Designing double Z-scheme heterojunction of g-C3N4/Bi2MoO6/Bi2WO6 for efficient visible-light photocatalysis of organic pollutants

This work designed a composite photocatalyst of graphitic carbon nitride (g-C3N4) and Bi2WO6 modified perovskite-like material Bi2MoO6 for effective photodegradation of tetracycline (TC) in pharmaceutical wastewater. Characterization of the photocatalyst g-C3N4/Bi2MoO6/Bi2WO6 (CN/MO/WO) by various test techniques showed that the injection of Bi2WO6 and Bi2MoO6 not only enhanced the response range and absorption of the composite catalyst to visible light but also suppressed the photogenerated electron-hole (e--h+) complexation. g-C3N4 was introduced to increase the specific surface area of the catalytic system while effectively promoting carrier transfer. As a result, the composites exhibited more vigorous photocatalytic activity than the monomer. Among them, the 15% CN/MO/WO catalyst showed the highest photocatalytic activity, and the photodegradation rate of TC could reach 98% under limited 30 min visible light irradiation. The results of total organic carbon (TOC) showed that the ternary photocatalytic system could improve the mineralization efficiency of TC. Therefore, it's a potential solution for effectively treating pharmaceutical wastewater by catalyst under visible light.