Holey graphene oxide interfacial water engineering for the separations of oil-in-water emulsions

Effective removal of oily pollutants from water remains a key challenge in wastewater treatment, necessitating advanced membranes with high flux and robust fouling resistance. Interfacial water plays a central role in water treatment processes, and systematically unraveling and regulating its fundamental properties is pivotal for designing high-performance separation membranes. Two-dimensional membranes fabricated from holey graphene oxide have garnered wide attention in water treatment owing to their abundant transport channels and stable physicochemical properties. Consequently, elucidating the nature of interfacial water and the molecular- level separation kinetics is important. Herein, we utilize Raman spectroscopy and ab initio molecular dynamics to uncover, for the first time, a stable hydrogen bonding configuration at the interface of holey graphene oxide and water. This interfacial arrangement suppresses contaminant adhesion while promoting selective adsorption of oil-phase molecules, enabling efficient separation of surfactant-stabilized emulsions. The resulting twodimensional membranes achieve oil removal efficiencies exceeding 99.98 % and maintain fluxes above 375 L m- 2 h- 1 through multiple reuse cycles. These findings elucidate the critical role of interfacial water structuring in enhancing water purification performance and provide a blueprint for designing next-generation separation technologies with superior pollutant removal capabilities.