Biomass‐Derived Hydro‐Sponge for Ultra‐Efficient Atmospheric Water Harvesting

Abstract Sorption‐based atmospheric water harvesting (SAWH) presents a promising solution for the global freshwater shortage. However, the efficiency of current water harvesting systems is significantly limited by high energy consumption, primarily due to the inefficiency of existing sorbents and the lack of in‐depth research on material‐water interactions inside. Thus, a novel biomass‐based hydro‐sponge porous material, CPPY is prepared, by using carboxymethyl chitosan, γ‐polyglutamic acid, polyvinylpyrrolidone, and photothermal additive polypyrrole. Combined with physical and chemical foaming to create porous channels, the porosity can achieve 70%. CPPY is developed with super water storage properties up to 40 g g −1 while containing a large amount of activated water, which reduces the energy consumption for evaporation by 40% compared to pure water. The CPPY@LiCl prepared using CPPY loaded with LiCl achieved ultra‐high‐water uptake of 1.64, 2.65, and 4.21 g g −1 at 30%, 60%, and 80% RH, respectively, with fast water vapor release at a desorption temperature of 50 °C. A remarkable water yield of 6.29 L m − 2 day −1 utilizing CPPY@LiCl integrated with a batch treatment strategy under natural sunlight is achieved.