Large scale synthesis of FeS coated Fe nanoparticles as reusable magnetic photocatalysts

The FeS coated Fe nanoparticles were prepared by using high temperature reactions between the commercial Fe nanoparticles and the S powders in a sealed quartz tube. The simple method developed in this work is effective for large scale synthesis of FeS/Fe nanoparticles with tunable shell/core structures, which can be obtained by controlling the atomic ratio of Fe to S. The structural, magnetic and photocatalytic properties of the nanoparticles were investigated systematically. The good photocatalytic performance originating from the FeS shell in degradation of methylene blue under visible light and the high saturation magnetization originating from the ferromagnetic Fe core make the FeS/Fe nanoparticles a good photocatalyst that can be collected and recycled easily with a magnet. An exchange bias up to tl mT induced in Fe by FeS was observed in the Fe/FeS nanoparticles with ferro/antiferromagnetic interfaces. The enhanced coercivi- ty up to 32 mT was ascribed to the size effect of Fe core.

Visible light photodegradation of methylene blue by AgBr-TiO_2/SiO_2@Fe_3O_4 magnetic photocatalysts

Visible photoactive AgBr/TiO2 was immobilized on a SiO2@Fe3O4 magnetic support by solvother- rnal and sol-gel methods to form a AgBr-TiO2/SiO2@Fe3O4 magnetic photocatalyst. Samples were characterized by X-ray diffraction, high-resolution transmission electron microscopy and magne- tometry. Hereto-structured AgBr/TiO2 was well seeded on the shell-core SiO2@Fe3O4 structure. The AgBr-TiO2/SiO2@Fe3O4 magnetic photocatalyst exhibited high photocatalytic activity in the degrada- tion of methylene blue under visible light. The photocatalyst was superparamagnetic, which is beneficial for facile magnetic separation.

Synthesis and Characterization of Magnetic TiO_2/SiO_2/NiFe_2O_4 Composite Photocatalysts

Magnetic TiO2/SiO2/NiFe204 composite photocatalytic particles with high crystalline TiO2 shell were synthesized via a mild solution route. The prepared composite particles were characterized with X-ray diffraction（XRD）, transmission electron microscopy（TEM）, high resolution transmission electron microscopy（HRTEM）, scanning electron microscopy（SEM）, ultraviolet-visible（UV-Vis） spectroscopy and vibrating sample magnetometer（VSM）. The results show that the obtained TiO2/SiO2/NiFe2O4 composite particles were composed of spherical nanoparticles, about 30 nm in diameter, with several NiFe/O4 fine particles about 20 nm in diameter as cores and silica as coatings and barrier layers between the magnetic cores and titania shells. The photocatalytic activity of the composite photocatalytic particles was also investigated for the degradation of Basic Violet 5BN（BV5） under UV irradiation. About 97% of original BV5 decomposed in 360 min in the presence of magnetic composite nanoparticles under UV light. The synthesized magnetic composite nanoparticles exhibited high photocatalytic efficiency that would find potential application to cleaning polluted water with the help of magnetic separation.

Reduced Graphene Oxide Coupled Magnetic CuFe2O4-TiO2 Nanoparticles with Enhanced Photocatalytic Activity for Methylene Blue Degradation

CuFe_2O_4-TiO_2/graphene nanocomposites have been prepared via a one-step hydrothermal method,and the as-prepared CuFe_2O_4-TiO_2/graphene was characterized by X-ray powder diffraction,Raman spectroscopy,scanning electron microscopy and transmission electron microscopy.The transmission electron microscopy demonstrated that CuFe_2O_4-TiO_2 nanoparticles were successfully dispersed on the graphene sheets.Photocatalytic activity of nanocomposites was evaluated in terms of degradation of methylene blue（MB） dye solution under visible light radiation.Results showed that the photocatalytic efficiency of CuFe_2O_4-TiO_2/graphene nanocomposites was higher than its individual pure oxides（CuFe_2O_4 or TiO_2） and TiO_2/graphene.The enhancing photocatalytic activity performance of the CuFe_2O_4-TiO_2/graphene nanocomposites may attributed to the mutual effect between the Cu Fe_2O_4,Ti O_2 nanoparticles and the graphene sheets.Moreover,Cu Fe_2O_4 nanoparticles have excellent magnetic property,which makes the CuFe_2O_4-TiO_2/graphene heteroarchitecture magnetically recyclable in a suspension system.

One-pot hydrothermal fabrication of BiVO_(4)/Fe_(3)O_(4)/rGO composite photocatalyst for the simulated solar light-driven degradation of Rhodamine B

Fabrication of easily recyclable photocatalyst with excellent photocatalytic activity for degradation of organic pollutants in wastewater is highly desirable for practical application.In this study,a novel ternary magnetic photocatalyst BiVO_(4)/Fe_(3)O_(4)/reduced graphene oxide(BiVO_(4)/Fe_(3)O_(4)/rGO)was synthesized via a facile hydrothermal strategy.The BiVO_(4)/Fe_(3)O_(4) with 0.5 wt%of rGO(BiVO_(4)/Fe_(3)O_(4)/0.5%rGO)exhibited superior activity,degrading greater than 99%Rhodamine B(RhB)after 120 min solar light radiation.The surface morphology and chemical composition of BiVO_(4)/Fe_(3)O_(4)/rGO were studied by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,UV–visible diffuse reflectance spectroscopy,Fourier transform infrared spectroscopy,and Raman spectroscopy.The free radicals scavenging experiments demonstrated that hole(h^(+))and superoxide radical(O_(2)•^(−))were the dominant species for RhB degradation over BiVO_(4)/Fe_(3)O_(4)/rGO under solar light.The reusability of this composite catalyst was also investigated after five successive runs under an external magnetic field.The BiVO_(4)/Fe_(3)O_(4)/rGO composite was easily separated,and the recycled catalyst retained high photocatalytic activity.This study demonstrates that catalyst BiVO_(4)/Fe_(3)O_(4)/rGO possessed high dye removal efficiency in water treatment with excellent recyclability from water after use.The current study provides a possibility for more practical and sustainable photocatalytic process.

Novel ternary g-C_3N_4/Fe_3O_4/MnWO_4 nanocomposites: Synthesis,characterization, and visible-light photocatalytic performance for environmental purposes

The g-C3 N4/Fe3 O4/MnWO4 nanocomposites were prepared by a refluxing-calcination procedure. Visiblelight-induced photocatalytic experiments showed that the g-C3 N4/Fe3 O4/MnWO4（10%） nanocomposite has excellent ability to degrade a range of contaminants including rhodamine B, methylene blue, methyl orange, and fuchsine, which is about 7, 10, 25, and 31 times of the g-C3 N4 photocatalyst, respectively.Reactive species trapping experiments revealed that superoxide anion radicals play major role in the photodegradation reaction of rhodamine B（RhB）. After the treatment process, the utilized photocatalyst was magnetically recovered and reused with negligible loss in the photocatalytic activity, which is vital in the photocatalytic processes. Finally, a mechanism was proposed for the enhanced interfacial carrier separation and transfer and the improved photocatalytic performance.

Defects and interface states related photocatalytic properties in reduced and subsequently nitridized Fe_3O_4/TiO_2

The Fe3O4@TiO2 catalyst was reduced in a mixed H2/N2 atmosphere at temperatures of 400, 600, 800 and 1000 ℃ in order to produce the oxygen vacancies （Ov） and Ti^3＋; Simultaneously, Fe3O4 was reduced to Fe, a strongly magnetic material, beneficial for the magnetic separation after the photo-degradation. The optimal catalyst was obtained at the reducing temperature of 800℃, which possesses the good photocatalytic performance and recycled activities; Moreover, its saturation magnetization Ms is highest, reaching 23.8 emu g 1 which improves the magnetic separability. This optimal catalyst was subsequently treated in the NH3 atmosphere at temperatures of 500, 600 and 700 ℃, aiming to investigate the effects of N-doping in TiO2. The 600 ℃ treated catalyst exhibited the optimal photocatalytic performance. The factors that affect the photocatalytic performance are revealed and discussed in detail, including the ratio of Ov and N dopant in TiO2 as well as the interface states between TiO2 and the magnetic particles.