• Title/Summary/Keyword: Ni Nanoparticles

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Preparation and Characterization of Palladium Nanoparticles Supported on Nickel Hexacyanoferrate for Fuel Cell Application

  • Choi, Kwang-Hyun;Shokouhimehr, Mohammadreza;Kang, Yun Sik;Chung, Dong Young;Chung, Young-Hoon;Ahn, Minjeh;Sung, Yung-Eun
    • Bulletin of the Korean Chemical Society
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    • v.34 no.4
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    • pp.1195-1198
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    • 2013
  • Nickel hexacyanoferrate supported palladium nanoparticles (Pd-NiHCF NPs) were synthesized and studied for oxygen reduction reactions in direct methanol fuel cell. The NiHCF support was readily synthesized by a comixing of $Ni(OCOCH_3)_2$ and equimolar $K_3[Fe(CN)_6]$ solution into DI water under rigorous stirring. After the preparation of NiHCF support, Pd NPs were loaded on NiHCF via L-ascorbic acid reduction method at $80^{\circ}C$. Pd-NiHCF NPs were electrochemically active for oxygen reduction reaction in 0.1 M $HClO_4$ solution. X-ray absorption near edge structure analysis was conducted to measure the white line intensity of Pd-NiHCF to verify the OH adsorption. As a comparison, carbon supported Pd NPs exhibited same white line intensity. This study provides a general synthetic approach to easily load Pd NPs on porous coordination polymers such as NiHCF and can provide further light to load Pd based alloy NPs on NiHCF framework.

P-Type Doping of Graphene Films by Hybridization with Nickel Nanoparticles

  • Lee, Su Il;Song, Wooseok;Kim, Yooseok;song, Inkyung;Park, Sangeun;Cha, Myung-Jun;Jung, Dae Sung;Jung, Min Wook;An, Ki-Seok;Park, Chong-Yun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.208-208
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    • 2013
  • Graphene has emerged as a fascinating material for next-generation nanoelectronics due to its outstanding electronic properties. In particular, graphene-based field effect transistors (GFETs) have been a promising research subject due to their superior response times, which are due to extremely high electron mobility at room temperature. The biggest challenges in GFET applications are control of carrier concentration and opening the bandgap of graphene. To overcome these problems, three approaches to doping graphene have been developed. Here we demonstrate the decoration of Ni nanoparticles (NPs) on graphene films by simple annealing for p-type doping of graphene. Ni NPs/graphene films were fabricated by coating a $NiCl2{\cdot}6H2O$ solution onto graphene followedby annealing. Scanning electron microscopy and atomic force microscopy revealed that high-density, uniformly sized Ni NPs were formed on the graphene films and the density of the Ni NPs increased gradually with increasing $NiCl2{\cdot}6H2O$ concentration. The formation of Ni NPs on graphene films was explained by heat-driven dechlorination and subsequent particlization, as investigated by X-ray photoelectron spectroscopy. The doping effect of Ni NPs onto graphene films was verified by Raman spectroscopy and electrical transport measurements.

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Synthesis and electromagnetic properties of FeNi alloy nanofibers using an electrospinning method

  • Lee, Young-In;Choa, Yong-Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.22 no.5
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    • pp.218-222
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    • 2012
  • FeNi alloy nanofibers have been prepared by an electrospinning process followed by air-calcination and H2 reduction to develop electromagnetic (EM) wave absorbers in the giga-hertz (GHz) frequency range. The thermal behavior and phase and morphology evolution in the synthetic processes were systematically investigated. Through the heat treatments of calcination and H2 reduction, as-spun PVP/FeNi precursor nanofiber has been stepwise transformed into nickel iron oxide and FeNi phases but the fibrous shape was maintained perfectly. The FeNi alloy nanofiber had the high aspect ratio and the average diameter of approximately 190 nm and primarily composed of FeNi nanocrystals with an average diameter of ~60 nm. The FeNi alloy nanofibers could be used for excellent EM wave absorbing materials in the GHz frequency range because the power loss of the FeNi nanofibers increased up to 20 GHz without a degradation and exhibited the superior EM wave absorption properties compared to commercial FeNi nanoparticles.

Carbon-Encapsulated Ni Catalysts for CO2 Methanation (탄소층으로 캡슐화된 Ni나노입자 촉매의 CO2 메탄화 반응)

  • Kim, Hye Jeong;Kim, Seung Bo;Kim, Dong Hyun;Youn, Jae-Rang;Kim, Min-Jae;Jeon, Sang Goo;Lee, Gyoung-Ja;Lee, Kyubock
    • Korean Journal of Materials Research
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    • v.31 no.9
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    • pp.525-531
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    • 2021
  • Carbon-encapsulated Ni catalysts are synthesized by an electrical explosion of wires (EEW) method and applied for CO2 methanation. We find that the presence of carbon shell on Ni nanoparticles as catalyst can positively affect CO2 methanation reaction. Ni@5C that is produced under 5 % CH4 partial pressure in Ar gas has highest conversions of 68 % at 350 ℃ and 70 % at 400 ℃, which are 73 and 75 % of the thermodynamic equilibrium conversion, respectively. The catalyst of Ni@10C with thicker carbon layer shows much reduced activity. The EEW-produced Ni catalysts with low specific surface area outperform Ni catalysts with high surface area synthesized by solution-based precipitation methods. Our finding in this study shows the possibility of utilizing carbon-encapsulated metal catalysts for heterogeneous catalysis reaction including CO2 methanation. Furthermore, EEW, which is a highly promising method for massive production of metal nanoparticles, can be applied for various catalysis system, requiring scaled-up synthesis of catalysts.

Suzuki-Miyaura Cross-coupling Reaction Catalyzed by Nickel Nanoparticles Supported on Poly(N-vinyl-2-pyrrolidone)/TiO2-ZrO2 Composite

  • Kalbasi, Roozbeh Javad;Mosaddegh, Neda
    • Bulletin of the Korean Chemical Society
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    • v.32 no.8
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    • pp.2584-2592
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    • 2011
  • Nickel nanoparticle-poly(N-vinyl-2-pyrrolidone)/$TiO_2-ZrO_2$ composite (Ni-PVP/$TiO_2-ZrO_2$) was prepared by in situ polymerization method. The physical and chemical properties of Ni-PVP/$TiO_2-ZrO_2$ were investigated by XRD, FT-IR, BET, TGA, SEM and TEM techniques. The catalytic performance of this novel heterogeneous catalyst was determined for the Suzuki-Miyaura cross-coupling reaction between aryl halides and phenylboronic acid in the presence of methanol-water mixture as solvent. The effects of reaction temperature, the amount of catalyst, amount of support, solvent, and amount of metal for the synthesis of Ni-PVP/$TiO_2-ZrO_2$, were investigated as well as recyclability of the heterogeneous composite. The catalyst used for this synthetically useful transformation showed considerable level of reusability besides very good activity.

Catalytic CO2 Methanation over Ni Catalyst Supported on Metal-Ceramic Core-Shell Microstructures (금속-세라믹 코어-쉘 복합체에 담지된 Ni 금속 촉매를 적용한 CO2 메탄화 반응 특성연구)

  • Lee, Hyunju;Han, Dohyun;Lee, Doohwan
    • Clean Technology
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    • v.28 no.2
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    • pp.154-162
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    • 2022
  • Microstructured Al@Al2O3 and Al@Ni-Al LDH (LDH = layered double hydroxide) core-shell metal-ceramic composites are prepared by hydrothermal reactions of aluminum (Al) metal substrates. Controlled hydrothermal reactions of Al metal substrates induce the hydrothermal dissolution of Al ions at the Al-substrate/solution interface and reconstruction as porous metal-hydroxides on the Al substrate, thereby constructing unique metal-ceramic core-shell composite structures. The morphology, composition, and crystal structure of the core-shell composites are affected largely by the ions in the hydrothermal solution; therefore, the critical physicochemical and surface properties of these unique metal-ceramic core-shell microstructures can be modulated effectively by varying the solution composition. A Ni/Al@Al2O3 catalyst with highly dispersed catalytic Ni nanoparticles on an Al@Al2O3 core-shell substrate was prepared by a controlled reduction of an Al@Ni-Al LDH core-shell prepared by hydrothermal reactions of Al in nickel nitrate solution. The reduction of Al@Ni-Al LDH leads to the exolution of Ni ions from the LDH shell, thereby constructing the Ni nanoparticles dispersed on the Al@Al2O3. The catalytic properties of the Ni/Al@Al2O3 catalyst were investigated for CO2 methanation reactions. The Ni/Al@Al2O3 catalyst exhibited 2 times greater CO2 conversion than a Ni/Al2O3 catalyst prepared by conventional incipient wetness impregnation and showed high structural stability. These results demonstrate the high effectiveness of the design and synthesis methods for the metal-ceramic composite catalysts derived by hydrothermal reactions of Al metal substrates.

Anode Properties of Sn-Ni Nanoparticle Composites for Rechargeable Lithium Batteries (주석-니켈 나노입자 복합체의 리튬 이차전지 음전극 특성)

  • Kim, Kwang-Man;Kang, Kun-Young;Choi, Min-Gyu;Lee, Young-Gi
    • Korean Chemical Engineering Research
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    • v.49 no.6
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    • pp.846-850
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    • 2011
  • Nanocomposite anodes for rechargeable lithium battery are prepared by mixing tin and nickel nanoparticles via wet method and their electrochemical properties are examined. The Sn-Ni nanocomposite anode shows a maximum discharge capacity of 700 mAh $g^{-1}$ at the first cycle but very poor cycle performance. This means that the electrode porosity and the Ni component formed by the simple mixing of nanoparticles no longer play the role of buffering the volume expansion/contraction of Sn component during charge-discharge. To solve the cycle performance problem, a novel nanostructured Sn-Ni anode should be designed and tested.