Bi₂₅FeO₄₀/α-Fe₂O₃复合纳米颗粒光催化剂的制备与性能

Pure Bi₂₅FeO₄₀ nanoparticles and Bi₂₅FeO₄₀/α-Fe₂O₃ composite nanoparticles were synthsized through solvothermal porcess by using polyamidoamine(PAMAM) dendrimer stabilizer with a Bi³⁺/Fe³⁺ molar ratio of 25: 1 and 1: 1 in the reaction system, respectively. The structure, morphology and properties of the samples were characterized by X-ray diffraction(XRD), high resolution transmission electron microscopy(HRTEM), X-ray photoelectron spectroscopy(XPS), ultraviolet-visible spectroscopy(UV-Vis), Brunauer-Emmett-Teller(BET) surface area analysis and magnetic hysteresis loops measurenent. The results show that these particles are uniform balls with the diameter less than 10 nm. Compared with pure Bi₂₅FeO₄₀ nanoparticles, Bi₂₅FeO₄₀/α-Fe₂O₃ composite nanoparticles have smaller band gap, broader visible light absorption range, and significantly greater saturation magnetization and photocatalytic activity. These excellent properties of Bi₂₅FeO₄₀/α-Fe₂O₃ composite nanoparticles come from the superparamagnetic α-Fe₂O₃ component, and the heterogeneous structure of the phase boundary which promotes the efficient separation and migration of photogenerated carriers at the junction interfaces. These nanoparticles could be recycled in external magnetic field, and the catalytic activity decreased slightly after being reused for 3 times.