ZnO@g-C3N4 S-scheme photocatalytic membrane with visible-light response and enhanced water treatment performance

Zinc oxide–Graphitic carbon nitride (ZnO@g-C3N4) composite membranes were prepared via in-situ growing ZnO crystals in the g-C3N4 membrane. In this composite membrane, ZnO crystals were embedded in loose surface layers of g-C3N4 membrane, which can repair some non-selective defects and improve the dye retention performance. In addition, the hetero-structures formed between ZnO and g-C3N4 nanosheets promoted the separation of photogenerated electron-holes in g-C3N4 layer, and improving the photocatalytic and anti-fouling performance of ZnO@g-C3N4 composite membranes. Herein, the prepared composite membranes showed excellent dye removal performance and self-cleaning property in dynamic recirculation filtration systems under visible light irradiation. The optimized sample (CNZ-0.15 g) showed MB removal efficiency of 94.4% and water flux of 336.8 L.m−2.bar−1.h−1. The outcome of this research would suggest the application of graphitic nitride nanomaterials for developing highly efficient photocatalytic membranes.