Novel Three-Dimensional Flowerlike BiOBr/Bi2SiO5 p–n Heterostructured Nanocomposite for Degradation of Tetracycline: Enhanced Visible Light Photocatalytic Activity and Mechanism

Fabricating p–n heterojunction structure is an effective approach to improve the separation efficiency of carriers in photocatalysts for degradation of organic pollutants. Herein, a novel 3D p–n heterostructured BiOBr/Bi2SiO5 nanosheet composite is fabricated successfully. The obtained BiOBr/Bi2SiO5 nanosheet composites exhibit higher visible-light photocatalytic efficiency for degrading tetracycline (TC), which is 3.6 times higher than BiOBr. Furthermore, the composite could still maintain good activity for photocatalytic degradation of TC after five recycles. The active species in the photocatalytic system are •OH, •O2–, and h+, which are proved by trapping experiments and electron spin resonance (ESR) analysis. We demonstrate that the enhanced photocatalytic activity of BiOBr/Bi2SiO5 nanocomposites is due to the formation of p–n junction, which supports the generation of •O2– and •OH. The photocatalytic mechanism of BiOBr/Bi2SiO5 composites for the degradation of TC is also proposed.