Efficient tetracycline degradation under visible light irradiation using CuBi2O4/ZnFe2O4 type II heterojunction photocatalyst based on two spinel oxides

• Type II heterojunction photocatalyst is synthesized from two spinel oxides. • The band structures are changed by the sites of metal captions on the spinel structure. • 80% tetracycline can be photo-degraded in 150 minutes. • Photogenerated h + and •OH are contributed to the removal of tetracycline. • The system of CuBi 2 O 4 /ZnFe 2 O 4 heterojunction promotes the separation efficiency of electron hole pairs. With the increasing use of tetracycline (TC) worldwide, it cannot be ignored the brought environmental risks. Therefore, it is critical to effectively solve TC in the environment. A novel type II heterojunction photocatalyst CuBi 2 O 4 /ZnFe 2 O 4 (CBO-ZFO) for efficient TC degradation under visible light irradiation was developed. Various characterization techniques including XRD, XPS, TEM, HRTEM, UV-vis, ESR, PL, etc were used. It was proved that the excellent photocatalytic performance of CBO-ZFO composite photocatalyst was attributed to the formation of heterojunction. The formed heterojunction could promote the separation and migration of photogenerated carriers and reduce the existence of potential barriers, which could reduce the electron-hole recombination. A good stability had been shown after 5 cycles. The h + and ·OH were the main active species of CBO-ZFO heterojunction composite in photocatalytic degradation mechanism.