A magnetically recyclable Fe3O4/ZnIn2S4 type-II heterojunction to boost photocatalytic degradation of gemifloxacin

In this study, a magnetic recyclable Fe3O4/ZnIn2S4 flower-like heterojunction photocatalyst was successfully constructed by means of a hydrothermal method. It not only exhibited an enlarged the specific surface area, but also improved the absorption of visible light, which greatly enhanced the photocatalytic degradation ability. The results of the photocatalytic activity tests showed that the maximum rate (0.01903 min−1) of degradation of gemifloxacin (GMF) by Fe3O4/ZnIn2S4 was significantly increased by 1.67 and 23.79 times compared with those of pure ZnIn2S4 and Fe3O4, respectively. Based on the difference in Fermi energy levels between ZnIn2S4 and Fe3O4 and the electron gain/loss of the elements of the Fe3O4/ZnIn2S4 heterojunction, a type-II electron transfer mechanism was proposed to illustrate that the Fe3O4/ZnIn2S4 heterojunction improved the photocatalytic activity by promoting the separation and transfer ability of the photogenerated carriers. By combining liquid chromatography mass spectrometry -ion trap-time of flight technology and a condensed Fukui function, a possible degradation mechanism of GMF was proposed.