CaCl2 Nanocrystals decorated photothermal Fe-ferrocene MOFs hollow microspheres for atmospheric water harvesting

Harvesting water from atmosphere is emerging as a potential strategy to solve the problem of water scarcity. In this work, CaCl 2 encapsulated Fe-ferrocene MOFs hollow microspheres (CaCl 2 @Fe-Fc-HCPs) were successfully fabricated. CaCl 2 plays as water sorbent and Fe-Fc-HCPs act as photothermal components for rapidly water release. In CaCl 2 @Fe-Fc-HCPs composites, the dissolving CaCl 2 in the adsorbed water are effectively prevented, while the water adsorption capacity of the encapsulated CaCl 2 is improved. The amount of water adsorbed by CaCl 2 @Fe-Fc-HCPs (80% RH, 15 °C) is 2.685 g H2O /g CaCl2 , 2.23 times as that adsorbed by pristine CaCl 2 powder. Furthermore, the hollow structure Fe-Fc-HCPs MOFs favorable for loading CaCl 2 nanoparticles and facilitating mass transport. The adsorbed water can be easily released by a simulated solar light (one sun) due to the high efficient photothermal property of Fe-Fc-HCPs. The performance shows no degradation after 5 cycles, indicating its nice stability. This may provide a promising and cost-effective way to harvest water from air only powered by natural sunlight and offer new insights to combine photothermal MOFs with traditional adsorbents to design high-efficiency water generators.