Tilted Crack-Engineered Photothermal Membranes Achieve Attenuation-Free Solar Evaporation and Oil Recovery From Emulsions.

Abstract

While solar-driven interfacial evaporation (SDIE) presents a sustainable solution for water purification, its application to challenging oily wastewater has been severely limited by inadequate water transport, oil-fouling-induced evaporation attenuation, and the inability to efficiently recover oil. To overcome these fundamental barriers, a novel tilted photothermal membrane featuring cracked metal-phenolic networks (C-MPNs) integrated with an oil collector for simultaneous solar-driven recovery of both water and oil from emulsions is introduced. Through synergistic material and interfacial engineering, the unique C-MPNs structure enhances water evaporation by dual mechanisms: 1) modulating water-water interactions via tannic acid molecules and 2) optimizing water transport pathways via engineered cracks. This design achieves a high evaporation rate of 2.86 kg m^-2 h^-1, ranking among the top-performing photothermal membranes. Critically, the network of cracks generates abundant submicron gates that selectively intercept oil droplets. Coupled with the tilted configuration, this system actively transports intercepted oil upward for efficient capture (90.6% recovery) while concurrently mitigating membrane fouling. Remarkably, the integrated system maintains an unprecedented evaporation rate of 2.6 kg m^-2·h^-1 for soybean oil-in-water emulsions with zero attenuation over 42 h of continuous operation. Extended outdoor testing over 23 days confirms exceptional operational stability and sustained, high-efficiency dual-resource recovery.