Review on the Preparation and Performance of Polyacrylamide-Based Composite Hygroscopic Hydrogels for Atmospheric Water Harvesting

With the rapid global economic development and population growth, the shortage of freshwater resources has become increasingly severe. Particularly in arid and semi-arid regions, the scarcity of freshwater poses a serious threat to local economic development and residents' lives. Therefore, the development of efficient water collection technologies is particularly important. Atmospheric Water Harvesting (AWH) technology, as an innovative method for obtaining water resources, has received extensive attention in recent years. This technology converts water vapor from the air into liquid water, providing a new approach to solving the problem of freshwater shortage. Among various AWH technologies, adsorption-based atmospheric water harvesting stands out due to its low energy consumption and wide applicability. This technology utilizes hygroscopic materials to adsorb water vapor from the air and release it for collection using low-grade energy sources such as solar energy. Polyacrylamide-based composite hygroscopic hydrogels, as a novel type of hygroscopic material, exhibit great potential in the field of adsorption-based atmospheric water harvesting due to their excellent hygroscopic and photothermal conversion properties. This review summarizes the preparation methods, performance characteristics, and research progress of polyacrylamide-based composite hygroscopic hydrogels in atmospheric water harvesting.