Pt-M(VIII B)觸媒於DMFC的應用 ;The Application of Pt-M(VIII B) electrocatalysts for DMFC

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題名:	Pt-M(VIII B)觸媒於DMFC的應用;The Application of Pt-M(VIII B) electrocatalysts for DMFC
作者:	李玉如;Yu-ru Lee
貢獻者:	化學工程與材料工程研究所
關鍵詞:	合金觸媒;抗甲醇毒化;methanol-tolerance;alloy catalysts
日期:	2007-06-26
上傳時間:	2009-09-21 12:28:47 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	目前應用於直接甲醇燃料電池最有效率的觸媒為鉑觸媒，主要原因是鉑對陽極甲醇的催化氧化及陰極氧分子還原反應，顯示出較高的活性，且鉑在酸性介質中有較高的穩定性及耐腐蝕性，而其他金屬雖然也可以催化甲醇的氧化反應，但性能和穩定性都不如鉑。即使貴重金屬的活性較佳，但是價格昂貴、資源匱乏，造成直接燃料電池的成本大大的提高，限制住了燃料電池在商業上的應用。降低鉑的使用量，以減少成本，同時提高電極觸媒的效能，成為一大重要課題。對於陰極觸媒，除了改進電極的結構，提高觸媒的使用率；另外一方面尋求高效能、廉價的替代金屬觸媒也是重點之一，此外，陰極觸媒亦須具備抗甲醇毒化功能。現下的研究發展趨勢是在觸媒中，加入第二金屬(例如過渡金屬元素或IIIA、IVA族元素)，除了可以降低貴金屬鉑的使用量外，亦可以提高觸媒的活性，二元合金金屬(例如：PtCo, PtNi, PtFe, PtW, PtMo等)幫助鉑吸附氧分子與抗甲醇毒化，同時試圖提高觸媒活性；其中陽極也是二元或多元金屬觸媒，不僅降低鉑使用量、含氧物吸附電位外，也促進鉑觸媒上甲醇脫氫物的脫離，可有效的解決白金的毒化作用。本研究目的是利用金屬鐵(Iron)、鈷(Cobalt)、鎳(Nickel)與鉑觸媒形成合金，以適當的條件來合成適合直接甲醇燃料電池的陰極觸媒，並取碳材為載體，進行EXAFS分析來檢測觸媒中，貴重金屬的原子間距是否有所改變，以氧分子還原活性(Oxygen Reduction Reaction, ORR)測試與其抗甲醇毒化能力(Methanol- tolerance)，來得知合金觸媒的特性，結果顯示合成所得觸媒活性高於商業品，且鉑鎳觸媒活性較佳而鉑鈷的抗甲醇毒化能力效果更好。 Platinum is the most effective electrocatalysts for use in Direct Methanol Fuel Cell (DMFC), because of its’ high catalytic activity for methanol oxygen reaction. Platinum has very high stablity and good corrosion resistant in acidic medium. Even though other metals have similar activity capabilites but fail to perform in acidic condition. Platinum is too expensive for use in DMFC, the cost of cathode catalyst is one of the major obstacles towards the realization of DMFC. The search for more active and less expensive catalysts for oxygen reduction reaction (ORR) is one of the most important studies in DMFC development. In recent years, there has been many studies concerning the preparation of more active DMFC catalysts materials by the formation of Pt alloys with transition metals. The utilization of platinum can be enhanced in this manner. By the addition of second element (For example: transition metals, IIIA or IVA groups), noble metal waste can be reduced. When platinum alloys with the first row transition metals, 5d vacancies of surface increase, because transition metals has more 5d vacancies than Platinum. Platinum alloys adsorbed Oxygen more easy when 5d vacancies increase 2π electron donation from oxygen to the Pt and weakening of the O-O bond energy. This study employs impregnate method to deposit transition metals (Iron, Cobalt and Nickel) and platinum onto carbon support. Examining bond length of alloy electrocatalysts by EXAFS (Extended X-ray Absorption Fine Structure) revealed that the bond length of Pt (Pt-Pt) alloy catalysts are shorteded compared with Pt/C catalyst. Electrochemical tests for cathode catalysts of DMFC to check electrocatalysts activity and methanol-tolerance. Pt-Ni/C alloy catalysts have highest activity and better than commercial catalysts. The best methanol-tolerance alloy catalyst is Pt-Co/C.
顯示於類別:	[化學工程與材料工程研究所] 博碩士論文

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