Synthesis of flower-like Bi2O4/ZnO heterojunction and mechanism of enhanced photodegradation for organic contaminants under visible light

A novel flower-like Bi2O4/ZnO heterojunction photocatalyst was synthesized through a facile two-step hydrothermal method and characterized by different technologies. The characterization results indicated that the photoluminescence spectrum of pure ZnO was greatly reduced by the formation of heterojunction at the interface of ZnO and Bi2O4 and the photocurrent intensity of the catalyst was 6.4 mu A, which was 4.9 times higher than that of pure ZnO, resulting in an efficient separation of electron-hole pairs. The experimental results displayed that the as-prepared heterojunction of (1:3) Bi2O4/ZnO effectively prevented the agglomeration of nano-ZnO in aqueous solution and had a great high photocatalytic activity on degrading methylene blue and tetracycline under visible light. The photodegradation rates of (1:3) Bi2O4/ZnO for methylene blue and tetracycline were approximately 380 and 309.5 times higher than those of pure ZnO, respectively, and 95.68% of methylene blue and 85.68% of tetracycline were degraded under visible light within half an hour. The mineralization results showed that the two pollutants were firstly decomposed into intermediate products and then further fully mineralized. The results also indicated that the catalyst of (1:3) Bi2O4/ZnO had good stabilization and high reusability. Moreover, reactive species of O-2(-) and h(+) were proved to play a dominant role on accelerating the process of degradation. In the end, the detailed mechanism of photocatalytic degradation was proposed. [GRAPHICS] .