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研究生:陳朝威
研究生(外文):Chao-wei Chen
論文名稱:利用多核寬變溫度固態核磁共振光譜研究Nafion 117中水的狀態
論文名稱(外文):States of water in Nafion 117 investigated with multinuclear and broad range variable temperature solid state nuclear magnetic resonance spectroscopy
指導教授:丁尚武
指導教授(外文):Shang-Wu Ding
學位類別:碩士
校院名稱:國立中山大學
系所名稱:化學系研究所
學門:自然科學學門
學類:化學學類
論文種類:學術論文
論文出版年:2014
畢業學年度:102
語文別:中文
論文頁數:79
中文關鍵詞:縱向鬆弛燃料電池Nafion侷限環境的水狀態固態核磁共振光譜
外文關鍵詞:solid state NMRwater in confined spacefuel cellsNafionlongitudinal relaxation
相關次數:
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全氟磺酸聚合物(perfluorinated sulfonate polymer)質子交換膜(PEM) Nafion是燃料電池中的核心部件,因為它負責質子傳導,分隔陰陽兩極,決定燃料電池的性能。對於Nafion中水狀態之理解有助於了解膜的質子傳導和老化,並且對開發新的、成本較低的質子交換膜也有一定的幫助。之前的研究證指出在Nafion裡面有三種類型的水,自由水(free water):行為類似bulk狀態的准自由水(~ ps的特徵翻滾時間);與磺酸根鍵結的水(sulfonate-binding water):與磺酸根有很強的作用力,通常比較像是固態(~ μs的特徵翻滾時間);結合力較弱的水(loosely bound water):指自由水與磺酸根鍵結的水間有著受較弱的作用力影響的水(~ ps的特徵翻滾時間但是比准自由水要慢很多)。但新的結果表明,這樣的分類太過簡化。膜裡面這些不同類型的水組成不但取決於它特定的結構(由於這些膜的製備過程的不同)而且也取決於溫度。在這個工作裡,我們使用多核(1H, 2D, 7Li, 23Na 和87Rb)變溫固態NMR方法在一個寬廣的溫度範圍(+15 ~ - 60 oC)去偵測Nafion裡水的狀態。我們使用幾種不同含水量的樣品,在各溫度下記錄上述各核種的光譜及1H的鬆弛速率,證明了Nafion中存在以往文獻沒有確認的水之結構及動態。主要結果如下:(1)1H化學位移及鬆弛速率在-10 ~ -15oC呈現突變,說明降溫時Nafion中冰水相變的存在;(2)冰水相變點的溫度以及NMR參數在相變點之變化與含水量與離子種類有關,說明依數效應的存在,但與整體溶液中的依數性質有顯著差別;(3)各樣品在低至-60 oC時水的1H光譜仍呈現較窄的線寬,說明有低至-60 oC時Nafion中仍有一部分過冷水;(4)在整個溫區1H, 7Li, 23Na 和87Rb之NMR光譜之線寬依次增加,說明離子與磺酸根結合度隨離子大小增加而增強。這些結果對理解Nafion以及一般PEM中水的狀態提供新的資料及啟發。這些結果也可以幫助我們更深入地了解Nafion中水如何影響膜裡的質子傳導,膜之機械和化學老化以及膜之性能改進等。
The perfluorinated sulfonate polymer Nafion is the most widely used proton exchange membrane (PEM) in fuel cells. Characterization of the water state in this material is essential for understanding its proton transport and degradation and for developing new and less expensive PEMs. After decades of intensive studies with various experimental and theoretical methods, however, this goal has not been achieved yet owing to the multi-scale structural and dynamical complexities of this material. Previous studies have established that there are three types of water in the material, i.e, free or bulk-like water (~ ps characteristic time), sulfonate-binding water (~ μs characteristic time) and loosely bound water (~ ps, but few times slower than free water). However, the compositions of different types of water depend not only on the specific structures of Nafion (which may differ depending on preparation process) but also on temperature, the presence of other ions and external electric field etc. Moreover, there may be far more complexities than above simple categorization. In this work, we apply multinuclear (1H, 2H, 7Li, 23Na and 87Rb) variable temperature (VT) solid state NMR method to investigate the state of water in Nafion over a broad range of temperature from 15 to -60 oC. The experimental results suggest the presence of new types of water structure and dynamics that previous studies have not observed. The results of the work help better understand the state of water in Nafion as well as the proton transport mechanism in the material. The significance of the findings to proton transport and degradation of Nafion is discussed.
第一章 質子交換膜Nafion 簡介 ................................... 1
1.1 前言.…………………………………………………………………………1
1.2 燃料電磁的介紹…………………………………………………………….2
1.3 質子交換膜Nafion 的介紹……………………………………………….10
第二章 Nafion 中水的狀態文獻回顧 .............................. 15
2.1 前言.………………………………………………………………….....15
2.2 Nafion 孔洞結構模型文獻回顧………………………………………...15
2.3 利用DSC 研究Nafion 質子交換膜中水的狀態…..…………………….20
2.4 利用DRS研究Nafion質子交換膜中水的狀態……………………….....24
2.5 利用NMR 鬆弛研究Nafion 質子交換膜中水的狀態……………….....26
2.6 研究動機…………………………………………..................…31
第三章 實驗部分................................................ 32
3.1 實驗的儀器及藥品……………………….........…………………….32
3.2 實驗樣品製備……………………….........………………………...32
3.3 不同含水量的實驗樣品製備……………………….........………….33
3.4 NMR變溫實驗………………………...............…………........34
3.5 實驗參數設置………………………...............………….......35
第四章 結果與討論...............................................38
4.1 一維光譜及化學位移分析……………………….........…………….38
4.2 7Li、23Na、87Rb 一維光譜及鬆弛時間分析……………………………46
4.3 1H、2H T1 鬆弛時間分析......................................50
4.4 1H T1 鬆弛時間與含水量變化分析..............................58
4.5 D2O與HOD樣品1H T1鬆弛時間與化學位移分析.....................63
第五章 結論.....................................................65
參考文獻........................................................66
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