Engineering of Defective MOF‐801 Nanostructures within Macroporous Spheres for Highly Efficient and Stable Water Harvesting

Abstract Water harvesting using the metal‐organic framework (MOF)‐801 is restricted by limited working capacity, powder structuring, and finite stability. To overcome these issues, MOF‐801 is crystallized on the surface of macroporous poly(N‐isopropylacrylamide‐glycidyl methacrylate) spheres, called P(NIPAM‐GMA), through an in situ confined growth strategy, forming spherical MOF‐801@P(NIPAM‐GMA) composite with temperature‐responsive function. By lowering the nucleation energy barrier, the average size of the MOF‐801 crystals decreases by 20 times. Thus, abundant defects as adsorption sites for water can be installed in the crystals lattices. As a consequence, the composite provides an unprecedented high water harvesting efficiency. The composite is produced in the kilogram‐scale and can capture 1.60 kg H₂O/kg composite/day from 20% relative humidity between 25 and 85 °C. This study provides an effective methodology for improving the adsorption capacity through controlled defects formation as adsorption sites and to improve the kinetics through the design of a composite with macroporous transport channel network.