| 摘要: | 直接甲醇燃料電池具有體積小、工作溫度低且易於貯存與處理的優點，但也有諸如較低的功率密度、白金觸媒易遭一氧化碳毒化(CO poisoning)、甲醇穿透(methanol crossover) 以及與白金觸媒價格相對高等缺點，為了解決這些難題， Pt 基合金觸媒在產業界與學術界已被廣泛地研究，並有許多關於提升觸媒效能的討論。本研究擬製備 Pt-Au/C 陰極催化劑應用於氧氣還原反應(ORR)。並以不同氣氛及/或促進劑改質方式，來改質合金觸媒的結構和表面物種，以期提昇觸媒之電化學活性。目的為系統性的研究催化劑之表面組成與結構- 活性關聯(surface compositions and structure – activity relationship)。本計畫第一年擬製備Pt-Au 合金觸媒，以氮氣和氫氣熱處理來改質合金觸媒的合金度和表面組成；第二年擬製備與改質Pt-Au 合金觸媒，以兩種改質劑CeO2 以及TiO2 的添加，研究在氣氛、促進劑與溫度的參數下，表面偏析，組成結構以及ORR 活性，期望能以這些參數操控合金觸媒的結構與表面，得到高活性的ORR 觸媒。本計畫使用電化學的活性測試，配合表面分析結果，提供高效能催化劑表面與結構訊息，提供PtAu 陰極催化劑改質的重要指標，期能在活性與耐久度，甚至甲醇容忍度上超越商用觸媒 Pt/C。對學術研究而言，本計畫可提供觸媒活性提升原理與改質機制，達到材料研究之目的。對於產業界而言，可提供活性佳之觸媒，以利於觸媒商品化以及燃料電池應用。本計畫將對於材料科技，表面化學，觸媒應用，燃料電池商業化帶來貢獻。 Direct methanol fuel cells (DMFCs) have many advantages, such as small size, low working temperature, and easy fuel-feeding. However, some disadvantages including low power density, CO poisoning of Pt, methanol crossover, and high cost for Pt catalysts retard the development of the green technology. Therefore, Pt-based alloy catalysts have been studied comprehensively and many researches have been focused on the promotion of their electro-activities. In this project, the Pt-Au/C cathode catalysts will be prepared for the oxygen reduction reaction (ORR). The catalysts will be modified by heat treatment processes and by the addition of modifiers in order to tune their phase structures and surface species, and thereby enhance their ORR performances. The relationship between surface composition, structure -activity will be also elucidated in this project. In phase one, heat treatment either by using N2 or H2 can be utilized to control the alloying degrees and surface compositions of the Pt-Au/C alloy catalysts. In phase two, two promoters, CeO2 and TiO2, will be introduced to facilitate the ORR performance of Pt-Au/C. The surface segregation, structure arrangement, and ORR performance of catalysts affected by various atmospheres and temperatures or even promoters will be investigated. It is highly expected that the structure-tunable and surface-controllable alloy catalysts can be obtained by the various preparation and promotion method. In this project, the combination of electrochemical measurements and surface characterizations will provide useful information and guideline for the design and modification of catalysts. The cathode catalysts with higher ORR performance, stability, and methanol resistance than commercial Pt/C catalysts will be prepared through those methods. Besides, some models will be proposed to get insight into the mechanism for the improvement of ORR performance and modification related surface segregation based on the theory of materials science. For the industrial applications, the preparation of novel catalysts can help the commercialization of fuel cells. The experimental results will make some contributions to the field of materials science, surface chemistry, catalysis and fuel cells. 研究期間：9908 ~ 10007 |
