中孔洞鉑基金屬空心奈米球的製備及其電催化性質之研究

Preparation and Electrocatalytic Studies of Mesoporous Platinum-based Metal Hollow Nanospheres

胡佑維

指導教授 ： 楊家銘

國立清華大學/理學院/化學系/碩士(2012年)

摘要

本研究旨在利用本實驗室合成出之具有Ia3d對稱結構的空心二氧化矽奈米球為模版，製備中孔洞鉑、鉑鈷及鉑鎳合金反結構並研究其電催化氧氣還原反應活性。由於我們的模版具有三維相通孔道及中空結構，可利用此高孔體積的特性，含浸大量金屬前驅物，以氫氣還原法使之還原在中孔洞，移除模版後得到一具中孔洞且高表面積的金屬薄球殼，克服了傳統上無法完整複製模版外觀形貌的問題。在鉑金屬反結構，我們以熔融態方式一步驟大量含浸前驅物，再以低溫還原成功複製完整反結構，而鉑鈷及鉑鎳合金方面，我們以初濕含浸法均勻分散前驅物，還原後可得合金反結構。在此以X光粉末繞射儀、物理吸脫附儀、掃描式和穿透式電子顯微鏡對結構與形貌進行分析，並以X光吸收光譜了解鉑金屬還原過程，最後藉由伏安法了解氧氣還原反應催化活性。結果顯示中孔洞鉑基金屬空心奈米球相較於商用觸媒碳載體白金及鉑黑有更佳之活性與穩定性。

關鍵字

燃料電池 ； 陰極觸媒 ； 中孔洞鉑基金屬

並列摘要

In this study, we used the mesoporous silica hollow spheres with Ia3d symmetry as template which was developed by our lab to synthesize mesoporous Platinum and Platinum-based alloy hollow spheres and apply it to oxygen reduction reaction (ORR). Traditionally, the template synthesis cannot make a complete replication of mesoporous silica. We solve the problem because our template has the property of high pore volume and hollow core and we could replicate template morphology completely by impregnating large quantity metal precursor and hydrogen reduction. In the Pt replica, we successfully synthesized by one step impregnating large quantity molted metal precursor and low temperature reduction. In the Pt-based alloy replica, we used incipient wetness impregnation to homogenize mixtures of the precursors and got alloy replica after reduction. The template and metal hollow spheres was characterized by X-ray diffraction, nitrogen physisorption, scanning electron microscopy, transmission electron microscopy and X-ray absorption spectroscopy. Finally, the replicas as catalysts were test by voltammetry. We found that the mesoporous Platinum and Platinum-based alloy hollow spheres have higher ORR catalytic activity and stability than the commercial carbon support platinum and platinum black catalysts.

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