Confined water-selective highways in a densified photothermal membrane enable ultrafast purification of complex wastewater.

Solar-driven interfacial evaporation (SDIE) is a sustainable, carbon-neutral approach for freshwater production. Nevertheless, achieving both high evaporation rates and efficient removal remains challenging, especially for wastewater enriched with concentrated ions and strongly polar volatile organic compounds (VOCs) from chemical and electronics manufacturing. Here, we report the confined water-selective highways within a densified photothermal membrane (DPM) for ultrafast purification of such complex wastewater. Through mechanical compression and the rational selection of hydrophilic polymers, DPM's interlayer nanostructures and chemical environments are engineered with molecular precision. Due to the synergistic effect of steric hindrance and chemical selectivity, this structure enables preferential water transport while effectively excluding highly concentrated ions and strongly polar VOCs. DPM exhibits a high water evaporation rate of 2.58 kg m-2 h-1 under 1 kW m-2. DPM retains stable performance for over 200 h in various near-saturated hypersaline solutions (20 wt% salinity) and enables clean water harvesting from both common (e.g., benzene, toluene, phenol) and strongly polar VOCs (e.g., ethanol, isopropanol, n-butanol) even at very high concentrations. Device integration further demonstrates its scalability for treating complex wastewater, highlighting the significance of molecularly engineered interfacial architectures for efficient SDIE under challenging conditions.