Novel Z-scheme Bi3O4Br/NH2-MIL-125(Ti) composite for efficient photocatalytic degradation of tetracycline

The present work demonstrates the synthesis of the microsphere composite photocatalyst Bi3O4Br/NH2-MIL-125(Ti) (BOB/NMILT) system, and the physicochemical properties of the material were analyzed by various characterization means. Further, the photocatalytic performance of the BOB/NMILT system was evaluated by degrading tetracycline (TC) under simulated sunlight. The degradation rate of TC using BOB/NMILT-5 reached 88.5% within 90 min. The degradation rate is 6.5 times and 3 times higher than that of individual catalysts NH2-MIL-125(Ti) (NMILT) and Bi3O4Br, respectively. The improvement in photocatalytic activity of composites mainly benefited from the construction of heterojunctions, which effectively inhibited the recombination of carriers. Importantly, the role of h+ and •O2− was found to be significant in the reaction of TC. Cumulatively, a Z-scheme photocatalytic degradation mechanism of tetracycline on the BOB/NMILT composite system was proposed. The proposal of this system is of great significance for the future development of photocatalytic materials that can degrade tetracycline. •Microsphere Bi3O4Br/NH2-MIL-125(Ti) was synthesized by hydrothermal method.•Z-scheme system can effectively improve the separation of electrons and holes.•Bi3O4Br/NH2-MIL-125(Ti) composite exhibits excellent removal efficiency for TC.•O− 2 and h+ are the dominant active species in photocatalytic process.