Potential Water Collection From Air by Chloride Perovskites

Abstract Directly capturing water from the air has become a compelling strategy to secure water resources. Yet, challenges persist with sorption‐based hygroscopic materials, such as inadequate water adsorption efficiency, material degradation post‐adsorption, and the need for energy input during water collection. This study introduces an alternative category of sorbent materials potentially for atmospheric water harvesting—metal chloride perovskites—that exhibit spontaneous water vapor adsorption and liquid water collection. This water uptake capability stems from the uncoordinated polar ions that form hydrogen bonds with water molecules, while the cubic lattice imparts a solid framework ensuring structural stability and inhibiting hydrolysis. The methylammonium lead chloride perovskite pellets exhibit efficient water collection performance, with a record absorption rate of 0.841 L m −2 h −1 and a total water collection of 3.675 L m −2 within a 7‐h cycle. This initiative attempts to provide a new material class candidate for the potential application of passive atmospheric water harvesting.