Synergistic roles of oxygen vacancies and interfacial chemical bonds in Z-scheme BiVO4/O-g-C3N4 4 /O-g-C 3 N 4 heterojunctions for enhanced photocatalytic tetracycline degradation

The misuse of tetracycline (TC) has led to an increasing problem of its residue in the water environment. A novel BiVO4/O-g-C3N4 4 /O-g-C 3 N 4 heterojunction is prepared by combining surfactant-modified BiVO4 4 with oxalic acid-modified g-C3N4 3 N 4 to remove TC efficiently. Compared with BiVO4 4 and O-g-C3N4, 3 N 4 , BOCN-5 (mass ratio of BiVO4:O-g-C3N4 4 :O-g-C 3 N 4 is 1:3, 0.3 g/L) has achieved 99.8 % removal of TC (20 mg/L) under irradiation. The results of five consecutive recycling experiments demonstrate the good stability and reusability of the BOCN-5 photocatalyst. The heterojunction photocatalyst maintains high TC removal levels in different practical water samples, proving its potential for real-world applications. The photocatalytic activity of BOCN-5 is attributed to the presence of surface oxygen vacancies (OVs) and interfacial chemical bonds. The OVs expose sufficient oxygen-active sites to assist in creating metal-O bonds, which improve the charge separation rates and ensure a high redox activity. OVs also promote activating molecular oxygen and forming electrophilic singlet oxygen (1O2) 1 O 2 ) by energy transfer, attacking the negatively charged moieties in TC structures, which leads to various reactions including deamidation, demethylation, and ring opening. This research offers a template for fabricating efficient Z-scheme photocatalysts with abundant OVs and interfacial chemical bonds.