Liquid-phase deposition of TiO2 nanoparticles on core–shell Fe3O4@SiO2 spheres: preparation, characterization, and photocatalytic activity

Abstract

To prevent and avoid magnetic loss caused by magnetite core phase transition involving in hightemperature crystallization of amorphous sol-gel TiO 2 , core-shell Fe3O4@SiO2@TiO2 composite spheres were synthesized via non-thermal process of TiO 2 . First, core-shell Fe 3 O 4 @SiO 2 particles were synthesized through a solvothermal method followed by a sol-gel process. Second, anatase TiO 2 nanoparticles (NPs) were directly coated on Fe 3 O 4 @SiO 2 surface by liquid-phase deposition method, which uses (NH 4 ) 2 TiF 6 as Ti source for TiO 2 and H 3 BO 3 as scavenger for F -ions at 50°C. The morphology, structure, composition, and magnetism of the resulting composites were characterized and their photocatalytic activities were also evaluated. The results demonstrate that TiO 2 NPs with an average size of 6-8 nm were uniformly deposited on the Fe 3 O 4 @SiO 2 surface. Magnetic hysteresis curves indicate that the composite spheres exhibit superparamagnetic characteristics with a magnetic saturation of 32.5 emu/g at room temperature. The magnetic TiO 2 composites show high photocatalytic performance and can be recycled five times by magnetic separation without major loss of activity, which meant that they can be used as efficient and conveniently renewable photocatalyst.

Advances in Magnetically Separable Photocatalysts: Smart, Recyclable Materials for Water Pollution Mitigation

“…Other core-shell Fe 3 O 4 @SiO 2 nanostructures decorated with TiO 2 have been fabricated and evaluated for the decomposition of various pollutants such as RhB, 2-chlorophenol (2-CP), phenol, MB, and MO. These materials showed improved photocatalytic properties, good stability, and sufficiently high magnetic response that enabled separation using an external magnetic field [124][125][126][127]. Table 1 provides a summary of the synthesis and photocatalytic properties of various other magnetite-incorporating titania-based photocatalysts towards water treatment applications.…”

Visible-light photoelectrocatalysis/H2O2 synergistic degradation of organic pollutants by a magnetic Fe3O4@SiO2@mesoporous TiO2 catalyst-loaded photoelectrode

“…26 In recent years, the research on magnetic TiO 2 composite photocatalysts based on Fe 3 O 4 has mostly focused on the application of Fe 3 O 4 @SiO 2 @TiO 2 in photocatalysis. [27][28][29][30][31][32][33] The role of Fe 3 O 4 in these studies is primarily in the area of magnetic separation, but less attention is paid to how to improve TiO 2 photocatalytic activity. Meanwhile, less research has been conducted on Fe 3 O 4 @SiO 2 @TiO 2 in photoelectrocatalysis, 34 and few studies have comprehensively discussed the issues of expanding the light absorption range, increasing the photoelectrocatalytic activity, effective charge separation performance, and stable recyclability.…”

A study on the preparation and performance of a graphene-supported, Ce ion-doped, high-efficiency, magnetic TiO2 photocatalyst

“…At present, several research groups have developed TiO 2 -based magnetic catalysts that can be quickly separated from wastewater. 14,15 However, the magnetic core can reduce the photocatalytic efficiency. 16 In fact, SiO 2 , as a magnetic isolation material, can be used as a protective film to avoid interactions between the magnetic core and the TiO 2 coating.…”