Facile fabrication of Z-scheme Ag2WO4/BiOBr heterostructure with oxygen vacancies for improved visible-light photocatalytic performance
Z-scheme Ag 2 WO 4 /BiOBr heterojunction with rich oxygen vacancies was successfully synthesized by the simplest hydrothermal method, which was systematically characterized in the structural, optical and electronic properties. The photocatalytic applications of Z-scheme Ag 2 WO 4 /BiOBr heterostructure with different weight percentages of Ag 2 WO 4 were studied. The optimized Ag 2 WO 4 (20%)/BiOBr heterostructure exhibited superior photodegradation efficiencies (98%) towards Lanasol Red 5 B (LR5B), which was 4.67- and 3.38-fold higher than pristine BiOBr and Ag 2 WO 4 , respectively. The principal reason for the elevated photocatalytic property of Ag 2 WO 4 /BiOBr was ascribed to the formation of oxygen vacancies and intimate Z-scheme heterostructure between Ag 2 WO 4 and BiOBr, improving the light trapping capability and facilitating separation of photo-induced charge. Moreover, the removal efficiencies of Ag 2 WO 4 /BiOBr heterostructure towards TC (tetracycline), CIP (ciprofloxacin) and RhB (rhodamine B) were 74%, 23%, and 13%, respectively. The simultaneous degradation experiment confirmed the competitiveness between LR5B and CIP for active species, leading to the inferior degradation efficiency for LR5B, along with the experimental factor towards LR5B was researched. The probable Z-scheme mechanism and the significant role of hydroxyl radical and superoxide radicals were demonstrated by the radical capture experiment and electron spin resonance (ESR). The Z-scheme mechanism has resulted in prominent improvement in charge separation, along with higher redox properties, which were responsible for the excellent photocatalytic activity.
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