Bioinspired Multilayer Membranes with Integrated Antifouling and Photocatalytic Self-Cleaning for Oil–Water Separation

Bioinspired surface engineering offers a powerful strategy to mitigate fouling-induced performance degradation in membrane-based separations. Here, we report a biomimetic SiO 2 @AMN-TiO 2 -lysine (ASTxL) coating that endows poly(vinylidene fluoride) (PVDF) membranes with synergistic antifouling and self-cleaning functionalities, inspired by the hierarchical layered architecture of shark skin. The rationally designed multilayer integrates a poly(aminomalononitrile)-SiO 2 interfacial layer for robust adhesion, a TiO 2 layer enabling photocatalytic self-cleaning, and an outer lysine-based zwitterionic layer that establishes a stable hydration barrier to suppress foulant adhesion. As a result, the ASTxL membranes exhibit exceptional wettability and high pure water flux of 5568 ± 479 L·m –2 ·h –1 ·bar –1, representing 37.4% increase over pristine PVDF. During oil-in-water emulsion separation, the membranes achieve a 3.32-fold enhancement in permeation flux and a flux recovery ratio of 95.5 ± 4.1% following UV-assisted regeneration. Moreover, the TiO 2 -functionalized surfaces enable efficient photocatalytic degradation of organic contaminants, achieving up to 70.6% methylene blue removal under UV irradiation. By coupling hydration-layer-driven passive antifouling with TiO 2 -mediated active photodegradation, this biomimetic coating strategy offers a scalable and versatile platform for durable, high-performance membrane separations in complex oily wastewater systems.