Surfactant-concentration-dependent shape evolution of Au-Pd alloy nanocrystals from rhombic dodecahedron to trisoctahedron and hexoctahedron.
Surfactant-concentration-dependent shape evolution of Au-Pd alloy nanocrystals from rhombic dodecahedron to trisoctahedron and hexoctahedron.
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DOI：
10.1002/smll.201202013
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发表时间：
2013-02
期刊：
影响因子：
13.3
通讯作者：
Jiawei Zhang;Changping Hou;Huang Huang-Huang;Lei Zhang;Zhiyuan Jiang;Guangxu Chen;Yanyan Jia;Q. Kuang;Zhaoxiong Xie;Lan-Sun Zheng
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文献类型：
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作者：
Jiawei Zhang;Changping Hou;Huang Huang-Huang;Lei Zhang;Zhiyuan Jiang;Guangxu Chen;Yanyan Jia;Q. Kuang;Zhaoxiong Xie;Lan-Sun Zheng
高折射率晶面约束的贵金属纳米晶(NCS)的表面结构控制合成因其具有显著提高催化性能的潜力而成为研究的热点。本研究通过改变表面活性物质的浓度制备了单分散的Au-Pd合金NCS，其形态由菱形十二面体(RD)向三八面体(TOH)和六面体(HOH)有序演化。所制备的三种合金NCS的尺寸和成分基本相同。结果表明，含有长链十八烷基三甲基铵(OTA(+))离子的表面活性剂在高指数晶面的形成中起着关键作用，晶体生长动力学也可能对不同纳米晶形态的形成产生影响。此外，通过结构敏感反应，包括乙醇电氧化和4-硝基苯酚(4-NPH)的催化还原，评价了这些纳米碳管的催化活性。这三种类型的Au-Pd合金NCS对这两个反应表现出不同的催化选择性。对乙醇电氧化的催化活性大小顺序为HOH>；RD>；TOH，并遵循其对应的表面能大小。而对4-NPH的催化还原活性大小顺序为RD>；TOH>；HOH，这与表面的局部结构有关。
The surface structure-controlled synthesis of noble metal nanocrystals (NCs) bounded by high-index facets has become a hot research topic due to their potential to significantly improve catalytic performance. This study reports the preparation of monodisperse Au-Pd alloy NCs with systematic shape evolution from rhombic dodecahedral (RD) to trisoctahedral (TOH), and hexoctahedral (HOH) structures by varying the concentration of surfactant in the surfactant-mediated synthesis. The as-prepared three kinds of alloy NCs possess almost the same size and composition as each other. It is suggested that the surfactant containing long-chain octadecyltrimethyl ammonium (OTA(+)) ions plays a key role in the formation of high index facets, and the crystal growth kinetics may also have an effect on the formation of different nanocrystal morphologies. In addition, the catalytic activities of these NCs are evaluated by structure-sensitive reactions, including ethanol electro-oxidation and the catalytic reduction of 4-nitrophenol (4-NPh). These three types of Au-Pd alloy NCs exhibit different catalytic selectivities towards these two reactions. The catalytic activities toward electro-oxidation of ethanol are in the order of HOH > RD > TOH, which follows the order of their corresponding surface energies. However, the activities toward catalytic reduction of 4-NPh are in the order of RD > TOH > HOH, which should be related to the local structure of the surfaces.