Highly efficient photocatalytic degradation for antibiotics and mechanism insight for Bi₂S₃/g-C₃N₄ with fast interfacial charges transfer and excellent stability: Highly efficient photocatalytic degradation for antibiotics and mechanism insight for Bi₂S₃/g-C₃N₄

Bi₂S₃/g-C₃N₄ (BSCN) samples with different mass ratios of CN to BS were prepared by a facile and practicable hydrothermal method with 2D g-C₃N₄ nanosheets (CN). The microscopic morphology and structure of pure CN, BS and BSCN were measured by multiple testing methods. Analysis results show that the BSCN was prepared successfully, and the Bi₂S₃ nanoparticles closely and uniformly adhered to the surface of CN with sheet-like structure. The introduction of Bi₂S₃ did not change the structure of the CN. The results of the ultraviolet–visible spectroscopic analysis, photoluminescence spectra and electrochemical performance indicated that BSCN showed superior visible-light response compared with CN, and the separation and transfer efficiency of photogenerated carriers was significantly improved. With the decrease of mass ratio of CN/BS, the photocatalytic activity of BSCN initially increased and then decreased for 20 ppm of Rhodamine B solution (RhB), and the Bi₂S₃/g-C₃N₄-B with a mass ratio of 8:1 for CN to BS showed optimal photocatalytic performance (98.98%). Furthermore, the Bi₂S₃/g-C₃N₄-B exhibited apparent degradation effects (1.021 x10^-2, 0.879 x10^-2 and 0.793 x10^-2 min⁻¹) to three kinds of antibiotics (tetracycline, ciprofloxacin, and oxytetracycline). The BSCN samples still maintained higher degradation efficiency after five cycles of degradation to tetracycline. The capture experiments and the electron spin resonance (ESR) spectra analysis indicated that the h⁺ and ·O₂⁻ played a major role, and ·OH played secondary role during the photocatalytic reaction.