Insights into initial kinetic nucleation of gold nanocrystals.
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 AuCl(4)(-) in aqueous solution. The in situ XAFS results present the experimental revelation of the formation of intermediate Cl(3)(-)Au-AuCl(3)(-) dimer and the subsequent higher complexes 'Au(n)Cl(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.
Yao
Tao
T
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China.
Sun
Zhihu
Z
Li
Yuanyuan
Y
Pan
Zhiyun
Z
Wei
He
H
Xie
Yi
Y
Nomura
Masaharu
M
Niwa
Yasuhiro
Y
Yan
Wensheng
W
Wu
Ziyu
Z
Jiang
Yong
Y
Liu
Qinghua
Q
Wei
Shiqiang
S