Fabrication of Ag nanoparticles-coated macroporous SiO2 structure by using polystyrene spheres

Ag nanoparticles-coated macroporous SiO2 structure was fabricated by a novel approach in which at first Ag nanoparticles were coated onto polystyrene (PS) spheres without a surfactant, then these Ag nanoparticles-coated PS beads (Ag/PS) were self-assembled by sedimentation-aggregation with tetraethyl orthosilicate (TEOS), and finally Ag nanoparticles-coated macroporous silica (Ag/SiO2) was obtained after removal of the PS cores. The heat-treatment temperature and the gelation time were investigated to optimize the microstructural morphology, thermal decomposition of organic materials, matrix wall thickness and densification behavior. The three dimensionally assembled Ag/SiO2 had 200 nm uniform macropores and a high specific surface area of 142 m2 g−1. The XRD, FE-SEM, EDX, BET and optical absorbance analysis indicated that the exactly three-dimensional structure of the template had been imprinted in the final samples and the walls of the macroporous SiO2 were coated uniformly with Ag nanoparticles.