Center for Nanoscale Materials, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
Nano Lett. 2011 Oct 12;11(10):4386-92. doi: 10.1021/nl202538q. Epub 2011 Sep 9.
Galvanic replacement reaction between silver nanowires and an aqueous solution of HAuCl(4) has been successfully monitored in real time by using in situ transmission X-ray microscopy (TXM) in combination with a flow cell reactor. The in situ observations clearly show the morphological evolution of the solid silver nanowires to hollow gold nanotubes in the course of the reaction. Careful analysis of the images reveals that the galvanic replacement reaction on the silver nanowires involves multiple steps: (i) local initiation of pitting process; (ii) anisotropic etching of the silver nanowires and uniform deposition of the resulting gold atoms on the surfaces of the nanowires; and (iii) reconstruction of the nanotube walls via an Ostwald ripening process. The in situ TXM represents a promising approach for studying dynamic processes involved in the growth and chemical transformation of nanomaterials in solutions, in particular for nanostructures with dimensions larger than 50 nm.
通过原位传输 X 射线显微镜（TXM）与流动池反应器相结合，成功地实时监测了银纳米线与 HAuCl4水溶液之间的电置换反应。原位观察清楚地显示了在反应过程中固体银纳米线向中空金纳米管的形态演变。对图像的仔细分析表明，银纳米线上的电置换反应涉及多个步骤：（i）局部点蚀过程的起始；（ii）银纳米线的各向异性蚀刻和生成的金原子在纳米线表面上的均匀沉积；以及（iii）通过奥斯特瓦尔德熟化过程重建纳米管壁。原位 TXM 是研究溶液中纳米材料生长和化学转化过程的一种很有前途的方法，特别是对于尺寸大于 50nm 的纳米结构。
