Multifunctional PVDF mixed matrix membranes with vacancy-engineered CeO₂–Ag/AgFeO₂ nanostructures for visible-light photocatalytic water purification

Novel photocatalytic mixed matrix photocatalytic membranes (PMMMs) were fabricated by embedding oxygen-vacancy-rich CeO₂ nanostructures decorated with plasmonic Ag/AgFeO₂ heterojunctions into a polyvinylidene fluoride (PVDF) matrix via phase inversion. The engineered nanocomposites exhibited strong visible-light absorption (up to 800 nm), well-defined spherical morphology, and uniform dispersion of each constituent phases, enabling enhanced photocatalytic functionality. PMMMs with varying nanocomposite loadings (2, 5, and 10 wt%) were systematically evaluated for their structural, physicochemical, and filtration properties. Among them, PMMM-5 (PVDF loaded with 5 wt% nanocomposite) demonstrated the most favorable balance between photocatalytic activity and membrane integrity, achieving significantly higher permeation fluxes for pure water (122.2 L/m²·h), BSA (80.2 L/m²·h), dye (67.7 L/m²·h), and antibiotic (75.3 L/m²·h) solutions, more than twice that of the unloaded PVDF membrane. This performance enhancement is attributed to increased porosity (80.9 %) and improved hydrophilicity (contact angle 58.1°) compared to unloaded PVDF (69.3 % porosity; 78.1° contact angle). Higher nanocomposite loading (PMMM-10) resulted in reduced performance due to nanoparticle agglomeration and decreased pore connectivity. In addition to superior permeability, PMMM-5 exhibited enhanced antifouling behavior, with a 49 % increase in flux recovery ratio under visible-light irradiation relative to unloaded PVDF, and demonstrated potent antibacterial activity, with inhibition rates of 43.6 % against S. aureus and 52.4 % against E. coli . These findings underscore the potential of plasmon-enhanced, vacancy-engineered photocatalytic membranes as multifunctional platforms for efficient, light-responsive water purification and biofouling control.