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

Atmospheric water harvesting (AWH) has been recognized as 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-(acryloyloxyethyl) 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 h sunlight exposure. Coupled with its low cost, we believed that the DLH will be one of the promising AWH materials for practical applications.