Construction of ZnO/oxygen-deficient Bi2WO6 photocatalyst for highly efficient degradation of TCH

Abstract More and more attention has been paid to the photocatalytic degradation of tetracycline hydrochloride (TCH). Constructing heterojunctions and designing defect structures are important means to improve the separation efficiency of photogenerated carriers and catalytic activity. ZnO/BWO-x composite photocatalyst with n-n heterojunction and oxygen vacancy was synthesized through the solvothermal method. Compared with ZnO and BWO-x, ZnO/BWO-x has a wider visible light absorption range, higher photogenerated charge migration rate, and lower photogenerated electron-hole pair recombination rate. When the molar ratio of ZnO and BWO-O3 is 1:1, the prepared composite photocatalyst (ZnO/BWO-5) has the highest photocatalytic activity, and under visible light irradiation for 180 min, the degradation rate of TCH reaches 85.53% significantly higher than that before compounding. After further exploration, it is found that the photocatalytic effect of ZnO/BWO-5 is the best under the conditions of pH=9, photocatalyst dosage of 40 mg, and tetracycline concentration of 20 mg/L. The reasons for the enhanced photocatalytic activity of ZnO/BWO-x composites are summarized as follows: (1)Oxygen vacancies reduce the band gap and improve the utilization of visible light; (2)The lower conduction band potential of ZnO can complement with Bi2WO6, and the staggered composite energy levels form an n-n heterojunction, which is conducive to the rapid separation of photogenerated carriers.