Silver dendrites are found to be the most effective materials for surface enhanced Raman spectroscopy (SERS). They are mostly produced by the traditional wet-chemical reactions using polyvinyl pyrrolidone as the surfactant. Many other protocols, including the electrochemical or photochemical technologies and galvanic displacement reaction are now also available to obtain silver dendrites. Notwithstanding, it is important to develop green and facile methods to synthesize well-defined silver dendrites.

A simple organic-free replacement process for synthesis of hierarchical silver dendrites was realized by collaboration between researchers from Institute of Process Engineering and Institute of Chemistry, Chinese Academy of Sciences, China and Laboratoire de Chimie Physique, Equipe d’Electrochimie et de Photoélectrochimie, France.

They presented a new and facile method for synthesis of silver dendrites with multi-scale structures. The silver dendrites were synthesized between an aqueous silver nitrate solution and an aluminum wafer, in the presence of a polyoxometalate (POM), [PW12O40]3- (PW12). Base on the controlled experiments, they discovered that the morphology of the formed nanostructure showed strong dependence on the initial concentration of reactants and the ratio of [Ag+]/[POM]. Through time-dependent observations, they found that the presence of the POM and Ag nanoparticles modulated the reaction kinetics and the POM played a key role in the formation of Ag dendrites. The POM served as a kind of soft template, maintaining the anisotropic conditions and directing the Ag nanoparticles in the solution to the seeds. Furthermore, they found that these as-prepared silver dendrites exhibited Raman enhancement effect.

According to one of the reviewer of this manscript, this work is significant for the interaction understanding of POMs with nanoparticles and the application of POMs in the preparation process of metal nanoparticles.

This work has been published on the Cryst. Growth Des., 2011, 11 (8), pp 3424–3431 and the related research work was supported by the National Natural Science Foundation of China (No. 21071146, 51002155，20733006), the CNRS (UMR 8000) and the Université Paris-Sud 11, France. 

Contact:

ZHANG Guangjin

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Email: zhanggj@home.ipe.ac.cn

Schematic diagram indicating the growth process of the silver dendrites. (Image by IPE)