Design of a Z-Scheme System with g-C3N4/WO3/ZnFe2O4 Nanocomposite for Photocatalytic Degradation of Rhodamine B

Abstract

In this work, the g-C₃N₄/WO₃/ZnFe₂O₄ nanocomposite was synthesized using a combination of hydrothermal and ultrasonic techniques to design a Z-scheme system for the decolorization of the colored pollutant Rhodamine B (RhB). Initially, the synthesized catalyst was investigated using various characterization techniques, including X-ray diffraction, X-ray Photoelectron Spectroscopy, Fourier Transform Infrared Spectroscopy and Field emission scanning electron microscopy. The results confirmed the successful formation of crystalline g-C₃N₄/WO₃/ZnFe₂O₄. The XPS results clearly exhibited the presence of all constituent elements along with their respective oxidation states. Subsequently, g-C₃N₄/WO₃/ZnFe₂O₄ was examined for the first time for the photocatalytic decolorization of RhB dye under visible light illumination. To optimize the photodecolorization process, various parameters, including irradiation time, catalyst dosage, initial RhB dye concentration, and pH, were investigated. The results indicate that the Z-scheme system designed with g-C₃N₄/WO₃/ZnFe₂O₄ exhibits excellent capability in degrading RhB. Under optimal conditions of pH 7 and a catalyst dosage of 0.15 g/L, the system was able to degrade 98.7% of RhB (10 mg/L) within 75 min. Additionally, the results of scavenger experiments demonstrated that superoxide and hydroxyl radical species played a more significant role in the photocatalytic decolorization of RhB dye.