Template-free synthesis of core-shell Fe3O4@MoS2@mesoporous TiO2 magnetic photocatalyst for wastewater treatment

TiO2 is the dominant and most widely researched photocatalyst for environmental remediation, however, the drawbacks, such as only responding to UV light (<5% of sunlight), low charge separation efficiency, and difficulties in recycling, have severely hindered its practical application. Herein, we synthesized magnetically separable Fe3O4@MoS2@mesoporous TiO2 (FMmT) photocatalysts via a simple, green, and template-free solvothermal method combined with ultrasonic hydrolysis. It is found that FMmT possesses a high specific surface area (55.09 m(2)center dot g(-1)), enhanced visible-light responsiveness (similar to 521 nm), and remarkable photogenerated charge separation efficiency. In addition, the photocatalytic degradation efficiencies of FMmT for methylene blue (MB), rhodamine B (RhB), and tetracycline (TC) are 99.4%, 98.5%, and 89.3% within 300 min, respectively. The corresponding degradation rates are 4.5, 4.3, and 3.1 times higher than those of pure TiO2 separately. Owing to the high saturation magnetization (43.1 A center dot m(2)center dot kg(-1)), FMmT can achieve effective recycling with an applied magnetic field. The improved photocatalytic activity is closely related to the effective transport of photogenerated electrons by the active interlayer MoS2 and the electron-hole separation caused by the MoS2@TiO2 heterojunction. Meanwhile, the excellent light-harvesting ability and abundant reactive sites of the mesoporous TiO2 shell further boost the photocatalytic efficiency of FMmT. This work provides a new approach and some experimental basis for the design and performance improvement of magnetic photocatalysts by innovatively incorporating MoS2 as the active interlayer and integrating it with a mesoporous shell.