Zihan Li, Jinlong Wang, Lin Li, Xing Li, Yitan Li, Jiaqian Li
The integration of solar interfacial evaporation and passive fog collection constitutes an efficient hybrid paradigm for all-day continuous freshwater harvesting, but their collection efficiencies undesirably compromise each other, failing to enable synergistic reinforcement. In this study, we develop a Pistia stratiotes inspired armored Janus system consisting of a superhydrophilic carbon nanotube aerogel armored by superhydrophobic copper meshes on three surfaces for all-day continuous freshwater harvesting. This biomimetic armored Janus system enables a superior water harvesting performance, including an evaporation rate of 6.60 kg m-2 h-1 (system height 4 cm) under one-sun illumination and a fog collection rate of 5.53 g cm-2 h-1 (system height 0.5 cm) under high humidity conditions, completely surpassing previous all-weather water harvesting strategies. The substantial improvement in water harvesting efficiency intrinsically stems from the exquisite biomimetic design of the harvesting system, which effectively enhances the photothermal effect and salt resistance simultaneously. More importantly, although the two water harvesting strategies are independent in time and have different mechanisms, they synergistically enhance each other as manifested by the fact that fog droplets dissolve the salt deposition on the superhydrophilic aerogel caused by seawater evaporation, while evaporation removes the excessive accumulation of fog droplets on the superhydrophobic meshes. The designed system enables a stable continuous freshwater collection performance, approximately 33.49 L m-2 each day under natural conditions for 15 days. The bionic design of the daylong freshwater harvesting system with excellent self-cleaning function provides an effective route for realizing continuous all-day freshwater production with robust anti-salt fouling performance, and holds great application potential in practical water harvesting scenarios.