Degradation mechanism of antibiotics by flower-like Bi2S3 sensitized anatase/rutile TiO2 coupled with SiO2 photonic crystals

Antibiotic pollution has posed environmental risks, and the crucial point lies in the elimination efficiency of antibiotics from wastewater. Herein, a ternary-structured B-TiO2/Bi2S3/PCs (photonic crystals) film, in which B-TiO2 was a blend of anatase and rutile crystalline phases, was fabricated to evaluate the efficiency of antibiotic photodegradation under visible light irradiation. The synthesized B-TiO2(80 %)/Bi2S3/PCs(458) film exhibited superior photocatalytic efficiency of tetracycline hydrochloride (TC), with a degradation rate 7.56 times greater than that of pristine B-TiO2. These findings are closely related to the excellent photoelectron separation of the heterojunction between B-TiO2 and Bi2S3, as well as the bandgap reflection effect and light localization effect of the PCs. Notably, the B-TiO2(80 %)/Bi2S3/PCs(458) film also displayed favourable degradation performance for ofloxacin (OFLX) and ciprofloxacin (CIP), with degradation rates of 83.98 % and 72.79 %, respectively. Active species trapping experiments and electron spin resonance (ESR) measurements revealed superoxide radicals (•O2−) and photogenerated holes (h+) as the main active species. Furthermore, potential photodegradation pathways were proposed by analyzing the degradation intermediates of TC and OFLX via liquid chromatography-mass spectrometry (LC–MS). In a word, the B-TiO2(80 %)/Bi2S3/PCs(458) film exhibited high efficiency in the treatment of antibiotic pollutants, thereby offering promising prospects for practical application.