Autonomous Atmospheric Water Harvesting over a Wide Rh Range Enabled by Super Hygroscopic Composite Aerogels

Abstract Sorption‐based atmospheric water harvesting (SAWH) offers a sustainable strategy to address the global freshwater shortage. However, obtaining sorbents with excellent performance over a wide relative humidity (RH) range and devices with fully autonomous water production remains challenging. Herein, we innovatively converted magnesium chloride (MgCl 2 ) into super hygroscopic magnesium complex (MC), which can effectively solve the problems of salt deliquescence and agglomeration. The MC were then integrated with photothermal aerogels composed of sodium alginate and carbon nanotubes (SA/CNTs) to form composite aerogels, which showed high water uptake over a wide RH range, reaching 5.43 and 0.27 kg kg −1 at 95% and 20% RH, respectively. The hierarchical porous structure enables the as‐prepared SA/CNTs/MC to exhibit rapid absorption/desorption kinetics with 12 cycles per day at 70% RH, equivalent to a water yield of 10.0 L kg −1 day −1 . To further realize continuous and practical freshwater production, a fully solar‐driven autonomous atmospheric water generator (AWG) was designed and constructed with two SA/CNTs/MC‐based absorption layers, which can alternately conduct the water absorption/desorption process without any other energy consumption. Our design provides a promising approach to achieving autonomous, high‐performance, and scalable SAWH. This article is protected by copyright. All rights reserved