以電鍍法製備催化劑於碳纖維布上成長奈米碳纖維

Synthesis of Carbon Nanofibers on Carbon Fiber Fabrics Using Electrodeposited Catalysts

莊博凱(Po-Kai Chuang)

指導教授 ： 曾信雄

大同大學/工程學院/材料工程學系所/碩士(2007年)

摘要

奈米碳纖維與奈米碳管，因具有特殊的結構而造成許多優越的性質，因此被廣泛研究，若將奈米碳纖維或奈米碳管筆直的成長在傳統纖維布上，可應用於許多領域上。本研究中利用電化學沉積催化劑於ＰＡＮ系碳纖維布上，再以化學氣相沉積法成長奈米碳纖維；而在製程中如何有效均勻分散催化劑以及控制催化劑大小是相當重要的，因此吾人於沉積催化劑前，先行將纖維布進行表面改質，試圖增加催化劑的分散，使後續於複合材料的應用有更顯著的效能呈現。
　　研究中先針對三種不同電極製備方式進行，探討並尋找最佳電極製備方式，之後再探討表面改質溶液濃度對電化學沉積催化劑有何影響，以及不同成長時間、溫度、流量對成長奈米碳纖維的影響。實驗結果顯示，以環狀銅膠帶電極所製備之顆粒狀催化劑較適合後續之纖維成長。表面改質部分結果顯示，經表面改質後能增加催化劑於纖維表面的分散性以及實驗的再現性，催化劑的粒徑隨著改質溶液濃度的降低而減小；反之，未經表面改質之纖維布的再現性並不高；在脈衝循環次數方面，其粒徑也會隨著催化劑的脈衝次數減少而減小。
在奈米碳纖維生長型態部分，未經表面改質所生長之奈米碳纖維容易出現糾結、彎曲型態；而經表面改質所生長之奈米碳纖維其成長方向大部分仍是彎曲的型態，但纖維的長徑比有較大的現象，且隨改質溶液濃度降低，其長徑比較大之碳纖維也會隨之減少。透過TEM分析結果，奈米碳纖維之內部碳層結構的排列相當混亂；在溫度方面，奈米碳纖維較適合於低溫下生長，且會隨溫度升高導致管徑分布範圍變大；最後，在成長時間與乙炔濃度方面，奈米碳纖維產量會隨時間及濃度增加而增加。

關鍵字

PAN系碳纖維布 ； 奈米碳纖維 ； 化學氣相沉積法 ； 電鍍法

並列摘要

Carbon nanofibers(CNFs) and carbon nanotubes(CNTs) are widely investigated because of their excellent physical and chemical properties. Previous reports mentioned that CNFs and CNTs grown on the conventional carbon fiber cloth were proposed for several applications. In this research, CNFs were grown by chemical vapor deposition using electrodepositied Ni catalysts on the PAN-based carbon fiber cloth. In the catalytic growth of CNFs and CNTs, to produce well distributed nano-sized catalysts is a critical processing, thus a surface modification pretreatment to carbon fiber cloth was used to improve the distribution of catalysts on the surface of fiber cloth.
Three different electrode assembly methods were employed in the electro-deposition process and the effect of surface modification pretreatment was also investigated. The electrodeposition results indicated that the catalyst particles deposited using a ring-like electrode method showed a better distribuition than that of the other two methods. The electrodeposited Ni catalysts showed a much better distribution on carbon fiber cloth after a surface modification pretreatment, and reproducible results could be achieved. The pacticles size decreased when a lower concentration of surface modification solution was used.
CNFs showed a entangled morphology when using the electrodeposited Ni catalyst with or without a surface modification pretreatment. CNFs with a larger aspect ratio were found when the Ni catalyst were electrodepositied with a surface modification pretreatment. CNFs with uniform diameter distribution can be grown at a low temperature of 540℃.As the growth temperature was raised, CNFs with a wider diameter distribution were obtained. The carbon yield increased with an increase of deposition time and acetylene concentration. The TEM results indicated that the graphene layers of CNFs are not well ordered.

並列關鍵字

PAN-based carbon fiber ； carbon nanofibers ； chemical vapor deposition ； electrodeposition

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