and products, Ag@AgBr-gelatin film showed excellent visible light activity for MO
degradation. Based on recycle experiments, the film exhibited excellent stability and
recyclability in the application of organic contaminant degradation. Moreover, it
should be noticed that this synthetic route can be used to fabricate photocatalytic
films in a large scale, which is meaningful for practical application.
13.7.2 Combined with Magnetic Components
Besides loading AgX materials on subtracts, immobilizing photocatalysts on the
surface of magnetic nano- or microparticles is another effective strategy to enhance
the recoverability, by which the photocatalysts can be easily separated by an external
magnet under the premise of keeping photocatalytic activity. Recently, CoFe 2 O 4
[134–136], Fe 3 O 4 [137–139], Fe 2 O 3 [140–142], and γ-Fe 2 O 3 [131] were used as
photocatalyst carriers to obtain efficient recyclable AgX-based materials for water
treatment. For example, Xu et al. attempted to construct ferromagnetic plasmonic
nanophotocatalysts by coupling Ag/AgCl with magnetic material CoFe 2 O 4 , which
enhanced the photo-activity of Ag/AgCl/CoFe 2 O 4 [134]. They also prepared
Ag/AgBr@Fe 2 O 3 magnetic photocatalyst by solvothermal process. The Ag/AgBr
was covered by Fe 2 O 3 and formed a uniquely core–shell nanostructure, which would
provide a high surface area and numerous active sites for the photocatalytic reaction
(Fig. 13.26a) [140]. Zhang et al. reported a magnetic adsorptive photocatalyst
composite, Ag/AgCl-magnetic activated carbon (MAC) synthesized via a facile
deposition–precipitation–photoreduction method (Fig. 13.26b) [143]. The resulting
composites possessed quasi-superparamagnetic behavior and exhibited good visible
light-induced photocatalytic activity toward the inactivation of E. coli K-12 and
degradation of methyl orange and phenol.
Although these composite photocatalysts can be successfully separated by applying an external magnetic field, there still exist some deficiencies, such as wide size
distribution and irregular morphological structures. These deficiencies will cause a
longer time for completely harvesting photocatalysts. To solve this problem, Tian
et al. fabricated core–shell structured γ-Fe 2 O 3 @SiO 2 @AgBr:Ag composite microspheres with narrow size distribution by a versatile multistep route, including
solvothermal method to fabricate magnetic core, modified Stöber method to coat
SiO 2 interlayer, electrostatic assembly to deposit AgBr shell, and light reduction to
form Ag nanoparticles (Fig. 13.26c, d) [131]. Beneficial from the narrow size
distribution, high saturation magnetization, and superparamagnetic property, the
core–shell structured γ-Fe 2 O 3 @SiO 2 @AgBr:Ag shows excellent magnetic separation and recovery performances (completely harvesting in 30 s), as shown in
Fig. 13.26e.
334
13 Syntheses and Applications of Silver Halide-Based Photocatalysts
degradation. Based on recycle experiments, the film exhibited excellent stability and
recyclability in the application of organic contaminant degradation. Moreover, it
should be noticed that this synthetic route can be used to fabricate photocatalytic
films in a large scale, which is meaningful for practical application.
13.7.2 Combined with Magnetic Components
Besides loading AgX materials on subtracts, immobilizing photocatalysts on the
surface of magnetic nano- or microparticles is another effective strategy to enhance
the recoverability, by which the photocatalysts can be easily separated by an external
magnet under the premise of keeping photocatalytic activity. Recently, CoFe 2 O 4
[134–136], Fe 3 O 4 [137–139], Fe 2 O 3 [140–142], and γ-Fe 2 O 3 [131] were used as
photocatalyst carriers to obtain efficient recyclable AgX-based materials for water
treatment. For example, Xu et al. attempted to construct ferromagnetic plasmonic
nanophotocatalysts by coupling Ag/AgCl with magnetic material CoFe 2 O 4 , which
enhanced the photo-activity of Ag/AgCl/CoFe 2 O 4 [134]. They also prepared
Ag/AgBr@Fe 2 O 3 magnetic photocatalyst by solvothermal process. The Ag/AgBr
was covered by Fe 2 O 3 and formed a uniquely core–shell nanostructure, which would
provide a high surface area and numerous active sites for the photocatalytic reaction
(Fig. 13.26a) [140]. Zhang et al. reported a magnetic adsorptive photocatalyst
composite, Ag/AgCl-magnetic activated carbon (MAC) synthesized via a facile
deposition–precipitation–photoreduction method (Fig. 13.26b) [143]. The resulting
composites possessed quasi-superparamagnetic behavior and exhibited good visible
light-induced photocatalytic activity toward the inactivation of E. coli K-12 and
degradation of methyl orange and phenol.
Although these composite photocatalysts can be successfully separated by applying an external magnetic field, there still exist some deficiencies, such as wide size
distribution and irregular morphological structures. These deficiencies will cause a
longer time for completely harvesting photocatalysts. To solve this problem, Tian
et al. fabricated core–shell structured γ-Fe 2 O 3 @SiO 2 @AgBr:Ag composite microspheres with narrow size distribution by a versatile multistep route, including
solvothermal method to fabricate magnetic core, modified Stöber method to coat
SiO 2 interlayer, electrostatic assembly to deposit AgBr shell, and light reduction to
form Ag nanoparticles (Fig. 13.26c, d) [131]. Beneficial from the narrow size
distribution, high saturation magnetization, and superparamagnetic property, the
core–shell structured γ-Fe 2 O 3 @SiO 2 @AgBr:Ag shows excellent magnetic separation and recovery performances (completely harvesting in 30 s), as shown in
Fig. 13.26e.
334
13 Syntheses and Applications of Silver Halide-Based Photocatalysts