Embedding metal foam into metal-organic framework monoliths for triggering a highly efficient release of adsorbed atmospheric water by localized eddy current heating.

Abstract

Using metal-organic frameworks (MOFs) to harvest water from the atmosphere represents an attractive way to alleviate the global water shortage stress. However, the intrinsic thermal insulating nature of MOFs makes it rather challenging to scale-up water production by utilizing industrially favorable bulky MOF monoliths due to the insufficient water desorption triggered by the existing water desorption methods. To overcome this challenge, metal foam (MF) embedded MOF monoliths (MF@MOFs) are presented. In MF@MOFs, MF not only serves as the backbone of MOF monoliths to support them with excellent mechanical robustness, but also enables the rapid generation of enormous localized eddy current heating (LECH) upon their exposure to an alternating magnetic field. Compared with the traditional heating methods, the use of LECH can effectively overcome the thermal insulating nature of MOF monoliths and realize their rapid and uniform heating, thereby triggering a complete water desorption from MF@MOFs with significantly improved desorption kinetics. The viability of the LECH-triggered water release method for practical atmospheric water harvesting is also validated through a newly designed LECH-based atmospheric water harvester. Note that this is the first exploration that uses LECH to overcome the intrinsic insulating nature of MOF monoliths.