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研究生： 吳奕臻
Yi-Chen Wu
論文名稱： 製備高導電性二氧化鈦承載鉑及其電化學活性探討
Preparation of highly conductive TiO2 supported Pt catalyst and its electrochemical performance
指導教授： 黃炳照
Bing-Joe Hwang
口試委員: 蘇威年
Wei-Nien Su
陳景翔
Ching-Hsiang Chen
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： 2014
畢業學年度： 102
語文別： 中文
論文頁數： 148
中文關鍵詞： 高導電性 、燃料電池 、HMDS處理方法 、Magneli phase
外文關鍵詞： Highly conductive, Fuel cell, HMDS method, Magneli phase
相關次數： 點閱：208  下載：1 
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    • 本研究製備高導電性二氧化鈦(TiO2)作為載體並承載鉑(Pt)觸媒，進行燃料電池反應的探討。首先，以溶熱法(solvothermal)製備奈米級TiO2，利用HMDS處理方法將TiO2顆粒包覆SiO2，以抑制氫氣還原熱處理過程中TiO2顆粒的聚集。TiO2在還原氣氛下，由常溫熱處理至1000oC，其結構由Anatase相轉為Rutile相，最終形成Magneli相。結果顯示TiO2的導電度，隨還原溫度升高而增加，但表面積隨溫度升高而降低。
    電化學活性測量的結果發現，Pt觸媒承載於有HMDS處理且在850oC下，經氫氣還原熱處理的TiO2載體上(20% Pt /850 FHST)，有較好的電催化活性。對於甲醇氧化反應，最大電流密度為106 mA/cm2及起始電位為0.6 V (vs. NHE); 而對於氧氣還原反應，在0.9V (vs NHE)下的電流密度為0.049 mA/cm2及起始電位為0.86 V(vs. NHE)，此歸因於有HMDS處理之TiO2載體，具有較高之表面積和適當的導電度，且由吸收光譜的結果證實，20% Pt /850 FHST中Pt觸媒d軌域電子較飽滿，因此有助於提升電催化能力，而相較於同系列其他觸媒(不同熱處理溫度)，具有最佳的甲醇氧化及氧氣還原電催化能力。電化學穩定性測試顯示20% Pt /850 FHST觸媒相較於商業化觸媒(JM20 Pt/C)，有較佳的電催化穩定性及抗腐蝕能力。

    In this work, highly-conductive TiO2 supported Pt catalysts were synthesized and electrochemical performance was investigated for use in fuel cell application. First, TiO2 nanoparticles were synthesized using a solvothermal method. SiO2 coating was then applied to the TiO2 nanoparticle surface by using the Hexamethyldisilazane method (HMDS) in order to inhibit the particle growth during heat treatment under H2 environment. The phase of TiO2 nanoparticles changed from anatase phase to rutile phase and eventually transformed to Magneli phase when the temperature rises to 1000℃. It was found that the electrical conductivity of TiO2 increases with increasing reduction temperature but at the cost of decrease in the surface area.
    The electrochemical performance shows that Pt catalyst, loaded on the TiO2 support when treated by the HMDS method and H2 reduction at 850℃, exhibits the better reactivity (named by 20% Pt /850 FHST) with a maximum current density of 106 mA/cm2 and onset potential of 0.6 V (vs. NHE) for methanol oxidation reaction (MOR). For oxygen reduction reaction (ORR), 20% Pt /850 FHST showed a limiting current density of 0.049 mA/cm2 at 0.9 V (vs. NHE) and an onset potential of 0.86 V (vs. NHE). Such performance is attributed to a higher surface area and improved electrical conductivity. X-ray absorption spectroscopy (XAS) demonstrates that a higher electron population of the Pt 5d-orbital can improve the electrochemical reaction in which this catalyst shows the best performance for MOR and ORR compared to others within the same series i.e. different H2 reduction temperatures. Durability test show that 20% Pt /850 FHST has better stability and anti-corrosive abilities when compared to the commercial catalyst (JM20 Pt/C).

    摘要 I Abstract II 致謝 III 目錄 V 圖目錄 VIII 表目錄 XV 第一章 緒論 1 1.1 前言 1 1.2 燃料電池的介紹與應用 5 1.3 燃料電池種類 7 1.4 直接甲醇燃料電池(DMFC) 10 1.4.1 DMFC陽極觸媒 (Methanol Oxidation Reaction, MOR) 12 1.4.2 DMFC陰極觸媒 (Oxygen Reduction reaction, ORR) 13 1.4.3 電解質膜 18 1.5 研究動機與目的 19 第二章 文獻回顧 21 2.1 燃料電池觸媒開發 21 2.1.1 燃料電池觸媒介紹 21 2.1.2 碳載體觸媒開發 22 2.2 非碳觸媒載體開發 24 2.2.1 TiO2 24 2.2.2 TiO2摻雜金屬氧化物之載體開發 27 2.2.3 Ti4O7載體開發 30 2.3 HMDS處理之TiO2 35 第三章 實驗設備與方法 39 3.1 實驗設備 39 3.2 實驗藥品 40 3.3 實驗步驟 41 3.3.1 以溶熱法(solvothermal)合成之二氧化鈦 42 3.3.2 以HMDS修飾TiO2 43 3.3.3 純氫還原步驟 44 3.3.4 以2%HF洗淨SiO2 45 3.3.5 微波輔助乙二醇還原法(Micrcowave -assisted Ethylene glycol Reduction method) 45 3.4 儀器原理與材料鑑定 46 3.4.1 X射線繞射儀（XRD） 46 3.4.2 掃描式電子顯微鏡（SEM） 49 3.4.3 穿透式電子顯微鏡 (TEM) 53 3.4.4 感應偶合電漿光譜儀(ICP-AES) 53 3.4.5 拉曼散射光譜(Raman spectrum) 54 3.4.6 四點探針導電度量測儀(Four-Point Probe system) 56 3.4.7 表面積測定儀 57 3.4.8 X光吸收光譜原理 64 3.4.9 電化學原理 75 第四章 結果 83 4.1 HMDS抑制效果探討 83 4.1.1 HMDS反應前後烴基移除情形 (IR) 83 4.1.2 HMDS前後表面結構變化 84 4.1.3 HMDS處理前後表面型態差異(SEM) 84 4.1.4 高溫燒結後結晶型態差異 (XRD) 85 4.1.5 高溫燒結下表面積差異(BET及孔洞分布) 86 4.2 氫氣還原二氧化鈦特性分析 89 4.2.1 材料晶相之分析 89 4.2.2 不同溫度下ST及HST經氫氣還原之表面差異 94 4.2.3 以HF去除SiO2之表面結構分析 95 4.2.4 HMDS處理前後表面積之差異 99 4.2.5 導電度量測 100 4.3 Pt觸媒與載體之結構鑑定 102 4.3.1 載體承載Pt觸媒之晶相分析 102 4.3.2 Pt觸媒含量分析 103 4.3.1 X光吸收近邊緣結構 104 4.3.2 延伸X光吸收Pt微細結構 109 4.3.3 Pt觸媒分散度探討 110 4.4 電化學活性量測 113 4.4.1 甲醇氧化反應活性 113 4.4.2 氧氣還原反應活性 123 第五章 綜合討論 135 5.1 HMDS抑制效果 135 5.2 經有/無HMDS處理之二氧化鈦載體特性分析 135 5.3 不同二氧化鈦載體相結構觸媒對電化學活性 之影響 138 5.3.1 使用於陽極甲醇氧化反應之活性比較139 5.3.2 使用於陰極氧氣還原反應之活性比較 140 第六章 結論 141 第七章 未來展望 142 參考文獻 143

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