Ternary hybrid Ag/SnO2-X/Bi4O5I2 photocatalysts: Impressive efficiency for photocatalytic degradation of antibiotics and inactivation of bacteria

Ag/SnO2-x/Bi4O5I2 ternary composites were prepared to further improve the photocatalytic properties by introducing Ag nanoparticles into SnO2-x/Bi4O5I2 binary composites. X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) proved that the ternary composites were successfully synthesized. Photocurrent and electrochemical impedance tests (EIS) confirmed that the photogenerated carrier separation efficiency of Ag/SnO2-x/Bi4O5I2 was much higher than SnO2-x and Bi4O5I2. Ag/SnO2-x/Bi4O5I2 showed high efficiency in degradation and antibacterial. The optimum sample of 3% Ag/SnO2-x/Bi4O5I2 can degrade 80 % tetracycline (TC) in 120 min, inactivate Escherichia coli (E. coil) in 15 min and Staphylococcus aureus (S. aureus) in 20 min under the LED light. The intermediates of the degradation of TC were identified by mass spectrometry (MS). Scanning electron microscopy (SEM) and confocal laser scanning microscope (CLSM) images intuitively showed the death process of E. coil caused by the photocatalytic reaction. The results of the capture experiment identified the active substance, and the possible photocatalytic degradation pathway was proposed. Ag/SnO2-x/Bi4O5I2 followed the Z-scheme charge transfer mechanism.