Rational construction and significantly improved sonophotocatalytic performance of ZnIn₂S₄/Bi₂₅FeO₄₀ composites for the removal of organic pollutant

In this work, ZnIn2S4/Bi25FeO40 (ZIS/BFO) composites were prepared via a hydrothermal synthesis followed by ultrasound sonication method. Owing to the introduction of BFO, the obtained ZIS/BFO composites exhibited a higher visible-light absorption capacity than ZIS, which was revealed by the results of the diffusion reflectance spectra (DRS). Taking tetracycline hydrochloride (TCH) as the target pollutant, the decomposition experiments were conducted under ultrasonic coupling with visible-light irradiation to assess the sonophotocatalytic performance of the as-obtained catalysts. The results showed that the removal efficiency of BFO/ZIS composites was significantly improved compared with that of pure BFO and ZIS catalysts. Moreover, the loading amount of Bi25FeO40 imposed a substantial effect on the removal efficiency of TCH, namely that the removal efficiency of TCH first increased with the augment of loading amount, and declined thereafter. Specifically, the degradation rate of TCH reached up to 93.5% over ZIS/BFO composites with 10 wt% loading amount of Bi25FeO40. According to the results of radical scavenging experiments and electrochemical measurements, the proposed migration and separation pathway of charge carriers were put forward, and the possible enhancement mechanism toward sonophotocatalytic removal of TCH was achieved over ZIS/BFO catalysts. The significant improvement of the sonophotocatalytic performance over ZIS/BFO composites was mainly imputed to the synergistic effect of the improved visible-light absorption capacity and elevated sono/photo-activated charge transfer rate.