| Abstract
| - We describe here a novel method which shows that related large molecules, tannic acid, can control themorphology of silver/gold nanoparticles, resulting in the formation of multi-pod-shaped nanostructures. Inthis work, multi-pod-shaped gold/silver nanostructures have been synthesized using tannic acid as a reducingas well as a capping agent. The multi-pod-shaped Au/Ag nanostructures have been confirmed by transmissionelectron microscopy. The growth process of gold/silver nanostructures has been studied by UV/vis spectroscopyand extended X-ray absorption fine structure analysis. On the basis of these results, we propose a modelexplaining the role of tannic acid in the growth of gold/silver nanostructures. The reducing and cappingproperties of tannic acid favor the formation of unisotropic crystal growth. The growth of gold/silvernanostructures occurs as a consequence of the galvanic replacement reaction between Au3+ and Ag0 andsubsequent reduction of both metal ions by tannic acid. Furthermore, it was found that not only the amountof gold ions but also the galvanic replacement reaction between silver and chloroauric acid plays an importantrole in the morphology control of the multi-pod-shaped nanostructures.
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