| 摘要: | 摘 要 燃料電池是極具發展潛力的能源轉換技術，具有高發電效率、高體積能量密度(4780Wh/L)、低噪音、低污染等諸多優點。直接甲醇燃料電池(Direct Methanol Fuel Cell，DMFC)因擁有最低操作溫度(?80℃)、元件體積小和重量輕等多項優勢，很適合應用在非固定式的能源需求，如一般可攜帶式電子產品，用以取代目前鋰電池之應用範圍，因此已成為目前全球爭相研究的焦點。然而因觸媒催化效能不足，加上電極間甲醇穿透(Cross-over)等問題，直接甲醇燃料電池遲遲無法商業化大量應用。 本論文從改善觸媒催化能力，提升陽極效能方面著手進行研究：以多種還原方式製備鉑基(Pt-based)單金屬與雙元合金陽極觸媒(Pt/support、Pt-Ru/support)，搭配使用不同載體、嘗試改變鉑金金屬比例和製程條件(如：前驅物鹽類溶液酸鹼值、加熱迴流的溫度與時間等)以及不同的甲醇反應濃度。使用循環伏安法(Cyclic Voltammetry，CV)與計時安培分析法(Chronoamperometry，CA)探討觸媒對甲醇氧化反應的催化活性、穩定性及對一氧化碳毒化效應(CO-poisoning effect)的容忍度(Tolerance)。之後將電化學分析結果與由穿透式電子顯微鏡(TEM)、掃瞄式電子顯微鏡(SEM)、粉末X-光繞射儀(XRD)、X-光射線光電子光譜分析儀(XPS)，以及等溫氮氣物理吸附/脫附儀(BET)，測得載體與各製程所得觸媒的尺寸粒徑、分散性、比表面積及觸媒顆粒鍵結狀態等性質比對，探討這些因素對於觸媒電催化活性的影響，最後再與商業化觸媒E-tek Pt/C和Pt-Ru/C作比較。 Abstract Fuel cell shows excellent ability in power-transformation as a result of high efficiency, little noise, few pollutants, and so forth. Among all the fuel cells, direct methanol fuel cell (DMFC) is the best choice for mobile power supply, replacing the application of Li-ion battery at present. Although DMFC has attracted many research groups’ attention because of owning such a variety of superior properties, there are still some problems badly to be solved. The developing barriers are involved in electro-oxidation performance of catalysts and methanol cross-over between electrodes, blocking the accomplishment of DMFC commercialized products. The present study was focused on improving the electrochemical performance of the anodic catalyst to enhance the potency of anode. For this purpose, various procedures and reduction conditions were used for self-made Pt(/PtRu)-catalysts preparation, including pH-adjusting, temperature-control, different support materials, altered Pt-loading content as well as fuel concentration in the electrochemical tests. The electro-catalytical activity to methanol oxidation and the tolerance for CO-poisoning effect of self-made Pt(/PtRu)-catalysts were both measured with not only cyclic voltammetry (CV) but also chronoamperometry (CA), and afterwards the data were correlated with the results of XRD, BET, TEM, SEM, and XPS for the sake of confirming the relation between all of them. The self-made Pt(/PtRu)-catalysts, which behave better performance, were compared to the commercial ones namely E-tek Pt/C and also Pt-Ru/C. |
