Nanoparticle coupling effect allows enhanced localized field on Au bowl-like pore arrays

Abstract

A simple, effective, and productive method to fabricate an ordered Au pore array of Au/Ag nanoparticles is proposed in this article. Using a polystyrene sphere (PS) colloidal monolayer as the template, the electrodeposition is carried out in a HAuCl₄ electrolyte under a constant cathodic current density of 0.04 mA cm⁻² for 5 h at room temperature. After removing the PS colloidal monolayer, a Au bowl-like array is obtained. Then nanoparticles are ion-sputtered onto the array at a deposition current of 10 mA for 12 min. The ordered Au pore array with Au/Ag nanoparticles exhibits a strong SERS performance for R6G as the probe molecule. The enhancement mainly comes from coupling between the nanoparticles and the pores. The finite-difference time-domain (FDTD) method is used to calculate the local electric field distribution near the nanostructure. The simulation results agree well with the experiments.