In-situ HER flotation coupled superwetting membrane for high-flux and antifouling oil/water emulsion separation

Either hydrophilically modified passive antifouling membranes or photocatalysis/electrochemical oxidation-based active self-cleaning membranes eliminate contaminant in a point-to-point manner, which restricts permeation flux and oil-water separation performance. To overcome this bottleneck, in-situ hydrogen evolution reaction (HER) flotation emerges as a promising alternative that continuously refreshes the membrane surface during separation to form a robust antifouling system. Although electrocatalytic HER-based flotation technique has been widely investigated for aqueous solutions, systematic theoretical study and experimental verification on oil/water emulsion treatment remain insufficient. Based on the interfacial interactions between membrane-supported electrocatalytic active sites and oil droplets, this work proposes an integrated strategy using a cathodic membrane to realize in-situ HER and synchronous bubble flotation during oil/water emulsion separation. Specifically, a PTFE-NiCuDH electrocatalytic membrane is fabricated via dopamine-assisted electroless plating. Oil/water emulsion separation is carried out with the PTFE-NiCuDH membrane as cathode and carbon cloth as anode. The dynamically evolving membrane interface from in-situ generated hydrogen microbubbles promotes demulsification of surfactant-stabilized oil/water emulsions and drives oil droplets away from the membrane surface, while maintaining long-term stability of the membrane. Benefiting from this coupled effect, the PTFE-NiCuDH membrane exhibits outstanding separation performance: a permeation flux of 1444.1 L ·m −2 ·h −1 , separation efficiency exceeding 97%, and stable flux over 20 separation cycles even in various extreme environments. This work provides a theoretical basis and a promising strategy for constructing high-efficiency, multifunctional separation membranes to treat stable oily wastewater.