Constructing an S-scheme CuBi2O4/Bi4O5I2 heterojunction for light emitting diode-driven pollutant degradation and bacterial inactivation

The CuBi2O4/Bi4O5I2 S-scheme heterojunction structure was constructed by a hydrothermal and subsequent calcination route. The combination of CuBi2O4 and Bi4O5I2 produced excellent photocatalytic performance under an LED light. A series of technical characterizations, including X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), were used to determine the successful construction of S-scheme CuBi2O4/Bi4O5I2 composites. The improvement of photogenerated carrier separation efficiency helped to achieve the best photocatalytic performance of 37% CuBi2O4/Bi4O5I2, which can degrade tetracycline (TC) to 81.67% in 90 min, and completely inactivate Escherichia coli (E. coli) in 20 min and Staphylococcus aureus (S. aureus) in 40 min. The effects of some key parameters (such as the concentration of pollutants, the amount of catalyst, pH value of a solution, various inorganic anions and various water substrates) and the possible degradation path of tetracycline were systematically studied. Finally, the removal of pollutants and inactivation of bacterial mechanisms based on the S-scheme heterojunction (CuBi2O4/Bi4O5I2) was proposed. This study provides insight into the synthesis of S-scheme heterojunction photocatalysts, which can efficiently degrade organic pollutants and inactivate bacteria under LED light irradiation.