Solar Steam Generation: A Recyclable and Hydrophilic Polydopamine/Polyurethane Bio-Foam

Solar-driven interfacial evaporation has emerged as a promising solution to global freshwater scarcity by harnessing renewable solar energy with minimal carbon emissions. Nevertheless, the low solar-driven water evaporation rate, salt accumulation, and the nonrecyclability of evaporators have limited the practical large-scale application of solar-driven seawater desalination. Thus, developing a highly efficient, self-cleaning, and recyclable solar-driven evaporation system is critical to addressing the global freshwater shortage. In this article, the recyclable biobased polydopamine (PDA)/polyurethane (PU) foam was synthesized with a great photothermal conversion effect and self-cleaning performance. PDA can provide superior photothermal conversion properties and hydrophilicity for pure PU foam, enabling its application in solar interface evaporation. The temperature of the PDA/PU composite foam can reach 90.0 °C under laser irradiation, and 68.7 °C under simulated sunlight at the intensity of 1 kW/m². The solar-driven water evaporation rate of the PDA/PU foam was 1.39 kg m^-2 h^-1 under simulated sunlight (1 kW/m²) and also presented excellent continuous stability in a 12 h cyclic experiment. The water evaporation rate of PDA/PU foam in natural seawater is 1.34 kg m^-2 h^-1, demonstrating stable water evaporation and a self-cleaning performance in saline water. Further, the PDA/PU foam can degrade within 72 h in the presence of enzymes illustrating its good recyclability. On the whole, the as-prepared biobased PDA/PU foam exhibits great potential in large-scale solar-driven water evaporation system contributing to its high-efficient photothermal conversion effect, good recyclability, and self-cleaning performance.