A general strategy for synthesis of silver dendrites by galvanic displacement under hydrothermal conditions

A simple and straightforward strategy was developed to fabricate Ag dendrites with complex hierarchical structures by an aqueous chemical route based on spontaneous galvanic displacement between Ag ions and metal solid under hydrothermal conditions. High-quality Ag dendrites were produced on Cu substrate as a form of uniform solid film with a thickness of 1 mm, which was achieved at 160 degrees C in 1 h without the use of any additives, templates or electric field. The X-ray diffraction (XRD) analysis reveals that the cubic Ag phases are overwhelmingly dominant in the dendrites. Detailed structural examinations by scanning electron microscopy and transmission electron microscopy indicate that the Ag dendrites are the fractal assemblies of many nanorods with a fractal dimension of 1.83, of which the diameters are around 100-200 nm and the length of the trunk can reach up to 10-50 mu m. The selected area electron diffraction study reveals that the Ag dendrites are good single crystalline. It is believed that both the global diffusion-limited aggregation (DLA) and the locally oriented attachment of Ag grains are responsible for the formation of Ag dendrites under nonequilibrium conditions. The technique reported here may offer more opportunities for the commercial use of the Ag dendrite materials because of its simplicity and generality for various metal substrates with proper redox potential. (C) 2007 Elsevier Ltd. All rights reserved.