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        검색결과 13

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Dimethyl silicone oil is widely used due to its excellent thermal stability and good wetting properties. In this study, a series of thermal conductive materials was prepared by physically blending and chemically loading graphene as a thermal conductive filler into dimethyl silicone oil, and their thermal conductivity and tribological properties were investigated. The thermal conductivity of the composites was tested by a thermal conductivity meter and a thermal imaging camera, while the tribological properties of the composites were evaluated using a CSM friction and wear tester. The results showed that both thermal conductivity and tribological properties were improved to a certain extent. The particle size and amount of graphene had a significant influence on the thermal conductivity. For graphene with a single particle size, the thermal conductivity increased with increasing graphene content. The friction coefficient under dry friction conditions was significantly reduced by adding graphene to the silicone oil, as revealed by the friction and wear test.
        4,000원
        2.
        2023.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Decabromodiphenyl ether (BDE209) is a persistent aromatic compound widely associated with environmental pollutants. Given its persistence and possible bioaccumulation, exploring a feasible technique to eradicate BDE209 efficiently is critical for today’s environmentally sustainable societies. Herein, an advanced nanocomposite is elaborately constructed, in which a large number of titanium dioxide ( TiO2) nanoparticles are anchored uniformly on two-dimensional graphene oxide (GO) nanosheets ( TiO2/GO) via a modified Hummer’s method and subsequent solvothermal treatment to achieve efficient photocatalytic degradation BDE209. The obtained TiO2/ GO photocatalyst has excellent photocatalytic due to the intense coupling between conductive GO nanosheets and TiO2 nanoparticles. Under the optimal photocatalytic degradation test conditions, the degradation efficiency of BDE209 is more than 90%. In addition, this study also provides an efficient route for designing highly active catalytic materials.
        4,000원
        3.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cerium oxide decorated on nickel hydroxide anchored on reduced graphene oxide (Ce-Ni(OH)2/rGO) composite with hexagonal structures were synthesized by facile hydrothermal method. Fourier transform infrared spectroscopy (FT-IR), highresolution transmission electron microscopy with selected area diffraction (HRTEM-SAED), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer– Emmett–Teller (BET) surface area analysis and electrochemical technology were used to characterize the composite. Due to its unique two-dimensional structures and synergistic effect among Ce2O3, Ni(OH)2 and rGO components indicated twodimensional hexagonal nano Ce-Ni(OH)2/rGO composite is promising electrode material for improved electrochemical H2O2 sensing application. From 50 to 800 μM, the H2O2 concentration was linearly proportional to the oxidation current, with a lower detection of limit of 10.5 μM (S/N = 3). The sensor has a higher sensitivity of 0.625 μA μM−1 cm− 2. In addition, the sensor demonstrated high selectivity, repeatability and stability. These findings proved the viability of the synthetic method and the potential of the composites as a H2O2 sensing option.
        4,600원
        4.
        2022.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Despite having a low electrical conductivity, graphene oxide (GO) is used as an anode material in lithium-ion batteries (LIBs) owing its good processability in large quantities. GO is reduced by chemical or thermal treatments to enhance its electrical conductivity. In this study, high-performance GO anodes with polydopamine (PDA) and polyethylenimine (PEI) as binders were fabricated. Gamma (γ)-ray irradiation was applied to the GO–PDA–PEI hybrid sheets to covalently cross-link the GO sheets and binders with an amide bond. The covalent crosslinking was confirmed by Fourier-transform infrared spectroscopy analysis. Further, X-ray photoelectron spectroscopy results showed that γ-ray irradiation produced a reduced GO sheet, which resulted in an increase in the electrical conductivity by 30%. By characterizing the electrochemical properties, we found that the γ-ray irradiation facilitates the stability and increases the charge/discharge capacity by crosslinking GO and PDA–PEI binders and reducing the GO sheets.
        4,000원
        5.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Morphology control of a graphene nanosheet (GNS) is important for graphene-based battery electrodes to exhibit the increased practical surface area and the enhanced ion diffusion into the nanosheets. Nevertheless, it is very difficult to minutely control the shape of graphene nanosheets based on the conventional GNS suspension methods. In this work, we fabricated wrinkle textures of free-standing GNS for large area using Langmuir–Schaefer technique. The wrinkles are oriented vertically to the direction of the monolayer compression. The textured structure of GNS was obtained by cross-deposition of each layer with controlling the orientation of the wrinkle direction. These wrinkles can cause Li-ion to diffuse into the voids created by them and raise the specific surface area between the GNSs. Consequently, as a prospective anode for Li-ion battery, the wrinkled GNS multilayer, exhibits the high specific capacity of ~ 740 mAh g− 1 at 100 mA g−1 and the great power capability with ~ 404 mAh g− 1 being delivered even at 2 A g− 1. Furthermore, outstanding cycle performance of the wrinkled GNS multilayer is achieved over 200 cycles at 300 mA g−1 with high Coulombic efficiency of ~ 96%.
        4,000원
        7.
        2019.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        High-quality and solution processable graphene sheets are produced by a simple electrochemical exfoliation method and employed as a high-power anode for lithium-ion batteries (LIBs). The electrochemically exfoliated graphene (EEG) composed of a few layers of graphene sheets, have low oxygen content and high C/O ratio (~ 14.9). The LIBs with EEG anode exhibit ultrafast lithium storage and excellent cycling stability, but low initial efficiency. The excellent rate capability and cycling stability are attributed to the favorable structural and chemical properties of the EEG, but the large irreversibility needs to be overcome for practical applications.
        4,000원
        8.
        2018.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, graphene oxide(GO) was used as drug carriers to amorphize poorly watersoluble drugs via a co-spray drying process. Two poorly water-soluble drugs, fenofibrate and ibuprofen, were investigated. It was found that the drug molecules could be in the graphene nanosheets in amorphous or nano crystalline forms and thus have a significantly enhanced dissolution rate compared with the counterpart crystalline form. In addition, the dissolution of the amorphous drug enwrapped with the graphene oxide was higher than that of the amorphous drug in activated carbon (AC) even though the AC possessed a larger specific surface area than that of the graphene oxide. The amorphous formulations also remained stable under accelerated storage conditions (40°C and 75% relative humidity) for a study period of 14 months. Therefore, graphene oxide could be a potential drug carrier and amorphization agent for poorly water-soluble drugs to enhance their bioavailability.
        4,000원
        10.
        2017.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        그래핀 기반 소재는 높은 가공성과 초박성으로 인하여 분리막 소재로서 각광받고 있다. 본 연구에서는, 스핀 코팅 법을 이용하여 제조된 산화그래핀 분리막의 기체 투과 거동을 평가하였다. 산화그래핀 분리막의 구조는 산화그래핀의 크기와 산화그래핀 용액의 pH 조절을 통하여 조절될 수 있다. 산화그래핀의 크기가 작을수록 굴곡률이 작아짐에 따라 분리막의 기 체 투과도 및 선택도가 증가하는 경향을 보인다. 또한 산화그래핀에서의 기체 투과 거동은 적층된 산화그래핀 사이의 채널 크기에 따라 영향을 받는다. 특히 산화그래핀 분리막의 좁은 기공과 이산화탄소 선택적인 산화그래핀 자체의 특성으로 인하 여 산화그래핀 분리막은 이산화탄소에 대한 높은 투과도 및 선택성을 가지며, 이는 이산화탄소 포집에 적합한 특성을 가진다. 이러한 산화그래핀 분리막의 특이한 기체 투과 거동은 흡착-촉진 확산 거동(표면 확산 기작)으로 설명될 수 있다. 본 연구를 통하여 이산화탄소 선택성 분리막 소재 설계와 슬릿 형태의 기공과 적층 구조를 가진 분리막을 통한 기체 투과 거동 연구가 활발히 이루어질 것으로 기대한다.
        4,800원
        11.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nitrogen-atom doped graphene oxide was considered to prevent the dissolution of polysulfide and to guarantee the enhanced redox reaction of sulfur for good cycle performance of lithium sulfur cells. In this study, we used urea as a nitrogen source due to its low cost and easy preparation. To find the optimum urea content, we tested three different ratios of urea to graphene oxide. The morphology of the composites was examined by field emission scanning electron microscope. Functional groups and bonding characterization were measured by X-ray photoelectron spectroscopy. Electrochemical properties were characterized by cyclic voltammetry in an organic electrolyte solution. Compared with thermally reduced graphene/sulfur (S) composite, nitrogen-doped graphene/S composites showed higher electroactivity and more stable capacity retention.
        4,000원
        12.
        2014.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Due to their morphology, electrochemical stability, and function as a conducting carbon matrix, graphene nanosheets (GNS) have been studied for their potential roles in improving the performance of sulfur cathodes. In this study, a GNS/sulfur (GNS/S) composite was prepared using the infiltration method with organic solvent. The structure, morphology and crystallinity of the composites were examined using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The electrochemical properties were also characterized using cyclic voltammetry (CV). The CV data revealed that the GNS/S composites exhibited enhanced specific-current density and ~10% higher capacity, in comparison with the S-containing, activated-carbon samples. The composite electrode also showed better cycling performance for multiple charge/discharge cycles. The improvement in the capacity and cycling stability of the GNS/S composite electrode is probably related to the fact that the graphene in the composite improves conductivity and that the graphene is well dispersed in the composites.
        3,000원
        13.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nanocomposites comprised of graphene oxide (GO) nanosheets and magnesium oxide (MgO) nanoparticles were synthesized by a sol-gel process. The synthesized samples were studied by X-ray powder diffraction, atomic force microscopy, transmission electron microscopy, and energy-dispersive X-ray analysis. The results show that the MgO nanoparticles, with an average diameter of 70 nm, are decorated uniformly on the surface of the GOs. By controlling the concentration of the MgO precursors and reaction cycles, it was possible to control the loading density and the size of the resulting MgO particles. Because the MgO particles are robustly anchored on the GO structure, the MgO/GOs nanocomposites will have future applications in the fields of adsorption and chemical sensing.
        3,000원