Divide and Conquer: A Novel Dual‐Layered Hydrogel for Atmospheric Moisture Harvesting

Atmospheric water harvesting (AWH) has been recognized a next-generation technology to alleviate water shortages in arid areas. However, the current AWH materials suffer from insufficient water adsorption capacity and high water retention, which hinder the practical application of AWH materials. In this study, we developed a novel dual-layered hydrogel (DLH) composed of a light-to-heat conversion layer (LHL) containing novel polydopamine-manganese nanoparticles (PDA-Mn NPs) and a water adsorption layer (WAL) made of [2-(acryloyloxy)ethyl]trimethylammonium chloride (AEtMA). The WAL has a strong ability to adsorb water molecules in the air and has a high water storage capacity, and the PDA-Mn NPs embedded in the LHL have excellent photothermal conversion efficiency, leading to light-induced autonomous water release. As a result, the DLH displays a high-water adsorption capacity of 7.73 g g-1 under optimal conditions and could near-quantitatively release captured water within 4 hours sunlight exposure. Coupled with its low cost, we believed that the DLH will be one of the promising AWH materials for practical applications.