Construction of Bi5O7I/Bi3O4Br heterojunction with abundant oxygen vacancies to enhance photocatalytic performance

The low separation efficiency of photogenerated charge carriers is the main impediment to the practical application of photocatalysis. Herein, Bi5O7I nanoparticles with abundant oxygen vacancies (DBOI) were deposited on Bi3O4Br nanosheets (BOBr) to create a novel 0D/2D DBOI/BOBr heterojunction (DBOI-Br) using a facile solution method. The structure of surface oxygen vacancies (SOVs) was demonstrated using HRTEM, lowtemperature EPR, and XPS. The effective interface contact between DBOI and BOBr resulted in the establishment of an internal electric field (IEF) and band bending. The photogenerated charge transfer mechanism was validated through in situ irradiated XPS, work function calculation, and ERS measurement. The synergistic effect of IEF, band bending, and SOVs efficiently suppressed the recombination of photogenerated charge carriers, enhancing the photocatalytic activity. Almost 100 % of tetracycline, oxytetracycline, levofloxacin, ciprofloxacin, methylene blue, and rhodamine B, as well as 92.3 % of phenol, could be decomposed using DBOI-Br under visible light irradiation. The average production rates of H2, O2, and H2O2 were 805, 3800, and 562 mu mol h- 1 g- 1 over 4 h, corresponding to quantum efficiencies of 3.67 %, 10.4 %, and 5.26 % at 420 nm, respectively. This study introduces a new promising DBOI-Br heterojunction photocatalyst with rich SOVs to enhance the charge separation efficiency for various photocatalytic applications.