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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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Subject: search.filters.subject.Nitrogen doping

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Now showing 1 - 4 of 4
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    Improved lithium storage capacity and high rate capability of nitrogen-doped graphite-like electrode materials prepared from thermal pyrolysis of graphene quantum dots
    (2020-09-10)
    Gu, Siyong
    ;
    Christensen, Tommiejean
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    Hsieh, Chien-Te
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    Mallick, Bikash Chandra
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    Gandomi, Yasser Ashraf
    Adopting a solid-phase microwave-assisted technique followed by thermal pyrolysis of N-functionalized graphene quantum dots, novel nitrogen-doped graphite-like (NGL) electrode materials were synthesized and served as the anode for Li-ion batteries. The NGL anode demonstrated reversible capacity of 530 mAh g(-1) at 0.1C, superior rate capability at high C rate operation (420 mAh g(-1) at 5C), remarkable initial coulombic efficiency (>95.7%), and excellent cyclic stability along with high efficiency (>99.1%) during entire cycling. The NGL anode nanostructure enables improved lithium ion mobility and reversible Li+ storage during cycling. The analysis of the Ragone plots revealed that the specific energy of NGL anode reaches to ca. 840 Wh kg(-1) at the power density of 4200 W kg(-1). The diffusion coefficient of Li ions was measured as 1.69 x 10(-9) cm(2) s(-1) for the NGL anode material, substantially improving over commonly used graphite electrodes (15-26 times higher Li+ diffusivity). The high-rate cyclability as well as the cyclic stability of the NGL anodes were also confirmed via long-term cycling of full pouch cells assembled with ternary cathode and NGL anode. The robust design of the NGL anode materials introduced in this work, paves the way for designing next-generation lithium-ion batteries operating at ultrahigh C rates. (C) 2020 Elsevier Ltd. All rights reserved.
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    Fluorescence of functionalized graphene quantum dots prepared from infrared-assisted pyrolysis of citric acid and urea
    (2020-01-01)
    Gu, Siyong
    ;
    Hsieh, Chien-Te
    ;
    Yuan, Chun-Yao
    ;
    Gandomi, Yasser Ashraf
    ;
    Chang, Jeng-Kuei
    This paper reports an efficient fabrication of N-doped graphene quantum dots (GQDs) showing controllable chemical and fluorescence (FL) properties through infrared carbonization (IRC) of citric acid and urea. The GQDs prefer to form an equilibrium shapes of circle with an average particle size ranged from 5 to 10 nm. The N/C atomic ratio in GQDs can be precisely tailored in a range from 21.6 to 49.6 at.% by simply controlling the weight ratio of citric acid to urea. With increasing the urea content, the GQDs not only contain N-doped graphene but also incorporate with crystalline cyanuric acid, forming a binary crystallinity. The quantum yield of 22.2% is achieved by N-doped GQDs, prepared from the IRC synthesis of chemical precursor at the citric acid/urea at 3:1. Excessive N and cyanuric acid can lead to FL quenching, red shift and wide spectral distribution. The design of GQDs possesses a multiple chromophoric band-gap structure, originated from the presence of cyanuric acid, defect-related emissive traps, and functional group distributions. This work offers an effective and inspiring approach to engineering both chemical compositions and unique crystalline structures of GQDs, and will therefore facilitate their fundamental research and applications to optical, sensing, energy and biological fields.
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    Influences of Nitrogen Doping on the Electrical Characteristics of Indium-Zinc-Oxide Thin Film Transistors
    (2016-12)
    Han, Yanbing
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    Yan, Hai
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    Tsai, Yun-Chu
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    Li, Yan
    ;
    Zhang, Qun
    Thin film transistors (TFTs) with nitrogen doped amorphous indium-zinc-oxide (a-IZO:N) as the channel layer were prepared by rf magnetron sputtering with an argon, oxygen, and nitrogen gas mixture at room temperature. XRD measurements confirm the amorphous structure of a-IZO:N thin film and AFM verifies its uniformity. Transmittance curves show that nitrogen doping in a-IZO films can narrow the optical band gap and suppress oxygen vacancies, which is also proved by XPS. When the nitrogen flow rate is 4 SCCM, a-IZO TFTs possess optimized the characteristics, with saturation mobility 24.67 cm(2)V(-1)s(-1), subthreshold swing 0.41 V/decade, on/off ratio 1.7 x 10(9), and threshold voltage -14.46 V. Threshold voltages shift from -22.76 to -9.59 V as the nitrogen flow rate raises from 0 to 6.5 SCCM. The positive gate bias stability and negative bias illumination stability of a-IZO:N TFT are also improved with the nitrogen flow rate of 4 and 2.5 SCCM, respectively.
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    錳氧化物奈米複合材料與新穎三維碳奈米結構修飾電極製備及其應用於可撓式非對稱型超高電容器系統之研究
    (2015)
    曾俊元
    ;
    TSENG TSEUNG-YUEN
    ;
    國立交通大學電子工程學系及電子研究所
    在科技進步能源價格高漲的時代，能源材料開發與儲能技術的發展就更顯重要。超高電容器是現 階段受到重視的儲能元件之一，具備可靠性高、壽命長、可急速充放電等優異的特徵，與傳統電池相 比，雖能提供比電池更高的瞬間功率但其能量密度相顯遜色，成為超高電容器未來面臨的主要挑戰。 近年來，錳氧化物為超高電容器(擬電容器)中極具潛力的電極材料，具有價格低廉、無毒性、安全性 高等優點，然而，受限於材料本身導電率不佳，使元件等效串聯電阻ESR 過大，影響超高電容器的有 效儲能量及充放電循環壽命加上單體超高電容器耐電壓有限，因而造成應用上的限制。 根據上述所遭遇到之問題，本實驗室三年之研究計畫將提出改善解決方法，著重於三維新穎混合 型碳奈米網狀結構開發(石墨烯薄片上成長奈米碳管陣列)、低維度奈米複合式電極反應物材料 (Graphene/CNT/MnO2 Nanocomposites)合成、三維碳奈米網狀結構表面改質(氮摻雜)、複合式電極反應物 材料改質(銀原子摻雜錳氧化物)、超高電容器電極製備、超高電容器系統電解液選擇(離子液體)及可撓 式非對稱型正負極材料之超高電容器系統組裝等主題研究，探討其在超高電容器儲能性能及應用。 根據上述七大方向的改善，期待能藉由新穎混合型之碳奈米網狀結構具高比表面積特性並配合改 善奈米錳氧化物在石墨烯/碳管上之附著機制，以獲得較大反應面積及可靠的複合式奈米結構，期待能 開發出具有高功率密度(> 1,000 kW/kg)、高能量密度(> 200 Wh/kg)、寬操作電壓範圍(> 5 V)、高循環次 數 (> 50,000 cycles)及低充電時間 (3~5 分鐘)之高效能可撓式非對稱型正負極材料之超高電容器，隨後 積極於電容器廠配合，將研究的成果具體應用化。