• Title/Summary/Keyword: $NiCo_2O_4$

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3-Dimensional NiCo2O4 nanostructure prepared by hydrothermal process and its application for glucose sensor (수열합성에 의한 3차원 구조의 NiCo2O4 제조 및 글루코스 센서로서의 응용)

  • Jang, Kyu-bong;Mhin, Sungwook
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.31 no.2
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    • pp.78-83
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    • 2021
  • In this study, we prepared NiCo2O4 nanoparticles with large surface area by hydrothermal synthesis. In order to optimize the processing conditions for spinel NiCo2O4 nanoparticles with large surface area, experimental variables including concentration of Ni and Co precursor, reaction time, and temperature for post-heat treatment were evaluated. Optimized conditions for spinel NiCo2O4 with large surface area were [Ni]/[Co] 1:2 ratio, reaction time for 12 h, and post-heat treatment at 400℃. To investigate the feasibility as potential application for glucose sensor, electrochemical tests of the prepared NiCo2O4 nanoparticles in response to glucose was performed, which suggests that the NiCo2O4 can be suitable for a non-enzymatic-based electrochemical glucose sensor based on its high sensitivity and selectivity for glucose detection.

Characterization of NiO and Co3O4-Doped La(CoNi)O3 Perovskite Catalysts Synthesized from Excess Ni for Oxygen Reduction and Evolution Reaction in Alkaline Solution (과량의 니켈 첨가로 합성된 NiO와 Co3O4가 도핑된 La(CoNi)O3 페로브스 카이트의 알칼리용액에서 산소환원 및 발생반응 특성)

  • BO, LING;RIM, HYUNG-RYUL;LEE, HONG-KI;PARK, GYUNGSE;SHIM, JOONGPYO
    • Transactions of the Korean hydrogen and new energy society
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    • v.32 no.1
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    • pp.41-52
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    • 2021
  • NiO and Co3O4-doped porous La(CoNi)O3 perovskite oxides were prepared from excess Ni addition by a hydrothermal method using porous silica template, and characterized as bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for Zn-air rechargeable batteries in alkaline solution. Excess Ni induced to form NiO and Co3O4 in La(CoNi)O3 particles. The NiO and Co3O4-doped porous La(CoNi)O3 showed high specific surface area, up to nine times of conventionally synthesized perovskite oxide, and abundant pore volume with similar structure. Extra added Ni was partially substituted for Co as B site of ABO3 perovskite structure and formed to NiO and Co3O4 which was highly dispersed in particles. Excess Ni in La(CoNi)O3 catalysts increased OER performance (259 mA/㎠ at 2.4 V) in alkaline solution, although the activities (211 mA/㎠ at 0.5 V) for ORR were not changed with the content of excess Ni. La(CoNi)O3 with excess Ni showed very stable cyclability and low capacity fading rate (0.38 & 0.07 ㎶/hour for ORR & OER) until 300 hours (~70 cycles) but more excess content of Ni in La(CoNi)O3 gave negative effect to cyclability.

A Study on the Recovery of Li2CO3 from Cathode Active Material NCM(LiNiCoMnO2) of Spent Lithium Ion Batteries

  • Wang, Jei-Pil;Pyo, Jae-Jung;Ahn, Se-Ho;Choi, Dong-Hyeon;Lee, Byeong-Woo;Lee, Dong-Won
    • Journal of Powder Materials
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    • v.25 no.4
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    • pp.296-301
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    • 2018
  • In this study, an experiment is performed to recover the Li in $Li_2CO_3$ phase from the cathode active material NMC ($LiNiCoMnO_2$) in waste lithium ion batteries. Firstly, carbonation is performed to convert the LiNiO, LiCoO, and $Li_2MnO_3$ phases within the powder to $Li_2CO_3$ and NiO, CoO, and MnO. The carbonation for phase separation proceeds at a temperature range of $600^{\circ}C{\sim}800^{\circ}C$ in a $CO_2$ gas (300 cc/min) atmosphere. At $600{\sim}700^{\circ}C$, $Li_2CO_3$ and NiO, CoO, and MnO are not completely separated, while Li and other metallic compounds remain. At $800^{\circ}C$, we can confirm that LiNiO, LiCoO, and $Li_2MnO_3$ phases are separated into $Li_2CO_3$ and NiO, CoO, and MnO phases. After completing the phase separation, by using the solubility difference of $Li_2CO_3$ and NiO, CoO, and MnO, we set the ratio of solution (distilled water) to powder after carbonation as 30:1. Subsequently, water leaching is carried out. Then, the $Li_2CO_3$ within the solution melts and concentrates, while NiO, MnO, and CoO phases remain after filtering. Thus, $Li_2CO_3$ can be recovered.

Phase Evolution in LiMO2(M=Co,Ni) Cathode Materials for Secondary Lithium Ion Batteries : Effect of Temperature and Oxygen Partial Pressure (리튬 2차 전지용 양극활물질 LiMO2(M=Co,Ni)의 온도와 산소 분압에 따른 상전이 거동)

  • Huang, Cheng-Zhu;Kim, Ho-Jin;Jeong, Yeon-Uk;Lee, Joon-Hyung;Kim, Jeong-Joo
    • Journal of the Korean Ceramic Society
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    • v.42 no.4
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    • pp.292-297
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    • 2005
  • $LiMO_{2}(M=Co,Ni)$ samples were synthesized with $Li_{2}CO_{3},\;Co_{3}O_{4}$, and NiO by the solid-state reaction method. In the case of $LiCoO_{2}$, at low temperature$(T=400^{\circ}C)$ spinel structure was synthesized and the obtained spinel phase was transformed to layered phase at high temperature$(T\ge600^{\circ}C)$. The phase transition behaviors of $LiCoO_{2}$ were investigated with various heating temperature and time. The rate of transition was directly proportional to the concentrations of reactant, and activation energy of reaction was around 6.76 kcal/mol. When CoO(rock salt structure) was used as a starting material instead of $Co_{3}O_{4}$(spinel structure), layered structure of $LiCoO_{2}$ was obtained at low temperature. In the case of $LiNiO_{2}$ the transition from layered structure to rock salt structure occurred easily by disordering/ordering reaction, but did not occur in $LiCoO_{2}$. The difference in metal ion radii in $LiCoO_{2}$ and $LiNiO_{2}$ results in different behaviors of phase transitions.

Investigation of Electronic Structures of TCr2O4 (T = Fe, Co, Ni) Spinel Oxides by Employing Soft X ray Synchrotron Radiation Spectroscopy (연 X선 방사광 분광법을 이용한 TCr2O4(T = Fe, Co, Ni) 스피넬 산화물의 전자구조 연구)

  • Kim, Hyun Woo;Hwang, Jihoon;Kim, D.H.;Lee, Eunsook;Kang, J.S.
    • Journal of the Korean Magnetics Society
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    • v.23 no.5
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    • pp.149-153
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    • 2013
  • The electronic structures of $TCr_2O_4$ (T = Fe, Co, Ni) spinel oxides have been investigated by employing synchrotron radiation-based soft X ray absorption spectroscopy (XAS). The measured 2p XAS spectra of transition-metal ions reveal that Cr ions are trivalent ($Cr^{3+}$), and all the T (T = Fe, Co, Ni) ions are divalent ($Fe^{2+}$, $Co^{2+}$, $Ni^{2+}$). It is also found that most of T (T = Fe, Co, Ni) ions occupy the A sites under the tetrahedral symmetry, while Cr ions occupy mainly the B sites under the octahedral symmetry. These findings show that the structures of $TCr_2O_4$ (T = Fe, Co, Ni) are very close to the normal spinel structures. Based on these findings, it is expected that Jahn-Teller (JT) effects are important in $FeCr_2O_4$ and $NiCr_2O_4$. In contrast, $CoCr_2O_4$ maintains the cubic structure without having the JT distortion since both $Cr^{3+}$ and $Co^{2+}$ ions are non-JT ions. This work suggests that the antiferromagnetic interaction between $Cr^{3+}$ and $T^{2+}$ ions plays an important role in determining the magnetic properties of $TCr_2O_4$ (T = Fe, Co, Ni).

Synthesis and characterization of three-dimensional monodispersed NiO/NiCo2O4 via Ni3[Co(CN)6]2 PBA nanocubes (Ni3[Co(CN)6]2 PBA 나노큐브를 통한 단분산된 3차원 구조의 NiO/NiCo2O4 제조 및 특성 평가)

  • Kwag, Sung Hoon;Lee, Young Hun;Kim, Min Seob;Lee, Chul Woo;Kang, Bong Kyun;Yoon, Dae Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.27 no.3
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    • pp.110-114
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    • 2017
  • $NiO/NiCo_2O_4$ nanocubes were successfully synthesized via the calcination process of $Ni_3[Co(CN)_6]_2$ PBAs. The prepared monodispersed $Ni_3[Co(CN)_6]_2$ PBAs were aggregated by 'self-assembly' of the nuclei generated during the synthesis reaction. The self-assembly rate of the particles is affected by the temperature and the amount of surfactant SDBS (sodium dodecylbenzenesulfonate). FESEM analysis shows that monodispersed 200 nm PBA nanocubes are obtained at 0.25 g SDBS and $60^{\circ}C$ temperature. Thermal behavior was confirmed by thermogravimetric-differential thermal analysis (TG-DTA) to determine optimal calcination conditions. Then, field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analyzes were performed to investigate the morphology and crystallinity of the particles precursors and $NiO/NiCo_2O_4$ nanocubes.

LNG Combustion Characteristics of Oxygen Carrier Particles for Chemical-Looping Combustor (매체순환식 가스연소기 산소공여입자의 LNG 연소특성)

  • Ryu, Ho-Jung;Bae, Dal-Hee;Jin, Gyoung-Tae
    • 한국연소학회:학술대회논문집
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    • 2005.10a
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    • pp.141-147
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    • 2005
  • LNG combustion characteristics of oxygen carrier particles were investigated in a batch type bubbling fluidized bed reactor. Three particles, NiO/bentonite, $NiO/NiAl_2O_4$, $CO_xO_y/CoAl_2O_4$, were used as oxygen carrier particles and LNG and air were used as reactants for reduction and oxidation, respectively. In the reducer, high gas conversion and high $CO_2$ selectivity were achieved for all three particles. In the oxidizer, NOx was not detected. The results of exhaust gas analysis showed that inherent $CO_2$ separation and NOx-free combustion are possible in the LNG fueled chemical-looping combustion system with NiO/bentonite, $NiO/NiAl_2O_4$ and $Ca_xO_y/CoAl_2O_4$ particles.

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Bioassessment of Nanoparticle Toxicity based on Seed Germination and Germination Index of Various Seeds (다양한 씨앗의 발아 및 발아지수에 근거한 나노입자 생물학적 독성평가)

  • Gu, Bon Woo;Lee, Min Kyeung;Shi, Yu Tao;Kong, In Chul
    • Clean Technology
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    • v.21 no.1
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    • pp.39-44
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    • 2015
  • This study investigated the effects of six metal oxide nanoparticles (NPs: CuO, NiO, TiO2, Fe2O3, Co3O4, ZnO) on seed germination and germination index (G.I) for five types of seeds: Brassica napus L., Malva verticillata L., Brassica olercea L., Brassica campestris L., Daucus carota L. NPs of CuO, ZnO, NiO show significant toxicity impacts on seed activities [CuO (6-27 mg/L), ZnO (16-86 mg/L), NiO (48-112 mg/L)], while no significant effects were observed at > 1000 mg/L of TiO2, Fe2O3, Co3O4. Tested five types of seed showed different sensitivities on seed germination and root activity, especially on NPs of CuO, ZnO, NiO. Malva verticillata L. seed was highly sensitive to toxic metal oxide NPs and showed following EC50s : CuO 5.5 mg/L, ZnO 16.4 mg/L, NiO 53.4 mg/L. Mostly following order of toxicity was observed, CuO > ZnO > NiO > Fe2O3 ≈ Co3O4 ≈ TiO2, where slightly different toxicity order was observed for carrot, showing CuO > NiO ≈ ZnO > Fe2O3 ≈ Co3O4 ≈ TiO2.

Electrochemical Properties of LiMn1.92Co0.08O4 and LiNi0.7Co0.3O2 Mixtures Prepared by a Simplified Combustion Method (단순화한 연소법에 의해 합성한 LiMn1.92Co0.08O4와 LiNi0.7Co0.3O2 혼합물의 전기화학적 특성)

  • Song, Myoungyoup;Kwon, IkHyun;Kim, Hunuk
    • Journal of the Korean Ceramic Society
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    • v.41 no.10 s.269
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    • pp.735-741
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    • 2004
  • $LiMn_{1.92}Co_{0.08}O_4$ and $LiNi_{0.7}Co_{0.3}O_2$ synthesized by a simplified combustion method had good electrochemical properties. Mixtures $LiMn_{1.92}Co_{0.08}O_4$-x wt$\%$ $LiNi_{0.7}Co_{0.3}O_2$ (x=9, 23, 33, 41, and 47) were prepared by milling for 30 min and their electrochemical properties were investigated. The electrode with x=9 had a relatively large first discharge capacity (109.9 mAh/g at 0.1 C) and good cycling performance. The decrease in the discharge capacity of the mixture electrodes with cycling is considered to result mainly from the degradation of $LiNi_{0.7}Co_{0.3}O_2$, caused by coating of $LiNi_{0.7}Co_{0.3}O_2$ with Mn dissolved from $LiMn_{1.92}Co_{0.08}O_4$.

Variations in electrode characteristics through simplification of phosphorus-doped NiCo2O4 electrode manufacturing process (인이 도핑된 NiCo2O4 전극 제조 공정의 간소화를 통한 전극 특성의 변화)

  • Seokhee-Lee;Hyunjin Cha;Jeonghwan Park;Young Guk Son;Donghyun Hwang
    • Journal of the Korean institute of surface engineering
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    • v.56 no.5
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    • pp.299-308
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    • 2023
  • In this study, phosphorus (P)-doped nickel cobaltite (P-NiCo2O4) and nickel-cobalt layered double hydroxide (P-NiCo-LDH) were synthesized on nickel (Ni) foam as a conductive support using hydrothermal synthesis. The thermal properties, crystal structure, microscopic surface morphology, chemical distribution, electronic state of the constituent elements on the sample surface, and electrical properties of the synthesized P-NiCo2O4 and P-NiCo-LDH samples were analyzed using thermogravimetric analysis-differential scanning calorimetry (TGA-DSC), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The P-NiCo2O4 electrode exhibited a specific capacitance of 1,129 Fg-1 at a current density of 1 Ag-1, while the P-NiCo-LDH electrode displayed a specific capacitance of 1,012 Fg-1 at a current density of 1 Ag-1. When assessing capacity changes for 3,000 cycles, the P-NiCo2O4 electrode exhibited a capacity retention rate of 54%, whereas the P-NiCo-LDH electrode showed a capacity retention rate of 57%.