In situ Oxidation and Self-Assembly Synthesis of Dumbbell-like α-Fe₂O₃/Ag/AgX (X = Cl, Br, I) Heterostructures with Enhanced Photocatalytic Properties

In this work, the novel dumbbell-like α-Fe₂O₃/Ag/AgX (X = Cl, Br, I) heterostructures were successfully synthesized via an in situ oxidation reaction and self-assembly process by using the α-Fe₂O₃/Ag core-shell nanoparticles (NPs). The as-obtained dumbbell-like α-Fe₂O₃/Ag/AgX heterostructure contains an individual spindle-like α-Fe₂O₃ nanoparticle and a single near-spherical Ag/AgX nanoparticle. The morphology, microstructure, component and optical property of as-synthesized α-Fe₂O₃/Ag/AgX heterostructures were characterized by various analytical techniques. The great changing of morphology and component in such synthesis route make great effect on the final photocatalytic performance. The dumbbell-like α-Fe₂O₃/Ag/AgX heterostructures exhibit excellent photocatalytic activity for the degradation of RhB dye under simulated sunlight irradiation. In particular, the α-Fe₂O₃/Ag/AgCl can completely degrade RhB molecules within only 20 min under simulated sunlight irradiation, which is superior to the pure α-Fe₂O₃, α-Fe₂O₃/Ag NPs, and commercial P25. The enhanced activity is attributed to the efficient interfacial charge rectification and faster carrier migration in the α-Fe₂O₃/Ag/AgX heterostructures. Furthermore, the degradation rate of as-synthesized dumbbell-like α-Fe₂O₃/Ag/AgX (X = Cl, Br, I) heterostructures follows this order: α-Fe₂O₃/Ag/AgCl > α-Fe₂O₃/Ag/AgBr > α-Fe₂O₃/Ag/AgI. The results can be owing to that the oxidation capability of Cl⁰ is stronger than Br⁰ and I⁰. This unique synthetic work can provide physical insight into prepare novel nanomaterials with special structures and properties, which can apply in photocatalysis, photosplitting of water and solar cell, etc.