Novel Heterojunction Bi₂O₃/SrFe₁₂O₁₉ Magnetic Photocatalyst with Highly Enhanced Photocatalytic Activity

Magnetic composite photocatalyst Bi 2 O 3 /SrFe 12 O 19 was synthesized by hydrolysis with medium temperature sintering method. X-ray diffraction (XRD) investigation revealed that introduction of SrFe 12 O 19 did not change the favorite growth direction of Bi 2 O 3, [121] orientation. Micromorphology study indicated that SrFe 12 O 19 was distributed on the surface of Bi 2 O 3 to possess the best possibility of forming some heterojunction structures. Vibrating sample magnetometer (VSM) measurements manifested the composite possessed better magnetic properties, which was conducive to its separation, recycling, and reuse. Three main reasons for the increase in photocatalytic activity of Bi 2 O 3 /SrFe 12 O 19 were (1) the formation of p–n-type heterojunction between p-type Bi 2 O 3 and n-type SrFe 12 O 19 semiconductors, (2) magnetic field effect stemming from magnetic composite itself generated a shunt effect for photoexcited electrons, and (3) as a sensitizer absorbing visible light, SrFe 12 O 19 could help Bi 2 O 3 absorb more incident photons and then produce more photoexcited electron–hole pairs. In addition, this work was expected to provide a simple preparation method for various functional materials, especially magnetic functional materials.