Bromide ion induced formation of PVP-capped anisotropic gold nanoplates/nanotriangles

Anisotropic gold nanoparticles are particularly important owing to their exciting applications in plasmonics as well as nanophotonics and biosensing. Herein, we have synthesized gold nanoplates/nanotriangles with an average side-length varying from 80 to 150 nm via a single step room-temperature solution-phase chemical reduction method utilizing predominantly the PVP-bromine interaction. The concentration of bromine as well as the surrounding reaction medium/environment plays an important role in determining the yield of gold nanoplates/nanotriangles at a given PVP to metal ratio. In the presence of bromine ions, the distinctive binding of PVP with metal salt changes owing to its conformational variations, as illustrated successfully through FTIR, optical absorption and TEM, leading to the formation of anisotropic gold nanoplates/nanotriangles.