $10{\mu}m$. This result may indicate that the $R_f$ is not the primary factor for the HER activity in alkaline media.

The Effect of F-treatment on the Degradation Behavior of the $CaNi_{5}$ and MG-$CaNi_{5}$ Electrodes ($CaNi_{5}$ 및 MG-$CaNi_{5}$ 전극의 퇴화거동에 미치는 불화처리의 영향)

  • Lee, C.R.;Oh, S.J.;Kang, S.G.
    • Korean Journal of Materials Research
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    • v.9 no.6
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    • pp.622-629
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    • 1999
  • Effects of the fluorination in the $K_2$TiF\ulcorner solution and in-situ KF+ KOH electrolyte on the electrochemical charge-discharge properties of CaNi\ulcorner and the Mg-CaNi\ulcorner electrodes were investigated. In-situ fluorination in the KF+ KOH electrolyte compared with pre-fluorination in the$ K_2$TiF\ulcorner solution could improve the electrochemical cycling durability of CaNi\ulcorner and MG-CaN\ulcorner electrodes. The fluorinated layer on the alloy surface by pre-fluorination to improve the activity and anti-corrosion of the electrodes was dissolved in the pure KOH electrolyte during the cycling. The fluorinated layer was formed continuously on the surface of the electrode by thee2N KF addition in the 6N KOH electrolyte. The excess F\ulcorner ion addition in KOH electrolyte could improve the electrochemical cycling durability of CaNi\ulcorner and Mg-CaNi\ulcorner electrode. But, in case of MG-CaNi\ulcorner electrode, the discharge capacity of the electrode was reduced and the poor cycling property was shown with increasing of the MG process times.

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Organic Thin Film Transistors for Liquid Crystal Display Fabricated with Poly 3-Hexylthiophene Active Channel Layer and NiOx Electrodes

  • Oh, Yong-Cheul
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.12
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    • pp.1140-1143
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    • 2006
  • We report on the fabrication of P3HT-based thin-film transistors (TFTs) for liquid crystal display that consist of $NiO_x$, poly-vinyl phenol (PVP), and Ni for the source-drain (S/D) electrodes, gate dielectric layer, and gate electrode, respectively The $NiO_x$ S/D electrodes of which the work function is well matched to that of P3HT are deposited on a P3HT channel by electron-beam evaporation of NiO powder. The maximum saturation current of our P3HT-based TFT is about $15{\mu}A$ at a gate bias of -30 V showing a high field effect mobility of $0.079cm^2/Vs$ in the dark, and the on/off current ratio of our TFT is about $10^5$. It is concluded that jointly adopting $NiO_x$ for the S/D electrodes and PVP for gate dielectric realizes a high-quality P3HT-based TFT.

Organic Thin Film Transistor Fabricated with Soluble Pentacene Active Channel Layer and NiOx Electrodes

  • Han, Jin-Woo;Kim, Young-Hwan;Kim, Byoung-Yong;Han, Jeong-Min;Moon, Hyun-Chan;Park, Kwang-Bum;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.395-395
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    • 2007
  • We report on the fabrication of soluble pentacene-based thin-film transistors (TFTs) that consist of $NiO_x$, poly-vinyl phenol (PVP), and Ni for the source-drain (SID) electrodes, gate dielectric, and gate electrode, respectively. The $NiO_x$ SID electrodes of which the work function is well matched to that of soluble pentacene are deposited on a soluble pentacenechannel by sputter deposited of NiO powder and show a moderately low but still effective transmittance of ~65% in the visible range along with a good sheet resistance of ${\sim}40{\Omega}/{\square}$. The maximum saturation current of our soluble pentacene-based TFT is about $15{\mu}A$ at a gate bias of -40showing a high field effect mobility of $0.06cm^2/Vs$ in the dark, and the on/off current ratio of our TFT is about $10^4$. It is concluded that jointly adopting $NiO_x$ for the S/D electrodes and PVP for gate dielectric realizes a high-quality soluble pentacene-based TFT.

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Electrodeposition of Mn-Ni Oxide/PEDOT and Mn-Ni-Ru Oxide/PEDOT Films on Carbon Paper for Electro-osmotic Pump Electrode

  • Baek, Jaewook;Shin, Woonsup
    • Journal of Electrochemical Science and Technology
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    • v.9 no.2
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    • pp.93-98
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    • 2018
  • $MnO_2$, a metal oxide used as an electrode material in electrochemical capacitors (EDLCs), has been applied in binary oxide and conducting polymer hybrid electrodes to increase their stability and capacitance. We developed a method for electrodepositing Mn-Ni oxide/PANI, Mn-Ni oxide/PEDOT, and Mn-Ni-Ru oxide/PEDOT films on carbon paper in a single step using a mixed bath. Mn-Ni oxide/PEDOT and Mn-Ni-Ru oxide/PEDOT electrodes used in an electro-osmotic pump (EOP) have shown better efficiency compared to Mn-Ni oxide and Mn-Ni oxide/PANI electrodes through testing in water as a pumping solution. EOP using a Mn-Ni-Ru oxide/PEDOT electrode was also tested in a 0.5 mM $Li_2SO_4$ solution as a pumping solution to confirm the effect of the $Li^+$ insertion/de-insertion reaction of Ruthenium oxide on the EOP. Experimental results show that the flow rate increases with the increase in current in a 0.5 mM $Li_2SO_4$ solution compared to that obtained when water was used as a pumping solution.

A Study on the Cycle Life Improvement of V-Ti-Ni(V-rich) Alloy as a Negative Electrode for Ni/MH Rechargeable Battery (Ni/MH 2차전지의 음극으로써 V-Ti-Ni(V-rich) 수소저장합금의 전극수명 향상에 관한 연구)

  • Kim, Ju-Wan;Lee, Seong-Man;Lee, Jae-Yeong
    • Transactions of the Korean hydrogen and new energy society
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    • v.7 no.1
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    • pp.39-44
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    • 1996
  • The discharge capacity of V-Ti-Ni(V-rich) metal hydride electrode during the charge-discharge cycling was investigated in KOH electrolyte. All electrodes were degraded within 25 cycles. To investigate the cause of the degradation phenomena impedance measurements were performed by using E.I.S(electrochemical impedance spectroscopy). The surfaces of the degraded electrodes were examined by Auger electron spectroscopy (AES). It was observed that all electrodes were covered with oxygen from the surface to the bulk, titanium was enriched near surface, and vanadium was dissolved from the surface to the bulk.

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Facile preparation of nanoflake-structured nickel oxide/carbon nanotube composite films by electrophoretic deposition as binder-free electrodes for high-performance pseudocapacitors

  • Kazazi, Mahdi
    • Current Applied Physics
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    • v.17 no.2
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    • pp.240-248
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    • 2017
  • Nickel hydroxide nanoflakes with a-phase structure were prepared using a simple chemical precipitation method. The structure and morphology of the obtained nanoflakes were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. Cathodic electrophoretic deposition technique was used to fabricate porous pure nickel hydroxide and also multi-walled carbon nanotube/nickel hydroxide composite films from ethanolic suspensions using triethanolamine as a dispersant. Finally, the deposited electrodes were heated at $350^{\circ}C$ for 3 h to form NiO and NiO-CNT electrodes. The effect of triethanolamine and CNTs additives on the electrical conductivity of the suspensions, current density during electrophoretic, and deposition rate was studied. The deposition mechanism and kinetics of deposition were also discussed. Compared with the pure NiO electrode, the prepared NiO-CNT electrode exhibits excellent pseudocapacitive behavior with a higher specific capacitance of $786F\;g^{-1}$ at $1A\;g^{-1}$, better rate capability, and good cycling stability.

Remarkable Stability of Graphene/Ni-Al Layered Double Hydroxide Hybrid Composites for Electrochemical Capacitor Electrodes

  • Lee, Jeong Woo;In, Su-Il;Kim, Jong-Duk
    • Journal of Electrochemical Science and Technology
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    • v.4 no.1
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    • pp.19-26
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    • 2013
  • Graphene/Ni-Al layered double hydroxide (LDH) hybrid materials were synthesized by a hydrothermal reaction. Hexagonal Ni-Al LDH particles nucleated and grew on graphene sheets, thus preventing restacking of the graphene sheets and aggregation of the Ni-Al LDH nanoparticles upon drying. Electrode made from the graphene/Ni-Al LDH hybrid materials showed a substantial improvement in electrochemical capacitance relative to those made with pure Ni-Al LDH nanoparticles. In addition, the graphene/Ni-Al LDH hybrid composite materials showed remarkable stability after 4000 cycles with over 100% capacitance retention. These materials are thus very promising for use in electrochemical capacitor electrodes.