Copper Ion Assisted Reshaping and Etching of Gold Nanorods: Mechanism Studies and Applications

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• 作者：Tao Wen ; Hui Zhang ; Xiaoping Tang ; Weiguo Chu ; Wenqi Liu ; Yinglu Ji ; Zhijian Hu ; Shuai Hou ; Xiaona Hu ; Xiaochun Wu
• 刊名：Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：December 5, 2013
• 年：2013
• 卷：117
• 期：48
• 页码：25769-25777
• 全文大小：492K
• 年卷期：v.117,no.48(December 5, 2013)
• ISSN：1932-7455

文摘

This article describes copper ion assisted end-cap morphology transformation and anisotropic etching of gold nanorods (GNRs) under mild conditions. The copper ions are proposed to catalyze the oxidation of the GNRs by dissolved oxygen. We suggest that the surface Au atoms with high surface energy are stabilized by forming Au鈥揙 complexes (termed as static adsorbed oxygen). At low concentration of copper ions, the Au鈥揙 complexes are removed by oxidative etching, thus leaving a 鈥渃lean鈥?Au surface. Such a clean surface can relax to a more stable state via surface atom diffusion, leading to the GNR end-cap morphology variation. This is the first time that the existence of adsorbed oxygen species on the surface of the GNRs is probed and demonstrated. At high concentration of copper ions, anisotropic etching of the GNRs is initiated by dissolved oxygen (termed as dynamic adsorbed oxygen) and leads to shorter GNRs. For other etch agents such as H₂O₂ and Fe³⁺, addition of copper ions produces a synergistic effect. Due to the high affinity of oxygen to silver and palladium, such synergistic etching is observed in Au@Ag NRs and Au@Pd NRs as well. These interesting findings provide a new way to probe the surface reactivity of noble metal nanocrystals.