Rapid electrochemical fabrication of MOF-coated mesh membranes with complementary wettability for high-efficiency oil-water separation.

Abstract

Superhydrophobic and superoleophobic membranes offer great potential for energy-efficient oil-water separation, yet precise control of membrane wettability remains challenging. In this work, a pair of metal-organic framework (MOF)-coated mesh membranes were designed and successfully fabricated through a facile electrochemical fabrication process. By leveraging cathodically induced ligand assembly, this work achieved precise control over the surface chemistry, which resulted in a remarkable and reversible wettability transition between underwater superoleophobicity (θ_oil>150°) and superhydrophobicity (θ_water>150°). The electrochemical deposition facilitates precise wettability inversion through ligand modification, providing a rapid, controllable, and substrate-adherent fabrication approach. Capitalizing on this, the T-shaped separation device was designed by integrating these two membranes with opposing wettability, achieving > 99 % purity in both light and heavy oil/water mixtures. This universal design demonstrates high-performance separation for oil-water mixtures across a wide density range, offering significant potential for complex industrial oily wastewater.