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收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

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    Tunable nitrogen-doped graphene sheets produced with in situ electrochemical cathodic plasma at room temperature for lithium-ion batteries
    (2019-06-01)
    Yen, Po-Jen
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    Ilango, P. Robert
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    Chiang, Ya-Chi
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    Wu, Chia-Wei
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    Hsu, Yung-Chi
    This paper describes a facile and tunable method, performed at room temperature and amenable to mass-production, for the preparation of nitrogen-doped graphene sheets using in situ electrochemical cathodic plasma exfoliation of a graphite/melamine composite. The plasma generated at the submerged surface of the graphite/melamine composite electrode not only exfoliated the graphite granules into graphene sheets but also induced the doping of nitrogen atoms. The sizes and morphologies of the graphene sheets, comprising four to five layers of graphene, were confirmed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Tuning the concentration of melamine in the graphite/melamine composites led to different levels of nitrogen-doping in the graphene sheets; the stability of the nitrogen-doped graphene sheets was investigated in various harsh environments. Furthermore, the use of the 4.63 at% nitrogen-doped graphene sheets as anode materials resulted in lithium-ion batteries displaying excellent performance, with a capacity of 488 mA h g(-1) at 100 mA g(-1) after 100 cycles that was better than that of the device incorporating pristine graphene sheets (344 mA h g(-1) at 100 mA g(-1) after 100 cycles). This method is a new and tunable approach for producing massive amounts of nitrogen-doped graphene sheets from graphite powder at room temperature. (C) 2019 Elsevier Ltd. All rights reserved.
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    Prior vacuuming for supercritical fluid synthesis of SnO2/graphene nanocomposites with superior electrochemical Li+ storage performance
    (2018-12-01)
    Xie, Jian-De
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    Li, Hui-Ying
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    Umesh, Bharath
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    Lee, Tai-Chou
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    Chang, Jeng-Kuei
    Supercritical CO2 (SCCO2) fluid, exhibiting gas-like diffusivity, extremely low viscosity, and near-zero surface tension, is used to synthesize uniformly dispersed and tightly anchored SO2 nanoparticles (a 3-nm diameter was achieved) on graphene nanosheets (GNSs). Usually, the conventional synthesis processes (in the absence of SCCO2) results in aggregated SnO2 clusters; whereas the technique described in this work eliminates this limitation. This study reveals the significance of two crucial factors (the SCCO2 pressure (i.e., fluid density) and the degassing step (i.e., vacuuming stage) in autoclave before injecting CO2) on the uniform distribution of the synthesized SnO2 nanoparticles on GNSs. Increasing the pressure leads to an increase in SCCO2 density (and viscosity), suppressing the transport of SnO2 precursors throughout the sample. On the other hand, vacuuming the autoclave before injecting CO2 improves the uniformity of SnO2 particle distributions. To assess the electrochemical performance of the synthesized nanoparticles, the specific capacity, rate capability, and cyclic stability were determined for various samples. A capacity of similar to 787 mAh g(-1) at 100 mA g(-1) was achieved for an optimal configuration of the SnO2/GNS electrodes. The capacity retention was 60% when the charge-discharge rate increased to 6000 mA g(-1). (C) 2018 Elsevier Ltd. All rights reserved.