One-pot hydrothermal synthesis of g-C3N4/BiOBr/Bi2MoO6 as a Z-scheme heterojunction for efficient photocatalytic degradation of ciprofloxacin (CIP) antibiotic and Rhodamine B (RhB) dye

Abstract

Photocatalytic degradation of toxic organic pollutants using natural sunlight is a rapidly advancing area of research, particularly involving binary or ternary component photocatalysts with Z-type heterojunctions. In this study, ternary g-C3N4/BiOBr/Bi2MoO6 photocatalysts were fabricated using a simple one-pot solvothermal method. The morphology and physicochemical properties of the samples were characterized using various techniques, including X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), confirming the presence of BiOBr, Bi2MoO6, and g-C3N4 components. The inclusion of g-C3N4 increased the BET surface area of the composite up to 46 m2/g, compared with BiOBr. In addition, g-C3N4 also enhanced the light absorption capability of the composite into the visible light range, while BiOBr and Bi2MoO6 significantly improved separation of electron-hole pairs, as evidenced by photoluminescence (PL) intensity. Under visible light illumination (LED lamp), the prepared photocatalyst showed high efficiency, achieving 94 % degradation of ciprofloxacin (CIP) antibiotic in 180 min and 92 % degradation of Rhodamine B (RhB) dye in 240 min. Moreover, under natural sunlight irradiation, the photocatalyst achieved degradation efficiencies of approximately 91 % for CIP and 100 % for RhB within 180 minutes. The photodegradation of the pollutants followed first-order kinetics with a Z-scheme type heterojunction. The photogenerated electrons played a crucial role as the main active species involved in detoxification of the organic contaminants. The photocatalyst exhibited excellent structural stability and good cycling ability, maintaining its original photocatalytic performance even after five cycles of use. This work demonstrates a promising strategy for developing sunlight-active ternary heterojunctions for environmental remediation.