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研究生： 呂婉婷
Wan-Ting Lu
論文名稱： 以表面活化還原法合成Pd @ Pt雙金屬觸媒及其電化學活性之探討
Pd@Pt Bimetallic Catalysts Prepared by Surface-activated Reduction Method and Their Electrochemical Activities
指導教授： 黃炳照
Bing-Joe Hwang
口試委員: 周澤川
Tse-Chuan Chou
蔡大翔
Dah-Shyang Tsai
學位類別： 碩士
Master
系所名稱： 工程學院 - 化學工程系
Department of Chemical Engineering
論文出版年： 2009
畢業學年度： 97
語文別： 中文
論文頁數： 166
中文關鍵詞： 直接甲醇燃料電池 、陰極觸媒 、表面活化還原法 、X光吸收光譜 、氧氣還原反應 、甲醇氧化反應
外文關鍵詞： diect methanol fuel cell (DMFC), cathode catalyst, surface activated-reduction method, X-ray absorption spectroscopy (XAS), oxygen reduction reaction, methanol oxidation reaction
相關次數： 點閱：336  下載：2 
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  •  上一筆

    • 本研究主要目標為發展一種新穎方法(表面活化還原法)用以合成核心-殼層(Core-Shell)結構之Pd@Pt雙金屬觸媒，再以同步輻射X光吸收光譜分析觸媒之結構，並探討其對電化學催化甲醇氧化反應及氧氣還原之活性。
    由X光吸收光譜量測結果顯示，本研究成功合成Pd為核心-殼層富有多Pt的奈米粒子結構，並由XRD及TEM得知，觸媒之晶粒及顆粒大小均約為4-5 nm。在此Pd@Pt雙金屬觸媒之電化學特性部分，由於Pt受到Pd之電子效應影響，因而增加Pt之氧氣還原催化活性，並提高甲醇氧化之容忍度。實驗數據亦顯示，經由適當的合成方式可以得到近乎單層之Pt沈積於Pd奈米粒子表面，若同時利用低濃度氫氣環境下之熱處理可進一步增加Pt覆蓋率，其中以100 oC為最佳溫度條件，可在觸媒不聚集的情況之下，有效增加Pt覆蓋率，並同時提升電化學催化活性及穩定性。

    A new method to synthesize Pd@Pt core-shell bimetallic catalysts is developed in this research, which is called surface-activated reduction method. The catalyst structures of the synthesized Pd@Pt core-shell bimetallic catalysts are investigated by X-ray Absorption Spectroscopy (XAS) technique. In addition, their correlations between structures and electrochemical activity of oxygen reduction reaction (ORR) as well methanol oxidation reaction (MOR) are also investigated.
    The synthesized Pd@Pt core-shell bimetallic catalysts have been demonstrated that the structure of particle consists of a Pd-rich core and a Pt-rich shell with average size of 4-5 nm. Their electrochemical results show that the activity of ORR is improved due to electronic effect of Pd. However, the MOR tolerance is also increased because the dehydrogenation reaction is hampered by Pd.
    Under an appropriate heat-treatment procedure, the tendency of Pt monolayer structure, electrochemical activity and stability of Pd@Pt core-shell bimetallic catalysts are simultaneously and significantly improved.

    摘要 I 致謝 III 目錄 IV 圖目錄 VII 表目錄 XIII 第一章 緒論 1 1.1. 前言 1 1.1.1. DMFC陽極觸媒 8 1.2.2. DMFC電解質 12 1.2.3. DMFC陰極材料 13 1.2. 研究動機與目的 17 第二章 文獻回顧及理論基礎 18 2.1. Pt-Pd觸媒 18 2.2. 欠電位沈積法原理 (under-potential deposition) 22 2.3. UPD法概念之延伸-表面活化還原法 24 2.4. X光吸收光譜原理 26 2.4.1. EXAFS 27 2.4.2. XANES 31 2.4.3. 數據分析 32 2.5. 電化學原理 37 2.5.1. 循環伏安法 37 2.5.2. 極化曲線 42 2.5.3. 旋轉盤電極(Rotating Disc Electrode, RDE) 43 2.5.4. 旋轉環盤電極(Rotating Ring-Disc Electrode, RRDE) 45 2.6. XRD分析原理 48 第三章 實驗設備與方法 50 3.1. 實驗藥品及設備 50 3.1.1. 實驗藥品 50 3.1.2. 儀器設備 51 3.2. 實驗方法 52 3.2.1. 陰極觸媒製備 52 3.2.1.1. 以商業Pd/C觸媒合成PtPd/C觸媒 52 3.2.1.2. 以自製Pd/C觸媒合成PtPd/C觸媒 53 3.2.1.2.1. 碳黑之前處理 53 3.2.1.2.2. 合成Pd/C核點 54 3.2.1.2.3. 方法一 連續曝氫 55 3.2.1.2.4. 方法二 不連續曝氫 56 3.2.1.2.5. 熱處理 57 3.2.2. 材料鑑定與分析 58 3.2.2.1. XRD分析 58 3.2.2.2. TEM分析 59 3.2.2.3. ICP-AES感應偶合電漿放射光譜儀 60 3.2.2.4. 電化學特性測試 60 3.2.2.4.1. 電極片製備 61 3.2.2.4.2. 電化學特性量測 61 3.2.2.5. X光吸收光譜 63 3.2.2.5.1. EXAFS之曲線適配 63 3.2.2.5.2. 以X光吸收光譜分析觸媒結構 64 第四章 結果與討論 68 4.1. 陰極金屬觸媒材料之特性分析 68 4.1.1. ICP-AES感應耦合電漿放射光譜 69 4.1.2. 材料之晶相與形態之分析 70 4.2. 觸媒之結構鑑定 79 4.2.1. X光吸收進邊緣結構(XANES) 79 4.2.2. 延伸X光吸收微細結構(EXAFS) 85 4.3. 電化學特性量測結果 104 4.3.1. 觸媒在硫酸水溶液中之循環伏安分析 104 4.3.2. 氧氣還原極化曲線 109 4.3.3. 電催化甲醇氧化循環伏安分析 114 4.4. 觸媒穩定性測試 118 4.4.1. 電化學穩定性測試 118 4.5. 理論計算模擬 124 4.5.1. Pt(111)表面 125 4.5.2. 電荷轉移(charge transfer) 128 4.5.3. 氧氣還原反應 134 第五章 討論 138 5.1. 實驗方法差異與結構機制之探討 138 5.2. 陰極觸媒材料之氧化還原活性探討 146 5.3. 陰極觸媒材料之甲醇氧化活性碳討 153 5.4. 熱處理之影響 153 第六章 結論 159 參考文獻 161

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