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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/7574

    Title: 在氧化鋁上成長金與白金的和金奈米粒子;Alloying of Au-Pt nanoclusters on thin film Al2O3/NiAl(100)
    Authors: 王朝建;Chau-jian Wang
    Contributors: 物理研究所
    Keywords: 甲醇;合金;光激發電子能譜儀;白金;;alloy;methanol;Pt;Au;XPS
    Date: 2009-01-23
    Issue Date: 2009-09-22 11:00:11 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 我們利用同步輻射光源的光激發電子能譜儀(PES)來研究甲醇在良好奈 米白金觸媒模型上的吸附及分解反應,以及金與白金合金的生成與其對吸 附甲醇後的反應。 利用氣相沈積法,我們在超高真空中(小於3 x 10-10)於300 K 溫度下, 將白金奈米團簇成長在完整有序的氧化鋁薄膜Al2O3/NiAl(100)。在PES 中 我們發現白金的電性結構並不隨著白金的覆蓋量而影響,而在經過450K 的退火溫度後白金粒子有氧化的現象。 我們將甲醇在120 K 低溫下吸附於Pt/Al2O3/NiAl(100)表面上,在這之後 並加溫到各種不同的溫度。在加溫的過程中,我們發現甲醇的C1s 峰值隨 著加溫的溫度往高束縛能的方向偏移,這或許與產生的碳氫化合物吸附在 Pt 有關。我們也發現甲醇在300 K 的退火之後,產生了一個新峰值其值 與CO 吸附的峰值不同,我們認為是碳氫化合物的生成。 在研究金與白金的合金生成,由PES 所得到的結果是當合金生成時電子 會由白金傳遞到金上,並且在450 K 以上的退火溫度下白金的熱漂移與氧 化會造成合金的消失 當我們吸附甲醇在合金以及退火過的合金表面上時,由合金的增減情形 中得知當甲醇吸附在合金奈米團簇上時存在有特定的白金與金的比例。 We have studied the adsorption and decomposition of methanol on well-defined supported Pt nanoclusters as a model catalyst and the alloying of Au-Pt nanoclusters on thin film Al2O3/NiAl(100) by using synchrotron-based high-resolution photoemission spectroscopy (PES). Pt nanoclusters are deposited on well-ordered Al2O3 film grown on NiAl (100) through vapor deposition in the ultrahigh vacuum conditions (<3 x 10-10 torr) at 300 K. By using PES we find that the electron structure of Pt doesn’t change with Pt coverage. On annealing to 450 K the oxidized Pt form on the surface. To study methanol decomposition, methanol was adsorbed on Pt/Al2O3/NiAl (100) at 120 K and subsequent annealed to different temperatures. In our annealing experiment, the C1s peak shifts towards higher binding energy with increasing temperature, which is probably due to that the hydrocarbon-species (CHx) adsorb on Pt nanoclusters, and the hydrocarbon-species (CHx) formed at the surface at 300 K. According to the PES results, we observe evident shift for the Au-4f because of the electron transfer from Pt to Au when Au-Pt alloy formed. During the annealing procedure, the intensity of alloy decrease because of the Pt diffuse or oxidization. There are change in intensity of Pt, pure Au, and alloy signals when adsorbing methanol on (annealed) alloy cluster, which is probably due to a specific ratio of Pt to Au in alloy cluster when adsorbed methanol.
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