Tailoring gold and silver colloidal bimetallic nanoalloys towards SERS detection of rhodamine 6G

Abstract

Nanoparticles of gold, silver and their bimetallic alloys have been prepared by an adapted method of reduction of the aqueous salts using sodium borohydride. It is demonstrated that the temperature and order of addition of the corresponding salt solutions influence the nanoalloys chemical arrangement giving different surface plasmon resonance behavior. The colloidal dispersions show very good Surface-Enhanced Raman Spectroscopy (SERS) signal towards rhodamine 6G. The obtained nanoparticles were then successfully deposited onto glass supports by evaporation of the respective colloids and also used as functional SERS sensors with efficient detection of trace amounts of the analyzed dye. These spectroscopic studies demonstrated that both mono and bimetallic nanoparticles show very good SERS sensitivity with the advantage of being prepared using a straightforward synthetic method in the absence of an additional stabilizer as needed for commonly used core–shell systems.