MOF-Decorated Poly(tetrafluoroethylene)\nMembranes\nwith Underwater Superoleophobicity for Extracting Osmotic Energy from\nOily Wastewater Effluents

Industrial processes generate huge volumes of oily saline\nwastewater.\nInstead of being sent to the drainage system immediately, extracting\nosmotic energy from these effluents represents a promising means to\nreuse these wastes and contributes to mitigate the ever-growing energy\ncrisis. Herein, an MOF-decorated PTFE membrane is engineered to extract\nosmotic energy from oily wastewaters. Copper hydroxide nanowires (CHNs)\nare intertwined with polystyrenesulfonate sodium (PSS), deposited\nonto a poly(tetrafluoroethylene) (PTFE) membrane, and thereafter used\nas metal precursors to in situ generate HKUST-1 doped with negative\ncharges. The resulting HKUST-1<sub>PSS</sub>@PTFE hybrid membrane\npossesses abundant angstrom-scale channels capable of transporting\ncations efficiently and features a hierarchically structured surface\nwith underwater superoleophobicity. The energy conversion performance\nof the HKUST-1<sub>PSS3.5</sub>@PTFE membrane can reach an output\npower density of 6.21 W m<sup>–2</sup> at a 50-fold NaCl gradient,\nwhich is superior to those of pristine PTFE membranes. Once exposed\nto oily saline wastewater, the HKUST-1<sub>PSS</sub>@PTFE membrane\ncan exhibit an excellent oil-repellent ability, thus contributing\nto sustain its osmotic energy harvesting. This work may promote the\ndevelopment of antifouling osmotic energy harvesters with a long working\nlife and pave the way to fully exploit oily wastewater effluents as\nvaluable energy sources.