Construction of ZnIn2S4/MOF-525 heterojunction system to enhance photocatalytic degradation of tetracycline

Abstract Zirconium-based porphyrin metal organic framework (Zr-PMOF) is considered as a promising photocatalytic material due to its large specific surface area, wide visible light absorption capacity, good water stability and chemical stability. However, the recombination of photogenerated carriers of monomer PMOF limits its performance of photocatalytic organic pollutants degradation. Metal sulfide has a suitable visible band gap, which can form a heterojunction with MOF materials to enhance the photocatalytic efficiency of MOF. Therefore, a typical metal sulfide semiconductor ZnIn2S4 (ZIS) is introduced into a Zr-MOF (MOF-525) by solvothermal method to prepare the ZIS/MOF-525 composite photocatalyst in this work. The results of characterization analysis, optical analysis and electrochemical analysis show that the interface of ZIS/MOF-525 forms a typical type-Ⅱ heterojunction, which accelerates the electron transport rate and effectively inhibits the recombination of photogenerated e- and h+ in MOF-525. The optimal removal efficiency of tetracycline (TC) by ZIS/MOF-525-3 can reach 93.8% under 60 min visible light illumination, which is greater than that of pure MOF-525 (37.2%) and ZnIn2S4 (70.0%), and it can still maintain good stability after five cycles reusing experiment. This work provides feasible insight for the preparation of novel and efficient PMOF-based photocatalysts in the future.