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 m²·g⁻¹), enhanced visible-light responsiveness (~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·m²·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.