Electrically heatable carbon scaffold accommodated monolithic metal–organic frameworks for energy-efficient atmospheric water harvesting

Abstract

Atmospheric water harvesting (AWH) with metal–organic frameworks (MOFs) offers a promising solution to the freshwater scarcity in arid regions. However, given the intrinsic thermal insulating nature of MOFs, scaling-up such a concept with industrially favorable monolithic MOFs in bulky sizes remains challenging due to their insufficient water desorption efficiency with the existing heat-driven water desorption strategies. To overcome this challenge, herein, a bulky MOF monolith (CAS) is presented by embedding a carbon scaffold (CS) with 3D open porous structures into an Al-fumarate MOF monolith with abundant well-aligned microchannels. Upon electrical power applied, the embedded CS in CAS enables to deliver localized electrical heating (LEH) within the MOF matrix, leading to a rapid, uniform and sufficient heating of the entire CAS monolith. Triggered by such CS-delivered LEH, the CAS enables to exhibit a complete water desorption with fast kinetics. Using the CAS as atmospheric water adsorbent and CS-delivered LEH to drive water desorption, an AWH prototype is presented and delivers an outstanding 1.95 LH2O kgCAS−1 day−1 of practical water productivity (23 ∼ 26 °C and 28 ∼ 38 % relative humidity) while at the significantly lower energy consumption (1.57 kW·h LH2O−1) than the existing AWH devices. To the best of our knowledge, this is the first exploration in the use of CS-delivered LEH to overcome the intrinsic thermal insulting nature of bulky MOF monoliths, realize their sufficient heating and highly efficient water desorption, thereby offering a promising way to promote the real-world application of the industrially favorable MOF monoliths in the low-cost and energy efficient AWH at scales.