Boosting all-weather atmospheric water vapor harvesting with a solar-driven membrane system

Abstract Atmospheric water vapor harvesting (AVH) is vital to supply fresh water in arid regions. Sorbent-based harvesting stands out because it can adapt to weather conditions and utilize lowgrade energy. Current harvesting research focuses on sorbent material preparation (especially solid sorbents, such as MOFs) without integrating them into advanced water production systems. Moreover, solid sorbents show poor adaptability to changing relative humidities and temperatures in real-world applications. Here, we propose a novel AVH membrane system (AVH-MS) driven by solar energy to address these challenges. Liquid hygroscopic solutions were utilized as the working fluid in the AVH-MS to avoid the solid sorbents’ limitations. The advanced design of the AVH-MS helped boost water production and adapt to all weather conditions simultaneously. The feasibility of the system was demonstrated both theoretically and experimentally. The system could produce 6.27, 2.41, and 0.82 kg freshwater/m2/day at relative humidities of 69%, 35%, and 19% at 25 °C, respectively, using solar energy. The production improved by almost 700% compared with the reported study under the same weather condition. Our system's converted water production capacity (kg/J) is also the highest under various relative humidities compared with the reported studies.