Z-scheme MgFe2O4/Bi2MoO6 heterojunction photocatalyst with enhanced visible light photocatalytic activity for malachite green removal

A novel heterostructured MgFe2O4/Bi2MoO6 composites were rationally designed and successfully synthesized firstly by a successive hydrothermal process and in-situ ball-milling followed by high temperature calcination technology. The investigation showed that the MgFe2O4 nanoparticles were closely anchored on the surface and edge of Bi2MoO6 nanoplates. Under visible-light illumination, the 20 wt% MgFe2O4/Bi2MoO6 samples showed the highest photocatalytic activity for the degradation of Malachite Green (MG) with 120 min and had the maximum of reaction rate constant (0.0113 min(-1)), which was approximately 8.07 times than that of pure Bi2MoO6 (0.0014 min(-1)). Moreover, the effects of MG concentration, coexisting ions, and water sources for photocatalytic activity were also investigated. The detection of reactive species demonstrated that the center dot O-2(-) and h(+) were playing important roles during MG removal process. Besides, the Z-scheme transfer mechanism of photoexcited electron-hole over composite were proved by using nitrotetrazolium blue chloride (NBT, center dot O-2(-) trapping agent) and terephthalic acid (TA, center dot OH trapping agent) trapping methods. The significant improvement of photocatalytic performance can be predominantly interpreted as enhancing light harvesting ability, increasing charge carriers density as well as the formation of Z-scheme system between Bi2MoO6 and MgFe2O4 semiconductor.