Z-scheme heterojunction nanocomposite fabricated by decorating magnetic MnFe2O4 nanoparticles on BiOBr nanosheets for enhanced visible light photocatalytic degradation of 2,4-dichlorophenoxyacetic acid and Rhodamine B

Abstract

In this study, novel Z-scheme BiOBr/MnFe2O4 nanocomposites were successfully fabricated using a simple and surfactant-free hydrothermal synthetic route. The physicochemical and optical characteristics of the photocatalysts were analyzed by various instruments. The obtained BiOBr/MnFe2O4 nanocomposites significantly accelerated the photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and Rhodamine B (RhB) when compared with other analyzed photocatalysts under visible light irradiation. Among all samples, the BiOBr/MnFe2O4-10 nanocomposite exhibited the best photocatalytic performance. The improved photoactivity was ascribed to the formation of Z-scheme heterojunction between BiOBr and MnFe2O4, thereby resulting in efficient separation of charge carriers. Photoelectrochemical and photoluminescence analyses were carried out to validate this conclusion. Furthermore, the BiOBr/MnFe2O4 nanocomposite can be easily separated and recycled without significant loss of photoactivity after five consecutive uses. The intermediate products produced during the photodegradation of 2,4-D were also detected. Radical quenching experiments revealed that the hydroxyl radicals played critical roles in the photodegradation reactions. Finally, a possible photocatalytic enhancement mechanism of BiOBr/MnFe2O4 nanocomposites was proposed.