The Synthesis of Mesoporous TiO2/SiO2/Fe2O3 Hybrid Particles Containing Micelle- Induced Macropores through an Aerosol Based Process

Abstract

Mesoporous SiO₂/TiO₂/Fe₂O₃ particles containing macropores of about 50 nm in diameter have been prepared by an aerosol process using cetyltrimethylammonium bromide (CTAB) as a templating agent. In contrast to the traditional templating effect of CTAB to form ordered mesoporous silicas, the morphology here is vastly different due to the presence of precursor iron salts. The particles have mesoporosity templated by CTAB but additionally have large voids leading to a combined macroporous and mesoporous structure. The morphology is explained through the formation of colloidal structures containing species such as CTA⁺X^–1Fe³⁺ colloids in the aerosol droplets, indicating of a salt bridging effect. This dual porosity has applied implications, as the macropores provide easy entry to the particle interior in potentially diffusion limited situations. Furthermore, the particles encapsulate Fe₂O₃ and contain TiO₂ leading to the dual functional properties of magnetic response and photocatalytic activity.