Assemblable Carbon Fiber/Metal–Organic Framework\nMonoliths for Energy-Efficient Atmospheric Water Harvesting

Abstract

Atmospheric\nwater harvesting (AWH) with metal–organic frameworks\n(MOFs) represents an attractive way to alleviate water shortage stress\nin arid regions. However, scaling up such a concept has been partially\nlimited by the insufficient development of the highly efficient heating\nand suitable processing of MOF sorbents for making them more applicable\nto AWH devices. To overcome these limitations, a commercial carbon\nfiber (CF) bundle is embedded into an Al-fumarate MOF monolith assisted\nby a cross-linked sodium alginate (SA) network, resulting in a cylindrical\nCF/Al-fumarate/SA (CAS) monolith with a coaxial structure. On applying\nelectrical power, the embedded CFs could rapidly generate enormous\nlocalized electrical heating (LEH) within a CAS matrix with exceptionally\nhigh electrothermal conversion efficiency, thereby triggering the\nadsorbed water in CASs to be highly efficiently released in an energy-efficient\nway. In particular, such CAS monoliths can be easily connected to\neach other in either series or parallel, forming versatile CAS assemblies\nwith well-controlled LEH capacity. Using a serial CAS assembly as\natmospheric water sorbents, a newly atmospheric water harvester has\nbeen further developed based on an LEH-driven water desorption method.\nThe resulting prototype enables to continuously work for 7.2 water\nharvesting cycles per day and deliver 1.7 and 1.2 L_H2O kg_Al‑Fum/SA^–1 daily water productivity\nunder controlled indoor and outdoor conditions, corresponding to 4.4\nand 6.2 kW·h L_H2O^–1 energy consumption,\nrespectively. Please note that this is the first exploration in the\nuse of flexibly assemblable MOF monoliths and the LEH-driven water\ndesorption method for water production with AWH, demonstrating a promising\nway to achieve energy-efficient, scalable, low-cost, and industrially\nfavorable AWH in arid areas.