Dopamine-bridged CuS–ZnIn2S4/PAN nanofibrous membrane for purification of viscous emulsified oil pollutants with integrated oil resistance, photocatalytic self-cleaning, and photothermal conversion

The polymeric membrane encounters huge challenge in dealing with high-viscosity oil pollutants and complicated membrane fouling issues. Herein, the multi-functional polymeric composite membrane (ZCP) is fabricated via anchoring bio-adhesive dopamine bridged gear-like CuS–ZnIn 2 S 4 heterostructure onto PAN nanofiber support, which hits three birds with one stone. Firstly, the unique three-dimensional gear-like structure confers the ultra-low oil adhesion and high permeability to membrane by constructing underwater superoleophobicity (UWCA: up to 157.1° ± 1.6°) and providing efficient mass transfer channels, as confirmed by Molecular dynamics simulation and Hermia equation-fitted blocking models. The ZCP membrane demonstrates superior separation flux (3921.44 ± 196.1 L m −2  h −1 ) and separation efficiency (up to 99.53 %) for diverse oil-in-water emulsions. Besides, the ZCP membrane shows remarkable durability in harsh conditions and cyclic separation stability. Secondly, dopamine bridged CuS–ZnIn 2 S 4 heterostructure mitigates charge recombination, strengthens electron transfer, and extends light absorption, which results in favorable photocatalytic self-cleaning via peroxymonosulfate (PMS) activation. Under simulated sunlight and low PMS input, the ZCP membrane exhibits high-efficiency catalytic degradation of organic pollutants within 60 min (97.9 % tetracycline and 100 % dye degradation rates) and effective self-cleaning for membrane regeneration (98.51 ± 2.4 % flux recovery rate). Moreover, the band structure, charge transfer, and mechanism of photocatalytic PMS activation are elucidated. Thirdly, owing to the photothermal conversion function of CuS–ZnIn 2 S 4 heterostructure, the membrane surface temperature reaches 61.7 °C within 15 s, thus efficiently reducing oil viscosity and achieving 102.04 % enhancement in permeation flux during the simulated O/W separation application. This work opens a new avenue for treatment of complex emulsified oily wastewater and membrane fouling control.