Insights into Initial Kinetic Nucleation of Gold Nanocrystals

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• 作者：Tao Yao ; Zhihu Sun ; Yuanyuan Li ; Zhiyun Pan ; He Wei ; Yi Xie ; Masaharu Nomura ; Yasuhiro Niwa ; Wensheng Yan ; Ziyu Wu ; Yong Jiang ; Qinghua Liu ; Shiqiang Wei
• 刊名：Journal of the American Chemical Society
• 出版年：2010
• 出版时间：June 9, 2010
• 年：2010
• 卷：132
• 期：22
• 页码：7696-7701
• 全文大小：360K
• 年卷期：v.132,no.22(June 9, 2010)
• ISSN：1520-5126

文摘

Understanding the initial nucleation mechanism of monodisperse nanocrystals (NCs) during synthesis process is an important prerequisite to control the desired sizes and to manipulate the properties of nanoscale materials. The acquisition of information for the small nanocluster nucleation process, however, still remains challenging. Here, using a continuous-flow in situ X-ray absorption fine structure (XAFS) spectroscopy for time-resolved studies, we have clarified the initial kinetic nucleation of Au clusters under the grain size of 1 nm for the classical Au NCs synthesis via the reduction of AuCl₄⁻ in aqueous solution. The in situ XAFS results present the experimental revelation of the formation of intermediate Cl₃⁻Au−AuCl₃⁻ dimer and the subsequent higher complexes ‘Au_nCl_n+x’ in the initial nucleation stage. We propose a kinetic three-step mechanism involving the initial nucleation, slow growth, and eventual coalescence for the Au NCs formation, which may be helpful for the synthesis of metallic nanomaterials.