Enhanced photodegradation of ceftazidime by BiOBr(110)/BiOCl(110) composite: Its synthesis, mechanism, and degradation pathways

A simple and economical precipitation process was used to in situ synthesize a heterojunction of BiOBr(110)/BiOCl(110). Numerous techniques, such as SEM, XRD , HRTEM , BET, FTIR, and XPS , verified the successful creation of the heterostructure. In particular, the heterostructures exhibited significantly enhanced photocatalytic degradation efficiency towards ceftazidime (CFZ). The degradation kinetic constant of CFZ by BiOBr(110)/BiOCl(110) (5:5) was three times higher than those of BiOBr and BiOCl. Additionally, a type I heterojunction was reasonably suggested following UV–vis DRS and VB-XPS investigations. DFT calculations indicated that an internal electric field (IEF) was created when electrons (e - ) on the BiOBr surface were transferred to BiOCl in the dark. Upon visible light illuminated, photoinduced-e - was transferred from the conduction band (CB) of BiOCl to that of BiOBr under the action of IEF. In contrast, holes (h + ) moved in the opposite direction, realizing the separation of e - /h + pairs. Three degradation pathways were deduced based on intermediate products (IPs) detection by HPLC-MS. Importantly, the heterojunction catalyst exhibited efficient catalytic performance across solutions with different pH and maintained great reusability during four cycles of photodegradation . Overall, the work revealed distinctive insights concerning the mechanism of antibiotic degradation with BiOBr(110)/BiOCl(110) heterojunction structures .