本研究主要合成以碳為基材之新穎Pt@Ni@Pt三明治結構奈米觸媒，並探討其在鹼性環境中對甲醇氧化之行為。
在Pt@Ni@Pt三明治結構奈米觸媒之合成，首先合成Pt奈米粒子於碳擔體上(Pt/C)以作為核點，再將含有Ni2+-N2H4錯合物之溶液加入，此時N2H4因Pt之催化而於Pt表面分解，進而將Ni2+還原於Pt表面上形成粒徑約4~5 nm Pt@Ni之核/殼層結構。另一方面，於無Pt核點之存在下，吾人亦嘗試直接以N2H4將Ni2+還原於碳基材上，以減少Pt之用量，然而結果顯示，僅有極微量之Ni2+被還原，表示仍需合適之金屬奈米粒子，以催化N2H4之分解，以控制金屬離子選擇性還原於表面。而第三層Pt則以置換之方式將Pt2+還原於Ni之表面，此時部份Ni被氧化為Ni2+，形成所謂Pt@Ni@Pt之三明治結構，然而，第三層Pt於Ni表面形成島狀之奈米顆粒(約3~4 nm)，而非完整之Pt殼層。
本文亦以合成之Pt@Ni@Pt/C於鹼性環境下，進行甲醇氧化反應之研究，發現當第三層Pt量越多時，活性面積越大；且表面的Ni氧化形成Ni(OH)2也具有催化甲醇之功能；又由X光吸收光譜得知，第三層Pt量越多觸媒合金程度亦越高，所以當表面Pt量越多時催化甲醇效果越好。實驗結果得知Ni的存在可以有效幫助CO氧化，大幅改善Pt被CO毒化的問題。因此Pt@Ni@Pt/C觸媒透過Ni的摻入和第三層的Pt加入可以有效改善鹼性直接甲醇燃料電池陽極觸媒之催化效應，並進一步改善其燃料電池操作時因Pt毒化所造成之失效現象。

In this study, novel sandwich-like Pt@Ni@Pt nanosized catalysts on carbon supports are synthesized and the methanol oxidation behaviors on the catalysts are investigated in the alkaline media.
First, carbon supported Pt/C nanocatalysts are employed to be nucleus and then added into the solution of Ni2+-N2H4 complexes for the synthesis of Pt@Ni@Pt nanoparticles. The decomposition of hydrazine is catalyzed by the Pt nucleus and then Ni2+ ions are reduced on the Pt surface to form Pt@Ni catalysts with core/shell structure. The particle size of the obtained Pt@Ni catalysts is about 4~5 nm. We have also tried to reduce Ni2+ on carbon supports without Pt nucleus but only a little bit Ni2+ can be reduced. It indicates that nanocatalysts as nucleus is of great importance to facilitate the decomposition of hydrazine. Pt2+ ions are further reduced on the surface of Pt@Ni by a redox transmetallation reaction (RTM). Part of Ni is oxidized to Ni2+ and then the sandwich-like Pt@Ni@Pt catalysts are formed. However, the island-like growth of the outer Pt is observed instead a layer-like one.
Methanol oxidation reaction (MOR) is carried out on the synthesized catalysts in alkaline media. It is found that that the electrochemical active surface area increasea with an increase in Pt content. We observe that not only Pt but also Ni can facilitate MOR via the water dissociation to form Ni(OH)2. From the measurements of X-ray absorption spectroscopy we found that the alloy extent of Pt and Ni increases with an increase Pt content. We also observed that CO oxidation reaction on Pt can be promoted by the help of Ni.. Therefore, the sandwich-like Pt@Ni@Pt catalysts can enhance the catalytic activity of MOR in an alkanie DMFC.

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