Regulating interlayer transport in MXene-MOF hybrid membranes for oil-water separation

MXene-based membranes have attracted increasing attention for oil–water separation due to their high hydrophilicity and fast water transport through lamellar nanochannels. However, their long-term application is often hindered by interlayer restacking, instability of hydrated transport pathways, and fouling-induced blockage, especially when treating complex oil-in-water emulsions. While incorporating rigid nanomaterials has been shown to enhance MXene membrane performance, achieving stable hydrated transport pathways and long-term durability remains challenging. Herein, we report the design of hydration-stabilized MXene–MOF hybrid membranes with intercalated metal–organic frameworks in MXene interlayers, where the MOFs function as nano-spacers that maintain hydrated transport pathways and suppress structural collapse. Two metal–organic frameworks with distinct architectures, cluster-based MOF-808 and cage-based MIL-101(Cr), are incorporated into hydroxylated Ti₃C₂Tₓ MXene membranes and directly compared. The optimized MXene–MOF-808 (70:30) hybrid membrane containing 30 wt% MOF-808 exhibits ultrahigh water permeability (>12,000 L m⁻² h⁻¹) at 2 bar while maintaining oil rejection above 99.9% during repeated oil-in-water emulsion separation. Unlike the MIL-101(Cr)-based membranes, which suffer rapid flux decline, the MXene/MOF-808 hybrid membrane achieves stable performance over 25 filtration cycles and achieves nearly complete flux recovery after simple physical cleaning. The membrane further achieves up to 90% rejection of vegetable oil, and 95% rejection of crude oil emulsions, indicative of its practical durability. This study demonstrates the role of MOF topology in regulating MXene interlayer transport and the evolution of transport resistance, providing insight into the design of MXene-based hybrid membranes for oil–water separation.