Synthesis of magnetic mesoporous titania colloidal crystals through evaporation induced self-assembly in emulsion as effective and recyclable photocatalystsElectronic supplementary information (ESI) available. See DOI: 10.1039/c5cp05005g

This study illustrates the directed self-assembly of mesoporous TiO 2 with magnetic properties due to its colloidal crystal structure with Fe 3 O 4 . The Fe 3 O 4 nanoparticles were synthesized using co-precipitation techniques to a size of 28.2 nm and a magnetic saturation of 66.9 emu g −1 . Meanwhile, mesoporous titania nanoparticles (MTNs) with a particle diameter of 373 nm, a specific surface area of 236.3 m 2 g −1 , and a pore size of 2.8 nm were prepared by controlling the rate of hydrolysis. Magnetic colloidal crystals (a diameter of 10.2 μm) were formed by the aggregation of Fe 3 O 4 and MTNs caused by the interface phenomena during solvent evaporation in emulsion. Even the anatase octahedrite produced from the colloidal crystal after a hydrothermal reaction retained a magnetic saturation of 2.8 emu g −1 . This study also investigates the photodegradation activity of our synthesized material as a photocatalyst, while utilizing its capability for magnetic separation to prove its usefulness in catalyst recycling. This study illustrates the directed self-assembly of mesoporous TiO 2 with magnetic properties due to its colloidal crystal structure with Fe 3 O 4 .