A fluorine‐free <scp>MXene</scp> ‐based hydrogel membrane for oil–water separation enabling large‐scale production

Abstract Large‐scale MXene application for oil/water separation is currently bottlenecked by toxic fluorine‐based synthesis or costly inert‐gas‐dependent etching. To overcome this, we propose a paradigm‐shifting, fluorine‐free process using a low‐temperature NaCl/KCl/CuCl 2 eutectic molten salt. This method functions without inert gas, as the molten matrix acts as an oxidation shield and reactive etchant. During etching, Cu 2+ and generated Cu are uniformly distributed in MXene sheets and Cu is converted to Cu 2+ via ammonium persulfate (APS). These Cu 2+ ions anchor hydrogel functionalization by crosslinking sodium alginate (SA) polymer chains through coordination, hydrogen, and electrostatic interactions, integrating etching and functionalization. Highlighting industrial potential, we achieved 50 g batch raw material production, corresponding to a 1.42 m 2 MXene‐based hydrogel membrane. This membrane demonstrates exceptional superhydrophilicity and antifouling performance, delivering a flux of 11,346.2 L·m −2 ·h −1 ·bar −1 and 99.5% separation efficiency. This work provides a scalable, low‐cost route for manufacturing safe, and efficient MXene‐based separation materials.