Au-Ag bimetallic nanodendrite synthesized viasimultaneous co-electrodeposition and its application as a SERS substrate

We presented a novel Au-Ag bimetallic nanodendrite constructed through simple one-step co-electrodeposition on a Pt surface in the presence of iodide ions as a co-reagent. Simultaneously, we maneuvered to generate hydrogen bubbles from the same surface by the reduction of proton to drive the growth of deposition into the nanodendrite network structure. Au-Ag bimetallic nanodendrites composed of different atomic percentages of Au and Ag (0.00-5.12% Ag) were electrochemically synthesized by varying mole percentages of Au super(3+) and Ag super(+) in solutions. When atomic Ag concentration was from 0.39 to 3.84%, characteristic dendrite structure with high crystallinity was clearly observed; while, an imperfect nanodendrite structure became present when the atomic Ag concentration was over 3.84%. Further, the bimetallic nanodendrites with different Ag concentrations were used as a substrate for surface-enhanced Raman scattering (SERS) measurement. The SERS intensity of 2-naphthalenethiol was maximized when the nanodendrite containing 3.84% Ag was used. Incorporation of better plasmonic metal, Ag, into the nanodendrite structure was obviously advantages in enhancing SERS efficiency; while, maintaining a good bimetallic nanodendrite structure was a prerequisite for optimal SERS measurement.