Synergistic interaction of Z-scheme 2D/3D g-C3N4/BiOI heterojunction and porous PVDF membrane for greatly improving the photodegradation efficiency of tetracycline

Abstract Designing photocatalytic membranes with excellent photocatalytic and self-cleaning ability based on the synergistic effect between the crystal structure of membrane matrix and photocatalyst is highly desirable. Herein, Z-scheme 2D/3D g-C3N4/BiOI heterojunction blended in beta-phase polyvinylidene fluoride membrane (β-phase PVDF) was prepared via solvent crystallization and phase inversion technique. As expected, the designed g-C3N4/BiOI/β-phase PVDF photocatalytic membranes (CN/BI/β-phase PVDF PMs) achieved exceptional photocatalytic degradation efficiency for tetracycline (94.6%) as compared to the CN/BI heterojunction power (84.0%) and two other control membrane matrixes (CN/BI/PAN and CN/BI/CA PMs) within 120 min. Meanwhile, the dynamic cyclic degradation system of CN/BI/β-phase PVDF PMs was also investigated that reached to be 94.8% in 80 min. Besides, the CN/BI/β-phase PVDF PMs not only had outstanding self-cleaning activity and remarkable permeability (up to 30,688 L·m−2·h−1) but also had high stability and reusability even after five runs. Importantly, the hydroxyl radical detection and ESR analysis identified that the β-phase PVDF membrane could promote photoinduced carrier separation efficiency of 2D/3D g-C3N4/BiOI heterojunction. This work may open up a novel strategy for designing and constructing high-efficient photocatalytic membranes for water treatment.