Synthesis and characterization of magnetic ZnFe2O4/Bi0-Bi2MoO6 with Z-scheme heterojunction for antibiotics degradation under visible light

Abstract

A novel ZnFe 2 O 4 /Bi 0 -Bi 2 MoO 6 heterojunction photocatalyst, with high catalytic activity for tetracycline hydrochloride (TC), was synthesized and evaluated. Notably, this ternary composite showed higher degradation rate than pure Bi 2 MoO 6 and ZnFe 2 O 4 . Based on the characterization results, a possible mechanism of electron transmission was proposed. • A novel ZnFe 2 O 4 /Bi 0 -Bi 2 MoO 6 photocatalyst was synthesized with Z-scheme heterojunction. • Metal defect was created by the reduction of Bi 3+ via the liquid phase reduction method. • The surface plasmon resonance effect improves the ability of the catalyst to absorb visible light. • The catalyst shows excellent cycle stability and magnetic. In this work, a novel magnetic ZnFe 2 O 4 /Bi 0 -Bi 2 MoO 6 with Z-scheme heterojunction photocatalyst was successfully synthesized via a solvothermal-liquid phase reduction method. The structure, composition, morphology and optical property of the ternary photocatalyst were characterized. All the ZnFe 2 O 4 /Bi 0 -Bi 2 MoO 6 composites with different ZnFe 2 O 4 content showed enhanced visible-light photocatalytic activity for tetracycline hydrochloride (TC) degradation compared to pure Bi 2 MoO 6 and Bi 0 -Bi 2 MoO 6 . The maximum degradation rate for TC via 30%-ZnFe 2 O 4 /Bi 0 -Bi 2 MoO 6 reached 86.32% after 60 min reaction, and its kinetic constant is about 6.44 times than that of Bi 2 MoO 6 . Meanwhile, the ternary catalyst also has salt resistance and alkali resistance, and it also has good photocatalytic activity for norfloxacin and levofloxacin hydrochloride. Besides, ZnFe 2 O 4 /Bi 0 -Bi 2 MoO 6 was easy to be separated by an external magnetic field and steadily reused for several times. The characterization indicated that the improved activity of ZnFe 2 O 4 /Bi 0 -Bi 2 MoO 6 was mainly due to the formation of heterojunction and the surface plasmon resonance (SPR) effect, resulting in the wider spectrum response range, more stable structure and lower recombination rate of electron-hole pair. Trapping experiments and SPR tests showed that h + and O 2 − were the main active substances in the process of degrading TC by ZnFe 2 O 4 /Bi 0 -Bi 2 MoO 6 . Additionally, a possible Z-scheme heterojunction electron transfer mechanism was proposed. This work provide an idea for the use of magnetic photocatalysts with recycling stability to treat TC.