• 한국재료학회지
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• 제27권2호
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• pp.63-68
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• 2017

A black nickel oxide powder, one of the commercial nickel oxide ores, was reduced by hydrogen gas in a batch-type fluidized-bed reactor in a temperature range of 350 to $500^{\circ}C$ and in a residence time range of 5 to 120 min. The hydrogen reduction behavior of the black nickel oxide was found to be somewhat different from that of green nickel oxide ore. For the black nickel oxide, the maximum temperature (below which nickel oxide particles can be reduced without any agglomeration) was significantly lower than that observed for the green nickel oxide. In addition, the best curve fittings of the Avrami model were obtained at higher values of the overall rate constant "k" and at lower values of the exponent "m", compared to those values for the green nickel oxide. It may be inferred from these results that the hydrogen reduction rate of the black nickel oxide is faster than that of the green nickel oxide in the early stages, but the situation reverses in the later stages. For the black nickel oxide ore, in spite of the low temperature sintering, it was possible to achieve a high degree fluidized-bed reduction at lower temperatures and at lower gas consumption rates than was possible for the green nickel oxide. In this regard, the use of black nickel oxide is expected to yield a benefit if its ore price is sufficiently lower than that of the green nickel oxide.

• 한국수소및신에너지학회논문집
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• 제17권1호
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• pp.39-46
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• 2006

Highly ordered Li dispersed nickel oxide nanotubes were prepared with anodic aluminum oxide (AAO) template for hydrogen storage. Electron microscope results showed that uniform length and diameter of nickel oxide nanotubes were obtained. The wall thickness and outer diameter of nickel oxide nanotubes are about 40 - 50 nm and 200 - 400 nm, respectively. It was observed that the diameter of nickel oxide nanotubes is bigger than the pore diameter of AAO template. Li dispersed nickel oxide were consisted of nanoflakes and had structures of nanotubes and nanorods. For increasing the hydrogen adsorption and desorption capacity, the Li dispersed nickel oxide nanotubes were fluorinated. The fluorinated Li dispersed nickel oxide nanotubes showed 1.65 wt% of the hydrogen adsorption capacities at 77 K under 47 atm.

• 한국분말재료학회지
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• 제30권6호
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• pp.502-508
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• 2023

With the increasing demand for electronic products, the amount of multilayer ceramic capacitor (MLCC) waste has also increased. Recycling technology has recently gained attention because it can simultaneously address raw material supply and waste disposal issues. However, research on recovering valuable metals from MLCCs and converting the recovered metals into high-value-added materials remains insufficient. Herein, we describe an electrospinning (E-spinning) process to recover nickel from MLCCs and modulate the morphology of the recovered nickel oxide particles. The nickel oxalate powder was recovered using organic acid leaching and precipitation. Nickel oxide nanoparticles were prepared via heat treatment and ultrasonic milling. A mixture of nickel oxide particles and polyvinylpyrrolidone (PVP) was used as the E-spinning solution. A PVP/NiO nanowire composite was fabricated via E-spinning, and a nickel oxide nanowire with a network structure was manufactured through calcination. The nanowire diameters and morphologies are discussed based on the nickel oxide content in the E-spinning solution.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.900-903
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• 2003

Using $DV-X{\alpha}$ method, it is calculated that nickel reduces the energy band gap of manganese oxide in 3 additives of titanium, nickel and tin. Therefore, it is estimated that the electrical conductivity of manganese-nickel oxide has the lowest value in 3 kinds of manganese oxide. The manganese oxide and manganese-nickel oxide which were produced by anodic deposition under $30mA/cm^2$ at room temperature in manganese sulfate and manganese-nickel sulfate solution were thermal-analyzed by DTA and TGA. The weight change of manganese oxide continuously decreased below $508^{\circ}C$ and kept constant at $518{\sim}600^{\circ}C$. However, the manganeses-nickel oxide transformed at the temperature range of $510{\sim}537^{\circ}C$. It is observed that the nickel addition to manganese oxide increases transformation temperature and its range.

• Journal of Electrochemical Science and Technology
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• 제6권1호
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• pp.16-25
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• 2015

Transition metal oxide nanocrystalline materials are playing major role in energy storage application in this scenario. Nickel oxide is one of the best antiferromagnetic materials which is used as electrodes in energy storage devices such as, fuel cells, batteries, electrochemical capacitors, etc. In this research work, nickel oxide nanoparticles were synthesized by combustion route in presence of organic fuels such as, glycine, glucose and and urea. The prepared nickel oxide nanoparticles were calcined at 600℃ for 3 h to get phase pure materials. The calcined nanoparticles were preliminarily characterized by XRD, particle size analysis, SEM and EDAX. To prepare nickel oxide electrode materials for application in supercapacitors, the calcined NiO nanoparticles were mixed with di-methyl-acetamide and few drops of nafion solution for 12 to 16 h. The above slurry was coated in the graphite sheet and dried at 50℃ for 2 to 4 h in a hot air oven to remove organic solvent. The dried sample was subjected to electrochemical studies, such as cyclic voltammetry, AC impedance analysis and chrono-coulometry studies in KOH electrolyte medium. From the above studies, it was found that nickel oxide nanoparticles prepared by combustion synthesis using glucose as a fuel exhibited resulted in low particle diameter (42.23 nm). All the nickel oxide electrodes have shown better good capacitance values suitable for electrochemical capacitor applications.

• 센서학회지
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• 제24권5호
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• pp.348-352
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• 2015

Thin nickel oxide films formed on uncooled and cooled $SiO_2/Si$ substrates using a radio frequency (RF) magnetron sputter powered by 200 W in a mixed atmosphere of argon and oxygen. Grazing-incidence X-ray diffraction and field emission scanning electron microscopy are used for the structural analysis of nickel oxide films. The electrical conductivity required for better bolometric performance is estimated by means of a four-point probe system. Columnar and (200) preferred orientations are discovered in both films regardless of substrate cooling. Electric resistivity, however, is greatly influenced by the substrate cooling. Oxygen partial pressure increase during the nickel oxide deposition leads to a rapid decrease in resistivity, and the resistivity is higher in the cooled nickel oxide samples. Even when small microstructure variations are applied, lower resistivity in favor of low noise performance is acquired in the uncooled samples.

• 문화기술의 융합
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• 제9권3호
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• pp.593-599
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• 2023

질산니켈육수화물염(nickel(II) nitrate hexahydrate) 수용액을 공업용 펄프에 함침시킨 전구체를 이용하여 세라믹스 분말을 제조하는 간단한 액상 합성법으로 산화니켈(NiO) 나노입자를 성공적으로 합성하였다. 질산니켈육수화물염 수용액이 함침된 전구체의 미세구조를 주사전자현미경(SEM)으로 확인하였고, 전구체의 열처리온도 증가에 따라 생성되는 산화니켈(NiO) 입자의 결정구조 및 입자크기를 X선회절분석(XRD) 및 SEM으로 분석하였다. 그 결과 전구체의 유기물질이 완전하게 열분해 되는 온도는 495-500℃이며, 열처리 온도의 증가에 따라 생성되는 산화니켈 입자의 크기 및 결정성이 증가하는 것을 XRD, SEM 분석을 통하여 확인하였다. 500-800℃에서 각각 1시간 동안 열처리하여 얻어진 산화니켈 입자의 크기는 50-200nm였다. 열처리 온도 380℃에서 NiO 결정상이 형성되고, 800℃까지는 NiO 단일상만 존재하며, 열처리 온도가 높아짐에 따라 생성되는 입자의 크기가 커지고 있음을 XRD 및 SEM 분석으로 확인하였다.

• 자원리싸이클링
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• 제13권3호
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• pp.27-36
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• 2004

수소화 반응용 니켈 폐촉매를 배소하여 산화니켈을 회수한 다음, 회수한 산화니켈을 산처리하고 침전법으로 Kieselguhr에 담지 된 니켈 촉매로 재생시켰다. 폐촉매의 배소 조건이 니켈산화물의 회수에 미치는 영향을 조사하였다. 니켈 폐촉매의 재생 과정에서 $1,000^{\circ}C$의 온도에서 배소 하였을 경우에 대부분 니켈산화물로 회수할 수 있었다. 산화니켈을 산처리하여 얻은 질산니켈을 사용하여 Kieselguhr에 담지 된 니켈 촉매를 제조하였다. 이때 조촉매의 첨가, 침전 조건 및 환원 조건 등이 재생된 촉매의 식물성 오일의 수소화 반응 성능에 미치는 영향을 조사하였다. 알카리 금속인 CaO와 희토류 금속인 $Ce_2$$O_3$를 조촉매로 첨가했을 때 수소화 반응의 활성이 증가하였다.

• 한국재료학회지
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• 제28권1호
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• pp.24-31
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• 2018

This study reports an environment-friendly synthetic strategy to process nickel oxide nanocrystals. A mesoporous nickel oxide nanostructure was synthesized using an environmentally benign biomimetic method. We used a natural rambutan peel waste resource as a raw material to ligate nickel ions to form nickel-ellagate complexes. The direct decomposition of the obtained complexes at $700^{\circ}C$, $900^{\circ}C$ and $1100^{\circ}C$ in a static air atmosphere resulted in mesoporous nickel oxide nanostructures. The formation of columnar mesoporous NiO with a concentric stacked doughnuts architecture was purely dependent on the suitable direct decomposition temperature at $1100^{\circ}C$ when the synthesis was carried out. The prepared NiO nanocrystals were coated on cotton fabric and their antibacterial activity was also analyzed. The NiO nanoparticle-treated cotton fabric exhibited good antibacterial and wash durability performance.

• 한국세라믹학회지
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• 제45권6호
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• pp.368-373
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• 2008

An electrode for supercapacitor using 3-dimensional porous nickel foam as a current collector and cobalt oxide as an active material was prepared and characterized in terms of morphology observation, crystalline property analysis, and the investigation of electrochemical property. The electrode surface showed that the cobalt oxide was homogeneously coated as the crystalline phase of $Co_3O_4$. Cyclic voltammetry for the $Co_3O_4$/nickel foam electrode exhibited higher specific capacitance values (445 F/g at 10 mV/s and 350 F/g at 200 mV/s) and excellent capacitance retention ratio (99% after $10^4$ cycles). It was proved that the nickel foam substrate played the roles in reducing the interfacial resistance with cobalt oxide and in improving the electrode density by embedding greater amount of cobalt oxide within it.