Fe(Ⅲ)-doped ZnIn2S4-modified graphene oxide in-situ for the degradation of tetracycline hydrochloride in simulated sunlight

Abstract

To improve the efficiency of photocatalytic reactions, it is important to understand how to achieve fast directional migration and separation of photogenerated carriers at the interface. Here, Fe(III)-doped ZnIn2S4 (ZIS)-coated graphene oxide (GO) composite (GZF) was in-situ prepared via the low-temperature water bath method. Ultrathin Fe(III)-doped ZIS nanosheets were uniformly grown upright on the GO surface. The prepared samples were studied via, such as, X-ray diffraction, scanning electron microscopy combined with energy-dispersive spectroscopy, transmission electron microscopy, ultraviolet spectroscopy, N2 adsorption–desorption measurements, X-ray photoelectron spectroscopy, and electron spin resonance. Compared with ZnIn2S4 (ZIS)-coated graphene oxide (GZ), the GZF exhibit a 2.26-fold increase in the photocatalytic degradation performance of tetracycline hydrochloride (TCH) in simulated sunlight. Through density functional theory calculations, found that Fe(III) doping introduces new energy levels into ZIS, which effectively narrow its bandgap and thus enhance its light absorption efficiency. It was found that h+, ·O2−, and 1O2 were the major reactive oxygen species involved in the photocatalysis, and the effect of pH on the catalytic degradation of TCH was examined. Electron spin resonance and density functional theory results indicate that Fe(III) acts as an electron trap in the ZIS structure to promote the separation of photogenerated electron-hole pairs, which in turn enhances the photocatalytic efficiency of GZF-25.