Synthesis of magnetic mesoporous titania colloidal crystals through evaporation induced self-assembly in emulsion as effective and recyclable photocatalysts

Abstract

This study illustrates the directed self-assembly of mesoporous TiO2 with magnetic properties due to its colloidal crystal structure with Fe3O4. The Fe3O4 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 Fe3O4 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.

Noble metal-titania hybrid nanoparticle clusters and the interaction to proteins for photo-catalysis in aqueous environments

“…[1][2][3][4][5][6][7][8] The advantages of TiO 2 -NP include low cost, high chemical and thermal stability, ready availability, ease of handling, and non-toxicity. [4,5,9,10] The functional response of TiO 2 -NP is fundamentally governed by the generation of charge carrier by photons.…”

“…[4,5,9,10] The functional response of TiO 2 -NP is fundamentally governed by the generation of charge carrier by photons. [4][5][6][7][8]11] In principle, the positive holes can be used to oxidize the organic compounds, where the negative electrons can be used to reduce the conversion of molecular oxygen to superoxide radical anions in the complete cycle of photo-catalysis. [12][13][14] Therefore, the applications of TiO 2 -NP have extended into a variety of areas of photocatalysis, for example, the photo-decomposition of the toxic components, which has shown to very useful for a variety of environmental applications including the purification of water and air in the environment.…”

“…In principle, the homogeneous dispersions of the two components (i.e., at their molecular level homogeneity in solutions) are maintained, creating a large amount of interfaces between noble metal NP and TiO 2 -NP in the hybrid nanostructure. [6,[36][37][38] Recent advances have been achieved in morphology-controlled synthesis of functional NPs through the concept of gas-phase EISA, [36][37][38] where a homogeneous, bi-component hybrid nanostructure can be formed effectively with controlled physical size and chemical composition.…”

“…Using the evaporation-induced self-assembly (EISA, as depicted in Figure 1), [6,[36][37][38] the dilute, heterogeneous solution of noble metal aqueous precursor mixed with a TiO 2 -NP colloidal dispersion is nebulized into sub-micron droplets. A number of liquid-air interfaces are created and subsequently evaporated to become bi-component crystallites of precursors.…”

Synthesis and photocatalytic activities of a CuO/TiO2 composite catalyst using aquatic plants with accumulated copper as a template

“…[14][15][16][17][18] Among the techniques used, photocatalysis is a powerful method for the decontamination of wastewaters. 19,20 The photocatalytic degradation of pollutants by using high performance semiconductor catalysts has been also conrmed as one of the most promising strategies to clean the environment. 21 Currently, the remediation of environmental pollution is focused on using metal oxide based photocatalysts, and TiO 2 has become a promising metal oxide photocatalytic material because of its stability and catalytic efficiency.…”