Bioinspired Dual-Functional Hygroscopic Composite with Leakage-Free and Self-Cooling Behaviors for Efficient Water Harvesting

Solar-driven sorption-based atmospheric water harvesting (SAWH) is a transformative solution to the water crisis. Despite the promise of hygroscopic salt-embedded composites, their practical application in SAWH is still impeded by the potential risk of leakage and released sorption heat. Here, inspired by the asymmetric architecture of plant leaves, a dual-functional composite is designed. The cost-effective and scalable nanofibers are embedded with hygroscopic salt and functionalized by polydimethylsiloxane to confer hydrophobic properties and high emissivity, ensuring the high salt content without leakage and mitigating the sorption heat by radiative cooling. The synergistic enhancements result in a water uptake of 6.12 g/g and a maximum temperature reduction of 6.2 °C. The demonstration of practical water harvesting achieves a 148% improvement in water sorption capacity and a sustained daily yield of 5.4 g/g over 3 days of continuous operation. This biomimetic design overcomes the traditional limitations of salt-based composites, offering a promising strategy for efficient water harvesting.