Electrodeposition of silver nanodendrites

Nanodendrites of silver were synthesized by electrodeposition using AgNO3 as the source in ammoniacal solution. The method was remarkably fast, simple and scalable. X-ray diffraction (XRD) studies confirmed the formation of a cubic phase of silver. Scanning electron microscopy (SEM) revealed the formation of well-shaped dendrites. The nanodendrites were hyperbranched with lengths of the order of a few micrometres. The concentration of NH3 in the electrolyte solution was found to have remarkable influence on the morphology, crystallite size and formation of branched nanodendrites. The branchings were found to occur at regular intervals of similar to 50 nm along the main stem. Transmission electron microscopy (TEM) studies confirmed the SEM observation and revealed the 2D nature of the dendrites. Selected area electron diffraction (SAED) revealed that the dendrites were single crystalline in nature and the branching could have a crystalline origin. The direction of growth as inferred from SAED was < 110 >. UV-vis spectra showed a single broad band centred on similar to 380 nm indicating the spherical shape of the individual crystallites. The intrinsic size effect of the metal surface plasmon was used to explain the increase in the broadening on addition of NH3. The asymmetry of the band was explained on the basis of agglomeration of crystallites. The nanodendrites prepared by this method showed extension of the plasmon band through the entire visible region, indicating potential use in detection of single molecules based on enhanced Raman scattering. The deposition mechanism is described using the diffusion-limited aggregation model.