Hierarchical 0D/3D Z-scheme Heterojunction of ZnO Quantum Dots/Flower-like Bi2MoO6 Microspheres for Efficient Photocatalytic Degradation of Tetracycline

Abstract

The rapid development of modernization has accelerated environmental degradation, and antibiotic-induced water pollution has become one of the most concerning issues among them. In this study, a Z-scheme heterojunction catalyst of ZnO quantum dots (QDs)/Bi2MoO6 with a hierarchical 0D/3D structure was fabricated via a simple ultrasonic impregnation method for the photodegradation of representative antibiotic tetracycline (TC). This hierarchical 0D/3D heterojunction consists of flower-like Bi2MoO6 microspheres assembled from nanosheets and ZnO QDs decorating on nanosheets. The photocatalytic activity of the optimal heterojunction catalyst 8%ZnO QDs/Bi2MoO6 was 1.81 times that of pure Bi2MoO6. The enhanced photocatalytic activity of 8%ZnO QDs/Bi2MoO6 benefits from its broadened light absorption and efficient separation of photogenerated charge carriers, as evidenced by UV-vis DRS, photoluminescence spectroscopy, and transient photocurrent response. Under optimal degradation conditions, the photocatalytic degradation efficiency of TC by 8%ZnO QDs/Bi2MoO6 reached 94.20% within 120 min under simulated sunlight. Furthermore, the 8%ZnO QDs/Bi2MoO6 exhibited robust performance under complex environment. Additionally, combining the results of active species trapping experiments, Mott-Schottky curve, and band structure analysis, a Z-scheme photocatalytic mechanism for 8%ZnO QDs/Bi2MoO6 heterojunction was proposed. This work offers a sustainable solution for real aqueous environments remediation.