Facile preparation of ordered arrays of polystyrene spheres dissymmetrically decorated with gold nanoparticles at air/liquid interface and their SERS properties

Abstract

Ordered arrays of polystyrene (PS) spheres dissymmetrically decorated with gold nanoparticles (NPs) were facilely assembled at air/liquid interface by the combination of colloidal crystal templating and modified conventional electroless plating. Distinguishingly, Sn²⁺ ions served as the reductant and stabilizer in the preparation of Au colloid, and the immersed part of a floating monolayer of pristine PS spheres was also sensitized by the excessive amounts of Sn²⁺ ions in the Au colloid. Colloidal Au NPs spontaneously aggregated onto the sensitized portion of PS spheres due to oxygen-induced ligand replacement of SnCl₃⁻ with Cl⁻, forming asymmetric PS/Au composite sphere arrays. Moderate heating (60 °C) accelerated the assembly process. The method presented here is convenient, cost-effective and can be extended to prepare asymmetric composite sphere arrays of PS/Pd and PS/Au–Pd. Furthermore, the surface enhanced Raman scattering (SERS) performance of the ordered arrays of asymmetric PS/Au composite spheres was examined.