Regulation of charge transfer in ZnO/Bi2Sn2O7 heterojunction for enhanced photocatalytic performance towards antibiotic degradation

Regulating the migration behavior of photo-generated carriers is an effective strategy to design high-performance photocatalysts. Herein, ZnO/Bi 2 Sn 2 O 7 type II heterojunction was fabricated through the composite of wide-bandgap ZnO and narrow-bandgap Bi 2 Sn 2 O 7 , and the charge transfer mechanism was changed from type II into Z-scheme by photo-depositing Ag nanoparticles on ZnO/Bi 2 Sn 2 O 7 composite. The loaded Ag nanoparticles not only expanded absorption of ZnO to visible-light range through surface plasmon resonance effect, but also were served as bridge for photo-generated carriers, thereby changing transfer behavior of charge carriers in ZnO/Bi 2 Sn 2 O 7 composite system. Compared with ZnO/Bi 2 Sn 2 O 7 type II heterojunction, Ag@ZnO/Bi 2 Sn 2 O 7 Z-Scheme heterostructure promoted separation efficiency of photo-generated carriers, and the average carrier lifetime was increased by 2.0 times. The mineralization rate of ciprofloxacin by Ag@ZnO/Bi 2 Sn 2 O 7 composite was 2.6 times higher than that of ZnO/Bi 2 Sn 2 O 7 composite, which reached 16.9 times that of pure Bi 2 Sn 2 O 7 photocatalyst, exhibiting stronger redox ability.