3D flower-like Cu-BiOCl/Bi2S3 heterostructure with synergistic Cu ion doping: A study on efficient tetracycline degradation under visible light

In this study, a novel three-dimensional, flower-like Cu-BiOCl/Bi2S3 photocatalyst was synthesized using a two-step calcination and hydrothermal method, aiming at the efficient removal of tetracycline (TC). Through comprehensive characterization techniques, it was discerned that the incorporation of Cu ions extended the light absorption range of BiOCl. Additionally, the formation of a heterojunction significantly enhanced the separation efficiency of space charge. The unique three-dimensional flower-like architecture of the Cu-BiOCl/Bi2S3 photocatalyst augments its surface area exposure and consequently, the density of active sites. This catalyst exhibited a remarkable degradation rate of approximately 95% for TC under visible light irradiation. This performance exhibits a notable enhancement over the degradation rates of BiOCl and Bi2S3, which are approximately 39% and 53% respectively, surpassing them by factors of 2.39 and 1.78. Electron spin resonance (ESR) analysis coupled with free radical trapping experiments pinpointed superoxide radicals (•O2-) and photogenerated holes (h+) as the pivotal active species orchestrating the photocatalytic degradation. Concludingly, a possible TC degradation pathway was proposed based on the intermediates generated during the photocatalytic reaction as detected by Liquid Chromatograph Mass Spectrometer (LC-MS) and Three-Dimension Excitation Emission Matrix (3D EEM).