Electroless deposition of SERS active Au-nanostructures on variety of metallic substrates

Abstract

In this study, flower-like Au structures (three dimensional branched nanoparticles) were constructed by using a simple, template-free and cost effective electroless plating method. The key synthesis strategy was to perform controlled plating of Au on a variety of metals (Ag, Cu and Pt) deposited on the Si substrate. Herein, gold is deposited purely as a result of reaction of chemicals in bath to form Au nanoflowers/lawns. The size and shape of the Au nanoflowers could be tailored by controlling the immersion Au plating time on multitude of metallic substrates. Time course measurements by SEM and HR-TEM were used to follow reaction progress and evolution of flower-like shape. The generation of unique and reproducible morphological Au nanostructures onto each substrate implies that the Au nanostructures are substrate dependent. Fast Fourier Transform measurements were conducted using HR-TEM on isolated samples that proved the presence of anisotropic growth of Au polycrystalline structures. The gold nanostructures have shown the surface-enhanced Raman scattering (SERS) by detecting the enhanced Raman spectra of 4-Aminobenzenethiol (4-ABT) molecules. The enhancement of Raman signal was stronger for Au structures built on Pt or Ag thin films. The Au nanoflowers produced by this simple method exhibited effective surface-enhancement for biosensing applications.