Magnetically separable and recyclable photocatalyst MoS2-SrFe12O19 with p-n heterojunction: Fabrication, characterization, and photocatalytic mechanism

A novel magnetic photocatalyst MoS2-SrFe12O19 was successfully synthesized via a facile and reliable hydrothermal method. Flower-shaped nanospheres MoS2 was compactly decorated with hexagon nanoplate SrFe12O19, which formed a new p-n heterojunction. The superiority of this heterojunction structure has validated by characterizations and spectroscopic technique. Importantly, the MoS2-SrFe12O19 composite presents remarkable photocatalytic activity for the degradation of organic dyes (RhB and MB), far exceeding those for the pure MoS2 and SrFe12O19. In particular, the degradation rate of RhB reached to 96.5% after only 120 min photocatalytic reaction for the composite MoS2-SrFe12O19 (10 wt%). Based on the experiments and mechanism research, this magnetic photocatalyst can facilitate the separation of photogenerated electron-hole pairs, inhibit the recombination and prolong lifespan of charge. It is attributed to its unique composite structure and intimate interfacial contact, which can obtain a higher light utilization and electron transit path. In addition, MoS2-SrFe12O19 can be rapidly separated (5-10 seconds) and recycled under an external magnetic field, which verifies the satisfactory magnetism and reusability of the composite (Ms = 10.1 emu g(-1), Mr = 3.5 emu g(-1), Hci = 1407.7 Oe). Overall, this work provides a new insight for the recyclable photocatalytic systems with multi-functionalities.