Tunable Fractal Nanostructures for Surface-Enhanced Raman Scattering via Templated Electrodeposition of Silver on Low-Energy Surfaces

Here we demonstrate a facile method for growing nano-featured silver (Ag) structures on a planar microelectrode platform. The nanostructures are assembled along the electrically insulating substrate, growing from the microelectrode edge with the electrodes acting as the template. This is done by (a) limiting nucleation to the edges of the electrodes and (b) chemically functionalizing the insulating substrate to promote interaction between itself and the growing metallic structures. The structures able to reach lateral lengths greater than 100 microns. We performed an extended investigation on how the nanostructure morphology can be turned from spherical aggregates to fractal dendrites by altering the electrical signal and solution composition. We determined citrate to be a necessary additive and showed that it acts as a supporting electrolyte, capping agent and oxidizing/complexing agent. Next, using optimal deposition conditions we assemble Ag surface-enhanced Raman scattering (SERS) substrates with an e...