以靜電紡絲製備氧化鎳鈷奈米纖維

The preparation of Ni-Co-O nanofibers by electrospinning

何松恩(Song-En He)

指導教授 ： 林炯棟

義守大學/理工學院/材料科學與工程學系/碩士(2016年)

摘要

本論文利用靜電紡絲技術製備出奈米纖維前驅物，之後再進行煆燒
成氧化物，藉著改變前驅液的PVP 濃度、金屬離子濃度、鈷源與鎳鈷比
以及環境因素，探討其對奈米纖維顯微結構的影響，再利用三極式電極
系統以循環伏安法測量其電化學性質並計算其比電容值，氧化還原峰的
電位差越大時，代表氧化還原反應的可逆性變差，降低了電極的效能。
NiCo2O4 具有比單一氧化物較高的導電率與電化學活性，近年受
到大家的重視，當形成一維奈米結構時具有好的電荷與離子傳輸能力，
能得到極高的比電容。本研究藉由改變前驅液中不同聚乙烯吡咯烷酮濃
度，再經過熱處理後，形成氧化物奈米纖維，探討對奈米纖維的直徑、
表面形貌與比電容的影響。其結果顯示，靜電紡絲製備之奈米纖維，依
照不同配方及金屬濃度製備出不同形貌和不同直徑大小的奈米纖維。在
PVP 濃度改變上對於奈米纖維結構也有很大的影響，我們發現增加PVP
濃度時，奈米纖維結構上會從捲曲帶狀變成筆直管狀，管狀結構比表面
積較大，所以表現出較高的比電容值。金屬濃度(0.2M)較低時，所製備
出來的NiCo2O4奈米纖維表面較為粗糙，直徑也較大，比電容量123F/g，
而金屬濃度(0.49M)較高時，奈米纖維呈現光滑管狀結構，直徑明顯變
小，但比電容較低90F/g，顯然金屬濃度會對奈米纖維結構上造成影響。
根據XRD 分析，若鎳鈷比為3:7 時，只出現NiCo2O4單一相，若鎳鈷比例
較高時(6:4)時，則會出現NiCo2O4相與NiO 相共存。再以比電容的結果
發現，當NiCoO4相多於NiO 相時，比電容較大。
另外，試著更換鈷源進行電紡，換成醋酸鈷來進行前驅液的調配，
比電容值並沒有明顯的提升，但在電紡過程中發現紡絲更為順利，可以
看出以大量的奈米纖維，其表面光滑且完整，纖維的量明顯比使用硝酸
鈷所製備的奈米纖維多，所以鎳鈷比也會影響奈米纖維形成的因素。
此外，環境因素也是影響實驗過程和製備出來的奈米纖維表面形貌，
當環境濕度較高時，電紡過程中較難製備出奈米纖維，而電壓較不穩時，
所製備出來的奈米纖維表面會出現較多豆子狀的團聚物。

關鍵字

靜電紡絲 ； 超級電容 ； 鈷酸鎳

並列摘要

In this thesis, the electrospinning was used to prepare Ni-Co-O nanofiber precursor by changing the PVP concentration, the concentration of metal ions, and cobalt sources, the relationship between electrochemical characteristics and microstructure of the calcined nanofibers were further explored. Cyclic voltammetry was used to calculate specific capacitance, and the morphology and phase were analyzed by XRD and SEM/EDX. The results showed that various formulations and metal concentrations affected seriously the morphologies and diameter of nanofibers. When concentration of PVP increased, the Ni-Co-O nanofibers become a straight tubular curling ribbon from the nanofiber structure, the tubular structure possessed a larger specific surface area, so that the resulted electrodes showed a higher specific capacitance. Besides, as metal ion concentration (0.2M) was low, the Ni-Co-O nanofiber surface was rough, whereas the higher concentrations (0.49M) yielded a smooth tubular structure. As the metal concrentation increased,the diameter decreased and specific capacitance decreased, respectively.
According to XRD analysis, if the nickel and cobalt ratio was 3: 7, NiCo2O4 was single phase, once nickel content increased (6:4), NiCo2O4 and NiO phases coexisted. The specific capacitance NiCo2O4 phase uaually exhibited a larger value than NiO phase. In addition, the effect of cobalt sources (cobalt nitrate v.s cobalt acetate) was also studied, specific capacitance had no significant improvement, but a larger number of nanofibers can be obtained, the surface is smooth and continuous.

並列關鍵字

electrospinning ； Ni-Co-O nanofiber ； supercapacitor ； specific capacitance

參考文獻

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