Self-assembly of MOF-801 into robust hierarchically porous monoliths for scale-up atmospheric water harvesting

MOFs are becoming one of the most promising sorbents for atmospheric water harvesting (AWH), but their powder form limits the scale-up application. Conventional shaping methods tend to deteriorate the sorption performance or weaken the mechanical strength of the sorbents. Here, monolithic MOF-801 was constructed by coupling sol–gel phase separation and acid-heat post-treatment method. The porosity can be optimized up to 59.7% by regulating the phase separation progress and gelation time, and the specific surface area and micropore volume can be optimized up to 977.8 m2 g−1 and 0.234 cm3 g−1 by the acid-heat post-treatment. The special properties ensured the monolithic MOF-801 with an excellent moisture sorption capacity of 1.2 times higher than that of the conventional MOF-801 powder in small batches and 1.4 times higher than that of the conventional compressed tablet in large batches at 30% RH. The monolithic MOF-801 had centimeter-scale morphology and good mechanical strength with compressive Young's modulus up to 61.3 MPa. This study provides a feasible strategy for achieving the monolithic shaping of MOFs for industrial-scale AWH.