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 H2 O/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.
Keywords: abundant defects; highly efficient water harvesting; nanoscale engineering; rapid kinetics; temperature-responsive adsorption/desorption.
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