Biomimetic Seawater Evaporator Based on Organic 3D Light Capture and Suspension‐Protection Mechanism for In Situ Marine Cultivation

Abstract Efficient and durable seawater evaporation technologies are vital for expanding access to freshwater and developing novel irrigation systems. Here, a photothermal material termed as Y7, characterized by its fused‐ring, small‐molecule structure, and strong electron‐withdrawing end groups, is combined with an economical wood sponge. This combination is used to create a 3D solar desalination evaporator and to design a self‐circulating evaporative irrigation system. Mirroring the 3D light‐capture porous structure and underwater suspension of diatoms, this hydrophilic evaporator demonstrates efficient light absorption in the range of 300–1100 nm and excellent resistance to salt and photobleaching. With a mass of only 3 mg/3.14 cm 2 , the Y7‐evaporator realizes a solar‐energy‐to‐vapor conversion efficiency ( η ) of 91.7% and solar water evaporation rate ( ṁ ) of 1.62 kg m −2 h −1 , marking a new record for purely organic evaporators. After the desalination process, the concentration of primary ions is reduced by five to six orders of magnitude. Based on these findings, an in situ self‐irrigation system is developed using seawater, which efficiently cultivates several plant species. The results present a novel seawater evaporation strategy rooted in enhanced photothermal effects and durability, suggesting potential applications in future self‐sustaining marine cultivation.