Polymer microsphere-confined in-situ growth of MOF-303@poly(acrylate) composites for rapid atmospheric water harvesting under arid conditions

Harvesting water directly from the air has emerged as a promising strategy to alleviate water scarcity in arid and semi-arid regions. Among the materials explored for atmospheric water harvesting (AWH), metal–organic frameworks (MOFs) have attracted particular attention due to their exceptional ability to capture water vapor even under very low relative humidity. However, despite their impressive intrinsic adsorption performance, most MOF sorbents are used in powder form, where particle aggregation severely limits mass transfer, slows adsorption kinetics, and restricts real-world deployment.

To overcome this long-standing bottleneck, researchers have introduced a new composite design strategy that confines MOF growth within polymer microspheres. In this work, MOF-303 was grown in situ inside porous poly(acrylate) spheres, forming an organic–inorganic composite material, MOF-303@poly(acrylates), that combines high adsorption capacity with rapid water exchange.

Microscopic characterization revealed that when the MOF loading reached 87 wt%, MOF-303 crystals were uniformly distributed throughout the polymer microspheres. Importantly, the confined growth environment significantly reduced crystal size—by approximately 40% compared to conventional MOF-303 powder—while preventing particle agglomeration. Despite the reduced crystal size and composite structure, the material maintained a high-water vapor uptake of 0.348 g g^-1 at 20%RH and 298 K, comparable to that of pure MOF-303 powder with the same mass.

The most striking advantage of the composite emerged under dynamic flow conditions that more closely resemble real atmospheric operation. At a constant airflow of 50 mL min⁻¹, the composite exhibited an adsorption rate 2.74 times faster and a desorption rate twice as fast as MOF-303 powder. These accelerated kinetics enable much quicker “capture–release” cycles, a critical requirement for practical AWH devices.

Stability tests further demonstrated the robustness of the composite material. Under a high flow rate of 1780 mL min^-1—equivalent to light wind conditions (0.95 m s^-1)—the composite underwent 100 consecutive adsorption–desorption cycles without any noticeable loss in water uptake capacity. This performance highlights its strong resistance to mechanical stress and airflow-induced degradation.

By integrating MOF-303 into polymer microspheres, the study shows that it is possible to retain the excellent low-humidity adsorption capacity of MOFs while dramatically improving kinetics and durability. The authors note that this composite strategy offers a practical pathway for translating MOF-based atmospheric water harvesting from laboratory demonstrations to scalable, engineering-ready systems suitable for arid environments.

This work was supported by Joint Key Program of National Natural Science Foundation of China (U22B20147, 22575013).

DOI Link:

https://doi.org/10.26599/NR.2026.94908458

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