團鏈共聚物自組裝、石墨化及金屬碳合金材料之製備;Electrochemically Active N-doped and N/Fe-doped Graphite with Well Defined Morphology and Dimension Fabricated from Pyrolyzed PS-P2VP Block Copolymer Nanostructures

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题名:	團鏈共聚物自組裝、石墨化及金屬碳合金材料之製備;Electrochemically Active N-doped and N/Fe-doped Graphite with Well Defined Morphology and Dimension Fabricated from Pyrolyzed PS-P2VP Block Copolymer Nanostructures
作者:	黃偉華;Huang,Wei-hua
贡献者:	化學工程與材料工程學系
关键词:	雙團鏈共聚物;碳化;氧氣還原反應;石墨;溶劑退火;di-block copolymer;carbonization;oxygen reduction reaction;graphite;solvent annealing
日期:	2015-08-26
上传时间:	2015-09-23 11:08:13 (UTC+8)
出版者:	國立中央大學
摘要:	本研究分成兩個部分。第一個部分是以雙團鏈共聚物之自組裝奈米結構，製備具有氮摻雜之奈米碳材，第二部分則是製備含鐵/氮摻雜的奈米碳球。第一部份探討單純高分子所製備的碳材料，首先以溶劑退火法使高分子排列成垂直柱狀、平躺柱狀以及垂直的層板結構，再利用紫外光使高分子產生交聯反應以穩定其結構，之後以高溫碳化製備出能夠複製原有高分子結構的碳材。由於組成鏈段當中含有氮原子，造成該高分子燒製的碳材會有氮原子雜化，此現象能使碳材具備將氧還原的能力。因此除了分析碳材本身的結構特性之外，也利用旋轉電極法(RDE)、循環伏安法(CV)等電化學方法，探討該材料用於氧還原電催化反應(ORR)的潛力。第二部分是把鐵元素加入碳材當中，製備出含有氮/鐵摻雜的奈米碳球。由單純嵌段共聚物模板燒製的碳材，因為受限於高分子本身的熱裂解溫度，因此無法製備出具有較高石墨化程度的碳材料。進一步發現加入適當比例的含鐵化合物，可以大幅增加高分子在熱燒結之後的殘餘量，因此嘗試以更高的溫度對高分子進行熱燒結，最終得到石墨化程度較高的碳材。由於在極高的溫度下燒結有助於四級氮(Quaternary nitrogen)生成，而四級氮的含量與氧還原催化反應的效能呈正相關，因此加入含鐵化合物並在極高溫度下燒結的碳材除了石墨化程度增加，同時也能大幅的提高ORR的效果。進一步探討鐵的加入量對氧還原反應的影響，也比較在何種燒製條件下可以得到擁有最佳的催化特性的碳材。 ;The research is divided as two sections. The first section is using block copolymer (BCP) self-assembled nanostructures to fabricate nitrogen-rich carbon nanomaterials, the second section is fabricating Fe/N doped carbonaceous nanomaterials. In the first section, solvent annealing process was used to fabricate different BCP templates, such as perpendicular-oriented cylinders, lamellae, and parallel-oriented cylinders. The films were further exposed into UV-light to stabilize nanodomains; this process would increase the yield of solid carbonaceous materials during ptrolysis at elevated temperatures. As a result, the pyrolyzed graphitic nanostructures remained the original morphology of their pristine nanodomains. The pyrolysis of the nitrogen-containing block produced nitrogen-rich carbonaceous materials. The presence of nitrogen would cause an uneven distribution of electron density, giving rise to electrocatalytic activities of oxygen reduction reaction (ORR). In the second section, Fe/N doped carbonaceous materials were fabricated. The graphitic nanostructures fabricated from thermal pyrolysis of BCP templates have low degrees of graphitization since the pyrolysis could only be achieved at a temperature close to the decomposition temperatures of the constituted blocks. An incorporation of iron-containing compounds of various fractions into the BCP template can increase the amounts of residual of solid carbonaceous materials even at much higher pyrolysis temperatures. Thus a carbonaceous material with a high degree of crystallinity can be obtained. High-temperature pyrolysis not only increased the degree of crystallinity, but also improved the amount of graphitic nitrogen. The portions of graphitic nitrogen are correlated with the performance of ORR so that the electrocatalytic activity of such Fe/N containing carbonaceous materials can be increased. Relationships between the fraction of iron-containing species and the ORR performance were found and more details were discussed in the following.
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