- 學位論文
官能基可調控之石墨烯/聚苯胺/F-127複合薄膜合成、鑑定以及在超級電容上的應用
Synthesis, Charaterization and Supercapacitor Application of Functional Group Controllable Graphene/Polyaniline/F-127
摘要
本實驗分成兩個部分，第一個部分主要在探討不同含氧官能基含量的石墨烯/聚苯胺之薄膜對於超級電容器性能的影響。藉由不同鍛燒溫度，以熱還原法還原氧化石墨烯，造成石墨烯表面上含氧官能基(-COO、C-O-C和C-OH)比例產生變化，再以原位聚合的方式與聚苯胺做成奈米級的複合膜材。首先以X射線光電子能譜儀(XPS)確實的計算出不同鍛燒溫度之石墨烯上各種含氧官能基之比例，並藉由穿透式電子顯微鏡(TEM)證明了含氧官能基團含量的提升，有助於增進石墨烯在水溶液中分散均勻性，並減少在高分子中的團聚現象；並以凝膠滲透層析儀(GPC)與四點探針證實了石墨烯的團聚現象不利於石墨烯達到奈米級分散，並降低添加後的導電度提升效果；接著進一步以電化學儀器(cyclic voltammetry, charge–discharge)進行測試，實驗結果證明了添加低鍛燒溫度(300C)之石墨烯的聚苯胺複合膜材電容值表現優異，與純聚苯胺做比較，其充放電電容量在1A/g的電流密度下，可以從350F/g上升至514F/g，其上升幅度約有46%。 由於從第一個部分研究中已證明石墨烯在聚苯胺中的分散均勻性對於超級電容的電性展現有著顯著的影響，故第二部分的研究便是進一步探討分散性的提升方法。一般而言要使碳材增加水溶液中的分散均勻性，主要的方法為表面改質與分散劑的添加，而高鍛燒溫度之石墨烯已被證實具有高導電性，但所含有的含氧官能基團含量降低會導致在水溶液中產生團聚現象，因此本實驗進一步導入Pluronic F-127水溶性凝膠作為分散劑，並配合超音波震盪處理，形成高分散性的石墨烯水溶液，並用此與單體苯胺利用原位聚合製備出高分散性的石墨烯/聚苯胺複合材料。首先以TEM明顯證明導入分散劑後可大幅的降低高鍛燒溫度(1000C)石墨烯的團聚現象，並同樣以GPC和四點探針證實了團聚現象的消除確實可使高鍛燒溫度石墨烯/聚苯胺複合材料的導電度更進一步上升，最後同樣用電化學儀器對石墨烯/聚苯胺複合薄膜修飾之電極進行測試，實驗結果證實導入分散劑後，高鍛燒溫度石墨烯/聚苯胺複合材料可使電容值再進一步的提升，達到561F/g之電容值，與純聚苯胺做比較上升幅度約有60%，並優於低鍛燒溫度之石墨烯的聚苯胺複合膜材電容值514F/g。
並列摘要
Functional group controllable reduced graphene oxide was compounded with polyaniline to prepare supercapacitor electrode materials. Graphene oxides was reduced at different temperatures, and polymerized by in situ polymerization of aniline monomer. X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM) prove graphene calcining at 300C has wealthy oxygen-containing functional group(-COO, C-O-C, and C-OH), which can reduce aggregation of graphene in graphene/polyaniline composites. The constant current charge/discharge measurement shows 300C graphene/polyaniline composite has great capacitance of 426F/g at a scan rate of 1A/g, indicating that 300C is the best reduced temperatures of graphene for graphene/polyaniline supercapacitor electrode materials. In the first part, we have found extensive aggregation of graphene in 1000C graphene/polyaniline composites. To improve stabilization of graphene in water solution, we used Pluronic® F-127 (PEO-PPO-PEO block copolymer) as a dispersant. TEM prove F-127 can reduce aggregation of graphene effectively in 1000C graphene/polyaniline composites, which affects electron delivering more efficient. The constant current charge/discharge measurement shows 1000C graphene/polyaniline/F127 composites has the best capacitance of 561F/g at current density of 1A/g, better than 300C graphene/polyaniline composite. These easily fabricated PANI nanocomposite electrode reveals a great potential for energy storage application.