Preparation of large micron-sized monodisperse polystyrene/silver core–shell microspheres with compact shell structure and their electrical conductive and catalytic properties

Abstract

Utilizing a simple improved electroless plating method, ca. 6 μm sized monodisperse polystyrene/silver (PS/Ag) core–shell microspheres with a complete, homogeneous and compact coverage of Ag nanoparticles layer were successfully prepared. In this approach, modified lightly cross-linked PS (LCPS) microspheres with a uniform diameter of 5.6 μm were used as templates. After the LCPS cores were removed by dissolving with dimethyl formamide (DMF), the outer silver shells assembled by amounts of Ag nanoparticles maintain good hollow spherical structure. The size and coverage degree of Ag nanoparticles on the PS/Ag microspheres could be easily tuned by changing the concentration of [Ag(NH₃)₂]⁺ ions in aqueous media. The electrical conductivity of the obtained PS/Ag core–shell microspheres changes from 3.76 × 10⁴ S m⁻¹ to 3.33 × 10⁵ S m⁻¹ as increasing the coverage density of Ag nanoparticles. Moreover, the catalytic assays indicate that the resultant monodisperse PS/Ag core–shell microspheres show excellent catalytic activity for the reduction of methylene blue (MB) by NaBH₄. In particular, the corresponding hollow Ag spheres exhibit more outstanding catalytic activity due to their stable hollow structure and higher specific surface area.