Fabrication of S-scheme H-C3N4/FeNi2S4 heterojunction for visible light driven photocatalytic degradation of ciprofloxacin

Ciprofloxacin (CIP) is one of the most frequently used fluoroquinolone antibiotics. It is often nonbiodegradable and is only partially eliminated by normal water treatment procedures. Forming an S-scheme heterojunction photocatalyst is a viable idea for efficiently removing various organic pollutants. The objective of this investigation is to develop an S-scheme heterojunction photocatalyst to efficiently eliminate antibiotics pollutants from contaminated water. In this spirit, we present the synthesis of H-C3N4/FeNi2S4 heterojunction for the degradation of ciprofloxacin (CIP) under visible light irradiation. The synthesized catalysts were systematically characterized for structural, morphological, optical and charge transport traits. The results indicate that the combination significantly improved degradation efficiency in comparison to C3N4 and FeNi2S4 catalysts. The improved photo degradation efficacy of H-C3N4/FeNi2S4 catalysts can be attributed to the increased separation of charge carriers. The S-scheme electron transfer mechanism and efficiency in the HCN/FNS heterojunction was supported by in-situ XPS measurements, electrochemical impedance spectroscopy, UPS and photoluminescence. The radical scavenging tests and EPR results provided the direct evidence of ●O2− and ●OH radicals for CIP degradation. In addition, reusability tests confirmed the excellent stability of heterojunction catalyst. Furthermore, a viable S-scheme photocatalytic degradation mechanism is also explored.