Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), School of Materials Science and Engineering, Shandong University, Jingshi Road 17923, Jinan, 250061, PR China.
Nanoscale. 2011 Apr;3(4):1663-74. doi: 10.1039/c0nr00830c. Epub 2011 Feb 11.
We present a facile route to fabricate novel nanoporous bimetallic Pt-Au alloy nanocomposites by dealloying a rapidly solidified Al(75)Pt(15)Au(10) precursor under free corrosion conditions. The microstructure of the precursor and the as-dealloyed sample was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray (EDX) analysis. The Al(75)Pt(15)Au(10) precursor is composed of a single-phase Al(2)(Au,Pt) intermetallic compound, and can be fully dealloyed in a 20 wt.% NaOH or 5 wt.% HCl aqueous solution. The dealloying leads to the formation of the nanoporous Pt(60)Au(40) nanocomposites (np-Pt(60)Au(40) NCs) with an fcc structure. The morphology, size and crystal orientation of grains in the precursor can be conserved in the resultant nanoporous alloy. The np-Pt(60)Au(40) NCs consist of two zones with distinct ligament/channel sizes and compositions. The formation mechanism of these np-Pt(60)Au(40) NCs can be rationalized based upon surface diffusion of more noble elements and spinodal decomposition during dealloying. Electrochemical measurements demonstrate that the np-Pt(60)Au(40) NCs show superior catalytic activity towards the electro-oxidation of methanol and formic acid in the acid media compared to the commercial JM-Pt/C catalyst. This material can find potential applications in catalysis related areas, such as direct methanol or formic acid fuel cells. Our findings demonstrate that dealloying is an effective and simple strategy to realize the alloying of immiscible systems under mild conditions, and to fabricate novel nanostructures with superior performance.
我们提出了一种简便的方法，通过在自由腐蚀条件下对快速凝固的 Al(75)Pt(15)Au(10)前驱体制备的新型纳米多孔双金属 Pt-Au 合金纳米复合材料进行脱合金处理来制备。使用 X 射线衍射、扫描电子显微镜、透射电子显微镜、高分辨率透射电子显微镜和能量色散 X 射线 (EDX) 分析对前驱体和脱合金样品的微观结构进行了表征。Al(75)Pt(15)Au(10)前驱体由单相 Al(2)(Au，Pt)金属间化合物组成，并且可以在 20wt.%NaOH 或 5wt.%HCl 水溶液中完全脱合金。脱合金导致形成具有 fcc 结构的纳米多孔 Pt(60)Au(40)纳米复合材料 (np-Pt(60)Au(40)NCs)。前驱体中晶粒的形态、尺寸和晶体取向可以在所得纳米多孔合金中保留。np-Pt(60)Au(40)NCs 由两个具有明显的韧带/通道尺寸和组成的区域组成。根据脱合金过程中更贵元素的表面扩散和旋节分解，可以合理地解释这些 np-Pt(60)Au(40)NCs 的形成机制。电化学测量表明，与商用 JM-Pt/C 催化剂相比，np-Pt(60)Au(40)NCs 在酸性介质中对甲醇和甲酸的电氧化具有更高的催化活性。这种材料在与催化相关的领域，例如直接甲醇或甲酸燃料电池中具有潜在的应用。我们的研究结果表明，脱合金是一种在温和条件下实现不混溶体系合金化并制备具有优异性能的新型纳米结构的有效而简单的策略。
