Visible-light-driven AgI/Bi4O5I2 S-scheme heterojunction for efficient tetracycline hydrochloride removal: Mechanism and degradation pathway

Abstract

The existence of excessive tetracycline hydrochloride (TCH) in the ecological environment has seriously threatened human health, so there is an urgent need to develop a high-performance photocatalyst that can efficiently and greenly remove TCH. Currently, most photocatalysts have the problems of fast recombination of photogenerated charge carriers and low degradation efficiency. Herein, S-scheme AgI/Bi₄O₅I₂ (AB) heterojunctions was constructed for TCH removal. Compared with the single component, the apparent kinetic constant of the 0.7AB is 5.6 and 10.2 time as high as the AgI and Bi₄O₅I₂, and the photocatalytic activity only decreases by 3.0% after four recycle runs. In addition, to verify the potential practical application of the fabricated AgI/Bi₄O₅I₂ nanocomposite, the photocatalytic degradation of TCH was performed under different conditions by regulating the dosage of photocatalyst, the TCH concentration, pH, and the existence of various anions. Systematical characterizations are conducted to investigate the intrinsic physical and chemical properties of the constructed AgI/Bi₄O₅I₂ composites. Based on the synergetic characterizations by in situ X-ray photoelectron spectroscopy, band edge measurements, as well as reactive oxygen species (ROS) detections, the S-scheme photocatalytic mechanism is proved. This work provides a valuable reference for developing efficient and stable S-scheme AgI/Bi₄O₅I₂ photocatalyst for TCH removal.

Keywords: AgI/Bi(4)O(5)I(2); Photocatalysis; S-scheme heterojunction; Tetracycline hydrochloride.