A facile approach to fabricate Au nanoparticles loaded SiO2 microspheres for catalytic reduction of 4-nitrophenol

Hydrophilic and biocompatible macromolecules were used to improve and simplify the process for the fabrication of core/shell SiO2@Au composite particles. The influence of polymers on the morphology of SiO2@Au particles with different size of SiO2 cores was analyzed by transmission electron microscopy and scanning electron microscopy. The optical property of the SiO2@Au particles was studied with UV-Vis spectroscopy. The results indicate that the structure and composition of macromolecules affect the morphology of Au layers on SiO2 microspheres. The SiO2@Au particles prepared in the presence of polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) have thin and complete Au nanoshells owing to their inducing act in preferential growth of Au nanoparticles along the surface of SiO2 microspheres. SiO2@Au particles can be also prepared from SiO2 microspheres modified with 3-aminopropyltrimethoxysilane in the presence of PVA or PVP. This offers a simple way to fabricate a Au layer on SiO2 or other microspheres. The SiO2@Au particles demonstrated high catalytic activity in the reduction of 4-nitrophenol.