Huang Jianfeng, Vongehr Sascha, Tang Shaochun, Lu Haiming, Shen Jiancang, Meng Xiangkang
National Laboratory of Solid State Microstructures, Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, People's Republic of China.
Langmuir. 2009 Oct 6;25(19):11890-6. doi: 10.1021/la9015383.
Dendritic Ag/Au bimetallic nanostructures have been synthesized via a galvanic replacement reaction (GRR) of Ag dendrites in a chlorauric acid (HAuCl4) solution. After short periods of time, one obtains structures with protruding flakes; these will mature into very porous structures with little Ag left over. The morphological, compositional, and crystal structural changes involved with reaction time t were analyzed by using scanning and transmission electron microscopy (SEM and TEM, respectively), energy-dispersive X-ray spectrometry (EDX), and X-ray diffraction. High-resolution TEM combined with EDX and selected area electron diffraction confirmed the replacement of Ag with Au. A proposed formation mechanism of the original Ag dendrites developing pores while growing Au flakes cover this underlying structure at longer reaction times is confirmed by exploiting surface-enhanced Raman scattering (SERS). Catalytic reduction of 4-nitrophenol (4-NP) by sodium borohydride (NaBH4) is strongly enhanced, implying promising applications in catalysis.
通过在氯金酸（HAuCl4）溶液中对银树枝晶进行电化置换反应（GRR），合成了树枝状银/金双金属纳米结构。短时间后，会得到带有突出薄片的结构；这些结构会成熟为非常多孔的结构，几乎没有剩余的银。分别使用扫描电子显微镜和透射电子显微镜（SEM和TEM）、能量色散X射线光谱仪（EDX）以及X射线衍射分析了与反应时间t相关的形态、成分和晶体结构变化。高分辨率TEM结合EDX和选区电子衍射证实了银被金取代。通过利用表面增强拉曼散射（SERS），证实了最初的银树枝晶在生长的金薄片覆盖其底层结构时形成孔隙的拟议形成机制。硼氢化钠（NaBH4）对4-硝基苯酚（4-NP）的催化还原作用得到了显著增强，这意味着在催化领域有广阔的应用前景。
