Modification of bismuth-rich to synthesize floral spherical Z-type heterojunction CoAl2O4/Bi4O5Br2 photocatalysts for photocatalytic degradation of tetracycline: DFT calculations, toxicity assessment

Strategies were employed to boost responsiveness to visible light to augment the elimination of water-borne organic contaminants and mitigate the recombination of electron-hole pairs. Herein, a floral spherical CoAl2O4/Bi4O5Br2 Z-scheme heterojunction was effectively produced through in-situ construction, followed by an evaluation of its photocatalytic activity against tetracycline hydrochloride. The best-prepared photocatalyst CoAl2O4/Bi4O5Br2 showed good photodegradation performance (91.5 %) under visible light. In addition, it exhibits good removal efficiency for other antibiotics and dyes, and the prepared catalyst demonstrates favorable stability. The accomplishment of fabricating the CoAl2O4/Bi4O5Br2 heterojunction, along with the photo- generated carrier relay mechanism conforming to a Z-scheme process, was substantiated through a variety of analytical techniques and DFT calculations. Within the engineered Z-scheme heterojunction of CoAl2O4/ Bi4O5Br2, an intrinsic electric field facilitates the direct shuttling of photo-induced charges from Bi4O5Br2's conduction band to CoAl2O4's valence band. Simultaneously, this electric field formation serves to diminish the recombination rate of electrons and holes. Finally, possible degradation pathways were proposed, and the intermediates were evaluated for toxicity. The results indicate that the construction of CoAl2O4/Bi4O5Br2 heterojunction is a feasible pathway for the effective degradation of antibiotics.