In situ assembly of dispersed Ag nanoparticles on hierarchically porous organosilica microspheres for controllable reduction of 4-nitrophenol

Hierarchically porous organosilica microspheres have been facilely synthesized by improved self-assembly of flexible-bridged organosilica precursor without templates and harsh conditions. Subsequently, monodispersed silver nanoparticles (Ag NPs) are in situ grown on the porous microspheres via silver mirror reaction. The as-prepared hybrid composites of Ag supported on porous microspheres are characterized by scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, thermal gravimetric analysis and nitrogen adsorption and desorption, respectively. These results indicate that not only Ag NPs (20-40 nm) are grown on the organosilica uniformly but also the content of Ag NPs immobilized in the hybrid materials can be well controlled by simply tuning the amount of the Ag(NH3)(2)OH. The resultant hybrid microspheres exhibit remarkable and durable performances for the reduction of 4-nitrophenol to 4-aminophenol by NaBH4 in aqueous solution. Moreover, the catalytic kinetic mode can be tuned by adjusting the parameter in catalytic reaction, and it can be recycled for seven successive cycles with excellent conversion of 100 % within 8 min. Therefore, the present structure design and scalable route for the synthesis of hierarchical catalyst can provide a highly efficient solution for the reduction of nitro-aromatic compounds in the view of environmentally friendly strategy.