Mesoporous Microcapsules with Decorated Inner Surface: Fabrication and Photocatalytic Activity

Abstract

A simple and versatile strategy has been employed to fabricate a "microreactor" consisting of nanoparticles encapsulated in a hollow core of monodispersed mesoporous silica shell. First, based on our synthesis method for monodispersed silica spheres with radially aligned mesopores, hollow mesoporous silica spheres have been synthesized using amino modified polystyrene beads as a template. We then found that introduction of metal oxide precursor into the mesoporous silica spheres using the incipient wetness technique leads to selective formation of nanoparticles into the core of the hollow spheres. Using this strategy, inorganic nanoparticles (TiO2 and Fe2O3) are confined into the hollow cores, with high loading and high dispersion, to which widely accessible mesoporous channels were connected. The loading contents of TiO2 and Fe2O3 were 40.2 and 36.4 wt %, respectively. These values were considered quite high when compared to values previously reported for similar materials. The photocatalytic activity of TiO2 encapsulated silica capsules in the degradation of methyl orange was examined. The decomposition rate, especially at the initial reaction stage, for this capsule was considerably faster than that for other mesoporous silica-based TiO2/SiO2 composites. The methodology described here is versatile and convenient and thus can be extended to a broad range of guest species for high-performance catalysis, adsorption, and energy conversion materials.