Fabrication of silver vanadate quantum dots/reduced graphene oxide/graphitic carbon nitride Z-scheme heterostructure modified polyvinylidene fluoride self-cleaning membrane for enhancing photocatalysis and mechanism insight

The enhancement of the self-cleaning ability of photocatalytic membranes and their degradation efficiency over tetracycline (TC) still remains a challenge. In this study, an alternative silver vanadate quantum dots (AgVO 3 QDs) doped reduced graphene oxide (RGO) and graphitic carbon nitride (C 3 N 4 ) nanocomposites modified polyvinylidene fluoride (PVDF) membrane (AgVO 3 /RGO/C 3 N 4 -PVDF) was successfully fabricated to enhance the photocatalytic activity. The AgVO 3 /RGO/C 3 N 4 nanocomposites were functioned as the active component for the photocatalytic membrane. The unique Z-scheme heterostructure of AgVO 3 /RGO/C 3 N 4 and the porous PVDF framework synergistically enhanced the separation and transport efficiency of photogenerated carriers and facilitated the interaction between the photocatalyst and the pollutant. As a result, the degradation efficiency of TC for the AgVO 3 /RGO/C 3 N 4 -PVDF reached 88.53% within 120 min, which was higher than those of the binary component membranes (64.8% for RGO/C 3 N 4 -PVDF and 79.18% AgVO 3 /C 3 N 4 -PVDF). In addition, AgVO 3 /RGO/C 3 N 4 -PVDF exhibited high permeability (1977 L·m −2 ·h −1 ·bar −1 ) and excellent antifouling activity. Under visible-light irradiation, the flux recovery rate ( FRR ) increased from 92.4% to 99.1%. Furthermore, AgVO 3 /RGO/C 3 N 4 -PVDF could reject 97.4% of Escherichia coli ( E. coli ) owning to its self-cleaning capacity, and eliminated the E. coli under visible-light irradiation trough the photogeneration of h + . This study highlights a highly efficient photocatalytic membrane based on a Z-scheme heterostructure, which may have a great potential application in practical wastewater treatment.